{
  "spore": "profile",
  "id": "stainless-17-7ph",
  "spore_version": "0.2",
  "family": "stainless-precipitation-hardening",
  "name": "17-7 PH stainless steel",
  "abbreviation": "17-7 PH (UNS S17700, EN 1.4568, Type 631)",
  "role": "high-strength semi-austenitic precipitation-hardening stainless steel",
  "category": "metals",
  "type": "steels-and-stainless",
  "summary": "17-7 PH is a chromium-nickel-aluminium stainless steel (16.00 to 18.00 % Cr, 6.50 to 7.75 % Ni, 0.75 to 1.50 % Al) that is formed in the soft annealed condition (Condition A) and then hardened by simple low-temperature heat treatments. The Cleveland-Cliffs 2024 datasheet gives a yield strength of 185 ksi (1276 MPa) after the TH 1050 treatment and 275 ksi (1896 MPa) after the CH 900 treatment, against 45 ksi (310 MPa) when soft. Its density is 7.81 g/cm3 in Condition A. A NASA Goddard study of 1968 tested the alloy for rocket-driven spacecraft and found that its fittings cracked under stress in nitrogen tetroxide and hydrazine propellant, and a NASA Marshall study of 1969 found stress corrosion cracking in 3.5 % salt water in nearly every heat-treated condition except CH 900.\n",
  "best_for": "Springs, Belleville washers, eyelets and flat springs that need high strength and stainless corrosion resistance, with formability in the soft state",
  "weakest_at": "Stress corrosion cracking in chloride and in nitrogen tetroxide/hydrazine propellant, in every heat-treated condition except CH 900; ductility in CH 900 (2 % elongation)",
  "identity": {
    "formula": "Fe balance, 16.00 to 18.00 Cr, 6.50 to 7.75 Ni, 0.75 to 1.50 Al, max 0.09 C, max 1.00 Mn, max 1.00 Si, max 0.040 P, max 0.030 S (wt%)",
    "designations": [
      {
        "system": "UNS",
        "code": "S17700",
        "source": "combmet-pdf",
        "where": "Header block, UNS: S17700"
      },
      {
        "system": "EN",
        "code": "1.4568",
        "source": "combmet-pdf",
        "where": "Header block, EN DIN: 1.4568"
      },
      {
        "system": "EN name",
        "code": "X7CrNiAl17-7",
        "source": "totalmateria-17-7",
        "where": "Grade name line, EN X7CrNiAl17-7 Stainless steels"
      },
      {
        "system": "JIS",
        "code": "SUS631",
        "source": "totalmateria-17-7",
        "where": "Equivalents list, JIS row"
      },
      {
        "system": "AISI",
        "code": "631",
        "note": "called Type 631 in the datasheet",
        "source": "combmet-pdf",
        "where": "Description paragraph, also Type 631"
      },
      {
        "system": "ASTM",
        "code": "A693",
        "note": "plate, sheet and strip, Grade 631",
        "source": "combmet-pdf",
        "where": "Applicable Specifications, Strip and Sheet row, ASTM A693 (Type 631)"
      },
      {
        "system": "ASTM",
        "code": "A313",
        "note": "wire and bar",
        "source": "combmet-wire",
        "where": "Applicable Specifications, Wire and Bar row"
      },
      {
        "system": "AMS",
        "code": "5528",
        "note": "sheet, strip and plate",
        "source": "combmet-pdf",
        "where": "Applicable Specifications, Strip and Sheet row"
      },
      {
        "system": "AMS",
        "code": "5529",
        "note": "cold rolled sheet and strip",
        "source": "combmet-pdf",
        "where": "Applicable Specifications, Strip and Sheet row"
      },
      {
        "system": "AMS",
        "code": "5678",
        "note": "wire",
        "source": "combmet-wire",
        "where": "Applicable Specifications, Wire and Bar row"
      },
      {
        "system": "Trade name",
        "code": "17-7 PH",
        "source": "cc-17-7",
        "where": "Document title, 17-7 PH Stainless Steel"
      }
    ],
    "source": "cc-17-7",
    "where": "Composition table (wt %), Cleveland-Cliffs 17-7 PH datasheet, 2024"
  },
  "tags": {
    "environments": [],
    "stresses": [],
    "applications": [
      "structures",
      "mechanisms",
      "propulsion-and-tanks"
    ]
  },
  "properties": [
    {
      "benchmark": "density",
      "label": "Density, Condition A (annealed)",
      "value": 7.81,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "condition": "A (annealed)",
        "temperature": "not stated in table",
        "unit_in_source": "0.282 lb/in3"
      },
      "method": "Value printed in a manufacturer datasheet (Cleveland-Cliffs, 2024)",
      "status": "ground",
      "source": "cc-17-7",
      "where": "Table 7 Physical Properties, Density row, Condition A column",
      "source_detail": {
        "title": "Cleveland-Cliffs 17-7 PH Stainless Steel product data bulletin, Tables 1, 4 and 7 and Standard Heat Treatments",
        "id": "UNS S17700, AMS 5528, AMS 5529, ASTM A 693 (Grade 631)",
        "url": "https://www.clevelandcliffs.com/_assets/_eb15314af477616a40b17eafbaeabe27/clevelandcliffs/db/1190/10504/file/CLF_ProductData_17-7-PH+Stainless+Steel_72024.pdf",
        "year": 2024,
        "kind": "datasheet",
        "license": "Manufacturer product bulletin (cited, not reproduced)"
      }
    },
    {
      "benchmark": "density",
      "label": "Density, Condition TH 1050",
      "value": 7.65,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "condition": "TH 1050",
        "temperature": "not stated in table",
        "unit_in_source": "0.276 lb/in3"
      },
      "method": "Value printed in a manufacturer datasheet (Cleveland-Cliffs, 2024)",
      "status": "ground",
      "source": "cc-17-7",
      "where": "Table 7 Physical Properties, Density row, TH 1050 column",
      "source_detail": {
        "title": "Cleveland-Cliffs 17-7 PH Stainless Steel product data bulletin, Tables 1, 4 and 7 and Standard Heat Treatments",
        "id": "UNS S17700, AMS 5528, AMS 5529, ASTM A 693 (Grade 631)",
        "url": "https://www.clevelandcliffs.com/_assets/_eb15314af477616a40b17eafbaeabe27/clevelandcliffs/db/1190/10504/file/CLF_ProductData_17-7-PH+Stainless+Steel_72024.pdf",
        "year": 2024,
        "kind": "datasheet",
        "license": "Manufacturer product bulletin (cited, not reproduced)"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting range",
      "value": 1404,
      "value_high": 1440,
      "bound": "range",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "unit_in_source": "2560 to 2625 °F",
        "basis": "melting range printed for the alloy, not a single melting point"
      },
      "method": "Range printed in a manufacturer datasheet (United Performance Metals)",
      "status": "ground",
      "source": "upmet-17-7",
      "where": "Physical Properties of 17-7 PH table, Melting Range row",
      "source_detail": {
        "title": "United Performance Metals, Alloy 17-7 PH datasheet (AMS 5528 / UNS S17700)",
        "id": "AMS 5528, UNS S17700, Grade 631, W.NR. 1.4568",
        "url": "https://www.upmet.com/sites/default/files/products/datasheet/17-7-ph-datasheet.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "Distributor datasheet, information only (cited, not reproduced)"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, Condition TH 1050 at 149 °C",
      "value": 16.9,
      "bound": "exact",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "condition": "TH 1050",
        "temperature": "149 °C (300 °F)",
        "unit_in_source": "117 BTU·in/(hr·ft²·°F)"
      },
      "method": "Value printed in a manufacturer datasheet (Cleveland-Cliffs, 2024), rounded to one decimal as printed",
      "status": "ground",
      "source": "cc-17-7",
      "where": "Table 7 Physical Properties, Thermal Conductivity row, TH 1050 column, 300 °F (149 °C)",
      "source_detail": {
        "title": "Cleveland-Cliffs 17-7 PH Stainless Steel product data bulletin, Tables 1, 4 and 7 and Standard Heat Treatments",
        "id": "UNS S17700, AMS 5528, AMS 5529, ASTM A 693 (Grade 631)",
        "url": "https://www.clevelandcliffs.com/_assets/_eb15314af477616a40b17eafbaeabe27/clevelandcliffs/db/1190/10504/file/CLF_ProductData_17-7-PH+Stainless+Steel_72024.pdf",
        "year": 2024,
        "kind": "datasheet",
        "license": "Manufacturer product bulletin (cited, not reproduced)"
      }
    },
    {
      "benchmark": "cte",
      "label": "Mean coefficient of thermal expansion, Condition A, 21 to 427 °C",
