Stainless Steel 440C Stress Relieved
Heat-treated state
AISI/SAE 440C · UNS S44004 · EN 1.4125, X105CrMo17 · JIS SUS440C · GB 9Cr18Mo, 95Cr18
Intermediate step for thin or asymmetric parts to limit distortion during subsequent hardening.
Values for the Stress Relieved condition
Other 440C tempers and conditions
440C is listed in 7 conditions; see the grade overview at 440C.
- Annealed
- Stress Relieved
- Annealed + Cold Drawn
- H&T 48-52 HRC
- H&T 54-56 HRC
- Hardened & Tempered
- H&T 58-60 HRC
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault fully (subcritical/full) annealed, soft machinable condition | Stock condition for bar/plate that will be machined and then hardened by the customer. | 450 | 760 | 14 | 24 HRC | — |
Stress RelievedThis page sub-critical stress relief after rough machining of annealed stock | Intermediate step for thin or asymmetric parts to limit distortion during subsequent hardening. | 470 | 780 | 13 | 25 HRC | 2.9 % IACS |
Cold-finished bar, annealed then lightly drawn/ground | Choose for small-diameter precision bar with better straightness/surface than hot-rolled annealed. | 620 | 860 | 10 | 28 HRC | 2.9 % IACS |
Hardened and high-temperature tempered | Only for parts needing moderate hardness with elevated-temperature stability; corrosion resistance and toughness are reduced by carbide precipitation. | 1,500 | 1,650 | 4 | 50 HRC | — |
Hardened and tempered ~250–350 °C for improved toughness | Use where slightly higher toughness / lower cracking risk is worth a few points of hardness (cutlery, shafts). | 1,720 | 1,860 | 3 | 55 HRC | — |
austenitized ~1010–1065 °C, oil/air quenched, tempered 150–200 °C (≈58 HRC) | Standard service condition for bearings, knife blades and wear parts needing maximum hardness with usable corrosion resistance. | 1,900 | 1,970 | 2 | 58 HRC | — |
Hardened, deep-frozen and tempered 150 °C for maximum hardness | Pick when maximum wear resistance and dimensional stability are required (bearing races, valve balls). | 1,950 | 2,050 | 1.5 | 59 HRC | — |
What is 440C Stress Relieved?
440C Stress Relieved is 440C heat treated to Stress Relieved — intermediate step for thin or asymmetric parts to limit distortion during subsequent hardening. 440C Stress Relieved has a yield strength of 470 MPa (68.2 ksi) and a tensile strength of 780 MPa (113 ksi) — stronger than 74% of stainless steel grades. Elongation at break is 13% and the elastic modulus is 200 GPa (29 Msi). 440C Stress Relieved has a density of 7.68 g/cm³ (0.277 lb/in³), lighter than 94% of stainless steel grades. It melts at 1,370°C (2,498 °F). Annealed is the default condition FabDigit quotes; Stress Relieved is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 80/100, better than 89% of stainless steel grades
- High electrical conductivity — 2.9 % IACS, better than 87% of stainless steel grades
- Conducts heat well — 24.2 W/m·K (14 BTU/hr·ft·°F), better than 83% of stainless steel grades
Limitations
- Difficult to weld — 12/100, worse than 99% of stainless steel grades
- Limited ductility — 13%, worse than 93% of stainless steel grades
- Needs corrosion protection — 44/100, worse than 88% of stainless steel grades
- Limited formability — 23/100, worse than 82% of stainless steel grades
440C Stress Relieved properties
Typical room-temperature values for 440C Stress Relieved; 23 are specific to this condition. Other listed values are 440C reference data and may not represent this condition. Bars are the position among stainless steel grades.
Physical3
440C Stress Relieved has a density of 7.68 g/cm³ (0.277 lb/in³), lighter than 94% of stainless steel grades. It melts at 1,370°C (2,498 °F).
Mechanical16
440C Stress Relieved has a yield strength of 470 MPa (68.2 ksi) and a tensile strength of 780 MPa (113 ksi) — stronger than 74% of stainless steel grades. Elongation at break is 13% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
440C Stress Relieved is rated for continuous service to 425°C (797 °F). It conducts heat at 24.2 W/m·K (14 BTU/hr·ft·°F), better than 83% of stainless steel grades. Thermal expansion is 10.2 µm/m·K (5.67 µin/in·°F).
