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 reduct ion. 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 ofresidual 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. © 2019, Chongqing Wujiu Periodicals Press. All rights reserved.