      "value": 17.3,
      "bound": "exact",
      "unit": "µm/(m·°C)",
      "scope": "material",
      "conditions": {
        "condition": "A (annealed)",
        "temperature": "21 to 427 °C (70 to 800 °F), mean",
        "unit_in_source": "9.6 x 10-6 in/in/°F"
      },
      "method": "Value printed in a manufacturer datasheet (Combined Metals, rev 2022)",
      "status": "ground",
      "note": "The Cleveland-Cliffs 2024 table prints 16.0 µm/m·K for the same Condition A row, which does not match its own 9.6 x 10-6 in/in/°F; this entry uses the Combined Metals value, which matches the inch figure.",
      "source": "combmet-pdf",
      "where": "Physical Properties table, Coefficient of Expansion row, Annealed column, 70-800 °F and 21-427 °C line",
      "source_detail": {
        "title": "Combined Metals of Chicago, 17-7PH material datasheet (REV 2022 08 05)",
        "id": "UNS S17700, EN DIN 1.4568, Type 631",
        "url": "https://www.combmet.com/wp-content/uploads/2023/02/cmc_17-7ph_data_sheet.pdf",
        "year": 2022,
        "kind": "datasheet",
        "license": "Distributor datasheet with typical values, not for design (cited, not reproduced)"
      }
    },
    {
      "benchmark": "cte",
      "label": "Mean coefficient of thermal expansion, Condition TH 1050, 21 to 427 °C",
      "value": 11.9,
      "bound": "exact",
      "unit": "µm/(m·°C)",
      "scope": "material",
      "conditions": {
        "condition": "TH 1050",
        "temperature": "21 to 427 °C (70 to 800 °F), mean",
        "unit_in_source": "6.6 µin/in-°F"
      },
      "method": "Value printed in a manufacturer datasheet (Combined Metals, rev 2022)",
      "status": "ground",
      "source": "combmet-pdf",
      "where": "Physical Properties table, Coefficient of Expansion row, TH 1050 column, 70-800 °F and 21-427 °C line",
      "source_detail": {
        "title": "Combined Metals of Chicago, 17-7PH material datasheet (REV 2022 08 05)",
        "id": "UNS S17700, EN DIN 1.4568, Type 631",
        "url": "https://www.combmet.com/wp-content/uploads/2023/02/cmc_17-7ph_data_sheet.pdf",
        "year": 2022,
        "kind": "datasheet",
        "license": "Distributor datasheet with typical values, not for design (cited, not reproduced)"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Modulus of elasticity, Condition TH 1050",
      "value": 200,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "condition": "TH 1050",
        "unit_in_source": "29.0 x 10^3 ksi"
      },
      "method": "Value printed in a manufacturer datasheet (Cleveland-Cliffs, 2024); the annealed modulus is not printed",
      "status": "ground",
      "source": "cc-17-7",
      "where": "Table 7 Physical Properties, Modulus of Elasticity row, TH 1050 column",
      "source_detail": {
        "title": "Cleveland-Cliffs 17-7 PH Stainless Steel product data bulletin, Tables 1, 4 and 7 and Standard Heat Treatments",
        "id": "UNS S17700, AMS 5528, AMS 5529, ASTM A 693 (Grade 631)",
        "url": "https://www.clevelandcliffs.com/_assets/_eb15314af477616a40b17eafbaeabe27/clevelandcliffs/db/1190/10504/file/CLF_ProductData_17-7-PH+Stainless+Steel_72024.pdf",
        "year": 2024,
        "kind": "datasheet",
        "license": "Manufacturer product bulletin (cited, not reproduced)"
      }
    },
    {
      "benchmark": "electrical_resistivity",
      "label": "Electrical resistivity, Condition A (annealed)",
      "value": 80,
      "bound": "exact",
      "unit": "µΩ·cm",
      "scope": "material",
      "conditions": {
        "condition": "A (annealed)",
        "temperature": "not stated in table"
      },
      "method": "Value printed in a manufacturer datasheet (Cleveland-Cliffs, 2024)",
      "status": "ground",
      "source": "cc-17-7",
      "where": "Table 7 Physical Properties, Electrical Resistivity row, Condition A column",
      "source_detail": {
        "title": "Cleveland-Cliffs 17-7 PH Stainless Steel product data bulletin, Tables 1, 4 and 7 and Standard Heat Treatments",
        "id": "UNS S17700, AMS 5528, AMS 5529, ASTM A 693 (Grade 631)",
        "url": "https://www.clevelandcliffs.com/_assets/_eb15314af477616a40b17eafbaeabe27/clevelandcliffs/db/1190/10504/file/CLF_ProductData_17-7-PH+Stainless+Steel_72024.pdf",
        "year": 2024,
        "kind": "datasheet",
        "license": "Manufacturer product bulletin (cited, not reproduced)"
      }
    },
    {
      "benchmark": "yield_strength",
      "label": "Yield strength 0.2 % offset, Condition A (annealed)",
      "value": 310,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "condition": "A (annealed)",
        "basis": "typical, room temperature",
        "unit_in_source": "45 ksi",
        "form": "not stated in table"
      },
      "method": "Typical value printed in a manufacturer datasheet (Cleveland-Cliffs, 2024, Table 1)",
      "status": "ground",
      "note": "Earlier sheets give other values for the same condition: AK Steel (2007) prints 40 ksi (276 MPa) and Combined Metals (2022) prints 40 ksi (276 MPa). The Cleveland-Cliffs 2024 sheet is used throughout this profile.",
      "source": "cc-17-7",
      "where": "Table 1 Typical Mechanical Properties, 0.2% YS row, Condition A column",
      "source_detail": {
        "title": "Cleveland-Cliffs 17-7 PH Stainless Steel product data bulletin, Tables 1, 4 and 7 and Standard Heat Treatments",
        "id": "UNS S17700, AMS 5528, AMS 5529, ASTM A 693 (Grade 631)",
        "url": "https://www.clevelandcliffs.com/_assets/_eb15314af477616a40b17eafbaeabe27/clevelandcliffs/db/1190/10504/file/CLF_ProductData_17-7-PH+Stainless+Steel_72024.pdf",
        "year": 2024,
        "kind": "datasheet",
        "license": "Manufacturer product bulletin (cited, not reproduced)"
      }
    },
    {
      "benchmark": "yield_strength",
      "label": "Yield strength 0.2 % offset, Condition TH 1050",
      "value": 1276,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "condition": "TH 1050",
        "basis": "typical, room temperature",
        "unit_in_source": "185 ksi",
        "form": "not stated in table"
      },
      "method": "Typical value printed in a manufacturer datasheet (Cleveland-Cliffs, 2024, Table 1)",
      "status": "ground",
      "source": "cc-17-7",
      "where": "Table 1 Typical Mechanical Properties, 0.2% YS row, TH 1050 column",
      "source_detail": {
        "title": "Cleveland-Cliffs 17-7 PH Stainless Steel product data bulletin, Tables 1, 4 and 7 and Standard Heat Treatments",
        "id": "UNS S17700, AMS 5528, AMS 5529, ASTM A 693 (Grade 631)",
        "url": "https://www.clevelandcliffs.com/_assets/_eb15314af477616a40b17eafbaeabe27/clevelandcliffs/db/1190/10504/file/CLF_ProductData_17-7-PH+Stainless+Steel_72024.pdf",
        "year": 2024,
        "kind": "datasheet",
        "license": "Manufacturer product bulletin (cited, not reproduced)"
      }
    },
    {
      "benchmark": "yield_strength",
      "label": "Yield strength 0.2 % offset, Condition RH 950",
      "value": 1448,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "condition": "RH 950",
        "basis": "typical, room temperature",
        "unit_in_source": "210 ksi",
        "form": "not stated in table"
      },
      "method": "Typical value printed in a manufacturer datasheet (Cleveland-Cliffs, 2024, Table 1)",
      "status": "ground",
      "source": "cc-17-7",
      "where": "Table 1 Typical Mechanical Properties, 0.2% YS row, RH 950 column",
      "source_detail": {
        "title": "Cleveland-Cliffs 17-7 PH Stainless Steel product data bulletin, Tables 1, 4 and 7 and Standard Heat Treatments",
        "id": "UNS S17700, AMS 5528, AMS 5529, ASTM A 693 (Grade 631)",
        "url": "https://www.clevelandcliffs.com/_assets/_eb15314af477616a40b17eafbaeabe27/clevelandcliffs/db/1190/10504/file/CLF_ProductData_17-7-PH+Stainless+Steel_72024.pdf",
        "year": 2024,
        "kind": "datasheet",
        "license": "Manufacturer product bulletin (cited, not reproduced)"
      }
    },
    {
      "benchmark": "yield_strength",
      "label": "Yield strength 0.2 % offset, Condition CH 900",
      "value": 1896,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "condition": "CH 900",
