Surface integrity and tribological behavior of 17Cr2Ni2MoVNb steel under combined carburizing treatment and ultrasonic rolling

Carburizing combined with ultrasonic surface rolling (USR) were introduced to decrease wear rate and coeffi-cient of friction (COF) of a new type gear steel. Microstructure, microhardness, surface morphology and tribo-logical behavior were investigated. Results indicated that specimens underwent combined treatment can generate average surface particles size of 6.67 mu m, microhardness of 918 HV0.2, maximum surface compressive residual stress was-468 MPa. And wear rate of carburized specimen and specimen underwent combined treatment were 3.16 x 10-15 m3/Nm and 2.98 x 10-15 m3/Nm, respectively. Moreover, wear mechanisms of carburized specimens were three-body wear, and specimens underwent combined treatment mainly exhibited adhesive and oxidative wear.