脉冲激光表面强化数值模拟及热物性参量影响  

Numerical Simulation of Pulsed Laser Surface Hardening and the Influence of Material Thermophysical Parameters on Hardened Zone

作　　者：吴炜[1] 梁乃刚[1] 虞钢[2] 巴发海[3] 

机构地区：[1]中国科学院力学研究所非线性力学国家重点实验室,北京100080 [2]中国科学院力学研究所技术发展部,北京100080 [3]上海材料研究所,上海200437

出　　处：《中国激光》2005年第5期707-712,共6页Chinese Journal of Lasers

基　　金：国家自然科学基金(10232050);国家973项目(2002CB412706);中国科学院知识创新工程(KGCX111)资助项目。

摘　　要：建立了包含脉冲激光束时空分布、依赖于温度的材料参量、组织演化历史以及多次相变特征在内的脉冲激光表面强化三维有限元模型。针对常热物性和变热物性并考虑相变潜热两种情况,温度场及其演化分别得到了解析解和通用有限元软件的验证,强化区层深和宽度得到了实验验证。研究了材料热物性对强化区的影响,得到了一定范围内强化区层深随材料热物性参量的变化规律,即:热传导系数不变时,强化区层深随热扩散率的增加而增加;比热容不变时,强化区层深随热扩散率的增加而减小;热扩散率一定时,强化区层深随热传导系数和比热容的增加而降低。以球铁、共析钢和中碳钢为例,分析了两种确定材料热物性常数方法,即一定温度范围内的平均值法和选取奥氏体化温度附近参量方法的可行性,研究表明平均值法可以得到较好的结果。A three dimensional (3D) finite element model for simulating pulsed laser surface hardening is established, in which laser spatial and time-dependent intensity distribution, temperature-dependent thermophysical properties of material, microstructural evolution and multi-phase transformations are considered. For the two cases that thermophysical parameters are assumed to be constant, and are variable with temperature as well as latent heat is taken into account, temperature field and its evolution are validated with analytical method and general finite element software package MSC/NASTRAN, respectively. The hardening depth and width are verified with experimental ones. The influence of material thermophysical properties on hardened zone is investigated, and the regularity of relationship between hardening depth and thermophysical parameters in certain zone is obtained, i.e., hardening depth increases under invariable heat conductivity and decreases under invariable specific heat capacity with the increase of thermal diffusivity, and decreases with the increase of heat conductivity and specific heat capacity for given thermal diffusivity. Taking example for ductile iron, eutectoid steel and medium carbon steel, two methods to determine material thermophysical constants, i.e. mean value method and adopting parameters nearby austenitizing temperature method are explored, and results indicate that the mean value method can gain better predication.

关 键 词：激光技术 脉冲激光 表面强化 数值模拟 热物性参量 

分 类 号：TN249[电子电信—物理电子学] TG178[金属学及工艺—金属表面处理]