Strengthening mechanism and three-body impact abrasive wear behavior of the hot-rolled air-cooling martensitic wear resistant steel

Abstract

The microstructure, mechanical properties and three-body impact abrasive wear behavior were investigated. The results indicated that martensite transformation occurred even under air-cooling, and fully martensitic structure consisted of lath martensite and a small amount of twinned martensite was obtained. And the martensite auto-tempering occurred during the subsequent air cooling process, resulting in precipitation of fine ellipsoidal V(C, N) particles and acicular η-Fe2C cementite in the matrix. Meanwhile, the tensile strength, yield strength, Brinell hardness and impact energy (−40 °C) of experimental steel were 1526 MPa, 973 MPa, 454.3 HB and 28 J, respectively. The strengthening mechanism analysis showed that solution strengthening was still the dominant strengthening method even though a large number of carbides were precipitated in the matrix. The dislocation strengthening was limited due to lower dislocation density, and the hot rolled recrystallization led to considerable grain refinement strengthening. Moreover, the results of three-body impact abrasive wear tests indicated that the wear resistance of experimental steel reached a same level as commercial Hardox450 steel. The wear mechanisms of experimental steels were plastic deformation fatigue, abrasive embedded and cutting. The mass loss rates of experimental steel and Hardox450 steel were 0.0033 g/min and 0.0032 g/min under the impact energy of 2.5 J, respectively.