Research On Mechanical Performance Prediction Of High Strength Boron Steel By Spray Quenching

Heat treatment has a significant influence on the mechanical properties of steel.In the heat treatment of steel,the effect of quenching is very important.It determines the final quality and performance of the material to a great extent.The process of quenching requires the participation of the quenching medium.The gas mist is a new type of quenching medium.Compared with the traditional quenching medium,it has many advantages.Firstly,the cooling speed range of spray is relatively large,which is between air cooling and water cooling.Secondly,the cooling rate of the air mist ensures that the quenching speed of the quench is greater than the critical quenching speed,and the quenching process will not be conduced too quickly,and the component deformation after quenching is diminutive.Simultaneously,the composition of the spray is water and air,with low energy consumption and no pollution.In addition,the area of aerosol spray is surface like,so that the cooling zone is more uniform.Boron steel 22MnB5 is a kind of low carbon steel widely used in industry.Its chemical composition is simple,and its strength and stiffness have been significantly improved after quenching under different temperature.Therefore,it is of great significance to carry out the experimental research on mechanical performance prediction of high strength boron steel by spray quenching.In this paper,an experimental study of spray quenching medium of boron steel 22MnB5 is investigated.Firstly,the spray injection parameters influence on the performance of 22MnB5 steel is analyzed by response surface methodology.Through the difference analysis and variance analysis of the orthogonal experimental results,it is found that the initial quenching temperature has the greatest influence on the hardness of the hardened parts.Although the quenching height and the gas water pressure ratio have influence on the hardness of the quenched parts,the effects are not significant.By analyzing the response surface,it is verified that the atomizing quenching process can make the quenched parts get variable strength gradient performance.Subsequently,the temperature distribution in the quenching process of single nozzle is analyzed through the air mist quenching platform,thus the temperature distribution and range of the sample surface are obtained,and the effective quenching zone is defined for the subsequent phase transition simulation.Then through the obtained temperature field data,the heat balance method is used to calculate the surface heat transfer coefficient between the gas mist and the surface of the sample,which provides a strong data support for the phase change field simulation.The temperature distribution of the sample is analyzed with the FLUENT simulation software.Furthermore,based on the comparison of the experimental results and the simulation results,the heat transfer coefficient of the interface in the process of air mist quenching is solved.Furthermore,the hardness field distribution of quenched parts was obtained by using DEFORM simulation software,and the transformation in quenching process was predicted.Combined with the hardness data and metallographic map,the reliability and rationality of the finite element software is verified.Finally,the application prospect and value of spray quenching technology in automotive typical BIW component is preliminarily explored through the actual spray quenching experiment of U-type shape parts.