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.
440A and 440B are identical except for slightly lower carbon contents (0.60 - 0.75% and 0.75 - 0.95% respectively); these have lower attainable hardnesses but slightly higher corrosion resistances. Although all three versions of this grade are standard grades, in practice 440C is more available than the A or B variants.
A free-machining variant 440F (UNS S44020) also exists, with the same high carbon content as 440C.
Chemical Composition
Spec: EN 10088-3:2005 1.4125 Steel
| Chemical Element | % Present |
Carbon (C) | 0.95 - 1.20 |
Chromium (Cr) | 16.00 - 18.00 |
Manganese (Mn) | 1.00 max |
Silicon (Si) | 1.00 max |
Phosphorous (P) | 0.04 max |
Sulphur (S) | 0.03 max |
Molybdenum (Mo) | 0.40 - 0.80 |
Iron (Fe) | Balance |
Properties
| Physical Property | Value |
Density | 7.65 g/cm³ |
Thermal Expansion | 10.1 x10^-6 /K |
Modulus of Elasticity | 200 GPa |
Thermal Conductivity | 24.2 W/m.K |
Electrical Resistivity | 0.06 x10^-6 Ω .m |
Spec: EN 10088-3:2005
Bar - Up To 100mm Dia or Thickness
| Mechanical Property | Value |
Proof Stress | 448-1900 MPa |
Tensile Strength | 758-2030 MPa |
Elongation A50 mm | 4-14 % |
Alloy Designations
440C
UNS44004
1.4125
Applications
Typical applications include:
Rolling element bearings
Valve seats
High quality knife blades
Surgical instruments
Chisels
