Numerical Simulation On The Heat Treatment Process For Hot-rolling High-strength Seamless Pipes

The high-strength seamless pipes are widely used in the high pressure andcorrosion-resistancefields. The quantitythat marketrequires is increasinggreatlyevery year.In order to adapt to the rigorous operating environment, the study ofimproving the seamlesspipes performance becomes one of the hottest research topics now. The experimental resultsshow that the residual stress reduces obviously the performance of seamless pipes.Controlling the residual stress is an important method to improve the performance ofseamless pipes. This paper carries out an investigation about the residual stress of theseamless pipe during the quenching process based on large-scale nonlinear finite elementsoftware--MSC.Marc.Firstly, the factors including the temperature-dependent properties of material and thephase change are taken into account in this paper, and the computer simulation model of thetemperature field of quenching and temper is established based on the law of the firstthermodynamics. The results of simulation, which are basically consistent with theexperimental results, are base for further studying the stress field of quenching and temper.Secondly, using the incremental theory and corresponding elastic-plasticity constitutiveequations, assuming that the material meets the Prandtl-Reuss plastic flow law andconsidering the factors such as nonlinear material and phase transformation plasticity, thecircumference stress and the residual stress of quenching and temper are calculated. Theresults of simulation are consistent with the value measured. The proposed model is ananalytic model for further studying theeffect of heat treatment parameterduring the processquenching and temper. Finally, the paper carries out an investigation about the effect of theheatingtemperatureandthecoolingrateon thestressfieldsofquenchingandtemperwiththesamemethod.This paper has simulated the process of quenching and temper for high-strengthseamless pipes andcarriedout aninvestigation in theparameter,andtheresults are abaseforfurther studying mathematical model and intelligently controlling the process of quenchingandtemper.