        "basis": "typical, room temperature",
        "unit_in_source": "275 ksi",
        "form": "not stated in table"
      },
      "method": "Typical value printed in a manufacturer datasheet (Cleveland-Cliffs, 2024, Table 1)",
      "status": "ground",
      "source": "cc-17-7",
      "where": "Table 1 Typical Mechanical Properties, 0.2% YS row, CH 900 column",
      "source_detail": {
        "title": "Cleveland-Cliffs 17-7 PH Stainless Steel product data bulletin, Tables 1, 4 and 7 and Standard Heat Treatments",
        "id": "UNS S17700, AMS 5528, AMS 5529, ASTM A 693 (Grade 631)",
        "url": "https://www.clevelandcliffs.com/_assets/_eb15314af477616a40b17eafbaeabe27/clevelandcliffs/db/1190/10504/file/CLF_ProductData_17-7-PH+Stainless+Steel_72024.pdf",
        "year": 2024,
        "kind": "datasheet",
        "license": "Manufacturer product bulletin (cited, not reproduced)"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Tensile strength, Condition A (annealed)",
      "value": 827,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "condition": "A (annealed)",
        "basis": "typical, room temperature",
        "unit_in_source": "120 ksi",
        "form": "not stated in table"
      },
      "method": "Typical value printed in a manufacturer datasheet (Cleveland-Cliffs, 2024, Table 1)",
      "status": "ground",
      "source": "cc-17-7",
      "where": "Table 1 Typical Mechanical Properties, UTS row, Condition A column",
      "source_detail": {
        "title": "Cleveland-Cliffs 17-7 PH Stainless Steel product data bulletin, Tables 1, 4 and 7 and Standard Heat Treatments",
        "id": "UNS S17700, AMS 5528, AMS 5529, ASTM A 693 (Grade 631)",
        "url": "https://www.clevelandcliffs.com/_assets/_eb15314af477616a40b17eafbaeabe27/clevelandcliffs/db/1190/10504/file/CLF_ProductData_17-7-PH+Stainless+Steel_72024.pdf",
        "year": 2024,
        "kind": "datasheet",
        "license": "Manufacturer product bulletin (cited, not reproduced)"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Tensile strength, Condition TH 1050",
      "value": 1379,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "condition": "TH 1050",
        "basis": "typical, room temperature",
        "unit_in_source": "200 ksi",
        "form": "not stated in table"
      },
      "method": "Typical value printed in a manufacturer datasheet (Cleveland-Cliffs, 2024, Table 1)",
      "status": "ground",
      "source": "cc-17-7",
      "where": "Table 1 Typical Mechanical Properties, UTS row, TH 1050 column",
      "source_detail": {
        "title": "Cleveland-Cliffs 17-7 PH Stainless Steel product data bulletin, Tables 1, 4 and 7 and Standard Heat Treatments",
        "id": "UNS S17700, AMS 5528, AMS 5529, ASTM A 693 (Grade 631)",
        "url": "https://www.clevelandcliffs.com/_assets/_eb15314af477616a40b17eafbaeabe27/clevelandcliffs/db/1190/10504/file/CLF_ProductData_17-7-PH+Stainless+Steel_72024.pdf",
        "year": 2024,
        "kind": "datasheet",
        "license": "Manufacturer product bulletin (cited, not reproduced)"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Tensile strength, Condition RH 950",
      "value": 1586,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "condition": "RH 950",
        "basis": "typical, room temperature",
        "unit_in_source": "230 ksi",
        "form": "not stated in table"
      },
      "method": "Typical value printed in a manufacturer datasheet (Cleveland-Cliffs, 2024, Table 1)",
      "status": "ground",
      "source": "cc-17-7",
      "where": "Table 1 Typical Mechanical Properties, UTS row, RH 950 column",
      "source_detail": {
        "title": "Cleveland-Cliffs 17-7 PH Stainless Steel product data bulletin, Tables 1, 4 and 7 and Standard Heat Treatments",
        "id": "UNS S17700, AMS 5528, AMS 5529, ASTM A 693 (Grade 631)",
        "url": "https://www.clevelandcliffs.com/_assets/_eb15314af477616a40b17eafbaeabe27/clevelandcliffs/db/1190/10504/file/CLF_ProductData_17-7-PH+Stainless+Steel_72024.pdf",
        "year": 2024,
        "kind": "datasheet",
        "license": "Manufacturer product bulletin (cited, not reproduced)"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Tensile strength, Condition CH 900",
      "value": 2034,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "condition": "CH 900",
        "basis": "typical, room temperature",
        "unit_in_source": "295 ksi",
        "form": "not stated in table"
      },
      "method": "Typical value printed in a manufacturer datasheet (Cleveland-Cliffs, 2024, Table 1)",
      "status": "ground",
      "source": "cc-17-7",
      "where": "Table 1 Typical Mechanical Properties, UTS row, CH 900 column",
      "source_detail": {
        "title": "Cleveland-Cliffs 17-7 PH Stainless Steel product data bulletin, Tables 1, 4 and 7 and Standard Heat Treatments",
        "id": "UNS S17700, AMS 5528, AMS 5529, ASTM A 693 (Grade 631)",
        "url": "https://www.clevelandcliffs.com/_assets/_eb15314af477616a40b17eafbaeabe27/clevelandcliffs/db/1190/10504/file/CLF_ProductData_17-7-PH+Stainless+Steel_72024.pdf",
        "year": 2024,
        "kind": "datasheet",
        "license": "Manufacturer product bulletin (cited, not reproduced)"
      }
    },
    {
      "benchmark": "elongation",
      "label": "Elongation in 2 in., Condition A (annealed)",
      "value": 35,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "condition": "A (annealed)",
        "gauge_length": "2 in. (50.8 mm)",
        "basis": "typical"
      },
      "method": "Typical value printed in a manufacturer datasheet (Cleveland-Cliffs, 2024, Table 1)",
      "status": "ground",
      "source": "cc-17-7",
      "where": "Table 1 Typical Mechanical Properties, Elongation row, Condition A column",
      "source_detail": {
        "title": "Cleveland-Cliffs 17-7 PH Stainless Steel product data bulletin, Tables 1, 4 and 7 and Standard Heat Treatments",
        "id": "UNS S17700, AMS 5528, AMS 5529, ASTM A 693 (Grade 631)",
        "url": "https://www.clevelandcliffs.com/_assets/_eb15314af477616a40b17eafbaeabe27/clevelandcliffs/db/1190/10504/file/CLF_ProductData_17-7-PH+Stainless+Steel_72024.pdf",
        "year": 2024,
        "kind": "datasheet",
        "license": "Manufacturer product bulletin (cited, not reproduced)"
      }
    },
    {
      "benchmark": "elongation",
      "label": "Elongation in 2 in., Condition TH 1050",
      "value": 8,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "condition": "TH 1050",
        "gauge_length": "2 in. (50.8 mm)",
        "basis": "typical"
      },
      "method": "Typical value printed in a manufacturer datasheet (Cleveland-Cliffs, 2024, Table 1)",
      "status": "ground",
      "note": "AK Steel (2007) and Combined Metals (2022) print 9 % for the same condition.",
      "source": "cc-17-7",
      "where": "Table 1 Typical Mechanical Properties, Elongation row, TH 1050 column",
      "source_detail": {
        "title": "Cleveland-Cliffs 17-7 PH Stainless Steel product data bulletin, Tables 1, 4 and 7 and Standard Heat Treatments",
        "id": "UNS S17700, AMS 5528, AMS 5529, ASTM A 693 (Grade 631)",
        "url": "https://www.clevelandcliffs.com/_assets/_eb15314af477616a40b17eafbaeabe27/clevelandcliffs/db/1190/10504/file/CLF_ProductData_17-7-PH+Stainless+Steel_72024.pdf",
        "year": 2024,
        "kind": "datasheet",
        "license": "Manufacturer product bulletin (cited, not reproduced)"
      }
    },
    {
      "benchmark": "elongation",
      "label": "Elongation in 2 in., Condition CH 900",
      "value": 2,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "condition": "CH 900",
        "gauge_length": "2 in. (50.8 mm)",
        "basis": "typical"
      },
      "method": "Typical value printed in a manufacturer datasheet (Cleveland-Cliffs, 2024, Table 1)",
      "status": "ground",
      "source": "cc-17-7",
      "where": "Table 1 Typical Mechanical Properties, Elongation row, CH 900 column",
      "source_detail": {
        "title": "Cleveland-Cliffs 17-7 PH Stainless Steel product data bulletin, Tables 1, 4 and 7 and Standard Heat Treatments",
        "id": "UNS S17700, AMS 5528, AMS 5529, ASTM A 693 (Grade 631)",
