Materials & grades
440C stainless steel: S44004, 1.4125 (X105CrMo17), SUS440C and X108Cr17Mo
440C is a martensitic stainless steel with about 17 % chromium and 1 % carbon that reaches 58–60 HRC after hardening and tempering, among the hardest of the stainless grades. It is UNS S44004, 1.4125 (X105CrMo17) in Europe, SUS440C in Japan and X108Cr17Mo in IS 1570.
Names by standard
What it is called in each region
| Region | System | Designation | תקן | Match |
|---|---|---|---|---|
| USA | AISI/ASTM | 440CRolled Alloys lists ASTM A276, AMS 5630 and AMS 5880; Aircraft Materials adds A314, A473 and A580. | ASTM A276 (bar and shapes); AMS 5630; AMS 5880 (bearing bar) | Same material |
| UNS | S44004 | — | Same material | |
| EU | EN 10027-1 name | X105CrMo17Carbon 0.95–1.20 %, chromium 16.0–18.0 %, molybdenum 0.40–0.80 %. | EN 10088-1; EN 10088-3 | Equivalent |
| EN 10027-2 number | 1.4125Material number of X105CrMo17. | EN 10088-1; EN 10088-3 | Equivalent | |
| DIN 17440 (legacy) | 1.4125 / X105CrMo17Superseded German standard. The name and number carried over into EN 10088. | DIN 17440 | Equivalent | |
| הודו | IS 1570 (Part 5) | X108Cr17MoCarbon 0.95–1.20 %, chromium 16.0–18.0 %, molybdenum up to 0.75 %. The schedule also lists it as a cutlery steel with 58 HRC minimum after hardening and tempering. | IS 1570 (Part 5):1985 | Equivalent |
| Japan | JIS G 4303 | SUS440CCarbon 0.95–1.20 %, chromium 16.00–18.00 %. SUS440F is a separate free-machining variant. | JIS G 4303 (bar) | Equivalent |
On equivalence
- UNS S44004, EN 1.4125, SUS440C and IS X108Cr17Mo have essentially the same carbon (0.95–1.20 %) and chromium (16–18 %) windows. EN allows molybdenum 0.40–0.80 %, while ASTM A276, JIS and IS only cap it at 0.75 %.
- There is no BS 970 name for 440C. Atlas lists none in its BS column, so the UK uses the EN designation.
- EN 10088 sets sulphur at 0.015 % maximum for 1.4125, tighter than the ASTM and JIS limit of 0.030 %.
- 440C has the highest carbon content of the 400-series stainless steels (Rolled Alloys), which is why it reaches the highest hardness.
- Ball-bearing and aerospace grades (AMS 5630, 5880) are procured by specification. The same chemistry may be supplied vacuum melted (AMS 5618).
- Pages and datasheets quote a wide spread of annealed hardness. The EN delivery limit is 285 HB, JIS is 269 HBW, and typical annealed material is about 223–230 HB.
Chemical composition
Composition limits, mass %
| Element | 440C (S44004)USA · ASTM A276 (as given by Rolled Alloys) | X105CrMo17 (1.4125)EU · EN 10088-1 (as given by Jacques Allemann) | X108Cr17Moהודו · IS 1570 (Part 5) | SUS440CJapan · JIS G 4303 |
|---|---|---|---|---|
| C | 0.95–1.20 | 0.95–1.20 | 0.95–1.20 | 0.95–1.20 |
| Si | ≤1.00 | ≤1.00 | — | ≤1.00 |
| Mn | ≤1.00 | ≤1.00 | — | ≤1.00 |
| P | ≤0.040 | ≤0.040 | — | ≤0.040 |
| S | ≤0.030 | ≤0.015 | — | ≤0.030 |
| Cr | 16.0–18.0 | 16.0–18.0 | 16.0–18.0 | 16.00–18.00 |
| Mo | ≤0.75 | 0.40–0.80 | ≤0.75 | ≤0.75 |
Mechanical properties
Strength and hardness
| Condition | Tensile strength | Yield strength | Elongation | Hardness |
|---|---|---|---|---|
| Annealed (EN, mill delivery)Specified maximum hardness, bar and rod; no strength is specifiedBöhler N695 (1.4125 / 440C) datasheet | — | — | — | ≤285 HB |
| Annealed (JIS SUS440C)Specified maximum, barJIS G 4303 as given by Nose Stainless | — | — | — | ≤269 HBW (≤28 HRC) |
