spore: profile
id: cronidur-30
spore_version: 0.2
family: high-nitrogen-steels
name: Cronidur 30
role: bearing steel
category: tribology
type: bearing-materials
summary: |
  Cronidur 30 is a high-nitrogen martensitic stainless steel, EN 1.4108 (X30CrMoN15-1) to SAE AMS 5898, that the producer sells for bearings, ball screws, pumps and valves. The producer gives a hardness above 58 HRC in the hardened condition, and a distributor prints Rockwell C above 60 for the AMS 5898 bar. The producer rates the steel 9 on a scale of 1 to 10 for corrosion. The one space application found in the sources read is the bearing rings of the Space Shuttle main engine turbopump, which Pratt and Whitney tested with Cronidur 30 and AISI 9310 steel.
best_for: Bearings and ball screws that need a hardness above 58 HRC together with corrosion resistance (producer datasheet)
weakest_at: Density, strength and toughness are not in the sources read here, and the tempering limit is printed as 475 °C by the producer but as 500 °C by a distributor
identity:
  formula: 'Iron-based martensitic stainless steel, wt%: C 0.25–0.35, Cr 14.0–16.0, Mo 0.85–1.10, N 0.30–0.50, Si max 1.00, Mn max 1.00, Ni max 0.5'
  source: gmh-datasheet
  where: Chemical Analysis table, row 1.4108 X30CrMoN15-1, min and max values (wt.%, decimal commas in the source)
  designations:
    - system: UNS
      code: S42027
      source: gmh-datasheet
      where: Available according to list, first page
    - system: EN
      code: '1.4108'
      source: gmh-datasheet
      where: Mat.-no. line and Chemical Analysis table
    - system: EN name
      code: X30CrMoN15-1
      source: gmh-datasheet
      where: Mat.-no. line and Chemical Analysis table
    - system: AMS
      code: '5898'
      source: righton-pdf
      where: Title and Specifications box (AMS 5898)
    - system: ASTM
      code: F899
      source: gmh-datasheet
      where: Available according to list (ASTM F 899)
    - system: Trade name
      code: Cronidur 30
      source: righton-pdf
      where: Title (Bearing Steels, AMS 5898 Cronidur 30 Bar)
tags:
  environments:
    - launch
  applications:
    - propulsion-and-tanks
    - mechanisms
properties:
  - benchmark: hardness_rockwell_c
    label: Hardness, Rockwell C, AMS 5898 bar
    value: 60
    bound: lower
    unit: HRC
    scope: material
    conditions:
      grade: AMS 5898 (Cronidur 30) bar
      heat_treatment: not stated
      unit_in_source: Rockwell C >60
    method: Value printed in a distributor datasheet
    status: ground
    source: righton-pdf
    where: Mechanical properties table, row Hardness Rockwell C
  - benchmark: hardness_rockwell_c
    label: Hardness, Rockwell C, hardened condition
    value: 58
    bound: lower
    unit: HRC
    scope: material
    conditions:
      grade: 1.4108 Cronidur 30
      heat_treatment: hardened condition, treatment steps not stated in this line
    method: Value printed in the producer datasheet
    status: ground
    source: gmh-datasheet
    where: Key Advantages, first bullet
  - benchmark: hardness_rockwell_c
    label: Hardness after 2 x 180 °C temper
    value: 58
    value_high: 60
    bound: range
    unit: HRC
    scope: material
    conditions:
      grade: 1.4108 Cronidur 30
      heat_treatment: austenitize 1030 °C, cryogenic -80 °C, temper 2 x 180 °C
    method: Range printed in the producer heat-treatment recommendations
    status: ground
    source: gmh-datasheet
    where: Heat treatment recommendations, item 1
  - benchmark: hardness_rockwell_c
    label: Hardness after 2 x 280 °C temper
    value: 52
    value_high: 57
    bound: range
    unit: HRC
    scope: material
    conditions:
      grade: 1.4108 Cronidur 30
      heat_treatment: austenitize 1030 °C, cryogenic -80 °C, temper 2 x 280 °C
    method: Range printed in the producer heat-treatment recommendations
    status: ground
    source: gmh-datasheet
    where: Heat treatment recommendations, item 2
  - benchmark: hardness_rockwell_c
    label: Hardness after 2 x 475 °C temper
    value: 58
