{ "spore": "profile", "id": "stainless-15-7ph", "spore_version": "0.2", "family": "stainless-precipitation-hardening", "name": "PH 15-7 Mo stainless steel", "abbreviation": "15-7 PH", "role": "Semi-austenitic precipitation-hardening stainless steel for high-strength springs, rings and aircraft parts", "category": "metals", "type": "steels-and-stainless", "summary": "PH 15-7 Mo (UNS S15700, AISI Type 632, AMS 5520) is a chromium-nickel-molybdenum-aluminium stainless steel that is formed in a soft austenitic condition (Condition A) and then hardened by low-temperature heat treatment. The ATI datasheet prints a density of 7.67 g/cm3 for the RH 950 and TH 1050 conditions and 7.80 g/cm3 for Condition A, and an RH 950 yield strength of 220,000 psi (1515 MPa) with an ultimate tensile strength of 245,000 psi (1690 MPa). The Ulbrich datasheet gives a Condition C minimum tensile strength of 200 ksi (1380 MPa). The 1969 NASA test in 3.5 percent salt solution found the alloy susceptible to stress corrosion cracking in every condition except CH 900.\n", "best_for": "Springs, retaining rings and seal rings that need high strength with a low-distortion hardening heat treatment (ATI and Ulbrich list these uses)", "weakest_at": "Stress corrosion cracking in salt water: the 1969 NASA test found the alloy cracked in all conditions except CH 900, and corrosion resistance is below Type 304 (ATI)", "identity": { "formula": "Fe balance; Cr 14.00-16.00, Ni 6.50-7.75, Mo 2.00-3.00, Al 0.75-1.50, C 0.09 max, Mn 1.00 max, Si 1.00 max, P 0.040 max, S 0.030 max (wt %, AMS 5520 chemistry as printed)", "designations": [ { "system": "UNS", "code": "S15700", "source": "ati-15-7", "where": "Introduction, grade line '(S15700, AISI Type 632)'" }, { "system": "AISI", "code": "632", "source": "ati-15-7", "where": "Introduction, 'AISI Type 632'" }, { "system": "AMS", "code": "5520", "note": "sheet, strip and plate", "source": "ati-15-7", "where": "Specifications and Certificates table" }, { "system": "AMS", "code": "5657", "note": "bars and forgings", "source": "ati-15-7", "where": "Specifications and Certificates table" }, { "system": "ASTM", "code": "A693", "note": "plate, sheet and strip", "source": "ulbrich-15-7mo", "where": "Header line 'AMS 5520, ASTM A693'" }, { "system": "ASTM", "code": "A 564", "note": "bars, wire and shapes", "source": "ati-15-7", "where": "Specifications and Certificates table" }, { "system": "EN", "code": "1.4532", "note": "page lists the composition band Cr 14.0-16.0 and Al 0.70-1.50; Ni and Mo limits are not printed on that page", "source": "totalmateria-1055880", "where": "Page title 'EN 1.4532 Stainless steels' and composition table" } ], "source": "ati-15-7", "where": "Chemical in Weight Percent per AMS 5520 table; the same limits are printed by Ulbrich and Aircraft Materials" }, "tags": { "environments": [], "stresses": [], "applications": [ "structures", "mechanisms" ] }, "properties": [ { "benchmark": "density", "label": "Density, Condition A", "value": 7.8, "bound": "exact", "unit": "g/cm3", "scope": "material", "conditions": { "condition": "A (annealed, mostly austenite)", "unit_in_source": "0.280 lbs/in3 in the Ulbrich datasheet; 0.282 lbs/in3 in the ATI datasheet" }, "method": "Value printed in the Ulbrich datasheet (typical values, revision 2015)", "status": "ground", "source": "ulbrich-15-7mo", "where": "Physical Properties, 'Density: (Cond. A), 0.280 lbs/in3, 7.80 g/cm3'", "source_detail": { "title": "15-7 MO Stainless Steel, UNS S15700 (Ulbrich Stainless Steels and Special Metals)", "id": "Ulbrich datasheet, revision 6.1.2015", "url": "https://www.ulbrich.com/uploads/data-sheets/15-7-MO-Stainless-Steel-Wire-UNS-S15700.pdf", "year": 2015, "kind": "datasheet", "license": "supplier document, linked not reproduced" } }, { "benchmark": "density", "label": "Density, RH 950 condition", "value": 7.67, "bound": "exact", "unit": "g/cm3", "scope": "material", "conditions": { "condition": "RH 950 (precipitation-hardened from Condition A via sub-zero conditioning)", "unit_in_source": "0.277 lbs/in3" }, "method": "Value printed in the ATI typical-values datasheet (2014)", "status": "ground", "source": "ati-15-7", "where": "Physical Properties table, Density row, RH 950 column", "source_detail": { "title": "ATI 15-7 Technical Data Sheet (Semi-Austenitic Stainless Steel, UNS S15700)", "id": "ATI 15-7 TDS, version 1 (2/14/2014)", "url": "https://www.atimaterials.com/Products/Documents/datasheets/stainless-specialty-steel/precipitationhardening/ati_15-7_tds_en_v2.pdf", "year": 2014, "kind": "datasheet", "license": "supplier document, linked not reproduced" } }, { "benchmark": "elastic_modulus", "label": "Modulus of elasticity, all conditions (ATI typical)", "value": 28, "bound": "exact", "unit": "10^6 psi", "scope": "material", "conditions": { "condition": "Conditions A, RH 950 and TH 1050 (the same value is printed for each)", "test": "tension", "unit_in_source": "28 x 10^6 psi printed; the metric value (195) is printed in parentheses without a unit label" }, "method": "Typical value printed in the ATI datasheet; the datasheet says data are typical and not for design", "status": "ground", "source": "ati-15-7", "where": "Mechanical Properties, Elastic Modulus (Typical Values) table", "source_detail": { "title": "ATI 15-7 Technical Data Sheet (Semi-Austenitic Stainless Steel, UNS S15700)", "id": "ATI 15-7 TDS, version 1 (2/14/2014)", "url": "https://www.atimaterials.com/Products/Documents/datasheets/stainless-specialty-steel/precipitationhardening/ati_15-7_tds_en_v2.pdf", "year": 2014, "kind": "datasheet", "license": "supplier document, linked not reproduced" } }, { "benchmark": "elastic_modulus", "label": "Modulus of elasticity (Ulbrich)", "value": 200, "bound": "exact", "unit": "GPa", "scope": "material", "conditions": { "test": "tension", "unit_in_source": "29.0 x 10^3 ksi (200 x 10^3 MPa)", "condition": "not stated; the page gives one value" }, "method": "Value printed in the Ulbrich datasheet; differs from the ATI value (28 x 10^6 psi) by about 2 percent", "status": "ground", "source": "ulbrich-15-7mo", "where": "Modulus of Elasticity section", "source_detail": { "title": "15-7 MO Stainless Steel, UNS S15700 (Ulbrich Stainless Steels and Special Metals)", "id": "Ulbrich datasheet, revision 6.1.2015", "url": "https://www.ulbrich.com/uploads/data-sheets/15-7-MO-Stainless-Steel-Wire-UNS-S15700.pdf", "year": 2015, "kind": "datasheet", "license": "supplier document, linked not reproduced" } }, { "benchmark": "cte", "label": "Mean coefficient of thermal expansion, Condition A, 21 to 93 C", "value": 14.4, "bound": "exact", "unit": "10^-6/C", "scope": "material", "conditions": { "condition": "A", "temperature_range": "70 to 200 F (21 to 93 C)", "unit_in_source": "8.0 x 10^-6 per degF" }, "method": "Mean coefficient printed in the ATI datasheet; Ulbrich prints the same value in its own table", "status": "ground", "source": "ati-15-7", "where": "Physical Properties, Linear Coefficient of Thermal Expansion, Condition A, 70 to 200 F row", "source_detail": { "title": "ATI 15-7 Technical Data Sheet (Semi-Austenitic Stainless Steel, UNS S15700)", "id": "ATI 15-7 TDS, version 1 (2/14/2014)", "url": "https://www.atimaterials.com/Products/Documents/datasheets/stainless-specialty-steel/precipitationhardening/ati_15-7_tds_en_v2.pdf", "year": 2014, "kind": "datasheet", "license": "supplier document, linked not reproduced" } }, { "benchmark": "cte", "label": "Mean coefficient of thermal expansion, RH 950, 21 to 316 C", "value": 10.1, "bound": "exact", "unit": "10^-6/C", "scope": "material", "conditions": { "condition": "RH 950", "temperature_range": "70 to 600 F (21 to 316 C)", "unit_in_source": "5.6 x 10^-6 per degF" }, "method": "Mean coefficient printed in the ATI datasheet", "status": "ground", "source": "ati-15-7", "where": "Physical Properties, Linear Coefficient of Thermal Expansion, RH 950, 70 to 600 F row", "source_detail": { "title": "ATI 15-7 Technical Data Sheet (Semi-Austenitic Stainless Steel, UNS S15700)", "id": "ATI 15-7 TDS, version 1 (2/14/2014)", "url": "https://www.atimaterials.com/Products/Documents/datasheets/stainless-specialty-steel/precipitationhardening/ati_15-7_tds_en_v2.pdf", "year": 2014, "kind": "datasheet", "license": "supplier document, linked not reproduced" } }, { "benchmark": "thermal_conductivity", "label": "Thermal conductivity at 93 C", "value": 16.2, "bound": "exact", "unit": "W/m-K", "scope": "material", "conditions": { "temperature": "200 F (93 C)", "condition": "not stated in the source", "unit_in_source": "112 BTU/hr/ft2/in/degF" }, "method": "Value printed in the Ulbrich datasheet alongside the BTU value", "status": "ground", "source": "ulbrich-15-7mo", "where": "Physical Properties, Thermal Conductivity, at 200 F (93 C) row", "source_detail": { "title": "15-7 MO Stainless Steel, UNS S15700 (Ulbrich Stainless Steels and Special Metals)", "id": "Ulbrich datasheet, revision 6.1.2015", "url": "https://www.ulbrich.com/uploads/data-sheets/15-7-MO-Stainless-Steel-Wire-UNS-S15700.pdf", "year": 2015, "kind": "datasheet", "license": "supplier document, linked not reproduced" } }, { "benchmark": "electrical_resistivity", "label": "Electrical resistivity, annealed or hardened", "value": 82, "bound": "exact", "unit": "microhm-cm", "scope": "material", "conditions": { "condition": "annealed or hardened (the source gives one value for both)", "qualifier": "printed as approximately" }, "method": "Value printed in the ATI datasheet", "status": "ground", "source": "ati-15-7", "where": "Physical Properties, Electrical Resistivity row", "source_detail": { "title": "ATI 15-7 Technical Data Sheet (Semi-Austenitic Stainless Steel, UNS S15700)", "id": "ATI 15-7 TDS, version 1 (2/14/2014)", "url": "https://www.atimaterials.com/Products/Documents/datasheets/stainless-specialty-steel/precipitationhardening/ati_15-7_tds_en_v2.pdf", "year": 2014, "kind": "datasheet", "license": "supplier document, linked not reproduced" } }, { "benchmark": "yield_strength", "label": "0.2 percent yield strength, Condition A", "value": 380, "bound": "exact", "unit": "MPa", "scope": "material", "conditions": { "condition": "A (annealed)", "form": "sheet and strip", "unit_in_source": "55,000 psi" }, "method": "Typical room-temperature value printed in the ATI datasheet", "status": "ground", "source": "ati-15-7", "where": "Room Temperature Properties (Typical Values), Sheet and Strip, 0.2% Yield Strength row, Condition A column", "source_detail": { "title": "ATI 15-7 Technical Data Sheet (Semi-Austenitic Stainless Steel, UNS S15700)", "id": "ATI 15-7 TDS, version 1 (2/14/2014)", "url": "https://www.atimaterials.com/Products/Documents/datasheets/stainless-specialty-steel/precipitationhardening/ati_15-7_tds_en_v2.pdf", "year": 2014, "kind": "datasheet", "license": "supplier document, linked not reproduced" } }, { "benchmark": "yield_strength", "label": "0.2 percent yield strength, RH 950", "value": 