Numerical Simulation And Optimization Of Induction Hardening Prosess For High Speed Steel Work Roll

The work roll is an important component of rolling mill,of which the performance and service time affects the efficiency of the whole rolling line and the quality of the production.With the advantages of low energy consumption,high efficiency and less pollution to the environment,induction hardening technology is widely used in the surface hardening treatment of large rolls.The cost of induction quenching test for large cold rolls is high and the related equipment is complex.At the same time,it is difficult to measure the depth and stress of the hardened layer of the rolls.Therefore,it is of great importance to simulate the induction hardening process of the roller,optimize the quenching process and improve the performance of large work rolls by using finite element software.Based on the metallographic experiment of high speed steel samples which was treated at different heating rates,different heating temperatures and different times,the grain sizes were determined and the effect of heating rates,heating temperatures and holding times on the austenite grain growth behaviors was analyzed.Then austenite grain growth models with different heating rates,different temperatures and different holding times were obtained which provide theoretical basis for the heating process formulation in the follow-up heat treatment processes.The effect of stress levels under the different temperatures on kinetics of martensitic transformation was studied on Gleeble-3800 thermal simulation test machine which can simulate induction hardening process of roll under stress constraint.A series of tests such as X ray diffraction,metallographic experiment was conducted with quenched samples and martensitic transformation models under the stress constraint were built and modified using the finite element simulation.Finally,the induction quenching processes of high speed steel cold working rolls were simulated by DEFORM software,and the change of the temperature field,the microstructure field and the stress field of the work roll were analyzed in details,then the models were verified by comparing with experiment results.By using orthogonal design method,the related parameters of induction hardening processes of work roll were optimized and it found that the improved technologies could effectively reduce the residual stress and increase the depth of hardened layer through the comparison and analysis of the temperature-microstructure-stress field of the induction hardening processes before and after the optimization.The research results of this work have important theoretical guiding significance for making the induction hardening processes and process improvement of high speed steel working rolls.