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Stainless Steel 1.4021 +QT650

Heat-treated state

EN 1.4021 · UNS S42000 · AISI/SAE 420 · JIS SUS420J1 · GB 20Cr13, 2Cr13

+QT650 = quenched and tempered, Rm 650–850 MPa

Highest-temper Q&T class: pick when toughness and machinability matter more than strength.

Standard cost $$
Request a quote in 1.4021 +QT6501.4021 overview

Values for the +QT650 condition

Other 1.4021 tempers and conditions

1.4021 is listed in 8 conditions; see the grade overview at 1.4021.

Compare all 8 conditionsHide
Condition · open for datasheetBest forYield MPaTensile MPaElong. %HardnessConductivity
+A
Annealed
Softest condition for machining, cold forming or blanking before the part is hardened.37064024195 HB—
+AR
Hot rolled
Mill hot-rolled bar for re-forging or for parts that will be fully heat treated afterwards.4807601622 HRC3.1 % IACS
+QT650This page
Quenched and tempered, Rm 650–850 MPa
Highest-temper Q&T class: pick when toughness and machinability matter more than strength.5207301918 HRC—
+QT700Default
Quenched and tempered, Rm 700–850 MPa
Most widely stocked Q&T bar class — balanced strength, toughness and machinability for shafts, valve stems and fasteners.5807801722 HRC—
+QT750
Quenched and tempered, Rm 750–950 MPa
Higher-strength Q&T class for pump shafts and highly loaded bolts where some ductility is still required.6308401525 HRC—
+C
Cold drawn
Bright, close-tolerance bar for automatic-lathe parts and shafts that stay unhardened.6407801224 HRC3.1 % IACS
+QT800
Quenched and tempered, Rm 800–950 MPa
Strongest standard Q&T bar class of 1.4021 — for highly stressed shafts and wear parts with reduced impact demands.6808801428 HRC—
+H
Hardened 980–1050 °C and low-temperature tempered
Full-hardness condition for blades, cutting tools, wear plates and plastic-mould inserts; lowest toughness.1,3501,600648 HRC—

What is 1.4021 +QT650?

1.4021 +QT650 is 1.4021 heat treated to +QT650 — highest-temper Q&T class: pick when toughness and machinability matter more than strength. 1.4021 +QT650 has a yield strength of 520 MPa (75.4 ksi) and a tensile strength of 730 MPa (106 ksi) — stronger than 79% of stainless steel grades. Elongation at break is 19% and the elastic modulus is 215 GPa (31.2 Msi). 1.4021 +QT650 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). +QT700 is the default condition FabDigit quotes; +QT650 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
  • Polishes to a fine finish — 85/100, better than 97% of stainless steel grades
  • High strength — 520 MPa (75.4 ksi), better than 79% of stainless steel grades

Limitations

  • Difficult to weld — 30/100, worse than 88% of stainless steel grades
  • Low fracture toughness — 65 MPa·√m (59.2 ksi·√in), worse than 85% of stainless steel grades
  • Needs corrosion protection — 45/100, worse than 85% of stainless steel grades
  • Limited formability — 22/100, worse than 82% of stainless steel grades
  • Limited ductility — 19%, worse than 81% of stainless steel grades

1.4021 +QT650 properties

Typical room-temperature values for 1.4021 +QT650; 18 are specific to this condition. Other listed values are 1.4021 reference data and may not represent this condition. Bars are the position among stainless steel grades.

Physical3

1.4021 +QT650 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).

Density7.7 g/cm³0.28 lb/in³
Melting Point (Solidus)1,450°C2,642 °F
Liquidus Temperature1,510°C2,750 °F

Mechanical16

1.4021 +QT650 has a yield strength of 520 MPa (75.4 ksi) and a tensile strength of 730 MPa (106 ksi) — stronger than 79% of stainless steel grades. Elongation at break is 19% and the elastic modulus is 215 GPa (31.2 Msi).

Elastic (Young's) Modulus215 GPa31.2 Msi
Shear Modulus83 GPa12 Msi
Bulk Modulus162 GPa23.5 Msi
Poisson's Ratio0.29
Tensile Strength (Ultimate)730 MPa106 ksi
Yield Strength (0.2% offset)520 MPa75.4 ksi
Elongation at Break19%
Reduction in Area55%
Compressive Strength590 MPa85.6 ksi
Shear Strength440 MPa63.8 ksi
Fatigue Strength (Endurance Limit)340 MPa49.3 ksi
Fracture Toughness (K_IC)65 MPa·√m59.2 ksi·√in
Charpy V-Notch Impact (RT)45 J33.2 ft·lbf
Hardness, Brinell215 HB
Hardness, Rockwell C18 HRC
Hardness, Vickers225 HV

Thermal6

1.4021 +QT650 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).

Thermal Conductivity30 W/m·K17.3 BTU/hr·ft·°F
Specific Heat Capacity460 J/kg·K0.11 BTU/lb·°F
Thermal Expansion (CTE, 20–100 °C)10.5 µm/m·K5.8 µin/in·°F
Latent Heat of Fusion260 J/g112 BTU/lb
Max Service Temperature (continuous)500°C932 °F
Min Service Temperature-30°C-22 °F

Electrical3

1.4021 +QT650 conducts electricity at 3.1 % IACS, better than 99% of stainless steel grades.