        "url": "https://www.clevelandcliffs.com/_assets/_eb15314af477616a40b17eafbaeabe27/clevelandcliffs/db/1190/10504/file/CLF_ProductData_17-7-PH+Stainless+Steel_72024.pdf",
        "year": 2024,
        "kind": "datasheet",
        "license": "Manufacturer product bulletin (cited, not reproduced)"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Tensile strength at 482 °C, Condition TH 1050",
      "value": 855,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "condition": "TH 1050",
        "temperature": "482 °C (900 °F)",
        "unit_in_source": "124 ksi",
        "basis": "typical short-time tensile test"
      },
      "method": "Typical value printed in a manufacturer datasheet (Cleveland-Cliffs, 2024, Table 4)",
      "status": "ground",
      "source": "cc-17-7",
      "where": "Table 4 Typical Elevated Temperature Short-Time Tensile Properties, UTS row, TH 1050, 900 °F (482 °C) column",
      "source_detail": {
        "title": "Cleveland-Cliffs 17-7 PH Stainless Steel product data bulletin, Tables 1, 4 and 7 and Standard Heat Treatments",
        "id": "UNS S17700, AMS 5528, AMS 5529, ASTM A 693 (Grade 631)",
        "url": "https://www.clevelandcliffs.com/_assets/_eb15314af477616a40b17eafbaeabe27/clevelandcliffs/db/1190/10504/file/CLF_ProductData_17-7-PH+Stainless+Steel_72024.pdf",
        "year": 2024,
        "kind": "datasheet",
        "license": "Manufacturer product bulletin (cited, not reproduced)"
      }
    },
    {
      "benchmark": "ultimate_tensile_strength",
      "label": "Tensile strength at 482 °C, Condition RH 950",
      "value": 917,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "condition": "RH 950",
        "temperature": "482 °C (900 °F)",
        "unit_in_source": "133 ksi",
        "basis": "typical short-time tensile test"
      },
      "method": "Typical value printed in a manufacturer datasheet (Cleveland-Cliffs, 2024, Table 4)",
      "status": "ground",
      "source": "cc-17-7",
      "where": "Table 4 Typical Elevated Temperature Short-Time Tensile Properties, UTS row, RH 950, 900 °F (482 °C) column",
      "source_detail": {
        "title": "Cleveland-Cliffs 17-7 PH Stainless Steel product data bulletin, Tables 1, 4 and 7 and Standard Heat Treatments",
        "id": "UNS S17700, AMS 5528, AMS 5529, ASTM A 693 (Grade 631)",
        "url": "https://www.clevelandcliffs.com/_assets/_eb15314af477616a40b17eafbaeabe27/clevelandcliffs/db/1190/10504/file/CLF_ProductData_17-7-PH+Stainless+Steel_72024.pdf",
        "year": 2024,
        "kind": "datasheet",
        "license": "Manufacturer product bulletin (cited, not reproduced)"
      }
    },
    {
      "benchmark": "yield_strength",
      "label": "Yield strength at 482 °C, Condition TH 1050",
      "value": 690,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "condition": "TH 1050",
        "temperature": "482 °C (900 °F)",
        "unit_in_source": "100 ksi",
        "basis": "typical 0.2 % offset"
      },
      "method": "Typical value printed in a manufacturer datasheet (Cleveland-Cliffs, 2024, Table 4)",
      "status": "ground",
      "source": "cc-17-7",
      "where": "Table 4 Typical Elevated Temperature Short-Time Tensile Properties, 0.2% YS row, TH 1050, 900 °F (482 °C) column",
      "source_detail": {
        "title": "Cleveland-Cliffs 17-7 PH Stainless Steel product data bulletin, Tables 1, 4 and 7 and Standard Heat Treatments",
        "id": "UNS S17700, AMS 5528, AMS 5529, ASTM A 693 (Grade 631)",
        "url": "https://www.clevelandcliffs.com/_assets/_eb15314af477616a40b17eafbaeabe27/clevelandcliffs/db/1190/10504/file/CLF_ProductData_17-7-PH+Stainless+Steel_72024.pdf",
        "year": 2024,
        "kind": "datasheet",
        "license": "Manufacturer product bulletin (cited, not reproduced)"
      }
    },
    {
      "benchmark": "stress_corrosion_threshold",
      "label": "Threshold stress for stress corrosion cracking in boiling magnesium chloride",
      "value": 104000,
      "bound": "exact",
      "unit": "psi",
      "scope": "material",
      "conditions": {
        "environment": "boiling 42 % MgCl2 solution at 154 °C, closed reflux",
        "specimen": "stressed as a simple beam, sheet 0.63 in thick",
        "unit_in_source": "104,000 psi",
        "note_in_source": "below this stress no stress corrosion occurred, regardless of heat treatment"
      },
      "method": "Threshold printed in a NASA technical note (1968) on the heat treatment of 17-7 PH; the name stress_corrosion_threshold is not in the canonical list",
      "status": "ground",
      "source": "ntrs-tn-d4673",
      "where": "Results section, paragraph beginning A threshold stress level (104,000 psi)",
      "source_detail": {
        "title": "NASA TN D-4673: Heat Treatment for Improved Stress-Corrosion Resistance of 17-7 PH Stainless Steel (Johnson and Grimsley, Goddard Space Flight Center, 1968)",
        "id": "NASA TN D-4673, NTRS 19680019907",
        "url": "https://ntrs.nasa.gov/api/citations/19680019907/downloads/19680019907.pdf",
        "year": 1968,
        "kind": "report",
        "license": "Public domain (NASA)"
      }
    }
  ],
  "corrosion": [
    {
      "environment": "Boiling magnesium chloride solution (42 %, 154 °C) under sustained tensile stress",
      "headline": "Stress corrosion cracking begins above a threshold of about 104,000 psi in the NASA boiling-chloride test.",
      "effect": "NASA Goddard tested 17-7 PH sheet in a boiling 42 % MgCl2 solution with the stress applied as a beam. Below 104,000 psi no cracking occurred, whichever of the three heat treatments was used. Above that, cracking occurred, and one heat treatment gave longer life than the other two.",
      "rating": "severe",
      "conditions": {
        "medium": "42 % MgCl2, boiling, 154 °C, closed reflux",
        "specimen": "beam, sheet",
        "exposure": "stress applied for the test period, duration not stated in the summary"
      },
      "source": "ntrs-tn-d4673",
      "where": "Test method and Results sections; Summary"
    },
    {
      "environment": "Alternate immersion in 3.5 % salt solution under tensile stress",
      "headline": "In 3.5 % salt water 17-7 PH cracked under stress in every heat-treated condition except CH 900.",
      "effect": "NASA Marshall tested several precipitation-hardening stainless steels by alternate immersion in 3.5 % salt solution. PH 13-8 Mo, PH 14-8 Mo, 15-5 PH, 17-4 PH, A-286, Almar 362 and Unitemp 212 were highly resistant. 17-7 PH was susceptible in nearly all heat-treated conditions, and the only exception was CH 900, which resisted cracking.",
      "rating": "severe",
      "conditions": {
        "medium": "3.5 % salt solution",
        "method": "alternate immersion, round tensile, flat tensile and C-ring specimens",
        "stress": "loads up to 100 % of yield in the work described"
      },
      "source": "ntrs-tmx53910",
      "where": "Abstract; Conclusions, item 2"
    },
    {
      "environment": "Nitrogen tetroxide with hydrazine (MMH) rocket propellant",
      "headline": "Fittings of 17-7 PH cracked under stress corrosion in nitrogen tetroxide and MMH propellant.",
      "effect": "NASA Goddard reports that 17-7 PH has several times shown a tendency to crack under stress corrosion when exposed to the nitrogen-tetroxide/hydrazine (MMH) propellant system, and Figure 1 of the report shows cracking in fittings made from the alloy. The 1968 work set out to reduce this susceptibility by changing the thermal treatment.",
      "rating": "severe",
      "conditions": {
        "medium": "nitrogen tetroxide with MMH propellant",
        "part": "reaction-motor fittings"
      },
      "source": "ntrs-tn-d4673",
      "where": "Abstract and Introduction; Figure 1 caption"
    },
    {
      "environment": "General corrosion, compared with other stainless types",
      "headline": "In TH 1050 and RH 950 general corrosion resistance is better than Types 410, 420 and 431, and in CH 900 it is close to Type 304.",
      "effect": "Cleveland-Cliffs says corrosion resistance in Conditions TH 1050 and RH 950 is superior to the hardenable chromium types, and in some environments approximates the austenitic chromium-nickel steels. In Condition CH 900 general corrosion resistance is comparable to Type 304. The sheet gives no corrosion rate.",