    value_high: 60
    bound: range
    unit: HRC
    scope: material
    conditions:
      grade: 1.4108 Cronidur 30
      heat_treatment: austenitize 1030 °C, cryogenic -80 °C, temper 2 x 475 °C
    method: Range printed in the producer heat-treatment recommendations
    status: ground
    source: gmh-datasheet
    where: Heat treatment recommendations, item 3
  - benchmark: hardness_brinell
    label: Hardness after soft annealing
    value: 250
    bound: upper
    unit: HBW
    scope: material
    conditions:
      grade: 1.4108 Cronidur 30
      heat_treatment: soft annealing at 780–820 °C, holding time 8 h
      holding_time_h: 8
    method: Upper limit printed in the producer heat-treatment section
    status: ground
    source: gmh-datasheet
    where: Heat treatment, Soft annealing paragraph (<250 HBW for 8 h holding time)
  - benchmark: tempering_resistance_temperature
    label: Tempering resistance, producer statement
    value: 475
    bound: upper
    unit: °C
    scope: material
    conditions:
      grade: 1.4108 Cronidur 30
    method: Upper limit printed in the producer datasheet
    status: ground
    source: gmh-datasheet
    where: Introduction text, left column (tempering resistance up to 475 °C)
  - benchmark: tempering_resistance_temperature
    label: Tempering resistance, distributor statement
    value: 500
    bound: upper
    unit: °C
    scope: material
    conditions:
      grade: AMS 5898 Cronidur 30 bar
      unit_in_source: High temper resistance up to 500 °C
    method: Upper limit printed in a distributor datasheet
    status: ground
    note: Differs from the producer's 475 °C. Both values are recorded and the sources are not reconciled.
    source: righton-pdf
    where: Characteristics list, item High temper resistance
  - benchmark: elastic_modulus
    label: Modulus of elasticity, Cronidur 30 entry
    value: 190
    value_high: 215
    bound: range
    unit: GPa
    scope: material
    conditions:
      grade: PROPRIETARY Cronidur 30 (equivalent 1.4108)
      temperature: not stated; the page does not map the value to a temperature
    method: Range printed in a third-party materials database entry, not a producer datasheet
    status: ground
    source: totalmateria
    where: Physical and mechanical properties table, row Modulus of Elasticity
  - benchmark: thermal_conductivity
    label: Thermal conductivity, Cronidur 30 entry
    value: 13.848
    value_high: 20.873
    bound: range
    unit: W/(m·°C)
    scope: material
    conditions:
      grade: PROPRIETARY Cronidur 30 (equivalent 1.4108)
      temperature: not stated; the page does not map the value to a temperature
    method: Range printed in a third-party materials database entry, not a producer datasheet
    status: ground
    source: totalmateria
    where: Physical and mechanical properties table, row Thermal Conductivity
  - benchmark: pren
    label: Pitting resistance equivalent number, producer statement
    value: 20
    value_high: 24
    bound: range
    unit: '-'
    scope: material
    conditions:
      grade: 1.4108 Cronidur 30
      basis: approximately 20 to 24 as printed; the formula and element weights used are not stated
    method: Range printed in the producer FAQ; PREN is an index calculated from composition
    status: calculated
    source: gmh-web
    where: FAQ 3, answer for Cronidur 30
  - benchmark: austenitizing_temperature
    label: Austenitizing temperature range
    value: 990
    value_high: 1030
    bound: range
    unit: °C
    scope: material
    conditions:
      grade: 1.4108 Cronidur 30
      selection: chosen to suit product requirements, as printed
    method: Range printed in the producer hardening section
    status: ground
    source: gmh-datasheet
    where: Hardening section (990 to 1030 °C)
corrosion:
  - environment: Hardened condition after 1030 °C austenitizing, -80 °C cryogenic treatment and 2 x 180 °C tempering
    headline: The producer rates the 180 °C-tempered condition at 58 to 60 HRC with very good corrosion resistance.
