Effects of vanadium (V) addition on strain distribution, crack initiation and propagation behavior during low-cycle fatigue test in ferrite and martensite dual phase (DP) steel were revealed. V addition effectively extended the low-cycle fatigue life, even though the tensile properties were approximately identical between V-added DP and DP steels. The stress amplitude suddenly decreased just before fracture in the V-added DP steel. The fatigue crack initiated from the surface and propagated inside, and the brittle fracture occurred in the crack propagation region in the V-added DP steel. The strain distribution introduced during the low-cycle fatigue test was more inhomogeneous for the V-added DP steel than that for the DP steel, and the fatigue crack was generated from the high-strain region. Considering that the number of cycles for crack initiation in the V-added DP steel was larger than that in DP steel, the inhomogeneous strain distribution in the V-added steel promoted crack nucleation but suppressed crack growth in the crack initiation stage. Cracks propagated independent of the strain distribution in the V-added DP steel in the crack propagation stage. The crack propagation rate in the V-added DP steel was remarkably higher than that in DP steel in the crack propagation stage. Thus, V addition effectively extended the number of cycles for crack initiation but caused brittle fracture and faster crack propagation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.