| Annealed, typicalTypical, not a limitRolled Alloys 440C data sheet (anneal 845–870 °C, furnace cool) | — | — | — | about 223 HB |
| Hardened and tempered (JIS SUS440C)Specified minimum, bar; hardness is a minimumJIS G 4303 as given by Nose Stainless | — | — | — | ≥58 HRC |
| Hardened and tempered (IS X108Cr17Mo)Specified minimum, cutlery-steel schedule; hardness is a minimumIS 1570 (Part 5):1985, Table 5 | — | — | — | ≥58 HRC (≥660 HV) |
| Hardened 1040 °C, oil quenched, tempered 315 °CTypical values, 1 in bar, not minimums; reduction of area 10 %Rolled Alloys 440C data sheet (hardened 1900 °F, tempered 600 °F) | 1965 MPa285 ksi | 1896 MPa275 ksi | 2 % | 580 HB |
| Hardened, tempered at 150 °C (300 °F)Typical, 1 in round, hardened 1900 °F, oil quench, 1 h temperRolled Alloys 440C data sheet | — | — | — | 60 HRC |
| Hardened, tempered at 260 °C (500 °F)Typical, 1 in roundRolled Alloys 440C data sheet | — | — | — | 57 HRC |
| Hardened, tempered at 425 °C (800 °F)Typical, 1 in roundRolled Alloys 440C data sheet | — | — | — | 56 HRC |
| Hardened 1040 °C, sub-zero treated, tempered 140 °CTypical, Aubert & Duval XDBDAubert & Duval XDBD (X105CrMo17) data sheet | — | — | — | 59 HRC |
In practice
Behaviour, heat treatment and uses
Characteristics
- Highest carbon content of the 400-series stainless steels. After hardening it reaches the highest hardness of the stainless grades (Rolled Alloys), up to 58–60 HRC (Böhler).
- Magnetic and hardenable by heat treatment. In the annealed state it machines like a high-speed tool steel, with tough, stringy chips; machine in the annealed condition (Rolled Alloys).
- Corrosion resistance is moderate (Rolled Alloys). About 17 % chromium resists water, water vapour and mild acids, and resistance is highest when hardened, tempered and with a ground or polished surface (Allemann).
- Very high wear resistance; polishes and grinds well for cutlery and bearing surfaces (Böhler, Rolled Alloys).
- Seldom welded. If it must be, preheat to about 260 °C (500 °F), weld, then anneal for 6–8 hours at 730–760 °C (Rolled Alloys). Allemann advises against welding because of hardening cracks.
- Atlas notes that after tempering above about 510 °C the part should be cooled fairly rapidly to below 400 °C to avoid 475 °C embrittlement.
Heat treatment
- Annealing: about 845–870 °C, furnace cool, gives roughly 223 HB (Rolled Alloys). Aubert & Duval gives 870 °C; the JIS range is 800–920 °C slow cooled.
- Hardening: 1000–1050 °C, hold 15–30 minutes, then quench (Böhler); Rolled Alloys 1010–1065 °C in oil or air; JIS 1010–1070 °C in oil. Do not overheat.
- Sub-zero treatment between quenching and tempering (about −70 to −80 °C) is recommended for maximum hardness (Aubert & Duval). Atlas cites cooling to about −75 °C to transform retained austenite where dimensional stability matters, as in 440C gauge blocks.
- Temper immediately after quenching. For working hardness 100–200 °C (Böhler); JIS 100–180 °C; Aubert & Duval allows 120–500 °C depending on the hardness required. Typical hardness falls from 60 HRC at 150 °C to 56 HRC at 315–425 °C (Rolled Alloys).
- Stress relief: soft annealed material up to 650 °C, hardened material about 50 °C below the tempering temperature (Böhler).
- Hot working: preheat slowly to 760–815 °C, then 1040–1150 °C; do not forge below about 955 °C; furnace cool and anneal afterwards (Rolled Alloys).
