Carbides and mechanical properties in a Fe-Cr-Ni-Mo high-strength steel with different V contents

Fe-Cr-Ni-Mo high-strength steels with four different V contents (0%, 0.03%, 0.08% and 0.14%) were prepared in this paper and carbides evolution was investigated by means of three-dimensional atom probe (3DAP) and transmission electron microscopy (TEM). The results indicated that there appeared MC, M2C and M6C types of carbides after addition of V in the steels while it was M23C6 in 0.0%V steel (M is any combination of Cr, Mo, Mn, Fe or V), and the size of carbides decreased gradually with improving V content. The mechanical properties significantly depended on the content of V. The strength and elongation increased gradually with increase in the V content, meanwhile the impact toughness decreased gradually. The excellent combination of mechanical properties can be obtained in the steel with about 0.03%-V content.