Effects of Carbon and Cobalt on Mechanical and Hot Wear Properties of Multi-component White Cast Irons

Abstract

  Multi-component white cast irons containing Cr, Mo, W, V and Co have been widely popularized as roll materials for hot rolling mills because of their excellent wear performance. In this research, the effects of C and Co contents on mechanical properties and hot wear resistance were investigated using Fe-M (5%Cr-5%Mo-5%V-5%W) － Co-C (mass%) cast alloys. MC and M₂C carbides are crystalized in all specimens, and M₇C₃ carbide forms in specimens with high C and high Co. Martensitic matrix is obtained in specimens with C content of 1.5～2.5mass% and with Co content less than 7.5mass%. An increase of Co content promotes transformation of soft pearlite matrix. Martensitic matrix has over 600HV in micro-hardness, and the change of micro-hardness is similar to that of macro-hardness. Tensile strength, compressive 0.2% proof strength, and fracture toughness are high in cast irons with high hardness. Hot wear resistance is larger in cast irons with higher hardness and higher fracture toughness.