    effect: The producer's heat-treatment recommendation 1 pairs 1030 °C, -80 °C and 2 x 180 °C with very good corrosion resistance at 58 to 60 HRC. Its corrosion rating for the steel is 9 on a scale of 1 to 10, a relative score and not a measured value.
    rating: low
    conditions:
      basis: producer statement; no test method or exposure medium printed
      grade: 1.4108 Cronidur 30
    source: gmh-datasheet
    where: Heat treatment recommendations, item 1; Properties box (Corrosion rating 9)
  - environment: Tempered at 2 x 280 °C instead of 2 x 180 °C
    headline: A 280 °C temper keeps very good corrosion resistance but lowers hardness to 52 to 57 HRC.
    effect: The producer states that the 1030 °C, -80 °C and 2 x 280 °C route gives very good corrosion resistance with increased ductility, at 52 to 57 HRC.
    rating: low
    conditions:
      basis: producer statement; hardness range as printed
      grade: 1.4108 Cronidur 30
    source: gmh-datasheet
    where: Heat treatment recommendations, item 2
  - environment: Comparison with other stainless grades (distributor statement)
    headline: A bar distributor states higher corrosion resistance than 1.2083, 1.4112, 1.4301 and 1.4571, and greater corrosion resistance than 440C.
    effect: Righton Blackburns states superior corrosion resistance over 1.2083, 1.4112, 1.4301 and 1.4571 and greater corrosion resistance than 440C. It also states good wear resistance, higher than 1.4034, 1.2363 and 1.4528. The sheet gives no test method, medium or numbers, so the claims are not checked here.
    rating: low
    conditions:
      basis: distributor statement; no test conditions printed
    source: righton-pdf
    where: Introductory description and Characteristics list (page 1)
risks:
  hazards:
    - text: A generic stainless steel safety data sheet (GPT Industries, revision V1.0 dated 12.15.16) states that stainless steel is an article and not hazardous in its solid form. That sheet is not specific to the 1.4108 bar, so the bar's own classification is not confirmed here.
      ghs: []
      source: gpt-stainless-sds
      where: Section 2, Classification paragraph
    - text: 'The same sheet says that cutting, milling, grinding, melting and welding could emit hazardous materials. Its GHS table lists the classes for the elements that may be emitted: carcinogenicity Category 1B, respiratory sensitizer Category 1, STOT repeated exposure Category 1, toxic to reproduction Category 1B, acute oral toxicity Category 4, skin sensitizer Category 1, STOT single exposure Category 3 and eye irritation Category 2B.'
      ghs: []
      source: gpt-stainless-sds
      where: Section 2, GHS classification table and hazard statements
    - text: The sheet says that processing byproducts may cause irritation, difficulty in breathing, coughing or wheezing, and may cause allergic skin reactions. It advises avoiding dust formation, and local exhaust ventilation during welding, brazing, grinding and machining.
      ghs: []
      source: gpt-stainless-sds
      where: Sections 4, 6 and 8
  failure_risks:
    - mode: Retained austenite after hardening above 1000 °C
      trigger: Hardening above 1000 °C without an immediate cryogenic step
      consequence: The producer says the nitrogen content strongly stabilizes retained austenite, so the steel must reach at least -80 °C and be held at least 60 minutes before tempering. The sources give no hardness figure for an untreated part.
      severity: moderate
      source: gmh-datasheet
      where: Tempering section
    - mode: Nitrogen depletion or enrichment at the surface
      trigger: Vacuum hardening without a nitrogen partial pressure of 100 to 200 mbar
      consequence: The producer warns of nitrogen depletion or nitrogen enrichment in the surface layer and advises an all-round grinding allowance of about 0.2 mm when the furnace cannot hold the pressure.
      severity: moderate
      source: gmh-datasheet
      where: Hardening section
  side_effects:
    - text: Tempering at 2 x 280 °C gives increased ductility and very good corrosion resistance at 52 to 57 HRC, against 58 to 60 HRC after 2 x 180 °C.
      affects: Hardness of the finished part
      source: gmh-datasheet
      where: Heat treatment recommendations, items 1 and 2
  handling:
    - text: Soft anneal at 780–820 °C for 4 to 8 hours before machining. Hardness is below 300 HBW after 4 hours and below 250 HBW after 8 hours.