1515, "bound": "exact", "unit": "MPa", "scope": "material", "conditions": { "condition": "RH 950", "form": "sheet and strip", "heat_treatment": "solution treat 1950 F, air cool; austenite conditioning at 1750 F, hold 10 minutes, then sub-zero at -100 F for 8 hours; precipitation harden at 950 F for 90 minutes (Aircraft Materials, ATI)", "unit_in_source": "220,000 psi" }, "method": "Typical room-temperature value printed in the ATI datasheet", "status": "ground", "source": "ati-15-7", "where": "Room Temperature Properties (Typical Values), Sheet and Strip, 0.2% Yield Strength row, RH 950 column", "source_detail": { "title": "ATI 15-7 Technical Data Sheet (Semi-Austenitic Stainless Steel, UNS S15700)", "id": "ATI 15-7 TDS, version 1 (2/14/2014)", "url": "https://www.atimaterials.com/Products/Documents/datasheets/stainless-specialty-steel/precipitationhardening/ati_15-7_tds_en_v2.pdf", "year": 2014, "kind": "datasheet", "license": "supplier document, linked not reproduced" } }, { "benchmark": "yield_strength", "label": "0.2 percent yield strength, TH 1050", "value": 1380, "bound": "exact", "unit": "MPa", "scope": "material", "conditions": { "condition": "TH 1050", "form": "sheet and strip", "heat_treatment": "austenite conditioning at 1400 F for 90 minutes; precipitation harden at 1050 F for 90 minutes (ATI)", "unit_in_source": "200,000 psi" }, "method": "Typical room-temperature value printed in the ATI datasheet", "status": "ground", "source": "ati-15-7", "where": "Room Temperature Properties (Typical Values), 0.2% Yield Strength row, TH 1050 column", "source_detail": { "title": "ATI 15-7 Technical Data Sheet (Semi-Austenitic Stainless Steel, UNS S15700)", "id": "ATI 15-7 TDS, version 1 (2/14/2014)", "url": "https://www.atimaterials.com/Products/Documents/datasheets/stainless-specialty-steel/precipitationhardening/ati_15-7_tds_en_v2.pdf", "year": 2014, "kind": "datasheet", "license": "supplier document, linked not reproduced" } }, { "benchmark": "yield_strength", "label": "0.2 percent yield strength at 316 C, RH 950", "value": 1225, "bound": "exact", "unit": "MPa", "scope": "material", "conditions": { "condition": "RH 950", "temperature": "600 F (316 C)", "test": "short-time tension, S15700", "unit_in_source": "178,000 psi" }, "method": "Short-time elevated-temperature value printed in the ATI datasheet", "status": "ground", "source": "ati-15-7", "where": "Elevated Temperature Properties, 600 F row, RH 950 S15700 column", "source_detail": { "title": "ATI 15-7 Technical Data Sheet (Semi-Austenitic Stainless Steel, UNS S15700)", "id": "ATI 15-7 TDS, version 1 (2/14/2014)", "url": "https://www.atimaterials.com/Products/Documents/datasheets/stainless-specialty-steel/precipitationhardening/ati_15-7_tds_en_v2.pdf", "year": 2014, "kind": "datasheet", "license": "supplier document, linked not reproduced" } }, { "benchmark": "yield_strength", "label": "0.2 percent yield strength, Condition C minimum", "value": 1205, "bound": "lower", "unit": "MPa", "scope": "material", "conditions": { "condition": "C (cold worked, martensitic before ageing)", "unit_in_source": "175 ksi min" }, "method": "Minimum value printed in the Ulbrich datasheet", "status": "ground", "source": "ulbrich-15-7mo", "where": "Properties: Condition C, Yield Strength row", "source_detail": { "title": "15-7 MO Stainless Steel, UNS S15700 (Ulbrich Stainless Steels and Special Metals)", "id": "Ulbrich datasheet, revision 6.1.2015", "url": "https://www.ulbrich.com/uploads/data-sheets/15-7-MO-Stainless-Steel-Wire-UNS-S15700.pdf", "year": 2015, "kind": "datasheet", "license": "supplier document, linked not reproduced" } }, { "benchmark": "ultimate_tensile_strength", "label": "Ultimate tensile strength, Condition A", "value": 860, "bound": "exact", "unit": "MPa", "scope": "material", "conditions": { "condition": "A (annealed)", "form": "sheet and strip", "unit_in_source": "125,000 psi" }, "method": "Typical room-temperature value printed in the ATI datasheet", "status": "ground", "source": "ati-15-7", "where": "Room Temperature Properties (Typical Values), Ultimate Tensile Strength row, Condition A column", "source_detail": { "title": "ATI 15-7 Technical Data Sheet (Semi-Austenitic Stainless Steel, UNS S15700)", "id": "ATI 15-7 TDS, version 1 (2/14/2014)", "url": "https://www.atimaterials.com/Products/Documents/datasheets/stainless-specialty-steel/precipitationhardening/ati_15-7_tds_en_v2.pdf", "year": 2014, "kind": "datasheet", "license": "supplier document, linked not reproduced" } }, { "benchmark": "ultimate_tensile_strength", "label": "Ultimate tensile strength, RH 950", "value": 1690, "bound": "exact", "unit": "MPa", "scope": "material", "conditions": { "condition": "RH 950", "form": "sheet and strip", "unit_in_source": "245,000 psi" }, "method": "Typical room-temperature value printed in the ATI datasheet", "status": "ground", "source": "ati-15-7", "where": "Room Temperature Properties (Typical Values), Ultimate Tensile Strength row, RH 950 column", "source_detail": { "title": "ATI 15-7 Technical Data Sheet (Semi-Austenitic Stainless Steel, UNS S15700)", "id": "ATI 15-7 TDS, version 1 (2/14/2014)", "url": "https://www.atimaterials.com/Products/Documents/datasheets/stainless-specialty-steel/precipitationhardening/ati_15-7_tds_en_v2.pdf", "year": 2014, "kind": "datasheet", "license": "supplier document, linked not reproduced" } }, { "benchmark": "ultimate_tensile_strength", "label": "Ultimate tensile strength, TH 1050", "value": 