The Influence of Ni Content on the Microstructure and Impact Wear Resistance Performance of High-Chromium Casting Infiltration Coating

Abstract

Casting infiltration technology was used to fabricate a high-chromium coating on the surface of parent ZG45 steel with different Ni content. SEM, EDS analysis, CALPHAD-type calculations, Rockwell hardness test and impact wear test were utilized to investigate the influence of Ni on the microstructure, hardness and impact wear resistance performance. The as-cast microstructure of the casting infiltration coatings with Ni content less than 2.82 wt.% was a pearlite matrix with reticular eutectic M7C3 carbide, while the matrix of the coatings with 5.53 wt.% Ni showed austenite. The content of Ni had little effect on both the solidification behavior and the amount of eutectic M7C3. After heat treatment, the transformation of the matrix to martensite occurred, and the Rockwell hardness significantly increased. The proportion of the retained austenite in the casting infiltration coatings increased from 6.4 vol.% to 27.5 vol.% with increasing Ni content, resulting in a decrease in the hardness. Due to a better balance of the hardness and toughness, the casting infiltration coating with 1.53 wt.% Ni showed the best impact wear resistance performance.