Mechanisms governing cyclic fracture behavior of two high-strength steels: role of composition and microstructure

In this article, the cyclic fatigue fracture behavior of two high-strength specialty steels denoted as Tenax 310 and 300 M, is presented and discussed. The two chosen specialty steels have noticeably improved properties to offer than most steels in this category and even other competing high-strength steels. The observed improvement can be ascribed to be because of the synergistic and mutually interactive influences of chemical composition and secondary processing technique used for the two steels. The two chosen high-strength steels, designated by the manufacturer as Tenax 310 and 300 M, were produced by initial melting using vacuum arc remelting and then casting to obtain ingots. The cast ingots were mechanically deformed by hot working to get the starting blocks. At the fine microscopic level, cyclic fatigue fracture of these two steels revealed features reminiscent of the occurrence of “locally” ductile and brittle failure mechanisms. Over the range of maximum stress and at the two different load ratios, the two steels were cyclically deformed. It was observed that the cyclic fatigue resistance of the candidate steels was noticeably higher than their high-strength steels counterparts for which data are available in the literature. The key mechanisms responsible for the observed fracture behavior of the two steels, cyclically deformed over a range of maximum stress, are presented and discussed.