440C
440C is a 400 series stainless steel, and is the highest carbon content from 400 stainless steel series. It is usually heat treated to reach hardness of 58–60 HRC. It is a bearing steel, and used in rolling contact stainless bearings, e.g. ball and roller bearings. It is also used to make knife blades. 440C can be oil quenched to achieve maximum hardness.
440C has the highest strength, hardness, and wear resistance of all the commonplace 440-series stainless alloys with high carbon content and moderate corrosion resistance.