1450, "bound": "exact", "unit": "MPa", "scope": "material", "conditions": { "condition": "TH 1050", "form": "sheet and strip", "unit_in_source": "210,000 psi" }, "method": "Typical room-temperature value printed in the ATI datasheet", "status": "ground", "source": "ati-15-7", "where": "Room Temperature Properties (Typical Values), Ultimate Tensile Strength row, TH 1050 column", "source_detail": { "title": "ATI 15-7 Technical Data Sheet (Semi-Austenitic Stainless Steel, UNS S15700)", "id": "ATI 15-7 TDS, version 1 (2/14/2014)", "url": "https://www.atimaterials.com/Products/Documents/datasheets/stainless-specialty-steel/precipitationhardening/ati_15-7_tds_en_v2.pdf", "year": 2014, "kind": "datasheet", "license": "supplier document, linked not reproduced" } }, { "benchmark": "ultimate_tensile_strength", "label": "Ultimate tensile strength, Condition C minimum", "value": 1380, "bound": "lower", "unit": "MPa", "scope": "material", "conditions": { "condition": "C (cold worked)", "unit_in_source": "200 KSI min" }, "method": "Minimum value printed in the Ulbrich datasheet", "status": "ground", "source": "ulbrich-15-7mo", "where": "Properties: Condition C, Ultimate Tensile Strength row", "source_detail": { "title": "15-7 MO Stainless Steel, UNS S15700 (Ulbrich Stainless Steels and Special Metals)", "id": "Ulbrich datasheet, revision 6.1.2015", "url": "https://www.ulbrich.com/uploads/data-sheets/15-7-MO-Stainless-Steel-Wire-UNS-S15700.pdf", "year": 2015, "kind": "datasheet", "license": "supplier document, linked not reproduced" } }, { "benchmark": "ultimate_tensile_strength", "label": "Ultimate tensile strength, RH 950 (Aircraft Materials, 0.020 to 0.1875 in)", "value": 225, "bound": "exact", "unit": "ksi", "scope": "material", "conditions": { "condition": "RH 950 (AMS 5520)", "thickness": "0.020 to 0.1875 in", "note": "Aircraft Materials labels this alloy 15-7 Mo; the RH 950 value is 20 ksi below the ATI typical value of 245,000 psi" }, "method": "Value printed in a typical-properties table (not a specification minimum)", "status": "ground", "source": "aircraftmaterials-15-7", "where": "Typical Mechanical Properties table, Alloy 15-7 Mo, RH950 (AMS 5520), 0.020-0.1875 row", "source_detail": { "title": "PH 15-7 Mo Stainless Steel (AMS 5520 / UNS S15700)", "id": "Aircraft Materials data page", "url": "https://mail.aircraftmaterials.com/data/alstst/15-7.html", "year": 2026, "kind": "web", "license": "supplier page, linked not reproduced" } }, { "benchmark": "elongation", "label": "Elongation, Condition A", "value": 30, "bound": "exact", "unit": "%", "scope": "material", "conditions": { "condition": "A (annealed)", "form": "sheet and strip", "gauge": "in 2 in" }, "method": "Typical value printed in the ATI datasheet", "status": "ground", "source": "ati-15-7", "where": "Room Temperature Properties (Typical Values), Elongation row, Condition A column", "source_detail": { "title": "ATI 15-7 Technical Data Sheet (Semi-Austenitic Stainless Steel, UNS S15700)", "id": "ATI 15-7 TDS, version 1 (2/14/2014)", "url": "https://www.atimaterials.com/Products/Documents/datasheets/stainless-specialty-steel/precipitationhardening/ati_15-7_tds_en_v2.pdf", "year": 2014, "kind": "datasheet", "license": "supplier document, linked not reproduced" } }, { "benchmark": "elongation", "label": "Elongation, RH 950", "value": 6, "bound": "exact", "unit": "%", "scope": "material", "conditions": { "condition": "RH 950", "form": "sheet and strip", "gauge": "in 2 in" }, "method": "Typical value printed in the ATI datasheet", "status": "ground", "source": "ati-15-7", "where": "Room Temperature Properties (Typical Values), Elongation row, RH 950 column", "source_detail": { "title": "ATI 15-7 Technical Data Sheet (Semi-Austenitic Stainless Steel, UNS S15700)", "id": "ATI 15-7 TDS, version 1 (2/14/2014)", "url": "https://www.atimaterials.com/Products/Documents/datasheets/stainless-specialty-steel/precipitationhardening/ati_15-7_tds_en_v2.pdf", "year": 2014, "kind": "datasheet", "license": "supplier document, linked not reproduced" } }, { "benchmark": "hardness", "label": "Hardness, Condition A", "value": 88, "bound": "exact", "unit": "HRB", "scope": "material", "conditions": { "condition": "A (annealed)", "form": "sheet and strip" }, "method": "Typical value printed in the ATI datasheet", "status": "ground", "source": "ati-15-7", "where": "Room Temperature Properties (Typical Values), Hardness Rockwell B row, Condition A column", "source_detail": { "title": "ATI 15-7 Technical Data Sheet (Semi-Austenitic Stainless Steel, UNS S15700)", "id": "ATI 15-7 TDS, version 1 (2/14/2014)", "url": "https://www.atimaterials.com/Products/Documents/datasheets/stainless-specialty-steel/precipitationhardening/ati_15-7_tds_en_v2.pdf", "year": 2014, "kind": "datasheet", "license": "supplier document, linked not reproduced" } }, { "benchmark": "hardness", "label": "Hardness, RH 950", "value": 48, "bound": "exact", "unit": "HRC", "scope": "material", "conditions": { "condition": "RH 950", "form": "sheet and strip" }, "method": "Typical value printed in the ATI datasheet", "status": "ground", "source": "ati-15-7", "where": "Room Temperature Properties (Typical Values), Hardness Rockwell C row, RH 950 column", "source_detail": { "title": "ATI 15-7 Technical Data Sheet (Semi-Austenitic Stainless Steel, UNS S15700)", "id": "ATI 15-7 TDS, version 1 (2/14/2014)", "url": "https://www.atimaterials.com/Products/Documents/datasheets/stainless-specialty-steel/precipitationhardening/ati_15-7_tds_en_v2.pdf", "year": 