      "rating": "moderate",
      "conditions": {
        "basis": "comparison with other stainless grades, no test data printed"
      },
      "source": "cc-17-7",
      "where": "Product Description paragraph, page 1"
    }
  ],
  "risks": {
    "hazards": [
      {
        "text": "The Washington Alloy stainless wire and rod safety data sheet lists 17-7PH among its products. It says the welding product is not GHS classified, and that welding fumes and gases cannot be classified simply: they depend on the metal welded and the process, and may affect eyes, skin, the respiratory system, the pancreas and the liver. This describes welding fume, not the base metal in solid form.",
        "ghs": [],
        "source": "stoody-ss-sds",
        "where": "Section II, GHS Hazard Classification and Other Hazards; Section on welding fumes and gases"
      },
      {
        "text": "The same data sheet says chromium in fume may form hexavalent chromium, and that acute overexposure to welding fume can cause metal fume fever while chronic overexposure can lead to siderosis.",
        "ghs": [],
        "source": "stoody-ss-sds",
        "where": "Hazards to health paragraphs (acute and chronic symptoms) and the OSHA hexavalent chromium note"
      }
    ],
    "failure_risks": [
      {
        "mode": "Stress corrosion cracking in salt water",
        "trigger": "Tensile stress in heat-treated 17-7 PH exposed to chloride (3.5 % salt, alternate immersion), in any condition except CH 900",
        "consequence": "NASA found cracking in nearly all heat-treated conditions; CH 900 was the only condition that resisted it in that test.",
        "severity": "high",
        "source": "ntrs-tmx53910",
        "where": "Abstract; Conclusions, item 2"
      },
      {
        "mode": "Stress corrosion cracking of propulsion fittings",
        "trigger": "Stressed reaction-motor fittings in contact with nitrogen tetroxide and MMH propellant",
        "consequence": "Fittings cracked in the Goddard work, which led to a search for a better heat treatment.",
        "severity": "high",
        "source": "ntrs-tn-d4673",
        "where": "Abstract and Introduction; Figure 1 caption"
      },
      {
        "mode": "Cracking above the chloride threshold stress",
        "trigger": "Tensile stress above about 104,000 psi in boiling 42 % magnesium chloride at 154 °C",
        "consequence": "Cracking above the threshold in the test; none was seen below it, whichever heat treatment was used.",
        "severity": "moderate",
        "source": "ntrs-tn-d4673",
        "where": "Results section, threshold paragraph"
      },
      {
        "mode": "Low strength in welded joints",
        "trigger": "Welding without the full heat-treatment sequence afterwards",
        "consequence": "AK Steel says austenite conditioning and precipitation hardening must both be carried out after welding to reach high strength levels, and that the alloy has poorer weldability than 17-4 PH, mainly because of its high aluminium content.",
        "severity": "moderate",
        "source": "ak-17-7",
        "where": "Weldability section"
      }
    ],
    "side_effects": [
      {
        "text": "On heat treatment from Condition A to RH 950 or TH 1050 the alloy expands by about 0.004 in/in, which matters for the size of machined or formed parts.",
        "affects": "Dimensions of finished parts",
        "source": "cc-17-7",
        "where": "Dimensional Changes paragraph, page 4"
      }
    ],
    "handling": [
      {
        "text": "Form the part in Condition A (annealed), then heat treat it. The datasheet says the alloy works harden rapidly and may need intermediate annealing for deep drawing or intricate parts.",
        "source": "ak-17-7",
        "where": "Formability section"
      },
      {
        "text": "Heat treatments printed for the standard routes: TH 1050 at 1050 ± 10 °F (566 ± 5.5 °C) for 90 min; RH 950 at 950 ± 10 °F (510 ± 5.5 °C) for 60 min; CH 900 at 900 ± 10 °F (482 ± 5.5 °C) for 60 min, all followed by air cooling.",
        "source": "cc-17-7",
        "where": "Standard Heat Treatments, Figure 1"
      },
      {
        "text": "Mill annealing (Condition A) is at 1950 ± 25 °F (1066 ± 14 °C). For TH 1050, austenite conditioning is at 1400 ± 25 °F (760 ± 14 °C) for 90 min before cooling to form martensite.",
        "source": "cc-17-7",
        "where": "Standard Heat Treatments, Figure 1"
      },
      {
        "text": "The NASA 1969 work found CH 900 to be the only heat-treated condition that resisted stress corrosion cracking in salt water. The Cleveland-Cliffs sheet gives CH 900 an elongation of 2 %, so it has the least ductility.",
        "source": "ntrs-tmx53910",
        "where": "Conclusions, item 2; ductility from Table 1 of cc-17-7"
      }
    ],
    "mitigations": [
      {
        "text": "Use the aging condition for the environment as well as the strength: NASA reported that CH 900 was the one heat-treated condition that resisted cracking in 3.5 % salt water, and the Cleveland-Cliffs sheet gives it the lowest elongation of the aged conditions.",
        "source": "ntrs-tmx53910",
        "where": "Abstract and Conclusions"
      }
    ]
  },
  "uses": [
    {
      "application": "propulsion-and-tanks",
      "device": "Reaction-motor and support-equipment fittings for rocket-driven spacecraft",
      "example": "NASA Goddard's 1968 report says the alloy was considered for reaction-motor and support equipment in rocket-driven spacecraft, where fittings made of it were tested with nitrogen tetroxide and MMH propellant, and the report notes that fittings cracked under stress corrosion.",
      "source": "ntrs-tn-d4673",
      "where": "Abstract, Introduction, Figure 1 caption"
    },
    {
      "application": "mechanisms",
      "device": "Flat springs, Belleville (conical spring) washers and eyelets",
      "example": "Cleveland-Cliffs lists aerospace parts, Belleville washers, eyelets and flat springs among the uses of 17-7 PH, with excellent properties for these parts up to 600 °F (316 °C).",
      "source": "cc-17-7",
      "where": "Cover page application list and introduction paragraph"
    },
    {
      "application": "structures",
      "device": "Aerospace bulkheads, retaining rings and tooling",
      "example": "Smiths Metal Centres lists aerospace tooling, bulkheads, retaining rings and springs among the typical applications of 17-7 PH.",
      "source": "smith-17-7",
      "where": "Typical Applications list"
    },
    {
      "application": "mechanisms",
      "device": "Springs and washers from wire and bar",
      "example": "Elgiloy Specialty Metals lists springs, rings, washers, heat exchangers and tubing among the applications of 17-7 PH wire and bar, with spring temper strengths of 240 to 300 ksi (1655 to 2070 MPa) for diameters up to 0.100 in, with use up to 650 °F (343 °C).",
      "source": "combmet-wire",
      "where": "Description and Typical Mechanical Properties table, Spring row"
    }
  ],
  "supply": [
    {
      "subject": "Nickel (mine production, 2025 estimate), main source of the 6.50 to 7.75 % nickel in the alloy",
      "abundance": "World mine production 3,900,000 t in 2025 (estimate); world reserves more than 140,000,000 t (USGS 2026).",
      "producers": [
        {
          "country": "Indonesia",
          "share_percent": 66.7,
          "year": 2025
        },
        {
          "country": "Philippines",
          "share_percent": 6.9,
          "year": 2025
        },
        {
          "country": "Russia",
          "share_percent": 5.1,
          "year": 2025
        },
        {
          "country": "Canada",
          "share_percent": 3.6,
          "year": 2025
        },
        {
          "country": "New Caledonia",
          "share_percent": 3.6,
          "year": 2025
        }
      ],
      "critical_lists": [],
      "recycling": "USGS: nickel recovered from scrap, mainly stainless steel scrap, accounted for about 60 % of 2025 apparent consumption.",
      "substitutes": [
        "USGS: low-nickel, duplex and ultrahigh-chromium stainless steels have been substituted for austenitic grades in construction."