      source: gmh-datasheet
      where: Heat treatment, Soft annealing paragraph
    - text: Stress relieve at 600–650 °C after rough machining. Hold for about 2 hours, cool in the furnace to about 350 °C, then cool in still air.
      source: gmh-datasheet
      where: Heat treatment, Stress relief annealing paragraph
    - text: For vacuum hardening, keep a nitrogen partial pressure of 100 to 200 mbar. If the furnace cannot hold it, allow an all-round grinding allowance of about 0.2 mm.
      source: gmh-datasheet
      where: Hardening section
  mitigations:
    - text: Cool to at least -80 °C after hardening and hold for at least 60 minutes after complete cooling, then temper for 2 x 2 hours at the chosen temperature.
      source: gmh-datasheet
      where: Tempering section
uses:
  - application: propulsion-and-tanks
    device: Bearing rings in the high-pressure oxygen turbopump of the Space Shuttle main engine
    example: A 2010 NASA Marshall history of Shuttle main engine turbopump bearing tests states that Pratt and Whitney used Cronidur 30 and AISI 9310 steel for the bearing rings.
    source: ntrs-gibson2010
    where: Full report text, passage on Pratt and Whitney bearing materials (topics discussed in the summary of NTRS 20100023061)
  - application: mechanisms
    device: High-precision ball and roller bearings, ball screw drives
    example: The producer lists high-precision ball bearings, ball and roller bearings, ball screw drives, extruder screws, pumps and valves among its main application areas.
    source: gmh-datasheet
    where: Main application areas, first page
supply:
  - subject: Chromium (chromite ore)
    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
    critical_lists: []
    recycling: 'USGS: in 2025 recycled chromium in reported stainless-steel scrap receipts accounted for 21% of apparent consumption.'
    substitutes:
      - 'USGS: chromium has no substitute in stainless steel, the leading end use.'
    source: usgs-mcs2026-chromium
    where: World Mine Production and Reserves table, chromite ore, 2025e (world total 51,000 thousand t; shares calculated by Space Mushroom from the country values 23,000, 9,000 and 7,000 thousand t); Recycling; Substitutes
  - subject: Molybdenum (mine production)
    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: []
    recycling: 'USGS: molybdenum recycled as part of new and old steel and other scrap may be as much as 30% of apparent supply.'
    substitutes:
      - 'USGS: there is little substitution for molybdenum in steels; potential alloy-steel substitutes include boron, chromium, niobium and vanadium.'
    source: usgs-mcs2026-molybdenum
    where: World Mine Production and Reserves table, mine production 2025e (world total 260,000 t; shares calculated by Space Mushroom from the country values 97,000, 42,000, 40,000 and 39,000 t); Recycling; Substitutes
documents:
  - title: GMH Gruppe, Cronidur 30 product datasheet (EN, 2025 edition)
    type: datasheet
    url: https://www.gmh-gruppe.de/wp-content/uploads/2025/11/GMH_ETE_Produktdatenblatt_Cronidur30_EN_1125.pdf
    year: 2025
  - title: Righton Blackburns, Bearing Steels AMS 5898 (Cronidur 30) Bar datasheet (28 July 2025)
    type: datasheet
    url: https://www.rightonblackburns.co.uk/datasheets/view/Righton-Blackburns-Ltd_Bearing-Steels-AMS-5898-Cronidur-30-Bar_405.pdf
    year: 2025
  - title: GMH Gruppe, high-nitrogen steels product page with Cronidur 30 FAQ
    type: datasheet
    url: https://www.gmh-gruppe.de/en/products/high-nitrogen-steels
  - title: TotalMateria, PROPRIETARY Cronidur 30 Stainless steels (material 1451444)
    type: database
    url: https://www.totalmateria.com/en-us/material/1451444
  - title: Gibson et al., History of Space Shuttle Main Engine Turbopump Bearing Testing at the Marshall Space Flight Center (JANNAF 2010), NTRS 20100023061
    type: report
    url: https://ntrs.nasa.gov/citations/20100023061
    year: 2010
  - 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: Molybdenum'
    type: report
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-molybdenum.pdf
    year: 2026
  - title: GPT Industries, Stainless Steel Safety Data Sheet (generic solid stainless steel, revision V1.0 dated 12.15.16)
    type: sds
    url: https://www.gptindustries.com/wp-content/uploads/2022/01/Stainless-Steel-Safety-Data-Sheet.pdf
    year: 2016
gaps:
  - Density is not in any source read here. The GMH datasheet prints no density, and TotalMateria shows density only as a gated placeholder.
