Stainless Steel 420F · heat-treated state
Stainless Steel 420F Hardened & Tempered
Properties of the Hardened & Tempered condition, compared with the other 420F tempers.
Default hardened condition for cutting edges, valve stems and wear surfaces where maximum hardness and best corrosion behaviour of the hardened states are needed.
What is 420F Hardened & Tempered?
420F Hardened & Tempered is 420F heat treated to Hardened & Tempered — default hardened condition for cutting edges, valve stems and wear surfaces where maximum hardness and best corrosion behaviour of the hardened states are needed. 420F Hardened & Tempered has a yield strength of 1,480 MPa (215 ksi) and a tensile strength of 1,720 MPa (249 ksi) — stronger than 100% of stainless steel grades. Elongation at break is 8% and the elastic modulus is 200 GPa (29 Msi). 420F Hardened & Tempered has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 66% of stainless steel grades. It melts at 1,450°C (2,642 °F). Annealed is the default condition FabDigit quotes; Hardened & Tempered is available on request or by drawing note.
Advantages
- High strength — 1,480 MPa (215 ksi), better than 100% of stainless steel grades
- High electrical conductivity — 3.1 % IACS, better than 99% of stainless steel grades
- Low embodied carbon — 3.4 kg CO₂/kg, better than 91% of stainless steel grades
- Conducts heat well — 24.9 W/m·K (14.4 BTU/hr·ft·°F), better than 88% of stainless steel grades
Limitations
- Limited service temperature — 200°C (392 °F), worse than 100% of stainless steel grades
- Limited formability — 3/100, worse than 100% of stainless steel grades
- Limited ductility — 8%, worse than 99% of stainless steel grades
- Difficult to weld — 12/100, worse than 99% of stainless steel grades
- Difficult to machine — 22/100, worse than 95% of stainless steel grades
420F Hardened & Tempered properties
Typical room-temperature values for 420F Hardened & Tempered — 17 properties are specific to this condition; the rest are grade-level values shared by every 420F temper. Each bar shows where the value sits among the stainless steel grades in FabDigit's library — further right is higher.
Physical3
420F Hardened & Tempered has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 66% of stainless steel grades. It melts at 1,450°C (2,642 °F).
Mechanical13
420F Hardened & Tempered has a yield strength of 1,480 MPa (215 ksi) and a tensile strength of 1,720 MPa (249 ksi) — stronger than 100% of stainless steel grades. Elongation at break is 8% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
420F Hardened & Tempered is rated for continuous service to 200°C (392 °F). It conducts heat at 24.9 W/m·K (14.4 BTU/hr·ft·°F), better than 88% of stainless steel grades. Thermal expansion is 10.3 µm/m·K (5.72 µin/in·°F).
Electrical3
420F Hardened & Tempered conducts electricity at 3.1 % IACS, better than 99% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is fair (40/100), worse than 93% of stainless steel grades.
Sustainability4
Producing a kilogram of 420F Hardened & Tempered takes about 45 MJ of energy and emits 3.4 kg of CO₂ — less than 91% of stainless steel grades. Typical recycled content is 65%.
Manufacturability8
420F Hardened & Tempered's machinability is poor (22/100, worse than 95% of stainless steel grades); weldability not recommended (12/100); formability not recommended (3/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 420F tempers and conditions
420F is also supplied in 4 other conditions. The full side-by-side table is on the 420F overview.
- AnnealedDefaultStandard stock condition for screw-machine work; machine here, then harden the finished part.380 MPa yield · 220 HB
- Hardened & TemperedDefault hardened condition for cutting edges, valve stems and wear surfaces where maximum hardness and best corrosion behaviour of the hardened states are needed.1,480 MPa yield · 50 HRC
- Q&T 40-45 HRCUse when a little more toughness than the 50 HRC condition is required and corrosion exposure is mild.1,180 MPa yield · 43 HRC
- Q&T 28-32 HRCTough, machinable heat-treated condition for shafts and stems where hardness is secondary; corrosion resistance is the lowest of all conditions.800 MPa yield · 30 HRC
- Annealed Cold DrawnPick for tight-tolerance turned parts needing better surface finish, straightness and chip control than hot-rolled annealed bar.620 MPa yield · 25 HRC
Working with 420F Hardened & Tempered
Is 420F easy to machine?
