Stainless Steel 420C · heat-treated state · default condition
Stainless Steel 420C +A
Properties of the +A condition, compared with the other 420C tempers.
Stock condition for machining, blanking and subsequent hardening; lowest hardness and best machinability.
What is 420C +A?
420C +A is 420C heat treated to +A — stock condition for machining, blanking and subsequent hardening; lowest hardness and best machinability. 420C +A has a yield strength of 460 MPa (66.7 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 73% of stainless steel grades. Elongation at break is 17% and the elastic modulus is 215 GPa (31.2 Msi). 420C +A has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 83% of stainless steel grades. It melts at 1,425°C (2,597 °F).
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 — 3.4 kg CO₂/kg, better than 91% of stainless steel grades
- Easy to machine — 45/100, better than 84% of stainless steel grades
Limitations
- Difficult to weld — 20/100, worse than 96% of stainless steel grades
- Low fracture toughness — 55 MPa·√m (50.1 ksi·√in), worse than 94% of stainless steel grades
- Needs corrosion protection — 42/100, worse than 90% of stainless steel grades
- Limited ductility — 17%, worse than 86% of stainless steel grades
- Limited service temperature — 400°C (752 °F), worse than 78% of stainless steel grades
420C +A properties
Typical room-temperature values for 420C +A — 14 properties are specific to this condition; the rest are grade-level values shared by every 420C temper. Each bar shows where the value sits among the stainless steel grades in FabDigit's library — further right is higher.
Physical3
420C +A has a density of 7.7 g/cm³ (0.278 lb/in³), lighter than 83% of stainless steel grades. It melts at 1,425°C (2,597 °F).
Mechanical17
420C +A has a yield strength of 460 MPa (66.7 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 73% of stainless steel grades. Elongation at break is 17% and the elastic modulus is 215 GPa (31.2 Msi).
Thermal6
420C +A is rated for continuous service to 400°C (752 °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
420C +A conducts electricity at 3.1 % IACS, better than 99% of stainless steel grades.
Chemical & Environmental3
Corrosion resistance is fair (42/100), worse than 90% of stainless steel grades.
Sustainability4
Producing a kilogram of 420C +A takes about 50 MJ of energy and emits 3.4 kg of CO₂ — less than 81% of stainless steel grades. Typical recycled content is 45%.
Manufacturability8
420C +A's machinability is fair (45/100, better than 84% of stainless steel grades); weldability poor (20/100); formability poor (30/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other 420C tempers and conditions
420C is also supplied in 7 other conditions. The full side-by-side table is on the 420C overview.
- +ADefaultStock condition for machining, blanking and subsequent hardening; lowest hardness and best machinability.460 MPa yield · 20 HRC
- CR+HT stripPrecision-rolled, continuously hardened-and-tempered thin strip supplied ready to blank and grind into blades.1,850 MPa tensile
- QT 50-55 HRCStandard cutlery/surgical-blade condition: maximum wear resistance and edge retention with acceptable corrosion resistance.1,550 MPa yield · 54 HRC
- QT 45-50 HRCBest hardness/toughness compromise for shear blades, valve components and moulds.1,300 MPa yield · 48 HRC
- +QT800Medium-strength Q&T condition where some impact toughness must be retained alongside higher strength.650 MPa yield · 28 HRC
- +QT650High-temperature-tempered condition for shafts and structural parts needing ductility rather than wear resistance.500 MPa yield · 21 HRC
Working with 420C +A
Is 420C easy to machine?
Machine in the annealed condition with sharp, rigid carbide or HSS-Co tooling, moderate speed and heavy flood coolant; above ~45 HRC switch to CBN/ceramic turning or grinding/EDM.
Can 420C be welded?
Poor weldability — high carbon promotes hard, crack-prone martensite; if unavoidable, preheat 200–300 °C, use 410NiMo/309 filler, and temper immediately after welding.
Can 420C be formed, bent or molded?
Only light cold forming and blanking in the annealed state (generous bend radii, R ≥ 2t); hot work 1100–850 °C followed by slow cooling and full anneal to avoid quench cracks.
What surface finishes work on 420C?
Takes a mirror polish; harden, temper and then passivate (ASTM A967 nitric/citric) for best corrosion resistance — hard chrome, nitriding or PVD coatings are common for wear parts.
420C 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 |
|---|---|---|
| CGB/T 1220 4Cr13 typically 0.36–0.45 %C | 0.43 – 0.5 | 0.46 |
| Si | ≤ 1 | 0.4 |
| Mn | ≤ 1 | 0.5 |
| P | ≤ 0.04 | 0.02 |
| S | ≤ 0.03 | 0.01 |
| Cr | 12.5 – 14.5 | 13.5 |
| Niresidual, not specified in all standards | ≤ 0.5 | 0.2 |
| Moresidual | ≤ 0.3 | — |
| Fe | balance | — |
420C +A — frequently asked
What is 420C +A used for?
420C +A is typically used for cutlery & blades, surgical instruments and bearings. In short: high-carbon cutlery stainless.
What is the yield strength of 420C +A?
420C +A has a typical yield strength of 460 MPa (66.7 ksi) and a tensile strength of 760 MPa (110 ksi) — stronger than 73% of stainless steel grades. Strength varies by condition: see the 8 listed tempers.
Is 420C +A 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 carbide or HSS-Co tooling, moderate speed and heavy flood coolant; above ~45 HRC switch to CBN/ceramic turning or grinding/EDM.
Can 420C +A be welded?
Not readily — weldability is rated poor (20/100). Poor weldability — high carbon promotes hard, crack-prone martensite; if unavoidable, preheat 200–300 °C, use 410NiMo/309 filler, and temper immediately after welding.
What surface finishes work on 420C +A?
Takes a mirror polish; harden, temper and then passivate (ASTM A967 nitric/citric) for best corrosion resistance — hard chrome, nitriding or PVD coatings are common for wear parts.
Can 420C +A be formed, bent or molded?
Only light cold forming and blanking in the annealed state (generous bend radii, R ≥ 2t); hot work 1100–850 °C followed by slow cooling and full anneal to avoid quench cracks.
What is the maximum service temperature of 420C +A?
420C +A 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.
Can FabDigit make parts in 420C +A?
Yes — 420C +A is available for CNC machining with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- EN 10088-1/-2/-3 (X46Cr13, 1.4034) — CEN (2014)
- GB/T 1220 (4Cr13) — SAC (2007)
- ASTM A276/A582 (Type 420) — ASTM (2017)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
- ASM Handbook Vol.13B / Vol.16 — Corrosion and Machining — ASM International (2005)
- Martensitic knife/blade strip datasheets (1.4034-class) — Alleima/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.