General characteristics of stainless steel 440C
This martensitic alloy shows good stainless steel properties with maximum hardness and is mainly used as bearing steel. It is used in hardened and tempered condition and can be obtained Rc60 by heat treatment.
Application of stainless steel 440C
Alloy 440C is used in bearing assemblies, balls and ball-tables, needle valves, ball check valves, valve seats, pump parts, ball studs, bushings and wear-resistant textile components. This alloy is not suitable for use at high temperatures, but is fine in normal household and mild industrial environments.
Forged stainless steel 440C
This steel heat works like a high speed tool steel. Preheat to 1400/1500oF (760/815oC), then slowly lower to 1900/2100oF (1040/1150oC). Do not forge below 1700oF (925oC) and reheat as necessary. The furnace is as cool as possible, or in warm lime or ash. Anneal after forging, but parts may be cooled to room temperature before annealing. The alloy must be careful to avoid cracking.
heat treatment
annealing
For maximum softness heat evenly to 1550/1600oF (840/870oC) and steep, then cool very slowly in the oven.
For intermediate or process annealing, uniform heating to 1350/1400°F (730/760oC), furnace or air cooling.
hardening
Preheat to 1400/1500oF (760/815oC) - then to 1850/1950oF (1010/1065oC) - immerse in warm oil or air to cool. For better carbide solution, heat to 2000oF (1090oC)
Temper
The alloy will achieve Rc 60. To relieve peak stresses and maintain maximum hardness temper at 300/350oF (150/175°C) for at least 1 hour.
Machinability
For best machinability, dead soft annealing conditions are optimal, as well as the use of carbide or ceramic tools and chip coilers and breakers.
Weldability
This alloy is seldom welded, but if you actually heat it before and after it needs to be very careful. A typical welding process consists of preheating, held at 500oF (260oC), followed by welding, followed by six hour annealing at 1350/1400°F (730/760oC) - cooling in a slow furnace between welding and annealing to below 500oF (260oC).
