Usefulness of Non-Uniform Heating and Quenching Method for Residual Stress of Bimetallic Roll: FEM Simulation Considering Creep Behavior

Abstract

Bimetallic rolls are widely used in steel rolling industries because of the excellent hardness, wear resistance, and high temperature properties. Controlling the residual stress distribution is important to improve the roll fatigue life due to the compressive residual stress at the roll surface. Recently, to reduce the tensile residual stress appearing at the roll center, quenching heat treatment is performed just after heating the roll non-uniformly instead of heating the roll uniformly with enough time. In this paper, therefore, the residual stresses are compared after between the uniform heating quenching and the non-uniform heating quenching on the basis of the FEM simulation. The results show that tensile stresses at the roll center for non-uniform heating are smaller than that for uniform heating by 400 MPa, although the same compressive stresses appear at the surface. The effect of creep on stress relaxation is also considered in this study. By considering creep, the maximum tensile residual stress decreases by 8% for uniform heating and by 15% for non-uniform heating.

Residual Stress Differences between Uniform and Non-Uniform Heating Treatment of Bimetallic Roll: Effect of Creep Behavior on Residual Stress

“…Meanwhile the inner DCI has a composition of Carbon (2.5-4%), Silicon (1.5-3.1%), Manganese (<1%), Phosphorus (<0.1%), Sulphur (<0.1%), Nickel (0.4-5%), Chromium (0.01-1.5%), Molybdenum (0.1-1%), Cobalt (<1%), Vanadium (<1%), Wolfram (<1%) and Magnesium (0.02-0.08%) in its composition. In our previous study [17][18][19], the usefulness of non-uniform heating treatments was explained, although the material data were not indicated at the request of the company with which we collaborated. Since the material data could not be indicated, the detailed effect of the material on the residual stress has not yet been clarified.…”

“…Bimetallic rolls are manufactured by the centrifugal casting method, in which high-speed steel (HSS) is used as the shell and ductile casting iron (DCI) is used as the core (see Figure 1) [6][7][8]. In our previous study [17][18][19], the usefulness of non-uniform heating treatments was explained, although the material data were not indicated at the request of the company with which we collaborated. Since the material data could not be indicated, the detailed effect of the material on the residual stress has not yet been clarified.…”

“…In our previous study [17][18][19], the usefulness of non-uniform heating treatments was explained, although the material data were not indicated at the request of the company with which we collaborated. Since the material data could not be indicated, the detailed effect of the material on the residual stress has not yet been clarified.…”

Accuracy of Disk Method to Predict Roll Residual Stress by Measuring the Sliced Disk Stress

“…Assume the cylinder surface temperature Ts = T(300) = 800°C, which may produce the surface stress σ z (300) ≅ − 600 MPa often appearing at the surface after the standard quenching. 9,10) Here, assume that all material data of DCI are depending on temperature distribution T(r) as shown in Figs. 4(a), 4(b) and 4(c) for Young's modulus E, thermal expansion coefficient α and Poisson's ratio ν.…”

“…This thermal breakage originates near the roll center and breaks out to the barrel surface. [6][7][8] In our previous studies, 9,10) therefore, different quenching methods were discussed through FEM simulation to produce suitable surface compressive residual stresses and reduce the center tensile residual stress. In real work rolls, however, the existence of suitable residual stress distribution should be confirmed experimentally.…”