Tribological Characteristics of Sintered Martensitic Stainless Steels by Nano-Scratch and Nanoindentation Tests

The degradation of parts by wear is inevitable in service, but a reduced rate is encouraged by materials with high abrasion resistance. This paper investigates the scratch resistance of a supersolidus liquid-phase sintered, X190CrVMo20-4-1 martensitic stainless steel densified in a vacuum, and a nitrogen atmosphere after heat treatment. Micromechanical properties of the constituents of the steel samples obtained via nanoindentation supplemented the scratch experiments. Worn grooves on the steel samples were examined using a confocal laser scanning microscope and a scanning electron microscope. A good agreement was among the mechanical properties, scratch hardness, specific scratch wear rate, and instantaneous coefficient of friction of the various microstructural constituents in the steel samples. Nitrogen-sintered steel sample, deep cryogenically treated, had a better scratch resistance owing to the presence of a eutectic network of M7C3 carbides and M(C, N) carbonitrides in a hardened, martensitic matrix. An effective load transfer between the hard phases and the matrix is essential for the excellent abrasive resistance of the steel.