      ],
      "source": "usgs-ni",
      "where": "World Mine Production and Reserves table, 2025e column; Recycling; Substitutes"
    },
    {
      "subject": "Chromium (mine production, 2025 estimate), main source of the 16.00 to 18.00 % chromium in the alloy",
      "abundance": "World chromite mine production 51,000 thousand t in 2025 (estimate, gross weight); world ore reserves more than 1,200,000 thousand t, gross weight (USGS 2026).",
      "producers": [
        {
          "country": "South Africa",
          "share_percent": 45.1,
          "year": 2025
        },
        {
          "country": "Turkey",
          "share_percent": 17.6,
          "year": 2025
        },
        {
          "country": "Brazil",
          "share_percent": 3.9,
          "year": 2025
        },
        {
          "country": "Finland",
          "share_percent": 3.7,
          "year": 2025
        }
      ],
      "critical_lists": [],
      "substitutes": [],
      "source": "usgs-cr",
      "where": "World Mine Production and Reserves table, 2025e column; Events, Trends, and Issues; reserves column"
    }
  ],
  "media": [],
  "documents": [
    {
      "title": "Cleveland-Cliffs 17-7 PH Stainless Steel product data bulletin (2024)",
      "type": "datasheet",
      "url": "https://www.clevelandcliffs.com/_assets/_eb15314af477616a40b17eafbaeabe27/clevelandcliffs/db/1190/10504/file/CLF_ProductData_17-7-PH+Stainless+Steel_72024.pdf",
      "year": 2024
    },
    {
      "title": "Combined Metals material datasheet, 17-7PH stainless steel (rev 2022)",
      "type": "datasheet",
      "url": "https://www.combmet.com/wp-content/uploads/2023/02/cmc_17-7ph_data_sheet.pdf",
      "year": 2022
    },
    {
      "title": "Elgiloy Specialty Metals, 17-7 PH wire products datasheet (rev 6/17/2020)",
      "type": "datasheet",
      "url": "https://www.combmet.com/wp-content/uploads/2023/06/Wire-17-7-PH-Apr-2020-1.pdf",
      "year": 2020
    },
    {
      "title": "United Performance Metals, Alloy 17-7 PH datasheet (AMS 5528, UNS S17700)",
      "type": "datasheet",
      "url": "https://www.upmet.com/sites/default/files/products/datasheet/17-7-ph-datasheet.pdf"
    },
    {
      "title": "AK Steel 17-7 PH Stainless Steel Data Sheet, 7100-0096 7/07 (copy on AWS server)",
      "type": "datasheet",
      "url": "https://app.aws.org/mwf/attachments//82/222882/17-7_PH_Data_Sheet.pdf",
      "year": 2007
    },
    {
      "title": "Smiths Metal Centres, 17-7PH Technical Datasheet (2023)",
      "type": "datasheet",
      "url": "https://www.smithmetal.com/pdf/stainless/ph/17-7ph.pdf",
      "year": 2023
    },
    {
      "title": "Total Materia, X7CrNiAl17-7 (EN) material page, grade name and equivalents",
      "type": "database",
      "url": "https://www.totalmateria.com/en-us/material/1050855"
    },
    {
      "title": "NASA TN D-4673, Heat Treatment for Improved Stress-Corrosion Resistance of 17-7 PH Stainless Steel (Johnson and Grimsley, Goddard, 1968)",
      "type": "report",
      "url": "https://ntrs.nasa.gov/api/citations/19680019907/downloads/19680019907.pdf",
      "year": 1968
    },
    {
      "title": "NASA TM X-53910, Stress Corrosion Cracking Evaluation of Several Precipitation Hardening Stainless Steels (Humphries and Nelson, MSFC, 1969)",
      "type": "report",
      "url": "https://ntrs.nasa.gov/api/citations/19690028850/downloads/19690028850.pdf",
      "year": 1969
    },
    {
      "title": "USGS Mineral Commodity Summaries 2026: Nickel",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-nickel.pdf",
      "year": 2026
    },
    {
      "title": "USGS Mineral Commodity Summaries 2026: Chromium",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-chromium.pdf",
      "year": 2026
    },
    {
      "title": "Washington Alloy, Stainless Steel Solid Wire and Rods safety data sheet, SDS 005-SS (rev 6-2015)",
      "type": "sds",
      "url": "https://www.stoodyind.com/Safety/MSDS/Stainless.pdf",
      "year": 2015
    }
  ],
  "gaps": [
    "No fracture toughness, Charpy impact or fatigue endurance value was entered. The Cleveland-Cliffs endurance-limit table prints its cycle count in a way that is hard to read (15 x 10 with a superscript 6), so it was left out rather than guessed.",
    "No hardness value is a property entry. Rockwell values are printed in the datasheets (for example B85 soft, C43 TH 1050, C48 RH 950, C52 CH 900) and are quoted in the story text only, because the canonical list has no hardness name.",
    "No annealed (Condition A) modulus of elasticity is printed in any read source: the datasheets show a dash in that cell.",
    "No specific heat, emissivity or outgassing value was found for this alloy.",
    "No vacuum, atomic oxygen, radiation or cryogenic data was looked up for this alloy.",
    "No usable limit for hydrogen sulfide (sour service) was found. A search summary said the Upmet sheet warns of cracking in hydrogen sulfide, but that sentence is not in the Upmet datasheet text read in this run, so it is not recorded. NACE MR0175 and ISO 15156 were not opened.",
    "The threshold stress entry uses the non-canonical name stress_corrosion_threshold, because no canonical name fits a stress-corrosion threshold.",
    "The Cleveland-Cliffs 2024 sheet and the AK Steel 2007 sheet print different typical values for the same conditions (for example Condition A ultimate tensile strength 120 ksi against 130 ksi, and TH 1050 elongation 8 % against 9 %). The profile uses the 2024 sheet and records the differences in notes.",
    "The Cleveland-Cliffs metric column prints 16.0 µm/m·K for Condition A at 70 to 800 °F, which does not match its own inch figure. The profile uses the Combined Metals value 17.3 µm/m·°C for the same row, with a note.",
    "The EN 10088 part number for 1.4568 was not confirmed. Search results disagreed (EN 10088-1 against EN 10088-2 and EN 2540 for aerospace sheet and strip), and no standard page was opened.",
    "No AISI page was opened. The Type 631 number is taken from the Combined Metals datasheet, which calls the alloy also Type 631.",
    "The Wikipedia article for 17-7 PH could not be read (HTTP 404). No history of development (for example the Armco origin) was read in this run, so none is recorded.",
    "The DTIC report on precipitation-hardening stainless steels could not be read (the PDF failed to parse), so the semi-austenitic classification comes from the Cleveland-Cliffs sheet only.",
    "The aircraftmaterials.com AMS 5528 page was read, but its TH 1050 tensile range is printed in reversed order, so none of its numbers are used.",
    "No critical-mineral list entry for nickel or chromium was read in the USGS summaries that were opened, so critical_lists is empty.",
    "The hazard entries come from a welding-wire safety data sheet that lists 17-7PH among its products, not from a safety data sheet for the solid alloy. No base-metal SDS was read.",
    "The Aalco page for 1.4568 was not found in search results, so no Aalco value is used.",
    "The makeitfrom.com EN 1.4568 page returned HTTP 403 and was not read; its value ranges are not used.",
    "The Armco datasheet is held only behind an ASM Alloy Digest login, so it was not read."
