Stainless Steel 420 · heat-treated state
Stainless Steel 420 Stress Relieved
Properties of the Stress Relieved condition, compared with the other 420 tempers.
Use to remove machining, grinding or additive-build residual stress and prevent distortion/cracking, with only partial loss of hardness.
What is 420 Stress Relieved?
420 Stress Relieved is 420 heat treated to Stress Relieved — use to remove machining, grinding or additive-build residual stress and prevent distortion/cracking, with only partial loss of hardness. 420 Stress Relieved has a yield strength of 950 MPa (138 ksi) and a tensile strength of 1,200 MPa (174 ksi) — stronger than 98% of stainless steel grades. Elongation at break is 9% and the elastic modulus is 200 GPa (29 Msi). 420 Stress Relieved 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; Stress Relieved is available on request or by drawing note.
Advantages
- High electrical conductivity — 3.1 % IACS, better than 99% of stainless steel grades
- High strength — 950 MPa (138 ksi), better than 98% 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 — 9%, worse than 99% 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
- Low fracture toughness — 60 MPa·√m (54.6 ksi·√in), worse than 91% of stainless steel grades
- Limited service temperature — 400°C (752 °F), worse than 78% of stainless steel grades
420 Stress Relieved properties
Typical room-temperature values for 420 Stress Relieved — 9 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 Stress Relieved 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 Stress Relieved has a yield strength of 950 MPa (138 ksi) and a tensile strength of 1,200 MPa (174 ksi) — stronger than 98% of stainless steel grades. Elongation at break is 9% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
420 Stress Relieved is rated for continuous service to 400°C (752 °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 Stress Relieved 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 Stress Relieved 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 Stress Relieved's machinability is poor (30/100, worse than 71% 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 Stress Relieved
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 Stress Relieved — frequently asked
What is 420 Stress Relieved used for?
420 Stress Relieved 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 Stress Relieved?
420 Stress Relieved has a typical yield strength of 950 MPa (138 ksi) and a tensile strength of 1,200 MPa (174 ksi) — stronger than 98% of stainless steel grades. Strength varies by condition: see the 8 listed tempers.
Is 420 Stress Relieved easy to machine?
Not especially — machinability is rated poor (30/100, worse than 71% 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 Stress Relieved 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 Stress Relieved?
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 Stress Relieved 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 Stress Relieved?
420 Stress Relieved is rated for continuous use to about 400°C (752 °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 Stress Relieved?
Yes — 420 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)
- 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.