  - Tensile strength, yield strength and elongation against tempering temperature appear only as a chart in the GMH datasheet, and no numbers could be read from it.
  - Charpy impact energy for Cronidur 30 was not found. The GMH text gives 350 J only for high-nitrogen steels in general, so it is not recorded as a Cronidur value.
  - Specific heat, coefficient of thermal expansion and Poisson's ratio are gated on TotalMateria and absent from the datasheet.
  - Brinell hardness of 200 to 240 HB from TotalMateria is not recorded, because the page does not map the test condition.
  - No safety data sheet for the Cronidur 30 bar was read. The hazard entries use a generic stainless steel safety data sheet (GPT Industries, revision V1.0 dated 12.15.16), which is not specific to the 1.4108 bar. A PubChem GHS record for this alloy was not read.
  - No corrosion test data (salt spray, immersion or pitting rate) was read in a fetched source. The OSTI paper on Cronidur 30 bearing performance refused connection, and a DTIC wear report returned 403.
  - Rolling-contact fatigue or bearing life against 440C was not read. The NASA 2010 history names the material but gives no life figures.
  - A space use beyond the Shuttle turbopump bearing rings was not verified. The ISS mechanism claim returned no source, and the 1995 first-flight date from a German article could not be read.
  - Producer share of world supply for Cronidur 30 was not found. The producer named on the datasheet is Energietechnik Essen GmbH (GMH Gruppe), Essen, Germany.
  - Critical-mineral list status for chromium and molybdenum is not printed in the USGS 2026 summaries read here, and the EU list was not opened.
  - Nickel (maximum 0.5 wt%) is not profiled for supply.
  - Hardness (Rockwell C and Brinell), tempering resistance, PREN and austenitizing temperature have no canonical name in spores/property-canon.yaml, so snake_case names are used.
  - The knifesteelnerds article gives its composition table only as an image with no readable numbers, so it is not used as a source.
  - Radiation, vacuum outgassing and cryogen compatibility were not searched.
  - No abbreviation or media file was checked for this grade.
  - The profile holds 12 properties against the 15 wanted by the lithium standard, because the readable sources give no density, strength or thermal expansion values.
sources:
  gpt-stainless-sds:
    title: GPT Industries, Stainless Steel Safety Data Sheet (generic solid stainless steel, not specific to Cronidur 30)
    id: GHS product identifier STAINLESS STEEL; revision V1.0, 12.15.16
    url: https://www.gptindustries.com/wp-content/uploads/2022/01/Stainless-Steel-Safety-Data-Sheet.pdf
    year: 2016
    kind: datasheet
    license: supplier document, cited not reproduced
  gmh-datasheet:
    title: Cronidur 30 product datasheet (EN), Energietechnik Essen GmbH, GMH Gruppe
    id: Mat.-no. 1.4108, X30CrMoN15-1; file GMH_ETE_Produktdatenblatt_Cronidur30_EN_1125
    url: https://www.gmh-gruppe.de/wp-content/uploads/2025/11/GMH_ETE_Produktdatenblatt_Cronidur30_EN_1125.pdf
    year: 2025
    kind: datasheet
    license: supplier document, cited not reproduced
  gmh-web:
    title: GMH Gruppe, high-nitrogen steels product page with Cronidur 30 FAQ
    url: https://www.gmh-gruppe.de/en/products/high-nitrogen-steels
    kind: web
    license: supplier web page, cited not reproduced
  righton-pdf:
    title: Righton Blackburns, Bearing Steels AMS 5898 (Cronidur 30) Bar datasheet, updated 28 July 2025
    id: AMS 5898, Cronidur 30
    url: https://www.rightonblackburns.co.uk/datasheets/view/Righton-Blackburns-Ltd_Bearing-Steels-AMS-5898-Cronidur-30-Bar_405.pdf
    year: 2025
    kind: datasheet
    license: distributor document, cited not reproduced
  totalmateria:
    title: TotalMateria, PROPRIETARY Cronidur 30 Stainless steels
    id: material 1451444
    url: https://www.totalmateria.com/en-us/material/1451444
    kind: database
    license: database entry, cited not reproduced
  ntrs-gibson2010:
