Stainless Steel 420J1 · heat-treated state
Stainless Steel 420J1-QT800
Properties of the QT800 condition, compared with the other 420J1 tempers.
Highest tempered-strength EN condition, used for higher-load shafts and blades still needing measurable toughness.
What is 420J1-QT800?
420J1-QT800 is 420J1 heat treated to QT800 — highest tempered-strength EN condition, used for higher-load shafts and blades still needing measurable toughness. 420J1-QT800 has a yield strength of 660 MPa (95.7 ksi) and a tensile strength of 880 MPa (128 ksi) — stronger than 91% of stainless steel grades. Elongation at break is 13% and the elastic modulus is 200 GPa (29 Msi). 420J1-QT800 has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 83% of stainless steel grades. It melts at 1,450°C (2,642 °F). Annealed is the default condition FabDigit quotes; QT800 is available on request or by drawing note.
Advantages
- Conducts heat well — 30 W/m·K (17.3 BTU/hr·ft·°F), better than 99% of stainless steel grades
- High electrical conductivity — 3.1 % IACS, better than 99% of stainless steel grades
- Low embodied carbon — 3 kg CO₂/kg, better than 97% of stainless steel grades
- High strength — 660 MPa (95.7 ksi), better than 91% of stainless steel grades
- Polishes to a fine finish — 80/100, better than 89% of stainless steel grades
Limitations
- Needs corrosion protection — 38/100, worse than 95% of stainless steel grades
- Limited ductility — 13%, worse than 93% of stainless steel grades
- Difficult to weld — 35/100, worse than 86% of stainless steel grades
420J1-QT800 properties
Typical room-temperature values for 420J1-QT800 — 11 properties are specific to this condition; the rest are grade-level values shared by every 420J1 temper. Each bar shows where the value sits among the stainless steel grades in FabDigit's library — further right is higher.
Physical3
420J1-QT800 has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 83% of stainless steel grades. It melts at 1,450°C (2,642 °F).
Mechanical14
420J1-QT800 has a yield strength of 660 MPa (95.7 ksi) and a tensile strength of 880 MPa (128 ksi) — stronger than 91% of stainless steel grades. Elongation at break is 13% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
420J1-QT800 is rated for continuous service to 500°C (932 °F). It conducts heat at 30 W/m·K (17.3 BTU/hr·ft·°F), better than 99% of stainless steel grades. Thermal expansion is 10.5 µm/m·K (5.83 µin/in·°F).
Electrical3
420J1-QT800 conducts electricity at 3.1 % IACS, better than 99% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is fair (38/100), worse than 95% of stainless steel grades.
Sustainability4
Producing a kilogram of 420J1-QT800 takes about 42 MJ of energy and emits 3 kg of CO₂ — less than 95% of stainless steel grades. Typical recycled content is 55%.
Manufacturability7
420J1-QT800's machinability is poor (34/100, worse than 55% of stainless steel grades); weldability fair (35/100); formability fair (45/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 420J1 tempers and conditions
420J1 is also supplied in 7 other conditions. The full side-by-side table is on the 420J1 overview.
- AnnealedDefaultDefault stock condition for machining, cold forming and blanking before customer heat treatment.440 MPa yield · 195 HB
- Hardened & Stress RelievedMaximum-hardness cutting/wear condition supplied for knife blades and dies where toughness is secondary.1,500 MPa yield · 52 HRC
- Hardened & TemperedChoose for cutlery edges, wear parts and instruments that need maximum hardness and best passive-film corrosion behaviour.1,350 MPa yield · 48 HRC
- QT800Highest tempered-strength EN condition, used for higher-load shafts and blades still needing measurable toughness.660 MPa yield · 27 HRC
- Cold DrawnPick for close-tolerance bright bar with better surface and chip control where no subsequent hardening is planned.620 MPa yield · 23 HRC
- QT750Mid-strength engineering condition for valve stems, pump shafts and machined fittings.610 MPa yield · 24 HRC
- QT650Tough structural condition for shafts, bolts and fittings where ductility matters more than hardness.500 MPa yield · 18 HRC
Working with 420J1-QT800
Is 420J1 easy to machine?
