Effects of load on abrasive-wear behavior of Nb-strengthening hypoeutectic Fe-Cr-C hardfacing alloy at a 2-body abrasives environment

Abstract

The abrasive-wear test of pin on emery paper based on ASTM G132 was performed on Nb-strengthening hypoeutectic Fe–Cr–C hardfacing alloy and NM450 steel as comparative materials. The abrasive-wear behavior evolution of hardfacing alloy with various load conditions (5 N, 10 N, 15 N, 20 N, 25 N) was mainly investigated, through the methods of wear loss statistics, wear scar morphology analysis, wear scar roughness analysis, and the test of single furrow volume on wear scar. The results showed that the microstructures of hardfacing alloy consisted of the austenitic dendrites matrix, the dispersed NbC distributed on matrix, and the network eutectic. The microstructure of NM450 steel was mainly uniform tempered-sorbite. Although the wear-resistance of alloy was better than that of NM450 steel and always showed a lower level of wear loss under any load condition, the increase in load lifted the unevenness of the abrasive wear of alloy, causing the alloy wear loss to show a non-linear increase with the gradually-increasing growth rate. The micro wear mechanism of alloy was mainly ploughing and NbC spalling. The increasing load lifted the degree of NbC spalling, making it difficult for the austenite matrix to be effectively protected by dispersed NbC. In contrast, the wear mechanism of NM450 steel was fatigue wear. The presence of tempered-sorbite with low-hardness and good plasticity made the NM450 steel susceptible to severe tearing and fatigue, and the increasing load only contributed to a stable lifting in fatigue wear degree. For hardfacing alloy, the high-hardness NbC debris that were unstable to spall off tended to become the 3-body abrasives with high stress, improving the overall cutting ability of abrasives and aggravating abrasive-wear, which is the root cause of fact that the alloy wear loss showed non-linear growth with load condition.