440C (1.4125) grade stainless steel can achieve the highest strength, hardness and wear resistance among all stainless alloys after heat treatment. The very high carbon content is responsible for these properties that make the 440C particularly suitable for applications such as ball seats and valve parts.
The 440A and 440B grades are the same except for slightly lower carbon contents (0, 60 - 0.75% and 0.75 - 0.95 % respectively ); they have lower achievable hardness but slightly higher corrosion resistance.
A freehand variant 440F (UNS S44020) with the same high carbon content as the 440C is also available.
Martensitic stainless steels are optimized for high hardness and other properties are somewhat at risk. Fabrication should be done by methods that allow poor weldability and generally allow a final hardening and tempering heat treatment. Corrosion resistance is inferior to common austenitic grades, and the useful operating temperature range is limited by loss of ductility at sub-zero temperatures and power loss due to excessive tempering at high temperatures .
Good resistance to atmosphere, fresh water, food, alkalis and mild acids. Best resistance in hardened, annealed and passivated condition. The smooth polished surface also helps.
The corrosion resistance of 440C grade approaches 304 quality in many environments.
Source llama structure preheated at 250 ° C and if necessary follow the exact source of a backgammon. The 420 grade material filler will weld high hardness (although not as high as 440C), but will produce soft welds with a higher ductility of 309 or 310 .