Effect of Heat Treatment Conditions and Roll Diameter on Residual Stress of Bimetallic Roll

Abstract

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.

Effect of Heating Conditions before Quenching on Residual Stress in High-Speed Steel Type Cast Iron Rolls by Centrifugal Cast

“…Its theoretical analysis and measurement are considered to be difficult. 11) In recent years, analysis results of residual stress distribution of composite rolls have been reported, 10,12,13) but there are very few reports on the results of actual measurement of residual stress distribution in actual rolls. Figure 2 schematically shows the transformation characteristics of the outer and inner layers.…”