2014, "kind": "datasheet", "license": "supplier document, linked not reproduced" } }, { "benchmark": "hardness", "label": "Hardness, TH 1050", "value": 43, "bound": "exact", "unit": "HRC", "scope": "material", "conditions": { "condition": "TH 1050", "form": "sheet and strip" }, "method": "Typical value printed in the ATI datasheet", "status": "ground", "source": "ati-15-7", "where": "Room Temperature Properties (Typical Values), Hardness Rockwell C row, TH 1050 column", "source_detail": { "title": "ATI 15-7 Technical Data Sheet (Semi-Austenitic Stainless Steel, UNS S15700)", "id": "ATI 15-7 TDS, version 1 (2/14/2014)", "url": "https://www.atimaterials.com/Products/Documents/datasheets/stainless-specialty-steel/precipitationhardening/ati_15-7_tds_en_v2.pdf", "year": 2014, "kind": "datasheet", "license": "supplier document, linked not reproduced" } } ], "corrosion": [ { "environment": "3.5 percent salt solution, alternate immersion (general service of space vehicles before launch, as described by NASA)", "headline": "In the 1969 NASA test, PH 15-7 Mo cracked under stress in every condition except CH 900, which the report calls reportedly highly resistant.", "effect": "The report ranks PH 15-7 Mo and 17-7 PH as susceptible to stress corrosion cracking in all conditions except 17-7 PH CH 900. The authors add that PH 15-7 Mo is reportedly highly resistant in CH 900, and that PH 15-7 Mo is more resistant than 17-7 PH and the TH condition is more resistant than RH. Transverse grain direction was more susceptible than longitudinal, and hardening at 950 F was more susceptible than 1100 F.", "rating": "severe", "conditions": { "exposure": "alternate immersion in 3.5 percent salt solution", "stress": "loaded specimens; load levels are in the full report", "product_forms": "sheet and bar" }, "source": "nasa-tm-53910", "where": "Abstract, results paragraph; Conclusion 2; Discussion of PH 15-7 Mo and 17-7 PH" }, { "environment": "General corrosion in service (no test condition given in the source)", "headline": "Corrosion resistance is better than the 400-series hardenable stainless steels and not quite as good as Type 304.", "effect": "Ulbrich says the TH 1050 and RH 950 conditions are superior to Alloys 410, 420 and 431 and not quite as good as 304, and refers users to NACE for recommendations. ATI says the alloy approaches Type 304 in most media and is superior to the hardenable 400-series grades. Neither source prints a corrosion rate.", "rating": "moderate", "conditions": { "basis": "qualitative statements in two datasheets; no test data printed" }, "source": "ulbrich-15-7mo", "where": "Additional Properties, Corrosion Resistance" } ], "risks": { "hazards": [ { "text": "PubChem's GHS summary for nickel metal (an element, not this alloy) lists H317 (may cause an allergic skin reaction), H351 (suspected of causing cancer), H372 (causes damage to organs through prolonged or repeated exposure) and H412. No alloy-specific safety data sheet for 15-7 PH was opened in this run.", "ghs": [ "H317", "H351", "H372", "H412" ], "source": "pubchem-nickel", "where": "GHS Hazard Statements, CID 935 (Nickel)" } ], "failure_risks": [ { "mode": "Stress corrosion cracking in salt water", "trigger": "Tensile stress with exposure to 3.5 percent salt solution (alternate immersion, 1969 NASA test)", "consequence": "The 1969 test found cracking in every heat-treated condition except CH 900, so part life can be shorter than the strength suggests in a salt environment.", "severity": "high", "source": "nasa-tm-53910", "where": "Abstract; Conclusion 2" }, { "mode": "Low ductility in the cold-worked condition", "trigger": "Use in Condition C (cold worked and aged, the highest-strength condition)", "consequence": "Ulbrich prints a minimum elongation of 1 percent for Condition C, so the part has little ability to yield before fracture.", "severity": "moderate", "source": "ulbrich-15-7mo", "where": "Properties: Condition C, Elongation row" } ], "side_effects": [ { "text": "Molybdenum raises the ferrite content of the weld deposit compared with ATI 17-7 PH, according to ATI.", "affects": "Welded joints", "source": "ati-15-7", "where": "Weldability section" }, { "text": "Magnetic permeability changes with condition: weakly ferromagnetic when annealed and strongly ferromagnetic when heat treated, according to Ulbrich and ATI.", "affects": "Parts that must be non-magnetic or that sit near magnetic sensors", "source": "ati-15-7", "where": "Physical Properties, Magnetic Permeability row" } ], "handling": [ { "text": "Inert-gas welding protects the aluminium that the precipitation reaction depends on; ATI says this is why inert-gas methods are used.", "source": "ati-15-7", "where": "Weldability section" }, { "text": "Ulbrich refers welders to the SSINA publication 'Welding of Stainless Steels and Other Joining Methods' for best results.", "source": "ulbrich-15-7mo", "where": "Welding section" } ], "mitigations": [ { "text": "ATI says the alloy needs no preheat or post-weld anneal, unlike conventional hardenable stainless steels.", "source": "ati-15-7", "where": "Weldability section" } ] }, "uses": [ { "application": "mechanisms", "device": "Springs and spring-type parts", "example": "ATI says the alloy has been used in aerospace and many spring-type applications that need high strength.", "source": "ati-15-7", "where": "Introduction" }, { "application": "mechanisms", "device": "Seal