AISI 420 Martensitic Stainless Steel
AISI 420 (UNS S42000) — basic martensitic stainless, HRC 48–54, food-grade toughness. Compare with 440A/B/C for your cutting application.
AISI 420 (UNS S42000, DIN 1.4021) is the basic entry-grade martensitic stainless steel — modest carbon, modest hardness (HRC 48–54) but high corrosion resistance and good toughness. It is the default grade for food-processing blades, surgical instruments and pump / valve components where 440-grade hardness is not required and impact loading is the dominant failure mode.
Standard composition: C 0.15 % min, Cr 12.0–14.0 %, Mn ≤ 1.00 %, Si ≤ 1.00 %, Ni ≤ 0.75 %, balance Fe
Hardness: Annealed HB 195–230; hardened HRC 48–54
Heat treatment: Austenitise 980–1,030 °C, oil or air cool, temper 150–200 °C
Properties: The basic martensitic stainless. Modest hardness (HRC 50) but high corrosion resistance. Tough, easy to grind. The “20” in 420 indicates a 0.20 % C minimum; 420HC at 0.40 % C is a variant for cutlery.
Applications: Food processing blades, surgical instruments, pump shafts, valve parts, low-stress cutlery.
Cross-reference: ≈ JIS SUS420J1/J2, DIN 1.4021/1.4028, GB 2Cr13/3Cr13.
See also.
