440B

Stainless Steel

440B

High-C high-hardness martensitic, bearings & cutting tools. (ASTM A582; equiv ASTM 440C / EN 1.4125 / JIS SUS440C / GB 102Cr17Mo). Nominal values—confirm mill certificate.

Chemical Composition (%)

C0.75
SI1
MN1
P0.04
S0.03
CR16
MO0.75

Mechanical Properties

Hardness(hardened):≥56 HRC

Chinese Standard

ASTM A582 440B

Equivalent Standards

ASTM 440C / GB 102Cr17Mo

Equivalent Grades

EN 1.4125 / JIS SUS440C

Applications

高碳高硬马氏体，轴承刀具。,"Bar

Available Forms

Strip"

Uses

Martensitic stainless steel combining moderate corrosion resistance with high strength and hardness after heat treatment. Used for cutlery, surgical instruments, turbine blades, valves, pumps, fasteners and bearings in mildly corrosive environments.

Heat Treatment

Annealing/quench from 980–1050 °C (oil or air) then temper 150–650 °C; lower temper gives higher hardness, higher temper improves toughness.

Precautions

Preheat and post-weld heat treat to avoid hydrogen cracking; soft anneal before heavy machining. Lower corrosion resistance than austenitic grades — not for strong chlorides.

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