Effect of Cryogenic Treatment and Carbide Spray Coating on the Wear Behavior of Carburized Steel

Abstract

This study is to investigate the wear behavior of carburized JIS SNCM 415 Ni-Cr-Mo steel being cryotreated and followed by carbide spray coating for achieving improvement in wear resistance. Comparative specimens of JIS SNCM 439 steel were quenched and tempered to 45HRC to obtain a similar surface condition as the carburized JIS SNCM415 samples. The thickness of WC/Co coatings of 125 μm was deposited with the use of high velocity oxy-fuel (HVOF) process. The microhardness of the WC/Co coatings has been found to achieve 1025±75 HV. A series of wear tests have been carried out on steel samples subjected to various conditions under 95.9N with 180 rpm on a dry block-on-roller tester. From the result of 12 hr wear tests, the mass loss of carburized SNCM 415 steel through cryotreatment was 0.025 g improved from 0.05g of steel without cryotreatment. In addition, the mass loss of carburized SNCM 415 specimen under cryotreatment and HVOF process was further decreased from 0.025 g to 0.002 g. The mass loss of comparative JIS SNCM 439 steel coated by the HVOF process was decreased to 0.002 g from 0.045 g of steel without coating. The results clearly establish that cryotreatment and HVOF process significantly improve the surface hardness and wear resistance of carburized JIS SNCM 415 steel.