Stainless Steel 420 · heat-treated state
Stainless Steel 420 Hardened
Properties of the Hardened condition, compared with the other 420 tempers.
Maximum hardness condition; only for parts that will be tempered or for very hard wear surfaces tolerating brittleness.
What is 420 Hardened?
420 Hardened is 420 heat treated to Hardened — maximum hardness condition; only for parts that will be tempered or for very hard wear surfaces tolerating brittleness. 420 Hardened has a yield strength of 1,500 MPa (218 ksi) and a tensile strength of 1,800 MPa (261 ksi) — stronger than 100% of stainless steel grades. Elongation at break is 2% and the elastic modulus is 200 GPa (29 Msi). 420 Hardened has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 66% of stainless steel grades. It melts at 1,454°C (2,649 °F). Annealed is the default condition FabDigit quotes; Hardened is available on request or by drawing note.
Advantages
- High strength — 1,500 MPa (218 ksi), better than 100% of stainless steel grades
- High electrical conductivity — 3.1 % IACS, better than 99% of stainless steel grades
- Polishes to a fine finish — 85/100, better than 97% 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
- Low embodied carbon — 3.5 kg CO₂/kg, better than 88% of stainless steel grades
Limitations
- Limited ductility — 2%, worse than 100% of stainless steel grades
- Low fracture toughness — 18 MPa·√m (16.4 ksi·√in), worse than 100% of stainless steel grades
- Difficult to machine — 15/100, worse than 100% of stainless steel grades
- Needs corrosion protection — 40/100, worse than 93% of stainless steel grades
- Difficult to weld — 25/100, worse than 92% of stainless steel grades
420 Hardened properties
Typical room-temperature values for 420 Hardened — 10 properties are specific to this condition; the rest are grade-level values shared by every 420 temper. Each bar shows where the value sits among the stainless steel grades in FabDigit's library — further right is higher.
Physical3
420 Hardened has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 66% of stainless steel grades. It melts at 1,454°C (2,649 °F).
Mechanical16
420 Hardened has a yield strength of 1,500 MPa (218 ksi) and a tensile strength of 1,800 MPa (261 ksi) — stronger than 100% of stainless steel grades. Elongation at break is 2% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
420 Hardened is rated for continuous service to 300°C (572 °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
420 Hardened 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 420 Hardened takes about 55 MJ of energy and emits 3.5 kg of CO₂ — less than 51% of stainless steel grades. Typical recycled content is 45%.
Manufacturability7
420 Hardened's machinability is poor (15/100, worse than 100% of stainless steel grades); weldability poor (25/100); formability fair (40/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 420 tempers and conditions
420 is also supplied in 7 other conditions. The full side-by-side table is on the 420 overview.
- AnnealedDefaultStandard stocked condition for machining, blanking or forming before hardening.360 MPa yield · 200 HB
- HardenedMaximum hardness condition; only for parts that will be tempered or for very hard wear surfaces tolerating brittleness.1,500 MPa yield · 54 HRC
- Hardened & TemperedStandard service condition for cutlery, blades, tool and mould parts, valve trim and wear surfaces needing maximum hardness with best corrosion resistance.1,400 MPa yield · 50 HRC
- As PrintedAs-built AM condition: fine as-quenched martensite gives high hardness but low ductility and residual stress; normally stress-relieved or fully re-hardened before use.1,100 MPa yield · 49 HRC
- Stress RelievedUse to remove machining, grinding or additive-build residual stress and prevent distortion/cracking, with only partial loss of hardness.950 MPa yield · 40 HRC
- Q&T 30-35 HRCChoose when toughness and machinability matter more than wear resistance — shafts, pump/valve stems, structural fittings.800 MPa yield · 32 HRC
- Cold DrawnPick for close-tolerance turned parts, screws and shafts where extra as-supplied strength and better surface finish are wanted without heat treatment.640 MPa yield · 24 HRC
- HIPUse for powder-metallurgy, MIM or AM parts needing full density and closed internal porosity; delivered in a soft, machinable state ready for hardening.480 MPa yield · 21 HRC
Working with 420 Hardened
Is 420 easy to machine?
