Stainless Steel 420
AISI/SAE 420 · UNS S42000 · EN 1.4021, X20Cr13 · JIS SUS420, SUS420J1 · GB 20Cr13, 2Cr13
420 is a high-carbon (≥0.15 % C) 13 % Cr martensitic stainless steel that is supplied soft-annealed for machining and then hardened and tempered to 45–52 HRC.
Values for the Annealed condition
420 tempers and conditions
420 is supplied in 8 conditions, soft to hard. Annealed is the default FabDigit quotes; the values on this page are for it.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault soft annealed / mill annealed bar, plate and strip | Standard stocked condition for machining, blanking or forming before hardening. | 360 | 690 | 22 | 200 HB | — |
Hot isostatic pressed | Use for powder-metallurgy, MIM or AM parts needing full density and closed internal porosity; delivered in a soft, machinable state ready for hardening. | 480 | 750 | 15 | 21 HRC | — |
annealed and cold-drawn / cold-finished bar and wire | Pick for close-tolerance turned parts, screws and shafts where extra as-supplied strength and better surface finish are wanted without heat treatment. | 640 | 820 | 12 | 24 HRC | — |
Quenched and high-temperature tempered | Choose when toughness and machinability matter more than wear resistance — shafts, pump/valve stems, structural fittings. | 800 | 1,000 | 15 | 32 HRC | — |
sub-critical stress relief (typically 200–400 °C after hardening, or 650–700 °C after AM/machining) | Use to remove machining, grinding or additive-build residual stress and prevent distortion/cracking, with only partial loss of hardness. | 950 | 1,200 | 9 | 40 HRC | 3 % IACS |
laser powder-bed fusion (L-PBF), as-built from 420 powder | As-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 | 1,350 | 4 | 49 HRC | — |
quenched and tempered 150–350 °C, 48–52 HRC | Standard service condition for cutlery, blades, tool and mould parts, valve trim and wear surfaces needing maximum hardness with best corrosion resistance. | 1,400 | 1,650 | 8 | 50 HRC | — |
austenitised ~1000 °C, oil/air quenched, untempered | Maximum hardness condition; only for parts that will be tempered or for very hard wear surfaces tolerating brittleness. | 1,500 | 1,800 | 2 | 54 HRC | — |
What is 420?
420 is a high-carbon (≥0.15 % C) 13 % Cr martensitic stainless steel that is supplied soft-annealed for machining and then hardened and tempered to 45–52 HRC. It is chosen where moderate stainless corrosion resistance must be combined with high hardness, wear resistance and a mirror-polishable surface — cutlery, surgical and hand tools, valve trim, shafts, plastic-mould inserts and bearing races. Limits are poor weldability (air-hardening, needs pre/post heat), corrosion resistance well below 304/316 (and only good in the hardened-and-polished state), low toughness at high hardness and loss of hardness above ~400 °C. 420 has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 65% of stainless steel grades. It melts at 1,454°C (2,649 °F). 420 has a yield strength of 360 MPa (52.2 ksi) and a tensile strength of 690 MPa (100 ksi) — weaker than 51% of stainless steel grades. Elongation at break is 22% and the elastic modulus is 200 GPa (29 Msi).
What is 420 used for?
- Surgical scalpel blades
- Dental instruments
- Cutlery and knife blades
- Valve trim and seats
- Plastic mould inserts and cavities
- Shafts and bearing races
- Shear and slitting blades
Advantages
- 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
- Low embodied carbon — 3.5 kg CO₂/kg, better than 88% of stainless steel grades
- Conducts heat well — 24.9 W/m·K (14.4 BTU/hr·ft·°F), better than 87% of stainless steel grades
- Easy to machine — 45/100, better than 84% of stainless steel grades
Limitations
- 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 88% of stainless steel grades
- Limited ductility — 22%, worse than 75% of stainless steel grades
420 properties
Typical room-temperature values for 420-Annealed; bars are the position among stainless steel grades.
Physical3
420 has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 65% of stainless steel grades. It melts at 1,454°C (2,649 °F).
Mechanical16
420 has a yield strength of 360 MPa (52.2 ksi) and a tensile strength of 690 MPa (100 ksi) — weaker than 51% of stainless steel grades. Elongation at break is 22% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
420 is rated for continuous service to 650°C (1,202 °F). It conducts heat at 24.9 W/m·K (14.4 BTU/hr·ft·°F), better than 87% of stainless steel grades. Thermal expansion is 10.3 µm/m·K (5.72 µin/in·°F).
Electrical3
420 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 takes about 55 MJ of energy and emits 3.5 kg of CO₂ — more than 50% of stainless steel grades. Typical recycled content is 45%.
Manufacturability7
420's machinability is fair (45/100, better than 84% of stainless steel grades); weldability poor (25/100); formability fair (40/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the stainless steel family
Yield strength against density for every stainless steel grade FabDigit runs. 420 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with 420
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.
Manufacturability
The process limits FabDigit's quote engine applies to 420. Design inside these and the part quotes instantly; outside them it routes to an engineer.
CNC machining
| Machinability | Fair45 / 100 |
|---|---|
| ISO material group | M.4 |
| Cutting speed (rough / finish) | 140 / 170 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1.5 mm |
| Drill depth limit | 4× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
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 |
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.
Surface treatments FabDigit runs on stainless steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Plating
Organic Coating
CVD Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Stainless Steel 420 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
How much does 420 cost?
420 is a premium-cost stainless steel ($$$), cheaper than about 60% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
420 — frequently asked
What is 420 used for?
420 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?
420 has a typical yield strength of 360 MPa (52.2 ksi) and a tensile strength of 690 MPa (100 ksi) — weaker than 51% of stainless steel grades. Strength varies by condition: see the 8 listed tempers.
Is 420 easy to machine?
Reasonably — machinability is rated fair (45/100, better than 84% 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 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?
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 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?
420 is rated for continuous use to about 650°C (1,202 °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.
How much does 420 cost?
420 is a premium-cost stainless steel ($$$), cheaper than about 60% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Can FabDigit make parts in 420?
Yes — 420 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; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.