  ],
  "story": {
    "why": "17-7 PH is a stainless steel that can be formed soft and then made much stronger by simple heat treatments. In Condition A it has a yield strength of 310 MPa and an elongation of 35 %; in CH 900 it reaches a yield strength of 1896 MPa, with 2 % elongation. Its chromium (16 to 18 %) gives corrosion resistance in TH 1050 and RH 950 that is better than the hardenable Types 410, 420 and 431. That combination is why it is used for springs, Belleville washers and aerospace parts. The NASA work of 1968 looked at it for rocket-driven spacecraft, where the fittings cracked in propellant, and the 1969 work found cracking in 3.5 % salt water in nearly all heat-treated conditions except CH 900.",
    "uses": [
      {
        "where": "Rocket and spacecraft propulsion",
        "line": "NASA Goddard considered 17-7 PH for reaction-motor and support equipment in rocket-driven spacecraft, and studied its stress corrosion cracking in nitrogen tetroxide and MMH propellant. The report shows cracked fittings."
      },
      {
        "where": "Springs and washers",
        "line": "Cleveland-Cliffs lists flat springs, Belleville washers and eyelets for use up to 600 °F (316 °C). Elgiloy lists spring wire at 240 to 300 ksi for diameters up to 0.100 in, with use up to 650 °F (343 °C)."
      },
      {
        "where": "Aerospace hardware",
        "line": "Smiths lists aerospace tooling, bulkheads, retaining rings and springs as typical applications."
      }
    ],
    "can_do": [
      {
        "label": "Strength",
        "line": "In TH 1050 the tensile strength is 1379 MPa (200 ksi) and the 0.2 % yield strength is 1276 MPa (185 ksi), with 8 % elongation.",
        "benchmark": "ultimate_tensile_strength",
        "scope": "material",
        "value": "1379 MPa at TH 1050"
      },
      {
        "label": "Hot strength",
        "line": "At 482 °C (900 °F) the TH 1050 tensile strength is 855 MPa (124 ksi), and RH 950 gives 917 MPa (133 ksi).",
        "benchmark": "ultimate_tensile_strength",
        "scope": "material",
        "value": "855 MPa at 482 °C"
      },
      {
        "label": "Weight",
        "line": "Density is 7.81 g/cm3 in Condition A and 7.65 g/cm3 in TH 1050 and RH 950.",
        "benchmark": "density",
        "scope": "material",
        "value": "7.81 g/cm3"
      },
      {
        "label": "Heat conduction",
        "line": "Thermal conductivity in TH 1050 is 16.9 W/(m·K) at 149 °C, as printed in the Cleveland-Cliffs table.",
        "benchmark": "thermal_conductivity",
        "scope": "material",
        "value": "16.9 W/(m·K)"
      },
      {
        "label": "Melting",
        "line": "The melting range is 1404 to 1440 °C (2560 to 2625 °F), according to United Performance Metals.",
        "benchmark": "melting_point",
        "scope": "material",
        "value": "1404 to 1440 °C"
      }
    ],
    "compare": "AK Steel calls 17-4 PH the most common alloy of this class and says 17-7 PH has poorer weldability than 17-4 PH, mainly because its high aluminium content degrades penetration and enhances weld slag in arc welding. Cleveland-Cliffs describes 17-7 PH as a semi-austenitic precipitation-hardening grade that is formed in the annealed condition. The NASA 1969 work rated 17-4 PH as highly resistant to stress corrosion cracking in 3.5 % salt water, while 17-7 PH cracked in nearly all heat-treated conditions, so chloride cracking is the main difference that work reports between the two.",
    "compare_rows": [
      {
        "label": "Yield strength",
        "benchmark": "yield_strength",
        "scope": "material"
      },
      {
        "label": "Elastic modulus",
        "benchmark": "elastic_modulus",
        "scope": "material"
      },
      {
        "label": "Thermal expansion",
        "benchmark": "cte",
        "scope": "material"
      }
    ],
    "handling": [
      "Form the part in Condition A and heat treat it afterwards. Condition C is described as extremely hard and strong, so it needs suitable fabrication techniques (AK Steel).",
      "Use the datasheet temperatures: TH 1050 at 1050 °F (566 °C) for 90 min, RH 950 at 950 °F (510 °C) for 60 min, CH 900 at 900 °F (482 °C) for 60 min.",
      "Mill annealing (Condition A) is at 1950 ± 25 °F (1066 ± 14 °C). For TH 1050, austenite conditioning is at 1400 ± 25 °F (760 ± 14 °C) for 90 min before cooling to form martensite (Cleveland-Cliffs Figure 1).",
      "Keep tensile stress low in chloride or propellant service. NASA found cracking in salt water in nearly every heat-treated condition except CH 900.",
      "After welding, repeat both the austenite conditioning and the precipitation hardening treatment."
    ],
    "good_for": [
      "Springs and washers that must stay stiff and stainless in a range up to about 600 °F (316 °C).",
      "Aerospace parts that need high strength with a formable soft state, from one heat-treatment step.",
      "Hot strength to 482 °C (900 °F) in the TH 1050 and RH 950 conditions."
    ],
    "watch_out": [
      "Chloride: NASA found cracking under stress in 3.5 % salt water in nearly all heat-treated conditions except CH 900.",
      "Propellant: fittings of 17-7 PH cracked under stress in nitrogen tetroxide and MMH in the 1968 NASA work.",
      "Ductility: CH 900 gives the highest strength (1896 MPa yield) but only 2 % elongation.",
      "Welding needs the full heat-treatment sequence afterwards to reach high strength.",
      "No fatigue, toughness or outgassing values are entered in this profile."
    ],
    "verdict": "17-7 PH is a formable, high-strength stainless steel with 1276 MPa yield in TH 1050 and 1896 MPa in CH 900. Its general corrosion resistance is better than Types 410, 420 and 431 in TH 1050 and RH 950. NASA's 1969 test found stress corrosion cracking in 3.5 % salt water in nearly every heat-treated condition except CH 900, and NASA's 1968 fittings cracked in nitrogen tetroxide and MMH, so the aging condition must be chosen for the environment as well as the load.",
    "recipe": {
      "line": "17-7 PH is an iron-based precipitation-hardening stainless steel (UNS S17700, EN 1.4568) made to the composition limits in the identity record, with iron as the balance. It is mill annealed at 1950 ± 25 °F (1066 ± 14 °C) (Condition A). For TH 1050, the austenite is conditioned at 1400 ± 25 °F (760 ± 14 °C) for 90 min, cooled to 60 ± 10 °F (16 ± 5.5 °C) to form martensite, then aged at 1050 ± 10 °F (566 ± 5.5 °C) for 90 min. CH 900 is cold rolled to Condition C at the mill and then aged at 900 °F (482 °C) for 60 min (Cleveland-Cliffs).",
      "parts": [
        {
          "name": "Iron",
          "symbol": "Fe",
          "role": "Matrix of the alloy; the austenite conditioning and cooling steps transform it to martensite before ageing.",
          "share_note": "balance"
        },
        {
          "name": "Chromium",
          "symbol": "Cr",
          "role": "Chromium content of the stainless class; the datasheet compares its corrosion resistance with Types 410, 420, 431 and 304.",
          "share_percent": 16,
          "share_high": 18
        },
        {
          "name": "Nickel",
          "symbol": "Ni",
          "role": "Alloying element in the composition table; the datasheet calls the alloy semi-austenitic.",
          "share_percent": 6.5,
          "share_high": 7.75
        },
        {
          "name": "Aluminium",
          "symbol": "Al",
          "role": "Alloying element in the composition table; AK Steel names its high aluminium content as the main weldability difference from 17-4 PH.",
          "share_percent": 0.75,
          "share_high": 1.5
        },
        {
          "name": "Carbon",
          "symbol": "C",
          "role": "Residual element limit in the composition table.",
          "share_note": "max 0.09"
        },
        {
          "name": "Manganese, silicon, phosphorus, sulphur",
          "symbol": "Mn, Si, P, S",
          "role": "Residual and deoxidation elements, limited by the specification.",
          "share_note": "max 1.00 Mn, max 1.00 Si, max 0.040 P, max 0.030 S"
        }
      ]
    },
    "risk_groups": [
      {
        "title": "For people",
        "lead": "The alloy is a solid stainless steel, and the sources read do not describe health effects of the solid metal in use. Welding is the exposure route the sources describe.",
        "points": [
          {
            "label": "Solid alloy",
            "line": "The sources do not give a hazard classification for the solid alloy. The welding wire data sheet that lists 17-7PH says the product is not GHS classified, but that welding fume may affect the eyes, skin, lungs, pancreas and liver."
