Failure analysis of heat treated HSLA wheel bolt steels

摘要

Purpose - The aims of this study is to analyze failure of two types of high-strength low-alloy (HSLA)rnsteels which are used in wheel bolts 10.9 grade, boron steel and chromium-molybdenum steel, beforernand after heat treatment.rnDesign/methodology/approach - The optimum heat treatment to obtain the best tensile behaviorrnwas determined and Charpy impact and Rockwell hardness tests were performed on the two steelrntypes before and after the optimum heat treating.rnFindings - Fractographic studies show a ductile fracture for heat-treated boron steel while indicate arnsemi-brittle fracture for heat-treated chromium-molybdenum steel. Formation of a small boron carbidernamount during heat treating of boron steel results in increment the bolt's tensile strength while thernductility did not changed significantly. In the other hand, formation of chromium and molybdenumrncarbides during heat treating of chromium-molybdenum steel increased the bolt's tensile strength withrna considerable reduction in the final ductility.rnOriginality/value - This paper evaluates failure analysis of HSLA wheel bolt steels and comparesrntheir microstructure before and after the loading regime.