Numerical Simulation And Experimental Study On Quenching Process Of 45 Steel Cylinder Column Under Complex Working Conditions

With the continuous development of industrial production technology,higher requirements are put forward for the mechanical properties of metal workpieces.In the metal heat treatment industry,quenching is usually used to improve the mechanical properties of metal workpieces and reduce internal stress.The quenching process is a complex nonlinear process,accompanied by many violent physical processes,such as intense heat transfer,phase transition,microstructure change and thermal stress change.Reasonable control of cooling speed of quenched workpieces,which can effectively prevent the workpiece from breaking due to the high thermal stress caused by the excessive cooling rate.In this paper,the immersion quenching of 45 steel cylinder workpiece is studied experimentally.and use the commercial fluid simulation software AVL FIRE,a process of immersion quenching experiment numerical simulation research,numerical simulation analysis of the minimum heat flux correction coefficient,the critical heat flux correction coefficient and the influence of Leidenfrost temperature parameters on the cooling curve,The influence of the thermal properties of the workpiece and the turbulent conditions in the quenching tank on the cooling process of the quenched workpiece is discussed and the numerical simulation results are compared with the experimental data.The results show that:1.In this paper,the established numerical simulation model of the immersion quenching process of hardening workpieces temperature field and air bubbles generated on the surface of the workpiece is effectively forecast,the cooling curves obtained by numerical simulation are in good agreement with the experimental measurements.2.The effects of the minimum heat flux correction coefficient,critical heat flux correction coefficient and Leidenfrost temperature on the cooling curve in the process of numerical simulation are discussed.Combined with the experimental measurement of the cooling curve and the numerical value by adjusting the three parameters,can be to modify the numerical simulation to calculate the cooling curve,which make it more close to the experimental measurement of cooling curve,and realize the numerical calculation model of immersion quenching process optimization.3.When the thermal physical properties of the workpiece change with the temperature during quenching,it will have a great influence on the cooling curve of the internal temperature of the workpiece.By setting the thermal physical properties of the solid domain as a polynomial related to the temperature change,the rationality and accuracy of the numerical simulation results can be effectively improved.4.According to the results of numerical simulation can clearly see that the immersion quenching process of turbulent flow condition of quenching groove can significantly speed up the cooling rate of the quenching workpieces,the workpieces surface and the duration of each heat transfer phase have a significant impact,when fluid domain using turbulent conditions calculated results than liquid domain using the working condition of laminar flow calculation results more close to the experimental measurement results.