不同扫描策略下钛合金选择性激光熔化过程层间温度场的数值模拟

Numerical simulation of interlayer temperature field during selective laser melting of titanium alloy under different scanning strategies

为了改善选择性激光熔化(selective laser melting,SLM)过程的层间温度分布、降低层间热积累,采用移动热源法和生死单元技术对激光光斑定向移动和金属粉末逐层铺设过程进行数值模拟,研究了不同层间时间间隔和扫描策略对各层扫描路径及其特征点温度的影响.研究结果表明:层间时间间隔越小,各扫描路径层间热积累越多,且高速、高功率条件下的层间热积累要少于低速、低功率条件下的层间热积累;采用层间异向扫描策略时扫描路径末端会出现较明显的局部高温区域,且高速、高功率条件下的局部热积累要少于低速、低功率条件下的局部热积累;层间同向正交扫描策略能够使各扫描路径间的温度分布更均匀,是低搭接率下SLM过程的最优层间扫描策略.

In order to improve the interlayer temperature distribution and reduce the interlayer heat accumulation in the selective laser melting(SLM)process,this paper adopts the moving heat source method and the element birth and death technique to numerically simulate the laser spot directional movement and the metal powder layer⁃by⁃layer lay⁃up process,and investigates the effects of different interlayer time intervals and scanning strategies on the scanning path of each layer and its characteristic point temperature.The results show that the smaller the interlayer time interval,the more the interlayer heat accumulation in each scanning path,and the interlayer heat accumulation under high speed and high power conditions is less than that under low speed and low power conditions;a more obvious local high temperature area appears at the end of the scanning path when the interlayer reverse scanning strategy is used,and the local heat accumulation under high speed and high power conditions is less than that under low speed and low power conditions.The general orthogonal scanning strategy between layers can make the temperature distribution between scanning paths more uniform and is the optimal interlayer scanning strategy for SLM process with low lap rate.