Stainless Steel 420J2 · heat-treated state
Stainless Steel 420J2 +QT800
Properties of the +QT800 condition, compared with the other 420J2 tempers.
European mechanical-property class for tempered bar/forgings where ductility and machinability matter more than hardness.
What is 420J2 +QT800?
420J2 +QT800 is 420J2 heat treated to +QT800 — european mechanical-property class for tempered bar/forgings where ductility and machinability matter more than hardness. 420J2 +QT800 has a yield strength of 650 MPa (94.3 ksi) and a tensile strength of 880 MPa (128 ksi) — stronger than 90% of stainless steel grades. Elongation at break is 12% and the elastic modulus is 200 GPa (29 Msi). 420J2 +QT800 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; +QT800 is available on request or by drawing note.
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 — 3.2 kg CO₂/kg, better than 95% of stainless steel grades
- High strength — 650 MPa (94.3 ksi), better than 90% 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
- Needs corrosion protection — 35/100, worse than 97% of stainless steel grades
- Limited ductility — 12%, worse than 95% of stainless steel grades
- Difficult to weld — 25/100, worse than 92% of stainless steel grades
420J2 +QT800 properties
Typical room-temperature values for 420J2 +QT800 — 12 properties are specific to this condition; the rest are grade-level values shared by every 420J2 temper. Each bar shows where the value sits among the stainless steel grades in FabDigit's library — further right is higher.
Physical3
420J2 +QT800 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).
Mechanical15
420J2 +QT800 has a yield strength of 650 MPa (94.3 ksi) and a tensile strength of 880 MPa (128 ksi) — stronger than 90% of stainless steel grades. Elongation at break is 12% and the elastic modulus is 200 GPa (29 Msi).
Thermal6
420J2 +QT800 is rated for continuous service to 450°C (842 °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 10.5 µm/m·K (5.83 µin/in·°F).
Electrical3
420J2 +QT800 conducts electricity at 3.1 % IACS, better than 99% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is fair (35/100), worse than 97% of stainless steel grades.
Sustainability4
Producing a kilogram of 420J2 +QT800 takes about 45 MJ of energy and emits 3.2 kg of CO₂ — less than 91% of stainless steel grades. Typical recycled content is 60%.
Manufacturability6
420J2 +QT800's machinability is fair (42/100, better than 79% 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 420J2 tempers and conditions
420J2 is also supplied in 6 other conditions. The full side-by-side table is on the 420J2 overview.
- AnnealedDefaultDefault stock condition for machining, blanking and forming before hardening.400 MPa yield · 220 HB
- HardenedMaximum hardness for wear-only parts; brittle and residual-stressed, so a low temper/stress relief is normally applied.1,550 MPa yield · 55 HRC
- Q&T 50-55 HRCChoose for knife blades, scissors and wear surfaces where edge retention outranks toughness.1,550 MPa yield · 53 HRC
- Hardened & TemperedStandard service condition for blades, instruments and valve parts — best balance of hardness, strength and corrosion resistance.1,450 MPa yield · 50 HRC
- Q&T 45-50 HRCSlightly softer, tougher condition for shafts, pump sleeves and mould inserts that see impact.1,300 MPa yield · 47 HRC
- Cold DrawnPick for close-tolerance shafts and wire where extra strength and a bright surface are wanted without heat treatment.700 MPa yield · 26 HRC
- +QT800European mechanical-property class for tempered bar/forgings where ductility and machinability matter more than hardness.650 MPa yield · 27 HRC
Working with 420J2 +QT800
Is 420J2 easy to machine?
Machine in the annealed condition with sharp, rigid tooling, moderate speed and generous coolant; hardened parts above ~45 HRC need carbide or CBN, or should be finished by grinding/EDM.
Can 420J2 be welded?
Poor weldability — preheat 200–300 °C, use matching or 309/310 filler, and temper immediately after welding to avoid cracking of the hard martensite.
Can 420J2 be formed, bent or molded?
Only light cold bending/blanking in the annealed state; harden at 1000–1050 °C, quench in oil or air, then temper at 150–350 °C (avoid 400–550 °C temper embrittlement).
What surface finishes work on 420J2?
Polishes to a mirror finish and is the standard choice for polished mould inserts; passivate or lightly oil after grinding, and consider hard chrome/PVD for extra corrosion or wear protection.
420J2 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 SUS420J2 / GB 3Cr13; EN X30Cr13 is 0.26–0.35 | 0.26 – 0.4 | 0.32 |
| Si | ≤ 1 | 0.4 |
| Mn | ≤ 1 | 0.5 |
| P | ≤ 0.04 | 0.02 |
| SEN limit 0.015; free-machining variants up to 0.030 | ≤ 0.03 | 0.01 |
| Cr | 12 – 14 | 13 |
| Niresidual allowance (JIS/GB) | ≤ 0.6 | 0.3 |
| Fe | balance | — |
420J2 +QT800 — frequently asked
What is 420J2 +QT800 used for?
420J2 +QT800 is typically used for cutlery and kitchen knives, surgical scalpels and instruments, polished plastic mould inserts, scissors and shear blades, valve seats and needle valves and shafts and wear pins. In short: higher-carbon cutlery stainless.
What is the yield strength of 420J2 +QT800?
420J2 +QT800 has a typical yield strength of 650 MPa (94.3 ksi) and a tensile strength of 880 MPa (128 ksi) — stronger than 90% of stainless steel grades. Strength varies by condition: see the 7 listed tempers.
Is 420J2 +QT800 easy to machine?
Not especially — machinability is rated fair (42/100, better than 79% of stainless steel grades). Machine in the annealed condition with sharp, rigid tooling, moderate speed and generous coolant; hardened parts above ~45 HRC need carbide or CBN, or should be finished by grinding/EDM.
Can 420J2 +QT800 be welded?
Not readily — weldability is rated poor (25/100). Poor weldability — preheat 200–300 °C, use matching or 309/310 filler, and temper immediately after welding to avoid cracking of the hard martensite.
What surface finishes work on 420J2 +QT800?
Polishes to a mirror finish and is the standard choice for polished mould inserts; passivate or lightly oil after grinding, and consider hard chrome/PVD for extra corrosion or wear protection.
Can 420J2 +QT800 be formed, bent or molded?
Only light cold bending/blanking in the annealed state; harden at 1000–1050 °C, quench in oil or air, then temper at 150–350 °C (avoid 400–550 °C temper embrittlement).
What is the maximum service temperature of 420J2 +QT800?
420J2 +QT800 is rated for continuous use to about 450°C (842 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in 420J2 +QT800?
Yes — 420J2 +QT800 is available for CNC machining with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- JIS G 4303 — Stainless steel bars (SUS420J2) — JSA (2021)
- GB/T 1220 — Stainless steel bars (3Cr13/30Cr13) — SAC (2007)
- EN 10088-1 / 10088-3 — Stainless steels, X30Cr13 (1.4028) — CEN (2014)
- ASTM A276/A276M — Stainless steel bars and shapes (Type 420) — ASTM (2017)
- ASM Specialty Handbook: Stainless Steels — ASM International (1994)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- Martensitic stainless 1.4028 / 420 bar and strip datasheets — Outokumpu / Sandvik (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.