Influence of Vanadium on Thermal Healing of the Inner Cracks in Q235 Steels

Thermal healing experiment of inner cracks made by compressing a drilled hole on samples of Q235 steel with various vanadium addition was carried out.The effects of vanadium on inner cracks thermal healing and morphology evolution were investigated.SEM analysis results displayed that inner crack samples have apparent healing at 800℃ and the healing is best with 0.1% vanadium addition.After vanadium added to the matrix partial of it is soluted in the matrix.The soluted vanadium reduces the activation energy for diffusion of Fe atoms,accelerates the self-diffusion of Fe atoms.The primary mechanism of inner crack healing in metals is diffusion thermal healing and the recrystallization.It requires the systemic method to research the microstructure both of the crack zone and the matrix of internal cracks healing in the steel.