Excellent for a martensitic stainless — sulfides break chips; use sharp carbide, ~60–80 % of 12L14 speeds, and machine in the annealed state before hardening.
Can 420F be welded?
Not recommended: high carbon plus sulfur gives hot cracking and brittle martensite; if unavoidable, preheat 200–300 °C, use 309/410NiMo filler and temper immediately.
Can 420F be formed, bent or molded?
Cold forming limited to light heading or straightening in the annealed condition; hot work 1150–900 °C followed by slow cool and full anneal at 840–900 °C.
What surface finishes work on 420F?
Passivate per ASTM A967 (citric preferred, nitric can attack sulfides); accepts hard chrome, black oxide and PVD, but sulfide stringers prevent a defect-free mirror polish.
420F 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 |
|---|---|---|
| CJIS SUS420F allows 0.26–0.40 | 0.3 – 0.4 | 0.35 |
| Cr | 12 – 14 | 13 |
| Mn | ≤ 1.25 | 0.8 |
| Si | ≤ 1 | 0.5 |
| Sfree-machining addition; forms MnS stringers | ≥ 0.15 | 0.22 |
| P | ≤ 0.06 | 0.03 |
| Mooptional, at producer's discretion | ≤ 0.6 | — |
| Fe | balance | — |
420F Hardened & Tempered — frequently asked
What is 420F Hardened & Tempered used for?
420F Hardened & Tempered is typically used for cutlery blanks, dental and surgical instruments, scissor and shear blades, valve stems and seats, spindles and shafts and wear pins and bushings. In short: free-machining martensitic stainless.
What is the yield strength of 420F Hardened & Tempered?
420F Hardened & Tempered has a typical yield strength of 1,480 MPa (215 ksi) and a tensile strength of 1,720 MPa (249 ksi) — stronger than 100% of stainless steel grades. Strength varies by condition: see the 5 listed tempers.
Is 420F Hardened & Tempered easy to machine?
Not especially — machinability is rated poor (22/100, worse than 95% of stainless steel grades). Excellent for a martensitic stainless — sulfides break chips; use sharp carbide, ~60–80 % of 12L14 speeds, and machine in the annealed state before hardening.
Can 420F Hardened & Tempered be welded?
Not readily — weldability is rated not recommended (12/100). Not recommended: high carbon plus sulfur gives hot cracking and brittle martensite; if unavoidable, preheat 200–300 °C, use 309/410NiMo filler and temper immediately.
What surface finishes work on 420F Hardened & Tempered?
Passivate per ASTM A967 (citric preferred, nitric can attack sulfides); accepts hard chrome, black oxide and PVD, but sulfide stringers prevent a defect-free mirror polish.
Can 420F Hardened & Tempered be formed, bent or molded?
Cold forming limited to light heading or straightening in the annealed condition; hot work 1150–900 °C followed by slow cool and full anneal at 840–900 °C.
What is the maximum service temperature of 420F Hardened & Tempered?
420F Hardened & Tempered is rated for continuous use to about 200°C (392 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in 420F Hardened & Tempered?
Yes — 420F 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 A582/A582M — Free-Machining Stainless Steel Bars — ASTM International (2021)
- JIS G 4303 — Stainless Steel Bars (SUS420F) — JSA (2021)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASTM A967/A967M — Chemical Passivation Treatments for Stainless Steel Parts — ASTM International (2017)
- Martensitic free-machining stainless bar datasheets (Sandvik / Ugitech / Outokumpu 4028-type) — various producers (2023)
- (SMM / Mysteel / 1688 ) — SMM / Mysteel (2025)
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.