440C Stainless Steel

Stainless steels are high-alloy steels which have high corrosion resistance compared to other steels due to the presence of large amounts of chromium. Based on their crystalline structure, they are divided into three types such as ferritic, austenitic, and martensitic steels. Another group of stainless steels are precipitation-hardened steels. They are a combination of martensitic and austenitic steels.
Grade 440C stainless steel is a high carbon martensitic stainless steel. It has high strength, moderate corrosion resistance, and good hardness and wear resistance.
The following datasheet gives an overview of grade 440C stainless steel.

Other Designations

Other designations that are equivalent to grade 440C stainless steel include
AMS 5618
AMS 5630
AMS 5880
ASTM A276
ASTM A314
ASTM A473
ASTM A493
ASTM A580
DIN 1.4125
QQ S763
MIL-S-862
SAE 51440C
SAE J405 (51440C)

Fabrication and Heat Treatment

Machinability

Grade 440C stainless steel can be machined in the annealed condition. Chip breakers can be used to handle tough and stringy chips. Carbide or ceramic tooling is preferred for this alloy.

Welding

Grade 440C stainless steel is not welded because it can be easily air hardened. To weld this alloy, it should be preheated to 260°C (500°F) and post weld treated at 732-760°C (1350-1400°F) for 6 h followed by slowly cooling in the furnace to prevent cracking.

Hot Working

Grade 440C stainless steel is pre-heated at 760°C (1400°F). Temperature can be increased up to 1038-1204°C (1900-2200°F). It should not be heated below 927°C (1700°F). It is then slowly cooled at room temperature and fully annealed.

Cold Working

Grade 440C stainless steel is slightly cold workable using common practices.

Annealing

Grade 440C stainless steel is annealed at 843-871°C (1550-1600°F) followed by slowly cooling in the furnace.

Tempering

Grade 440C stainless steel can be tempered by soaking at 148°C (300°F).

Hardening

Grade 440C stainless steel can be hardened by heating at 760°C (1400°F). Temperature can be increased up to 1010°C (1850°F) followed by cooling in air or oil.

Applications

Grade 440C stainless steel is used in the following applications:
Gage blocks
Cutlery
Ball bearings and races
Molds and dies
Knives
Valve components
Measuring instruments