2018 Volume 59 Issue 684 Pages 1-7
Bimetallic rolls are widely used in steel rolling industries because of the excellent hardness, wear resistance, and high-temperature properties. The control of the residual stress distribution is necessary since the compressive residual stress at the surface may improve fatigue life although the central tensile residual stress may cause fracture originating at the center. Recently, to reduce the tensile stress appearing at the roll center, quenching heat treatment is performed just after heating the roll nonuniformly instead of uniformly with sufficient time. In this paper, the quenching processes after uniform and nonuniform heating are compared on the basis of FEM simulation. It should be noted that a large amount of experimental data of the core and shell materials is utilized for the wide range of temperature including the quenching process. The results show that the tensile stresses at the roll center for nonuniform heating are less than that for uniform heating by 89MPa (26%) at the maximum stress point, although the same compressive stresses appear at the surface. The inner layer tensile residual stress increased by 14% with increasing diameter from 600mm to 800mm in uniform heating, but tensile residual stress was almost unchanged in nonuniform heating.
