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Martensitic stainless steels are essentially alloys of chromium and carbon that possess a martensitic crystal structure in the hardened condition. They are ferromagnetic, hardenable by heat treatments, and are usually less resistant to corrosion than some other grades of stainless steel. Excess carbides may be present to enhance wear resistance or as in the case of knife blades, to maintain cutting edges.
The major alloying addition in martensitic stainless steels is chromium in the range of 11 to 17%. The carbon levels can vary from 0.10 to 0.65% in these alloys. The high carbon enables the material to be hardened by heating to a high temperature, followed by rapid cooling (quenching). This makes for a good combination of corrosion resistance and superior mechanical properties, as produced by heat treatment to develop maximum hardness, strength and resistance to abrasion and erosion.
End uses include cutlery, scissors, surgical instruments, wear plates, garbage disposal shredder lugs, and industrial knives. |