    title: History of Space Shuttle Main Engine Turbopump Bearing Testing at the Marshall Space Flight Center (JANNAF Joint Propulsion Meeting, 2010)
    id: NASA NTRS 20100023061; Gibson, Thom and Moore (NASA MSFC); Haluck (Pratt and Whitney Rocketdyne)
    url: https://ntrs.nasa.gov/citations/20100023061
    year: 2010
    kind: report
    license: public domain (NASA)
  usgs-mcs2026-chromium:
    title: Mineral Commodity Summaries 2026, Chromium
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-chromium.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
  usgs-mcs2026-molybdenum:
    title: Mineral Commodity Summaries 2026, Molybdenum
    url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-molybdenum.pdf
    year: 2026
    kind: report
    license: public domain (USGS)
license: CC-BY-4.0
updated: '2026-11-01'
review:
  status: draft
  method: assistant
  checked_values: 12
  unreachable: 2
  caveats: 1
  note: Written by an AI assistant on 2026-11-01 from the producer datasheet, a distributor datasheet, a database entry, a NASA report and two USGS summaries fetched in this run. Hazard entries added from a generic stainless steel safety data sheet, not one for this grade. Density, strength and thermal expansion were not available in readable form.
story:
  recipe:
    line: Cronidur 30 is an iron-based martensitic stainless steel with about 14 to 16 wt% chromium, 0.85 to 1.10 wt% molybdenum and 0.30 to 0.50 wt% nitrogen. The producer alloys the nitrogen beyond its usual solubility limit by high-pressure electro-slag remelting (PESR), which gives a homogeneous microstructure with fine carbonitrides (GMH datasheet).
    parts:
      - name: Carbon
        symbol: C
        share: 0.25–0.35 wt%
        role: Sets the hardness reached after quenching; the producer's composition table gives the range.
      - name: Chromium
        symbol: Cr
        share: 14.0–16.0 wt%
        role: The main alloying element of the stainless group, in the producer's composition table.
      - name: Molybdenum
        symbol: Mo
        share: 0.85–1.10 wt%
        role: An alloying element in the producer's table; its effect is not described in the sources read.
      - name: Nitrogen
        symbol: 'N'
        share: 0.30–0.50 wt%
        role: The distinguishing element. The producer says nitrogen enhances corrosion resistance and has a positive effect on mechanical properties.
      - name: Silicon and manganese
        symbol: Si, Mn
        share: max. 1.00 wt% each
        role: Minor elements held at the maximum in the producer's table.
      - name: Nickel
        symbol: Ni
        share: max. 0.5 wt%
        role: Minor element held at the maximum in the producer's table.
  risk_groups:
    - title: For people
      lead: The bar's own safety data sheet was not read. A generic stainless steel safety data sheet says the solid is not hazardous, but processing can release hazardous fumes and dust.
      points:
        - label: Dust and swarf
          line: The generic stainless steel sheet advises avoiding dust formation and using local exhaust ventilation during grinding, machining and welding. It says prolonged skin contact with dust may cause skin irritation in sensitive people. Check the bar supplier's own safety data sheet before machining or grinding.
    - title: In service
      lead: The producer's figures describe the steel in its heat-treated condition.
      points:
        - label: Hardness
          line: The producer gives a hardness above 58 HRC in the hardened condition, and a distributor prints Rockwell C above 60. Tempering at 2 x 280 °C gives 52 to 57 HRC instead.
        - label: Corrosion
          line: The producer rates the steel 9 on a scale of 1 to 10 and calls its corrosion resistance very good. These are relative ratings, not measured test results.
    - title: Heat treatment
      lead: Process steps from the producer's datasheet.
      points:
        - label: Cryogenic step
          line: After hardening above 1000 °C, the steel must reach at least -80 °C and be held at least 60 minutes before tempering, because the nitrogen strongly stabilizes retained austenite.