Machine in the annealed condition with sharp, rigid setups, positive-rake carbide, 60–120 m/min and heavy coolant; hardened 48–52 HRC parts need grinding, CBN or hard-turning.
Can 420 be welded?
Air-hardening and crack-prone: preheat 200–300 °C, use 410/420 or austenitic (309/312) filler, and temper/anneal immediately after welding — avoid welding hardened parts where possible.
Can 420 be formed, bent or molded?
Cold form only in the annealed state with generous radii and no more than mild bends; hot work 1100→850 °C then slow-cool or anneal at 750–800 °C to avoid quench cracks.
What surface finishes work on 420?
Takes an excellent mirror polish (mould and cutlery use); passivate or nitric-acid clean after grinding to restore the passive film, and hard-chrome or nitride for extra wear life — never leave scale or free iron on the surface.
420 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 |
|---|---|---|
| CASTM A276: 0.15 min; EN 1.4021 0.16–0.25, 1.4028 0.26–0.35 (X30Cr13) | 0.15 – 0.4 | 0.2 |
| Cr | 12 – 14 | 13 |
| Mn | ≤ 1 | 0.5 |
| SiEN limit 1.00; GB 20Cr13 ≤1.00 | ≤ 1 | 0.4 |
| Niresidual; EN 10088-3 ≤0.75 for 1.4021 | ≤ 0.75 | 0.3 |
| P | ≤ 0.04 | 0.02 |
| SEN ≤0.015; free-machining versions higher | ≤ 0.03 | 0.01 |
| Fe | balance | — |
420 Hardened — frequently asked
What is 420 Hardened used for?
420 Hardened is typically used for surgical scalpel blades, dental instruments, cutlery and knife blades, valve trim and seats, plastic mould inserts and cavities and shafts and bearing races. In short: standard cutting stainless.
What is the yield strength of 420 Hardened?
420 Hardened has a typical yield strength of 1,500 MPa (218 ksi) and a tensile strength of 1,800 MPa (261 ksi) — stronger than 100% of stainless steel grades. Strength varies by condition: see the 8 listed tempers.
Is 420 Hardened easy to machine?
Not especially — machinability is rated poor (15/100, worse than 100% of stainless steel grades). Machine in the annealed condition with sharp, rigid setups, positive-rake carbide, 60–120 m/min and heavy coolant; hardened 48–52 HRC parts need grinding, CBN or hard-turning.
Can 420 Hardened be welded?
Not readily — weldability is rated poor (25/100). Air-hardening and crack-prone: preheat 200–300 °C, use 410/420 or austenitic (309/312) filler, and temper/anneal immediately after welding — avoid welding hardened parts where possible.
What surface finishes work on 420 Hardened?
Takes an excellent mirror polish (mould and cutlery use); passivate or nitric-acid clean after grinding to restore the passive film, and hard-chrome or nitride for extra wear life — never leave scale or free iron on the surface.
Can 420 Hardened be formed, bent or molded?
Cold form only in the annealed state with generous radii and no more than mild bends; hot work 1100→850 °C then slow-cool or anneal at 750–800 °C to avoid quench cracks.
What is the maximum service temperature of 420 Hardened?
420 Hardened is rated for continuous use to about 300°C (572 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 420 Annealed and 420-HIP?
Annealed is the default condition — standard stocked condition for machining, blanking or forming before hardening. HIP: use for powder-metallurgy, MIM or AM parts needing full density and closed internal porosity; delivered in a soft, machinable state ready for hardening. Yield strength is 360 MPa in Annealed versus 480 MPa in HIP.
Can FabDigit make parts in 420 Hardened?
Yes — 420 Hardened 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)
- EN 10088-1/-3 — Stainless steels, X20Cr13 (1.4021), X30Cr13 (1.4028) — CEN (2014)
- GB/T 1220 — (20Cr13/2Cr13) — SAC (2007)
- JIS G 4303 — SUS420J1 / SUS420J2 stainless steel bars — JISC (2012)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- 420 Stainless Steel product data sheet — AK Steel / Cleveland-Cliffs (2020)
- Sandvik / Outokumpu martensitic 13Cr grade datasheets — Alleima / Outokumpu (2022)
- MatWeb / CES EduPack martensitic stainless steel records — MatWeb / Granta (2023)
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.