Enhanced High-Temperature Wear Resistance of Gcr15 Steels Balls by Generating a Ti+Nb Diffusion Layer Via Mechanical Alloying and Nh3·H2o Treatment

Abstract

In this study, mechanical alloying and NH3·H2O treatmentGCr15 steel balls were used to strengthen GCr15 steel balls. The steel balls were first coated with a Ti+Nb coating using ball mill equipped with a home-made grind jar, followed by a NH3·H2O treatment in a common jar to remove the Ti+Nb coating. Surprisingly, a Ti+Nb diffusion layer with a thickness of 5.1µm was generated. The mechanical properties of both processed sample and unprocessed samples were investigated, including grains, dislocations, microhardness, residual stress, and friction properties at different temperatures. The results showed that the processed sample had obvious grain refinement and large dislocation density, with maximum microhardness and compressive residual stress values of 934HV and -490 MPa, respectively. Moreover, the processed samples exhibit great high-temperature wear resistance. In particular, the friction coefficient drop to 0.26 at 400°C, which was 52.73% less than that of unprocessed samples. These findings indicated that the proposed method can improve the high-temperature resistance of some mechanical components, especially for steel balls.

Keywords: GCr15 steel balls, mechanical alloy, Ti+Nb diffusion layer, high temperature, friction