工件形状对激光相变硬化温度场和应力场的影响

Effects of the Shape of Workpiece on Temperature and Stress Field Distribution during Laser Transformation Hardening

利用Sysweld有限元软件建立三维有限元模型,采用三维高斯热源,考虑材料热物性能随温度的变化,对平板和回转体内壁进行了激光相变硬化数值模拟。分析了温度场、残余应力以及马氏体分布的异同,研究了工件形状对激光相变硬化温度场和残余应力的影响规律。结果表明,在表层方向上,平板模型和回转体内壁模型的热循环相似;截面方向上,内壁模型峰值温度高于平板模型。处理后相变区组织均主要以马氏体为主,其体积分数约为90%。相变区边缘及热影响区产生残余拉应力,相变区存在残余压应力;与内壁模型相比,平板模型相变区中心残余压应力数值较大。

A three-dimesional （3-D） finite element model for the numerical simulation of laser transformation hardening on the plate and inner wall of revolving body is established by means of a finite element code-Sysweld, in which the change of thermal mechanical parameters with temperature is considered and the 3-D Gaussian heat source is adopted. The temperature field, martensite distribution and residual stress field are predicted. The influence of workpiece shape on the temperature and residual stress are studied. The results show that the thermal cycles of different points on the surface direction are similar for the two model while the peak temperature of different points of inner wall model in the section direction are higher than that of the plate model. After treatment martensite can be obtained as a main phase in the hardened zone with an about phase volume fraction of 90 %. The tensile stress appears in the boundary of hardening zone and heat affected zone （HAZ） and the compressive stress exists in the hardening zone. Comparing with revolving body, the value of the compressive residual stress in the center of the surface of plate is higher.