rings and retaining rings", "example": "Ulbrich lists seal rings, retaining rings and springs among its applications for 15-7Mo.", "source": "ulbrich-15-7mo", "where": "Applications list" }, { "application": "structures", "device": "Aircraft components", "example": "Ulbrich lists aircraft components as an application; ATI describes the alloy as used in aerospace.", "source": "ulbrich-15-7mo", "where": "Applications list" } ], "supply": [ { "subject": "Chromium", "producers": [ { "country": "South Africa", "share_percent": 45.1, "year": 2025 }, { "country": "Turkey", "share_percent": 17.6, "year": 2025 }, { "country": "Kazakhstan", "share_percent": 13.7, "year": 2025 }, { "country": "India", "share_percent": 5.9, "year": 2025 } ], "critical_lists": [ { "list": "USGS 2025 List of Critical Minerals (listed as 'Chromium, used in stainless steel')", "listed": true }, { "list": "EU critical raw materials list (chromium not mentioned on the Commission page)", "listed": false } ], "recycling": "USGS: recycled chromium from stainless-steel scrap accounted for 21 percent of apparent consumption in 2025.", "substitutes": [ "USGS: chromium has no substitute in stainless steel, the leading end use." ], "source": "usgs-mcs2026-chromium", "where": "World Mine Production table, 2025e (world total 51,000 as printed; shares calculated by Space Mushroom); Recycling; Substitutes. Critical list: USGS 2025 List page." }, { "subject": "Nickel", "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 } ], "critical_lists": [ { "list": "USGS 2025 List of Critical Minerals (listed as 'Nickel, used to make high-strength steel, and rechargeable batteries')", "listed": true }, { "list": "EU critical raw materials list (the Commission page says nickel is included as a strategic raw material, though it does not meet the CRM thresholds)", "listed": true } ], "recycling": "USGS: nickel recovered from scrap accounted for about 60 percent of apparent consumption in 2025.", "substitutes": [ "USGS: low-nickel, duplex or ultrahigh-chromium stainless steels have been substituted for austenitic grades in construction." ], "source": "usgs-mcs2026-nickel", "where": "World Mine Production table, 2025e (world total 3,900,000 as printed; shares calculated by Space Mushroom); Recycling; Substitutes. Critical list: USGS 2025 List page and EU Commission page." }, { "subject": "Molybdenum", "producers": [ { "country": "China", "share_percent": 37.3, "year": 2025 }, { "country": "Chile", "share_percent": 16.2, "year": 2025 }, { "country": "United States", "share_percent": 15.4, "year": 2025 }, { "country": "Peru", "share_percent": 15, "year": 2025 } ], "critical_lists": [ { "list": "USGS 2025 List of Critical Minerals (molybdenum not listed)", "listed": false }, { "list": "EU critical raw materials list (molybdenum not mentioned on the Commission page)", "listed": false } ], "recycling": "USGS: molybdenum is recycled through catalysts, ferrous scrap and superalloy scrap; recycled molybdenum may be as much as 30 percent of apparent supply.", "substitutes": [ "USGS: there is little substitution for molybdenum in steels; potential substitutes include boron, chromium, niobium and vanadium." ], "source": "usgs-mcs2026-molybdenum", "where": "World Mine Production table, 2025e (world total 260,000 as printed; shares calculated by Space Mushroom); Recycling; Substitutes" } ], "media": [], "documents": [ { "title": "ATI 15-7 Technical Data Sheet (Semi-Austenitic Stainless Steel, UNS S15700), version 1", "type": "datasheet", "url": "https://www.atimaterials.com/Products/Documents/datasheets/stainless-specialty-steel/precipitationhardening/ati_15-7_tds_en_v2.pdf", "year": 2014 }, { "title": "Ulbrich 15-7 MO Stainless Steel, UNS S15700 (wire, bar and sheet datasheet)", "type": "datasheet", "url": "https://www.ulbrich.com/uploads/data-sheets/15-7-MO-Stainless-Steel-Wire-UNS-S15700.pdf", "year": 2015 }, { "title": "NASA Technical Memorandum: Stress Corrosion Cracking Evaluation of Several Precipitation Hardening Stainless Steels (Report No. 53910)", "type": "report", "url": "https://ntrs.nasa.gov/api/citations/19690028850/downloads/19690028850.pdf", "year": 1969 }, { "title": "PubChem compound record, Nickel (CID 935), GHS classification", "type": "database", "url": "https://pubchem.ncbi.nlm.nih.gov/compound/Nickel", "year": 2026 }, { "title": "USGS Mineral Commodity Summaries 2026: Chromium", "type": "report", "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-chromium.pdf", "year": 2026 }, { "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: Molybdenum", "type": "report", "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-molybdenum.pdf", "year": 2026 } ], "gaps": [ "No melting range found for 15-7 Mo in a source opened in this run (the ATI and Ulbrich datasheets do not print one).", "No alloy-specific safety data sheet for 15-7 PH was opened. The hazard entry rests on PubChem's element-level GHS summary for nickel; the chromium and welding-fume hazards for this alloy were not verified.", "The EN name (X8CrNiMoAl15-7-2) was not printed as this grade's name on the source page; only the EN 1.4532 number is listed, with the composition note.", "Modulus and RH 950 strength differ between sources (ATI 28 x 10^6 psi; Ulbrich 200 GPa; Aircraft Materials 225 ksi against ATI 245,000 psi). Each value is kept with its own source and none is chosen as the right one.", "No fatigue, fracture toughness, Charpy or long-term ageing data