Electrical3
440C Stress Relieved conducts electricity at 2.9 % IACS, better than 87% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is fair (44/100), worse than 88% of stainless steel grades.
Sustainability4
Producing a kilogram of 440C Stress Relieved takes about 53 MJ of energy and emits 4.3 kg of CO₂ — less than 67% of stainless steel grades. Typical recycled content is 60%.
Manufacturability6
440C Stress Relieved's machinability is fair (43/100, better than 81% of stainless steel grades); weldability not recommended (12/100); formability poor (23/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 440C Stress Relieved
Is 440C easy to machine?
Machine only in the annealed condition with rigid setups, sharp carbide tools, slow speeds and generous coolant; after hardening use grinding, EDM or CBN.
Can 440C be welded?
Welding is generally not recommended — preheat 200–300 °C, use 440C or austenitic filler, and follow with a full anneal to avoid cracking.
Can 440C be formed, bent or molded?
Cold forming is limited to gentle bending of annealed sheet; forge 1050–1150 °C and cool slowly with an immediate anneal to prevent quench cracks.
What surface finishes work on 440C?
Passivate in nitric or citric acid after grinding/polishing for best corrosion resistance; hard-chrome or PVD coatings and mirror polishing are common for knives and bearings.
440C chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Chigh carbon gives primary M23C6/M7C3 carbides for wear resistance | 0.95 – 1.2 | 1.05 |
| Cr | 16 – 18 | 17 |
| Mo | ≤ 0.75 | 0.5 |
| Mn | ≤ 1 | 0.4 |
| Si | ≤ 1 | 0.4 |
| P | ≤ 0.04 | — |
| S | ≤ 0.03 | — |
| Fe | balance | — |
440C Stress Relieved — frequently asked
What is 440C Stress Relieved used for?
440C Stress Relieved is typically used for ball and roller bearing races, surgical instruments, knife blades, valve components and seats, gauges and measuring tools and pump shafts. In short: highest hardness stainless tool.
What is the yield strength of 440C Stress Relieved?
440C Stress Relieved has a typical yield strength of 470 MPa (68.2 ksi) and a tensile strength of 780 MPa (113 ksi) — stronger than 74% of stainless steel grades. Strength varies by condition: see the 7 listed tempers.
Is 440C Stress Relieved easy to machine?
Not especially — machinability is rated fair (43/100, better than 81% of stainless steel grades). Machine only in the annealed condition with rigid setups, sharp carbide tools, slow speeds and generous coolant; after hardening use grinding, EDM or CBN.
Can 440C Stress Relieved be welded?
Not readily — weldability is rated not recommended (12/100). Welding is generally not recommended — preheat 200–300 °C, use 440C or austenitic filler, and follow with a full anneal to avoid cracking.
What surface finishes work on 440C Stress Relieved?
Passivate in nitric or citric acid after grinding/polishing for best corrosion resistance; hard-chrome or PVD coatings and mirror polishing are common for knives and bearings.
Can 440C Stress Relieved be formed, bent or molded?
Cold forming is limited to gentle bending of annealed sheet; forge 1050–1150 °C and cool slowly with an immediate anneal to prevent quench cracks.
What is the maximum service temperature of 440C Stress Relieved?
440C Stress Relieved is rated for continuous use to about 425°C (797 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in 440C Stress Relieved?
Yes — 440C Stress Relieved is available for CNC machining with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- ASTM A276/A276M — Stainless Steel Bars and Shapes — ASTM (2017)
- GB/T 1220 (9Cr18Mo) — SAC (2007)
- EN 10088-3 / X105CrMo17 (1.4125) — CEN (2014)
- ASM Specialty Handbook: Stainless Steels — ASM International (1994)
- 440C Stainless Steel Product Data Sheet — AK Steel / Cleveland-Cliffs (2016)
- Machinery's Handbook machinability ratings — Industrial Press (2020)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.