שימושים אופייניים
- Bearings, bearing balls and bushings
- Valve seats, valve parts and nozzles
- Cutting instruments, knife blades, chisels and surgical instruments
- Measuring instruments and gauge blocks
- Moulds and screws for plastics processing
Stainless steels
Similar grades compared
| דרגה | C % | Mn % | Cr % | Ni % | Tensile, first listed condition |
|---|---|---|---|---|---|
| 440C / 1.4125 | 0.95–1.20 | ≤1.00 | 16.0–18.0 | — | 1965 MPa |
| 410 / 1.4006 | 0.08–0.15 | ≤1.00 | 11.5–13.5 | ≤0.75 | ≥480 MPa |
| 416 / 1.4005 | ≤0.15 | ≤1.25 | 12.00–14.00 | — | 620–830 MPa |
| 420 / 1.4021 | ≥0.15 | ≤1.00 | 12.0–14.0 | ≤1.0 | 655 MPa |
| 431 / 1.4057 | ≤0.20 | ≤1.00 | 15.0–17.0 | 1.25–2.50 | 862 MPa |
| 201 / 1.4372 | ≤0.15 | 5.50–7.50 | 16.0–18.0 | 3.5–5.5 | ≥515 MPa |
| 301 / 1.4310 | ≤0.15 | ≤2.00 | 16.0–18.0 | 6.0–8.0 | ≥515 MPa |
| 303 / 1.4305 | ≤0.15 | ≤2.0 | 17.0–19.0 | 8.0–10.0 | 650 MPa |
| 304 / 1.4301 | ≤0.08 | ≤2.00 | 18.0–20.0 | 8.0–10.5 | ≥515 MPa |
| 304L / 1.4307 | ≤0.030 | ≤2.00 | 18.0–20.0 | 8.0–12.0 | ≥485 MPa |
Composition from the US standard where one exists, otherwise the first standard listed on each grade's page. Strength conditions differ between grades; open a grade for its full table.
תשובות לשאלות
Common questions
What is the equivalent of 440C stainless steel?
1.4125 (X105CrMo17) in Europe, SUS440C in Japan and X108Cr17Mo in IS 1570 (Part 5) in India. The UNS number is S44004. The UK has no BS 970 name for 440C.
How hard can 440C stainless steel get?
Up to 58–60 HRC after hardening and tempering at low temperature (Böhler). Rolled Alloys gives 60 HRC at a 150 °C temper, falling to about 56 HRC at 315–425 °C. JIS and IS 1570 set 58 HRC as the minimum for hardened and tempered material.
What heat treatment does 440C need?
Harden at about 1000–1070 °C, quench in oil (or air), and temper at once, usually at 100–200 °C for maximum hardness. Sub-zero treatment before tempering raises hardness and stability. Anneal at about 845–870 °C with furnace cooling to soften for machining.
Is 440C stainless steel rustproof?
Corrosion resistance is moderate (Rolled Alloys); 440C is chosen for hardness rather than corrosion resistance. It resists water, water vapour and mild acids, and does best when hardened, tempered and ground or polished (Allemann).
Can 440C be welded?
It is seldom welded. Allemann says it cannot be welded because of the risk of hardening cracks. If welding is unavoidable, Rolled Alloys advises preheating to about 260 °C, using matching filler, and annealing for 6–8 hours straight afterwards.
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Related references
References
Sources
- Rolled Alloys, 440C stainless steel data sheet (Bulletin 1142US, 2015) — ASTM A276 composition, hardened tensile values, hardness versus tempering temperature, working, welding.
- BÖHLER N695 (1.4125 / X105CrMo17 / 440C) datasheet — Delivery hardness, hardening and tempering, up to 58–60 HRC.
- Aubert & Duval, XDBD (X105CrMo17) data sheet — Typical values for heat treatment reference, annealing and sub-zero treatment.
- Jacques Allemann, 1.4125 wire data sheet — EN 10088-1 composition for 1.4125, thermal treatment, corrosion and welding notes.
- Nose Stainless: steel types, composition and mechanical properties (JIS G 4303 reference sheet) — JIS G 4303 composition, heat treatment and mechanical properties for bar. Catalog reproducing the JIS values.
- Bureau of Indian Standards, IS 1570 (Part 5):1985 Schedules for wrought steels, stainless and heat-resisting steels (Public.Resource.Org copy) — Scanned copy; the text layer is rough, so figures were read against the table layout.
- Atlas Steels Technical Handbook of Stainless Steels (revised 12/08/2021) — Grade comparison (UNS, BS, EN, SS, JIS) and family characteristics. Distributor handbook.
- United Performance Metals, 440C stainless plate datasheet — Distributor sheet; tensile value printed incompletely, not used.
- Aircraft Materials: cross-reference of stainless steel specifications — BS, EN, UNS, AMS and ASTM listings per grade. Trade reference.
Values summarize published limits and typical data. The governing standard and the current edition control; check them before specifying.