激光增材制造残余应力研究现状

首先介绍了激光增材制造中残余应力的产生和危害,指出高的温度梯度和不均匀相变是高残余应力的原因,列举了残余应力造成的热裂纹、翘曲和疲劳失效等危害。然后,从残余应力的试验测定、数值模拟以及调控消减三个方面总结了相关研究现状。残余应力试验测定部分包括表面和内部残余应力的测试,方法有X射线衍射法、中子衍射法和压痕法等。数值模拟部分主要评述了工艺参数和扫描策略对应力场的影响。残余应力调控指的是在成形过程中,通过工艺控制减少应力的产生,主要介绍了采用热处理、超声冲击降低已成形构件残余应力的相关研究。最后提出应开展微观残余应力到大型构件宏观残余应力的多尺度表征,表面残余应力和内部残余应力相结合的多手段定量测定等专题研究,为开展残余应力与工件失效的关联性研究打下基础。

Research Progress on Residual Stress in Laser Additive Manufacturing

This paper firstly introduces the generation and harm of residual stress in additive manufacturing, identifies that high temperature gradients and heterogeneous phase changes are the primary causes of high residual stress and lists hazards caused by residual stress such as thermal crack, warping, and fatigue failure. Then, the research progress is summarized from the results of the residual stress tests, numerical simulation, and regulation reduction. Experimental measurement includes surface and internal residual stress and adopted methods consist of X-ray diffraction, neutron diffraction and indentation methods. The numerical simulation mainly focuses on the influence of technological parameters and scanning strategy on stress field. Regulation refers to the reduction of stress by controlling parameters during the forming process. Correlational research on decreasing residual stress of formed components by heat treatment and ultrasonic shock are introduced. Finally, it is pointed out that the following monographic studies should be promoted: multi-scale characterization of residual stress from microcosmic to macrocosmic and quantitative measurement of surface and interior residual stress via multiple ways, to lay a foundation for the research on the correlation between residual stress and invalidation.