The wear behavior of carburized SNCM 220 steel subjected to cold treatment and carbide spray coating is investigated. WC/Co coatings in 15 +/- 5 mu m thickness were deposited on SNCM 220 specimens in a high velocity oxy-fuel (HVOF) process. Specimens were subjected to wear test under normal loads of 95.9 N at 180 rpm on a dry block-on-roller tester and to two different counter-roller materials with hardness values of 42 and 60 HRC. Wear test result after 12 h showed that the cumulative mass loss measurement of carburized SNCM 220 under 188 K subzero treatment was 15 mg, improved from 37 mg mass loss of SNCM 220 steel without cold treatment. In addition, the cumulative mass loss of carburized SNCM 220 specimens with sprayed carbide coating decreased from 37 mg to 4 mg. Moreover, wear tested specimens with HVOF coatings countered with 42 HRC rollers have resulted higher mass losses than those countered with 60 HRC rollers. Analysis of the wear microstructures has revealed the effects of the cold treatment and HVOF coatings. It has shown that 42 HRC counter roller induced plastic deformation on the specimen surface, which is detrimental to the specimen wear resistance. The compatibility of counter-roller and specimen hardness becomes the major factor to improve the wear of SNCM 220 steel.
