Correlation between crystal structure and mechanical performance of Cr-implanted 300M high-strength steel using X-ray diffraction method

Abstract

In order to study the influence of crystal structure change due to implantation dose on the hardness and wear performance of 300M high-strength steel, samples were surface modified by Cr implantation with dosages of 5.0 × 1016, 1.5 × 1017 and 3.0 × 1017 ions/cm2. X-ray diffraction method, which was already applied in studies on the microstructure of deformed and heat-treated materials, was used to study the crystal structure of the implanted steel, and the results were corrected with the hardness and wear performance. The solid solution strengthening effect and microstructure vary with increase in implantation dose. Owing to strong solid solution hardening of Cr, small average crystallite size and high dislocation density, the hardness and wear resistance of implanted steel with dose of 5.0 × 1016 ions/cm2 were found to be the highest compared with other samples. Moreover, although the crystallite size of the implanted sample with dose of 3 × 1017 ions/cm2 was similar to that of substrate and the dislocation density was lower than that of the substrate, its higher hardness and lower specific wear rate were due to the solid solution hardening and perhaps Cr clusters reinforcement.