Machine in the annealed condition with sharp, rigid tooling, moderate speeds and generous coolant; hardened material above ~45 HRC needs carbide/CBN or grinding.
Can 420J1 be welded?
Poor weldability: preheat 200–300 °C, low-hydrogen 410/420-type or austenitic filler, and post-weld temper at 700–750 °C to avoid martensitic cracking.
Can 420J1 be formed, bent or molded?
Cold-form only when fully annealed and with generous radii; hot work 1100–850 °C followed by slow cooling and annealing, harden from 980–1050 °C with oil or air quench.
What surface finishes work on 420J1?
Takes a bright mirror polish (cutlery finish) which is essential to corrosion performance; passivate after machining, and hard chrome, nitride or PVD coatings are common for extra wear resistance.
420J1 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 SUS420J1 / EN X20Cr13 | 0.16 – 0.25 | 0.2 |
| Si | ≤ 1 | 0.4 |
| Mn | ≤ 1 | 0.5 |
| PEN limit 0.040; JIS 0.040 | ≤ 0.04 | — |
| SEN 0.015 max for some products | ≤ 0.03 | — |
| Cr | 12 – 14 | 13 |
| Niresidual, JIS allowance | ≤ 0.6 | 0.25 |
| Fe | balance | — |
420J1-QT800 — frequently asked
What is 420J1-QT800 used for?
420J1-QT800 is typically used for cutlery, surgical instruments and plastic molds. In short: cutlery-grade martensitic stainless.
What is the yield strength of 420J1-QT800?
420J1-QT800 has a typical yield strength of 660 MPa (95.7 ksi) and a tensile strength of 880 MPa (128 ksi) — stronger than 91% of stainless steel grades. Strength varies by condition: see the 8 listed tempers.
Is 420J1-QT800 easy to machine?
Not especially — machinability is rated poor (34/100, worse than 55% of stainless steel grades). Machine in the annealed condition with sharp, rigid tooling, moderate speeds and generous coolant; hardened material above ~45 HRC needs carbide/CBN or grinding.
Can 420J1-QT800 be welded?
With care — weldability is rated fair (35/100). Poor weldability: preheat 200–300 °C, low-hydrogen 410/420-type or austenitic filler, and post-weld temper at 700–750 °C to avoid martensitic cracking.
What surface finishes work on 420J1-QT800?
Takes a bright mirror polish (cutlery finish) which is essential to corrosion performance; passivate after machining, and hard chrome, nitride or PVD coatings are common for extra wear resistance.
Can 420J1-QT800 be formed, bent or molded?
Cold-form only when fully annealed and with generous radii; hot work 1100–850 °C followed by slow cooling and annealing, harden from 980–1050 °C with oil or air quench.
What is the maximum service temperature of 420J1-QT800?
420J1-QT800 is rated for continuous use to about 500°C (932 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between 420J1 Annealed and 420J1-QT800?
Annealed is the default condition — default stock condition for machining, cold forming and blanking before customer heat treatment. QT800: highest tempered-strength EN condition, used for higher-load shafts and blades still needing measurable toughness. Yield strength is 440 MPa in Annealed versus 660 MPa in QT800.
Can FabDigit make parts in 420J1-QT800?
Yes — 420J1-QT800 is available for CNC machining with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- EN 10088-3 Stainless steels — semi-finished products, bars, rods (X20Cr13, 1.4021) — CEN (2014)
- JIS G 4303 Stainless steel bars (SUS420J1) — JSA (2021)
- GB/T 1220 (2Cr13 / 20Cr13) — SAC (2007)
- ASTM A276/A276M Stainless Steel Bars and Shapes (Type 420) — ASTM (2017)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.13B — Corrosion: Materials — ASM International (2005)
- Stainless steel 1.4021 / X20Cr13 bar and strip datasheets — Outokumpu / Sandvik / Böhler (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.