Study On Grain Refinement And Parameter Optimization Of Laser Quenching Of High-speed Steel

Laser surface hardening(LSH)is a heat treatment technology that uses a high-energy density laser beam to scan a metal workpiece to instantly form austenite on the surface,and then obtain a hardened layer containing a fine martensite structure during rapid cooling.It has the advantages that traditional quenching technology cannot replace under complicated working conditions such as small workpiece volume,difficult disassembly,and easy deformation when heated.This article focuses on exploring the influence of different processing parameters and cooling methods in the laser surface quenching(LSQ)process on the residual stress and temperature field distribution of the W6Mo5Cr4V2 high-speed steel matrix and the micro-grain size from two aspects.First,use Procast software to simulate(LSQ)process under the action of a uniformly distributed laser point heat source,and compare the effects of convective heat transfer coefficint and initial water temperature on the grain refinement effect under the two cooling conditions.Second,with the help of the ANSYS Workbench simulation platform,the mobile Gaussian heat source is used to simulate(LSQ)process,and the influence of laser processing parameters on the temperature field and stress field distribution is explored.The simulation results and main conclusions are as follows:The laser power has a great influence on the grain refinement effect.As the power increases,the grain size has a clear trend of refinement;the laser power density is the main factor that affects the distribution of the hardened layer.When the laser power is constant,Next,the use of a uniformly distributed laser heat source can effectively improve the problem of uneven distribution of the thickness of the hardened layer.The cooling rate is the main reason for the residual stress and has a great influence on the grain refinement effect.Under water cooling conditions,the grain refinement effect is obvious when the cooling rate reaches 1.3×103?/s or more,and the residual stress is mainly concentrated in the center area of the spot.The average grain size can reach 5.4 ?m.The effects of laser processing parameters on the temperature field distribution and residual stress are compared.The laser power and spot size have a greater influence on the temperature field distribution and residual stress.Within a certain range,both the temperature peak and residual stress increase with the increase of laser power,and the residual stress decreases with the increase of laser power.Increasing the spot size significantly reduces the temperature peak;increasing the laser power has a significant depth of thermal influence Deepening,the laser spot and scanning speed have less influence on the heat distribution in the thickness direction.