Numerical simulation and experiment of quenching process of 35CrMnSi by disk laser

Abstract

It is extremely difficult to reveal the thermo-mechanical coupling evolution mechanism of the laser quenching process by traditional experimental methods. The numerical simulation provides an effective way to obtain the dynamic evolution information of multifield coupling in the quenching process. Based on comsol multiphysics, a thermo-mechanical coupling model of the 35CrMnSi laser quenching process by a disk laser was established. In the model, the thermophysical parameters of the matrix during the quenching process were calculated by the CALPHAD method. The transient changes of temperature, phase change, and thermal stress during quenching were obtained by solving the model, revealing the transient change law of temperature field and microstructure transformation of a 35CrMnSi laser under different process parameters. The formation and transformation degree of martensite were characterized by the depth and width of the quenched transformation hardening layer. Laser quenching experiments of 35CrMnSi were carried out with a TruDisk 4002 laser. The quenching structure and phase transformation hardening rule were observed by Axioskop 2 SEM, Zeiss-ΣIGMA HD FE-SEM, and HXS-1000A micro hardness tester. Experiments show that the influence zone of laser hardening of a disk laser shows Gauss distribution. The quenching layer consists of complete quenching phase transformation zone, incomplete quenching zone, and core matrix in turn from the surface to inside. In the complete quenched zone, dense and fine acicular martensite and a small amount of retained austenite are formed, and the hardened layer is Gaussian distribution. The phase transformation layer width and the phase transformation layer depth of workpiece 1-1# are 10 352.9891 and 1091.0945 μm, respectively. The phase transformation layer width and the phase transformation layer depth of workpiece 1-2# are 6592.3963 and 754.6135 μm, respectively. The phase transformation layer width and the phase transformation layer depth of workpiece 1-3# are 4361.7892 and 416.2139 μm, respectively. The experimental results are in good agreement with the simulation results, which verifies the validity of the thermo-mechanical coupling model and provides a theoretical basis for obtaining the optimized process parameters.