Electrical Conductivity3.1 % IACS
Electrical Resistivity5.5×10⁻⁷ Ω·m21.7 µΩ·in
Magnetic Responseferromagnetic

Chemical & Environmental3

Corrosion resistance is fair (45/100), worse than 85% of stainless steel grades.

Galvanic Potential (seawater, vs SCE)-0.3 V
Corrosion ResistanceFair45/100
Chemical Resistance SummaryPassive in fresh water, steam, mild atmospheres, alcohols, many organics and dilute nitric acid when fully hardened and polished; attacked by chlorides (pitting/crevice), seawater, halogenated acids, reducing acids (HCl, H2SO4) and prolonged wet marine exposure.

Sustainability4

Producing a kilogram of 1.4021 +QT650 takes about 53 MJ of energy and emits 4.3 kg of CO₂ — less than 67% of stainless steel grades. Typical recycled content is 55%.

Embodied Energy (primary production)53 MJ/kg22,786 BTU/lb
Embodied Carbon (primary production)4.3 kg CO₂/kg
Embodied Water100 L/kg12 gal/lb
Typical Recycled Content55%

Manufacturability7

1.4021 +QT650's machinability is fair (44/100, better than 81% of stainless steel grades); weldability poor (30/100); formability poor (22/100).

MachinabilityFair44/100
Machinability Rating (AISI 1212 = 100 %)45%
WeldabilityPoor30/100
Formability (cold)Poor22/100
Brazeability / SolderabilityFair40/100
PolishabilityExcellent85/100
Anodizing Responsen/a — ferrous alloy; use passivation (ASTM A967), electropolishing, hard chrome or PVD instead

Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.

Working with 1.4021 +QT650

Is 1.4021 easy to machine?

Machine in the annealed or ≤ 250 HB Q&T condition with sharp, rigid tooling, ~25–35 % lower speed than 304 and generous coolant; above 40 HRC switch to ceramic/CBN or grinding.

Can 1.4021 be welded?

Weldable only with preheat 200–300 °C, matching 410/420 or austenitic 309L filler, and immediate 700–750 °C temper — otherwise hard, crack-prone HAZ martensite.

Can 1.4021 be formed, bent or molded?

Cold bending and light forming only in the +A condition with generous radii (≥2t); hot work at 1100–1150 °C, stop above 900 °C, then slow-cool or anneal to avoid quench cracking.

What surface finishes work on 1.4021?

Takes a mirror or blade polish very well; passivate per ASTM A967 (nitric or citric, avoid over-pickling) after machining, and hard chrome, nitride or PVD coat where extra wear/corrosion life is needed.

1.4021 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.

ElementSpec limit (wt %)Nominal
CEN 10088-3 X20Cr130.16 – 0.250.2
Si≤ 10.4
Mn≤ 1.50.5
P≤ 0.04—
S≤0.015 for improved polishability grades; free-machining variant 1.4029 has 0.15–0.35 S≤ 0.03—
Cr12 – 1413
NiNot limited by EN 10088-3; ASTM A276 Type 420 and many mill specs cap at ~0.75≤ 0.750.3
Febalance—

1.4021 +QT650 — frequently asked

What is 1.4021 +QT650 used for?

1.4021 +QT650 is typically used for cutlery, surgical instruments, valve trim, molds and pump shafts. In short: hardens to 45–50 HRC; workhorse 420 bar grade; stronger than 1.4006.

What is the yield strength of 1.4021 +QT650?

1.4021 +QT650 has a typical yield strength of 520 MPa (75.4 ksi) and a tensile strength of 730 MPa (106 ksi) — stronger than 79% of stainless steel grades. Strength varies by condition: see the 8 listed tempers.

Is 1.4021 +QT650 easy to machine?

Not especially — machinability is rated fair (44/100, better than 81% of stainless steel grades). Machine in the annealed or ≤ 250 HB Q&T condition with sharp, rigid tooling, ~25–35 % lower speed than 304 and generous coolant; above 40 HRC switch to ceramic/CBN or grinding.

Can 1.4021 +QT650 be welded?

Not readily — weldability is rated poor (30/100). Weldable only with preheat 200–300 °C, matching 410/420 or austenitic 309L filler, and immediate 700–750 °C temper — otherwise hard, crack-prone HAZ martensite.

What surface finishes work on 1.4021 +QT650?

Takes a mirror or blade polish very well; passivate per ASTM A967 (nitric or citric, avoid over-pickling) after machining, and hard chrome, nitride or PVD coat where extra wear/corrosion life is needed.

Can 1.4021 +QT650 be formed, bent or molded?

Cold bending and light forming only in the +A condition with generous radii (≥2t); hot work at 1100–1150 °C, stop above 900 °C, then slow-cool or anneal to avoid quench cracking.

What is the maximum service temperature of 1.4021 +QT650?

1.4021 +QT650 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.

Sources

  1. EN 10088-1 Stainless steels — List of stainless steels — CEN (2014)
  2. EN 10088-3 Stainless steels — Semi-finished products, bars, rods, wire, sections and bright products — CEN (2014)
  3. ASTM A276/A276M Stainless Steel Bars and Shapes (Type 420 / UNS S42000) — ASTM International (2017)
  4. GB/T 1220 (20Cr13) — SAC (2007)
  5. JIS G4303 Stainless steel bars (SUS420J1) — JSA (2021)
  6. ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
  7. ASM Specialty Handbook — Stainless Steels — ASM International (1994)
  8. Martensitic stainless bar datasheets (1.4021 / 420) — Outokumpu / Sandvik / Böhler-Uddeholm (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.