from a datasheet opened in this run. The 1968 NASA report that lists 15-7 Mo tables was not read.", "The Ulbrich datasheet gives no condition for its thermal conductivity value, and ATI's thermal conductivity table layout was not read clearly enough to use.", "Aluminium and iron supply shares were not gathered for this profile (USGS aluminium and iron pages were not read).", "No space, vacuum or flight result for 15-7 PH was found; the NASA sources found are a 1969 corrosion test and a 1968 propulsion study that was not opened.", "Corrosion is not quantified: the only salt-water result is the 1969 NASA qualitative test, and the NASA statement about CH 900 is internally inconsistent in the report." ], "story": { "why": "PH 15-7 Mo is a precipitation-hardening stainless steel. It is easy to form while soft, because it is mostly austenitic in Condition A (annealed). It is then hardened by a low-temperature heat treatment that turns part of the austenite into martensite and ages it. ATI notes that this route gives minimum distortion compared with quench-and-temper hardening. The result is a steel with a yield strength of 1515 MPa in RH 950, and that strength comes with a good balance of corrosion resistance for a hardenable grade.", "uses": [ { "where": "Springs and retaining rings", "line": "ATI and Ulbrich both list springs, seal rings and retaining rings as uses. ATI says the alloy has been used in aerospace and many spring-type applications that need high strength." }, { "where": "Aircraft components", "line": "Ulbrich lists aircraft components as an application. ATI describes the alloy as used in aerospace work." }, { "where": "Hot-strength applications", "line": "ATI says the alloy keeps useful strength at elevated temperature: RH 950 gives a yield strength of 1225 MPa at 316 C (600 F) in the short-time test it prints." } ], "can_do": [ { "label": "Strength", "line": "In RH 950 the ATI typical ultimate tensile strength is 1690 MPa (245,000 psi), against 860 MPa in Condition A. Ulbrich prints a Condition C minimum of 1380 MPa.", "benchmark": "ultimate_tensile_strength", "scope": "material", "value": "1690 MPa" }, { "label": "Hardness", "line": "ATI prints 48 HRC for RH 950 and 43 HRC for TH 1050, against 88 HRB in Condition A.", "benchmark": "hardness", "scope": "material", "value": "48 HRC" }, { "label": "Density", "line": "The ATI datasheet prints 7.67 g/cm3 for RH 950 and TH 1050, and 7.80 g/cm3 for Condition A.", "benchmark": "density", "scope": "material", "value": "7.67 g/cm3" }, { "label": "Stiffness", "line": "The ATI datasheet prints a modulus of 28 x 10^6 psi (195 in its metric column), and Ulbrich prints 200 GPa. The two datasheets differ by about 2 percent.", "benchmark": "elastic_modulus", "scope": "material", "value": "28 x 10^6 psi" } ], "compare": "PH 15-7 Mo is the molybdenum-bearing version of 17-7 PH, and ATI says it is somewhat stronger at room and elevated temperature than 17-7 PH. Its corrosion resistance is better than the 400-series hardenable grades, but the 1969 NASA test found it prone to stress corrosion cracking in every condition except CH 900. Its hardness and strength in RH 950 are higher than in TH 1050.", "compare_rows": [ { "label": "Ultimate tensile strength in RH 950", "benchmark": "ultimate_tensile_strength", "scope": "material" }, { "label": "Yield strength in RH 950", "benchmark": "yield_strength", "scope": "material" }, { "label": "Density", "benchmark": "density", "scope": "material" } ], "handling": [ "The composition and condition must match the purchase specification; ATI prints typical values and says they are not for design.", "Weld with inert gas to protect the aluminium, and expect a higher ferrite content in the weld than with 17-7 PH.", "Avoid salt environments under stress: the 1969 NASA test cracked the alloy in every condition except CH 900.", "Keep the sub-zero step in RH 950 and the aging temperature to the stated limits, because higher or longer ageing lowers strength." ], "good_for": [ "High strength at a low distortion heat treatment. ATI notes that low-temperature hardening keeps distortion small.", "Springs, rings and aircraft parts that need strength above that of 304 and that will not be exposed to salt water under stress." ], "watch_out": [ "Stress corrosion cracking. The 1969 NASA test found cracking in every condition except CH 900.", "Low ductility in CH 900 (1 percent minimum elongation in Ulbrich's Condition C).", "Corrosion resistance is below Type 304 in most media, according to ATI." ], "verdict": "PH 15-7 Mo gives high strength for springs and rings. Salt-water stress corrosion is the main reason to specify with care, and the strength data differ by supplier, so the mill certificate should govern.", "recipe": { "line": "PH 15-7 Mo is an iron-based alloy. Its composition in weight percent is the AMS 5520 limit set printed by ATI, Ulbrich and Aircraft Materials. It is melted and formed in the annealed Condition A, then hardened by low-temperature heat treatment; the melting route is not described in the sources opened.", "parts": [ { "name": "Iron", "symbol": "Fe", "role": "The matrix; the other elements dissolve in it." }, { "name": "Chromium", "symbol": "Cr", "role": "Gives the stainless steel its corrosion resistance. Ulbrich ranks the hardened condition above the 400-series grades but below 304." }, { "name": "Nickel", "symbol": "Ni", "role": "Keeps the alloy austenitic in Condition A so that it can be