Grade 440C stainless steel is a high carbon martensitic stainless steel. It has high strength, moderate corrosion resistance, and good hardness and wear resistance. Grade 440C is capable of attaining, after heat treatment, the highest strength, hardness and wear resistance of all the stainless alloys. Its very high carbon content is responsible for these characteristics, which make 440C particularly suited to such applications as ball bearings and valve parts.

440C Steel Grade Worldwide Equivalents

Country USA BS & DIN Japan
Standard ASTM A276 EN 10088 JIS G4303
Grades S44004/440C X105CrMo17/1.4125 SUS440C

Chemical Composition

Standard Grade C Mn P S Si Cr Mo
ASTM A276 S44004/440C 0.95-1.20 ≦1.00 ≦0.04 ≦0.03 ≦1.00 16.0-18.0 ≦0.75
EN10088 X105CrMo17/1.4125 0.95-1.20 ≦1.00 ≦0.04 ≦0.03 ≦1.00 16.0-18.0 0.40-0.80
JIS G4303 SUS 440C 0.95-1.20 ≦1.00 ≦0.04 ≦0.03 ≦1.00 16.0-18.0 ≦0.75

Physical Properties

Grade Density (kg/m3) Elastic Modulus (GPa) Mean Coefficient of Thermal Expansion (mm/m/°C) Thermal Conductivity(W/m.K) Specific Heat Electrical Resistivity (nW.m)
0-100°C 0-200°C 0-600°C at 100°C at 500°C 0-100°C (J/kg.K)
440 C 7650 200 10.1 10.3 11.7 24.2 460 600

What is 440C?

A martensitic stainless steel. It's composed of these major alloy elements (I don't list the minor elements since they don't play a major role) :
Carbon: 1.00-1.25% This increases hardenability and wear resistance, but decreases toughness in higher amounts.
Manganese: .45% This is added to reduce brittleness and improve forgeability, hardenability, and reducing deformation.
Silicon: .30% This is a deoxidizer and improves hot-forming properties.
Chromium: 17.00-18.00% Added in high amounts only to high alloy tool steels: this improves hardenability, high wear resistance, toughness, and corrosion resistance.
Molybdenum: .50% Improves deep hardening and toughness, along with wear resistance.
These basic elements (along with iron) are a simple combination that works well together, and has for many decades.

What Stainless Steel Grades We Have!

Qinghe Steel is a full line supplier and processer of stainless steel coil, sheet, plate, bar, and strip products. We stock many grades of stainless steel, including 300 and 400 series stainless, annealed and in various tempers and high temperature grades, for shipments worldwide. View our steel center here