Research On Heat Treatment Numerical Simulation Of Large Diameter Steel After Rolling For Oil Pipe

The oil pipe plays an important role in oil exploitation,the properties and service life of it has a significant influence on safety and reliability during oil exploitation.In order to improve the efficiency of oil exploitation,the diameter of oil pipe is increasing and its mechanical properties are also put forward higher requirements.Grade P100 steel shows the high comprehensive mechanical properties after quenching and tempering,which is often used in the production of oil pipes.Therefore,research and develop the heat treatment technology on large diameter steel which is used to oil pipe production are paid more attention between enterprises and scientific research institutes.In this paper,according to the heat treatment process and the measured data of the product properties of the factory and combining the method of numerical analysis and theoretical derivation,the the variation regularity of temperature,microstructure,stress and strain of 42 CrMo round steel during heat treatment were analyzed,the mechanical properties of steel after heat treatment were predicted and the heat treatment process of steel after rolling were optimized.This paper mainly completed the following works:1.The material model of 42 CrMo was established,which included the phase transformation kinetics curve,the model of thermal physical properties and hardness of different phases.Based on the model,the phase transformation characteristics,the changing of thermal physical properties with temperature of 42 CrMo during cooling and the hardness of different phase after quenching were analyzed.2.The temperature acquisition system and quenching device were designed and the temperature-time curves of 42 CrMo round steel during quenching in different quenching medium were measured by the system.The heat transfer coefficient parameter in different quenching conditions was calculated based on the theory of inverse heat transfer method and the accuracy of the results were verified.3.The field of temperature,microstructure and stress-strain of 42 CrMo round steel with different diameter during quenching was analyzed by numerical simulation.The method of combining numerical simulation and analytical calculation to predicte the mechanical properties of 42 CrMo steel after quenching and tempering was proposed.4.The effect of heat treatment parameter on the final properties of 42 CrMo steel was analyzed.Heat treatment experiment of 42 CrMo steel with different diameter were designed and simulated by Deform software.Based on the simulation results,the functional relations between heat treatment parameters and mechanical properties after quenching and tempering were established.5.The multi-objective optimization model was established according to the requirement of mechanical properties.The heat treatment processes of 42 CrMo round steel with different diameter of ?228.6mm??292.1mm??342.9mm were optimized.