Microstructure and properties of austenitic stainless steel reinforced with in situ TiC particulate

Austenitic stainless steel reinforced with 5 vol.% TiC particulate was in situ synthesized by in situ reaction during melting process successfully and its microstructure, mechanical properties as well as oxidation behavior were investigated. Microstructure observations revealed that in situ TiC particulates with an average size of 2–10 μm distributed uniformly in the matrix and the interface boundaries between TiC particulates and austenite matrix were clean without any impurities and contaminations. Addition of TiC particulates refined the grain structure of austenitic matrix, but did not cause formation of any new phases in microstructure. Beneficial effects of TiC addition to austenitic stainless steel on both mechanical properties and oxidation resistance were found. Both at ambient and elevated temperature, tensile strengths of the steel with TiC addition were notably higher than those of its matrix alloy, however, a decrease in ductility also appeared, as exhibited by other particulate reinforced alloys. Besides tensile strengths, creep resistance of austenitic stainless steel was also significantly increased by TiC addition at elevated temperature of 923 K. Oxidation test at 1073 K revealed that TiC addition to austenitic stainless steel raised the oxidation resistance of the steel remarkably.