        - label: Soft annealing
          line: Anneal at 780–820 °C for 4 to 8 hours before machining. The hardness is then below 250 HBW after 8 hours.
  why: Cronidur 30 (EN 1.4108, X30CrMoN15-1, AMS 5898) is a martensitic stainless steel for parts that must be hard, wear resistant and corrosion resistant. The producer, Energietechnik Essen (GMH Gruppe) of Essen, Germany, says the nitrogen gives high strength, high fracture toughness, tempering resistance and corrosion resistance. The reason to choose it is the combination of hardness above 58 HRC with corrosion resistance. A distributor says it resists corrosion better than 440C, but gives no test conditions for that claim.
  uses:
    - where: Space Shuttle main engine turbopump
      line: A 2010 NASA Marshall history of Shuttle main engine turbopump bearing tests says that Pratt and Whitney used Cronidur 30 and AISI 9310 steel for the bearing rings. It is the one space application found in the sources read.
    - where: Precision bearings and ball screws
      line: The producer lists high-precision ball and roller bearings, ball screw drives, pumps and valves among its main application areas.
  can_do:
    - label: Hardness
      value: 58 HRC or more
      line: 'Hardened Cronidur 30 is above 58 HRC according to the producer, and a distributor prints Rockwell C above 60 for the AMS 5898 bar. Heat treatment changes the figure: 58 to 60 HRC after 2 x 180 °C tempering, and 52 to 57 HRC after 2 x 280 °C.'
    - label: Tempering resistance
      value: Up to 475 °C
      line: The producer gives tempering resistance up to 475 °C, while the distributor prints up to 500 °C. The sources disagree, so the lower figure is the safer one to quote.
    - label: Stiffness
      value: 190 to 215 GPa
      line: TotalMateria lists a modulus of elasticity of 190 to 215 GPa for Cronidur 30, with no test temperature printed.
    - label: Thermal conductivity
      value: 13.848 to 20.873 W/(m·°C)
      line: TotalMateria lists thermal conductivity of 13.848 to 20.873 W/(m·°C), with no temperature printed.
    - label: Corrosion
      value: Rated 9 of 10
      line: The producer rates corrosion 9 on a scale of 1 to 10 and calls the hardened steel very corrosion resistant. These are relative scores, not test results.
  compare: Cronidur 30 is a hard, corrosion resistant steel for bearings. A distributor says it wears longer and resists corrosion better than 440C, and better than 1.2083, 1.4112, 1.4301 and 1.4571. It also says its wear resistance is higher than 1.4034, 1.2363 and 1.4528. These claims come from one distributor's sheet and carry no test conditions, so they should be checked against a test report before a design decision. No 440C figures from a fetched source were found, so the modulus and thermal conductivity ranges are not set against 440C here.
  compare_rows:
    - label: Elastic modulus
      benchmark: elastic_modulus
    - label: Thermal conductivity
      benchmark: thermal_conductivity
    - label: Hardness (Rockwell C)
      benchmark: hardness_rockwell_c
  handling:
    - Soft anneal at 780–820 °C for 4 to 8 hours before machining. Hardness is below 250 HBW after 8 hours.
    - Stress relieve at 600–650 °C after rough machining, then cool in the furnace to about 350 °C.
    - For vacuum hardening, keep a nitrogen partial pressure of 100 to 200 mbar, or allow about 0.2 mm of grinding stock.
  good_for:
    - Bearings, ball screws and valves that need more than 58 HRC with corrosion resistance (producer datasheet).
    - Aerospace parts. The Shuttle turbopump bearing rings are the one space use found in the sources read.
  watch_out:
    - Heat treatment sets both hardness and corrosion result. Skipping the -80 °C cryogenic step after hardening above 1000 °C leaves retained austenite (producer).
    - The tempering limit is printed as 475 °C by the producer and as 500 °C by a distributor.
    - The corrosion rating and the distributor's comparisons carry no test method.
  verdict: Cronidur 30 is a hard, corrosion resistant bearing steel whose heat treatment decides the result. The producer's figures support hardness above 58 HRC and very good corrosion resistance at 58 to 60 HRC after the 180 °C temper. Density, strength and corrosion test data are not in the sources read here.