          },
          {
            "label": "Welding fume",
            "line": "The same data sheet says chromium in fume may form hexavalent chromium, and that acute overexposure can cause metal fume fever while chronic overexposure can cause siderosis."
          }
        ],
        "level": 1,
        "verdict": "Welding fume is the concern"
      },
      {
        "title": "If it fails",
        "lead": "The failure routes in the sources are stress corrosion cracking. The NASA results are the strongest, because they are measured tests.",
        "points": [
          {
            "label": "Salt water",
            "line": "In NASA's 1969 test in 3.5 % salt water, 17-7 PH cracked under stress in nearly every heat-treated condition. CH 900 was the exception."
          },
          {
            "label": "Rocket propellant",
            "line": "In NASA's 1968 study, 17-7 PH fittings cracked under stress when exposed to nitrogen tetroxide and hydrazine (MMH). That result is why the heat treatment was studied."
          },
          {
            "label": "Threshold",
            "line": "In boiling 42 % magnesium chloride at 154 °C, NASA found no cracking below about 104,000 psi, whichever heat treatment was used."
          }
        ]
      },
      {
        "title": "Handling and storage",
        "points": [
          {
            "label": "Form soft, then harden",
            "line": "Form the part in Condition A, then heat treat. Heat treating changes the size by about 0.004 in/in on the Cleveland-Cliffs figures, so allow for it."
          },
          {
            "label": "Choose the condition for the job",
            "line": "TH 1050 and RH 950 give a balance of strength and corrosion resistance. CH 900 gives the highest strength and the best result in the salt test, but only 2 % elongation."
          },
          {
            "label": "Welding",
            "line": "After welding, both austenite conditioning and precipitation hardening must be repeated to get high strength (AK Steel). Filler W 17-7 PH is the one most often specified."
          }
        ]
      }
    ]
  },
  "updated": "2026-10-26",
  "review": {
    "status": "draft",
    "method": "assistant",
    "checked_values": 23,
    "unreachable": 4,
    "caveats": 6,
    "note": "Values were read by an AI assistant on 2026-10-26 from the pages and PDFs named in each entry (PDF text extracted with pdftotext). Unreachable: makeitfrom.com (HTTP 403), Wikipedia (HTTP 404), the DTIC PDF (did not parse) and the Armco datasheet (login). Caveats: the Cleveland-Cliffs 2024 and AK Steel 2007 sheets differ on some typical values; the mechanical values are typical, not minimums; the hazard entries are for welding wire; the chloride and propellant cracking entries come from 1968 and 1969 NASA tests on one or two sheet heats; the EN 10088 part number is unconfirmed."
  },
  "sources": {
    "cc-17-7": {
      "title": "Cleveland-Cliffs 17-7 PH Stainless Steel product data bulletin, Tables 1, 4 and 7 and Standard Heat Treatments",
      "id": "UNS S17700, AMS 5528, AMS 5529, ASTM A 693 (Grade 631)",
      "url": "https://www.clevelandcliffs.com/_assets/_eb15314af477616a40b17eafbaeabe27/clevelandcliffs/db/1190/10504/file/CLF_ProductData_17-7-PH+Stainless+Steel_72024.pdf",
      "year": 2024,
      "kind": "datasheet",
      "license": "Manufacturer product bulletin (cited, not reproduced)"
    },
    "combmet-pdf": {
      "title": "Combined Metals of Chicago, 17-7PH material datasheet (REV 2022 08 05)",
      "id": "UNS S17700, EN DIN 1.4568, Type 631",
      "url": "https://www.combmet.com/wp-content/uploads/2023/02/cmc_17-7ph_data_sheet.pdf",
      "year": 2022,
      "kind": "datasheet",
      "license": "Distributor datasheet with typical values, not for design (cited, not reproduced)"
    },
    "combmet-wire": {
      "title": "Elgiloy Specialty Metals (Combined Metals), 17-7 PH wire products datasheet (rev 6/17/2020)",
      "id": "UNS S17700, W. Nr 1.4568, ASTM A313, AMS 5678",
      "url": "https://www.combmet.com/wp-content/uploads/2023/06/Wire-17-7-PH-Apr-2020-1.pdf",
      "year": 2020,
      "kind": "datasheet",
      "license": "Distributor datasheet with typical values, not for design (cited, not reproduced)"
    },
    "upmet-17-7": {
      "title": "United Performance Metals, Alloy 17-7 PH datasheet (AMS 5528 / UNS S17700)",
      "id": "AMS 5528, UNS S17700, Grade 631, W.NR. 1.4568",
      "url": "https://www.upmet.com/sites/default/files/products/datasheet/17-7-ph-datasheet.pdf",
      "year": 2026,
      "kind": "datasheet",
      "license": "Distributor datasheet, information only (cited, not reproduced)"
    },
    "ak-17-7": {
      "title": "AK Steel 17-7 PH Stainless Steel Data Sheet (7100-0096 7/07)",
      "id": "UNS S17700, AK Steel PH data sheet",
      "url": "https://app.aws.org/mwf/attachments//82/222882/17-7_PH_Data_Sheet.pdf",
      "year": 2007,
      "kind": "datasheet",
      "license": "Manufacturer datasheet, 2007 (cited, not reproduced)"
    },
    "smith-17-7": {
      "title": "Smiths Metal Centres, 17-7PH technical datasheet (2023)",
      "id": "17-7PH precipitation hardening stainless steel",
      "url": "https://www.smithmetal.com/pdf/stainless/ph/17-7ph.pdf",
      "year": 2023,
      "kind": "datasheet",
      "license": "Distributor datasheet (cited, not reproduced)"
    },
    "totalmateria-17-7": {
      "title": "Total Materia, X7CrNiAl17-7 (EN) stainless steel equivalents",
      "id": "EN X7CrNiAl17-7, UNS S17700, JIS SUS631",
      "url": "https://www.totalmateria.com/en-us/material/1050855",
      "kind": "database",
      "license": "Database page (cited, not reproduced)"
    },
    "ntrs-tn-d4673": {
      "title": "NASA TN D-4673: Heat Treatment for Improved Stress-Corrosion Resistance of 17-7 PH Stainless Steel (Johnson and Grimsley, Goddard Space Flight Center, 1968)",
      "id": "NASA TN D-4673, NTRS 19680019907",
      "url": "https://ntrs.nasa.gov/api/citations/19680019907/downloads/19680019907.pdf",
      "year": 1968,
      "kind": "report",
      "license": "Public domain (NASA)"
    },
    "ntrs-tmx53910": {
      "title": "NASA TM X-53910: Stress Corrosion Cracking Evaluation of Several Precipitation Hardening Stainless Steels (Humphries and Nelson, Marshall Space Flight Center, 1969)",
      "id": "NASA TM X-53910, NTRS 19690028850",
      "url": "https://ntrs.nasa.gov/api/citations/19690028850/downloads/19690028850.pdf",
      "year": 1969,
      "kind": "report",
      "license": "Public domain (NASA)"
    },
    "usgs-ni": {
      "title": "USGS Mineral Commodity Summaries 2026: Nickel",
      "id": "USGS MCS 2026",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-nickel.pdf",
      "year": 2026,
      "kind": "report",
      "license": "Public domain (USGS)"
    },
    "usgs-cr": {
      "title": "USGS Mineral Commodity Summaries 2026: Chromium",
      "id": "USGS MCS 2026",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-chromium.pdf",
      "year": 2026,
      "kind": "report",
      "license": "Public domain (USGS)"
    },
    "stoody-ss-sds": {
      "title": "Washington Alloy stainless steel solid wire and rods, safety data sheet SDS 005-SS (rev 6-2015)",
      "id": "SDS 005-SS",
      "url": "https://www.stoodyind.com/Safety/MSDS/Stainless.pdf",
      "year": 2015,
      "kind": "datasheet",
      "license": "Manufacturer safety data sheet (cited, not reproduced)"
    }
  },
  "license": "CC-BY-4.0",
  "url": "https://spacemushroom.com/profiles/stainless-17-7ph/"
}