Stainless Steel 440C · heat-treated state
Stainless Steel 440C Hardened & Tempered
Properties of the Hardened & Tempered condition, compared with the other 440C tempers.
Standard service condition for bearings, knife blades and wear parts needing maximum hardness with usable corrosion resistance.
What is 440C Hardened & Tempered?
440C Hardened & Tempered is 440C heat treated to Hardened & Tempered — standard service condition for bearings, knife blades and wear parts needing maximum hardness with usable corrosion resistance. 440C Hardened & Tempered has a yield strength of 1,900 MPa (276 ksi) and a tensile strength of 1,970 MPa (286 ksi) — stronger than 100% of stainless steel grades. Elongation at break is 2% and the elastic modulus is 200 GPa (29 Msi). 440C Hardened & Tempered 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; Hardened & Tempered is available on request or by drawing note.
Advantages
- High strength — 1,900 MPa (276 ksi), better than 100% of stainless steel grades
- Polishes to a fine finish — 85/100, better than 97% 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 84% of stainless steel grades
Limitations
- Limited ductility — 2%, worse than 100% of stainless steel grades
- Difficult to machine — 10/100, worse than 100% of stainless steel grades
- Difficult to weld — 5/100, worse than 100% of stainless steel grades
- Limited formability — 2/100, worse than 100% of stainless steel grades
- Limited service temperature — 250°C (482 °F), worse than 99% of stainless steel grades
440C Hardened & Tempered properties
Typical room-temperature values for 440C Hardened & Tempered — 19 properties are specific to this condition; the rest are grade-level values shared by every 440C temper. Each bar shows where the value sits among the stainless steel grades in FabDigit's library — further right is higher.
Physical3
440C Hardened & Tempered 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 Hardened & Tempered has a yield strength of 1,900 MPa (276 ksi) and a tensile strength of 1,970 MPa (286 ksi) — stronger than 100% of stainless steel grades. Elongation at break is 2% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
440C Hardened & Tempered is rated for continuous service to 250°C (482 °F). It conducts heat at 24.2 W/m·K (14 BTU/hr·ft·°F), better than 84% of stainless steel grades. Thermal expansion is 10.2 µm/m·K (5.67 µin/in·°F).
Electrical3
440C Hardened & Tempered conducts electricity at 2.9 % IACS, better than 87% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is fair (50/100), worse than 79% of stainless steel grades.
Sustainability4
Producing a kilogram of 440C Hardened & Tempered 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 Hardened & Tempered's machinability is not recommended (10/100, worse than 100% of stainless steel grades); weldability not recommended (5/100); formability not recommended (2/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 440C tempers and conditions
440C is also supplied in 6 other conditions. The full side-by-side table is on the 440C overview.
- AnnealedDefaultStock condition for bar/plate that will be machined and then hardened by the customer.450 MPa yield · 24 HRC
- H&T 58-60 HRCPick when maximum wear resistance and dimensional stability are required (bearing races, valve balls).1,950 MPa yield · 59 HRC
- Hardened & TemperedStandard service condition for bearings, knife blades and wear parts needing maximum hardness with usable corrosion resistance.1,900 MPa yield · 58 HRC
- H&T 54-56 HRCUse where slightly higher toughness / lower cracking risk is worth a few points of hardness (cutlery, shafts).1,720 MPa yield · 55 HRC
- H&T 48-52 HRCOnly for parts needing moderate hardness with elevated-temperature stability; corrosion resistance and toughness are reduced by carbide precipitation.1,500 MPa yield · 50 HRC
- Annealed + Cold DrawnChoose for small-diameter precision bar with better straightness/surface than hot-rolled annealed.620 MPa yield · 28 HRC
Working with 440C Hardened & Tempered
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 Hardened & Tempered — frequently asked
What is 440C Hardened & Tempered used for?
440C Hardened & Tempered 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 Hardened & Tempered?
440C Hardened & Tempered has a typical yield strength of 1,900 MPa (276 ksi) and a tensile strength of 1,970 MPa (286 ksi) — stronger than 100% of stainless steel grades. Strength varies by condition: see the 7 listed tempers.
Is 440C Hardened & Tempered easy to machine?
Not especially — machinability is rated not recommended (10/100, worse than 100% 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 Hardened & Tempered be welded?
Not readily — weldability is rated not recommended (5/100). 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 Hardened & Tempered?
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 Hardened & Tempered 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 Hardened & Tempered?
440C Hardened & Tempered is rated for continuous use to about 250°C (482 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in 440C Hardened & Tempered?
Yes — 440C Hardened & Tempered 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.