440C | 1.4125 Stainless Steel
440C (1.4125 / X105CrMo17) is a high-carbon martensitic stainless steel offering high hardness, excellent wear resistance, and good corrosion resistance. Its strong hardening capability makes it suitable for precision bearings, cutting tools, industrial knives, and wear-resistant components.
Available Form
Round Bar
Custom Diameter & Length
Flat Bar
Custom Thickness, Width & Length
Square Bar
Custom Width & Length
Steel Plate
Custom Thickness, Width & Length
Steel Grade Comparison
| W-Nr | EN | AISI | JIS |
| 1.4125 | X105CrMo17 | 440C | SUS440C |
Chemical Composition(wt%)
| C | Cr | Mo | Mn | Si | P | S | Fe |
| 1.95~1.20 | 16.0~18.0 | ≤0.75 | ≤1.00 | ≤1.00 | ≤0.04 | ≤0.03 | Balance |
Physical Properties
Density: 7.70 g/cm³
Modulus of Elasticity: 200 GPa
Thermal Conductivity: 15.5 W/(m.K)
| Temperature | 20-100°C | 2-200°C | 2-300°C | 2-400°C |
| Coefficient of Thermal Expansion (×10-6 /K) | 10.4 | 10.8 | 11.2 | 11.6 |
Heat Treatment Process
Hardening: Pre-heat the steel, then heat to 1010~1070°C until the whole section reaches temperature. Quench in oil or air to cool.
Annealing: Heat the steel to 800~920°C, hold it well at temperature, and then let it cool slowly inside the furnace.
Tempering: Must be performed immediately after quenching. Heat the steel uniformly at 100~180°C, hold, then cool in air.
Application Fields
Ball bearings & races, moulds, tableware, valve parts, knives, measuring instruments & other high-hardness, wear-resistant products
Disclaimer: the information and data presented herein are typical values for reference and are not intended as warranties to readers.