formed easily before hardening." }, { "name": "Molybdenum", "symbol": "Mo", "role": "Replaces about 2 percent of the chromium found in 17-7 PH. ATI says this gives somewhat higher room and elevated temperature strength." }, { "name": "Aluminium", "symbol": "Al", "role": "The reactive element that drives the precipitation hardening reaction. ATI says inert-gas welding is needed to keep it from being lost." }, { "name": "Carbon", "symbol": "C", "role": "Kept low; it is an impurity limit in the AMS 5520 chemistry." } ] }, "risk_groups": [ { "title": "For people", "lead": "No alloy-specific safety data sheet was opened. The only hazard source is the PubChem summary for nickel metal, which the alloy contains.", "points": [ { "label": "Nickel", "line": "PubChem's summary for nickel metal lists H317 (allergic skin reaction), H351 (suspected of causing cancer), H372 (organ damage from repeated exposure) and H412 (long-lasting harm to aquatic life)." }, { "label": "Dust and fume", "line": "Grinding and welding can make fume. The alloy-specific hazard data for this fume were not verified in this run." } ], "level": 0, "verdict": "Not classified here; nickel is the main concern" }, { "title": "Handling and storage", "points": [ { "label": "Welding", "line": "ATI says the alloy welds with inert-gas methods, protecting the aluminium, and needs no preheat or post-weld anneal." }, { "label": "Conditioning", "line": "RH 950 needs a sub-zero step at -100 F for 8 hours after the austenite conditioning, according to Aircraft Materials and ATI." } ] } ] }, "updated": "2026-10-26", "review": { "status": "draft", "method": "assistant", "checked_values": 23, "unreachable": 0, "caveats": 2, "note": "Written from pages read in this run: ATI and Ulbrich datasheets (PDF text), Aircraft Materials and Total Materia pages, the 1969 NASA memorandum (PDF text), PubChem nickel record, and USGS 2026 commodity summaries. Designations, properties and supply shares are as printed; shares are calculated from the printed world totals." }, "sources": { "ati-15-7": { "title": "ATI 15-7 Technical Data Sheet (Semi-Austenitic Stainless Steel, UNS S15700)", "id": "ATI 15-7 TDS, version 1 (2/14/2014)", "url": "https://www.atimaterials.com/Products/Documents/datasheets/stainless-specialty-steel/precipitationhardening/ati_15-7_tds_en_v2.pdf", "year": 2014, "kind": "datasheet", "license": "supplier document, linked not reproduced" }, "ulbrich-15-7mo": { "title": "15-7 MO Stainless Steel, UNS S15700 (Ulbrich Stainless Steels and Special Metals)", "id": "Ulbrich datasheet, revision 6.1.2015", "url": "https://www.ulbrich.com/uploads/data-sheets/15-7-MO-Stainless-Steel-Wire-UNS-S15700.pdf", "year": 2015, "kind": "datasheet", "license": "supplier document, linked not reproduced" }, "aircraftmaterials-15-7": { "title": "PH 15-7 Mo Stainless Steel (AMS 5520 / UNS S15700)", "id": "Aircraft Materials data page", "url": "https://mail.aircraftmaterials.com/data/alstst/15-7.html", "year": 2026, "kind": "web", "license": "supplier page, linked not reproduced" }, "nasa-tm-53910": { "title": "Stress Corrosion Cracking Evaluation of Several Precipitation Hardening Stainless Steels (NASA Technical Memorandum, Report No. 53910)", "id": "NTRS 19690028850; Humphries and Nelson, Astronautics Laboratory, 12 September 1969", "url": "https://ntrs.nasa.gov/api/citations/19690028850/downloads/19690028850.pdf", "year": 1969, "kind": "report", "license": "public domain (NASA)" }, "totalmateria-1055880": { "title": "EN 1.4532 Stainless steels (Total Materia)", "id": "EN 1.4532, EN 10088-2 (1995)", "url": "https://www.totalmateria.com/en-us/material/1055880", "year": 2026, "kind": "database", "license": "database page, linked not reproduced" }, "pubchem-nickel": { "title": "PubChem compound record, Nickel (CID 935), GHS classification", "id": "CID 935", "url": "https://pubchem.ncbi.nlm.nih.gov/compound/Nickel", "year": 2026, "kind": "database", "license": "public domain (NCBI)" }, "usgs-mcs2026-chromium": { "title": "Mineral Commodity Summaries 2026: Chromium", "id": "USGS MCS 2026, February 2026", "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-chromium.pdf", "year": 2026, "kind": "report", "license": "public domain (USGS)" }, "usgs-mcs2026-nickel": { "title": "Mineral Commodity Summaries 2026: Nickel", "id": "USGS MCS 2026, February 2026", "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-nickel.pdf", "year": 2026, "kind": "report", "license": "public domain (USGS)" }, "usgs-mcs2026-molybdenum": { "title": "Mineral Commodity Summaries 2026: Molybdenum", "id": "USGS MCS 2026, February 2026", "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-molybdenum.pdf", "year": 2026, "kind": "report", "license": "public domain (USGS)" }, "usgs-crit2025": { "title": "About the 2025 List of Critical Minerals (USGS, final list of 60 minerals)", "id": "Final 2025 List of Critical Minerals, November 2025", "url": "https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals", "year": 2025, "kind": "web", "license": "public domain (USGS)" }, "ec-crm": { "title": "Critical raw materials (European Commission)", "id": "Regulation (EU) 2024/1252 (as cited on the Commission page)", "url": "https://single-market-economy.ec.europa.eu/sectors/raw-materials/areas-specific-interest/critical-raw-materials_en", "year": 2024, "kind": "web", "license": "European Commission web page" } }, "license": "CC-BY-4.0", "url": "https://spacemushroom.com/profiles/stainless-15-7ph/" }