Determining the optimal reduction ratio in temper rolling in terms of residual stress distribution across thickness

Abstract

Materials with compressive stresses on the surface withstand fatigue failures, cracking, galling, and corrosion. This compressive stress at the surface can be created by temper rolling. The rolling process must be conducted with an appropriate reduction to obtain the desired benefit from temper rolling. A 1% thickness reduction is usually applied to endow flatness and surface texture to the strip, and this reduction is sufficient to eliminate the discontinuous yielding phenomenon. In this study, 2.5-mm-thick low-carbon steel sheet (DC01 grade) samples were annealed at approximately 600°C for 5 minutes, temper-rolled at room temperature at various reduction ratios subsequently, and the residual stresses formed along the thickness by rolling were investigated. This study has revealed that a 1% reduction ratio is insufficient for developing compressive stresses on the surface, but this can only be achieved with a 1.5% reduction ratio. When the reduction ratio was increased to 1.8%, tensile stresses began to occur inside, along with compressive stresses on the surface. It was observed that at a reduction ratio of 2%, the situation was reversed again; tensile stresses began to regenerate at the surface, and this became more pronounced up to a 10% reduction ratio.