Contribution of cold-work to the wear resistance of materials and its limitation – A study combining molecular dynamics modeling and experimental investigation

Abstract

The wear resistance of metallic materials is largely dependent on their hardness. It is reported that the ratio of hardness to Young's modulus also reflects the wear resistance. The larger the H/E ratio, the higher the wear resistance. However, this ratio appears not working for strain-hardened materials. We observed that the increase in H/E ratio caused by cold-work did not benefit the wear resistance, since plastic deformation generates crystalline defects such as dislocations, leading to deteriorated crystalline integrity. In order to confirm the above points, molecular dynamics (MD) modeling was conducted to investigate the effect of cold-work on mechanical properties and wear resistance of iron as a sample material. Relevant experimental investigation was also conducted on a low carbon steel for further information. The MD modeling revealed how the strain-induced defects affected mechanical properties and wear resistance of the metal. Experimentally, variations in hardness, Young's modulus, wear loss and electron work function of the steel with respect to cold-rolling were measured and analyzed. Both the modeling and experimental studies show that cold-work increases hardness but decreases Young's modulus due to the damage to the overall atomic bond strength. As a result, the larger the increase in H/E ratio, the less beneficial is the cold-work to the wear resistance.