扫描策略对SLM 316L不锈钢零件残余应力影响机理研究

Study on influence mechanism of scanning strategy on residual stress in SLM 316L stainless steel parts

  • 摘要: 选区激光熔化(selective laser melting, SLM)可实现复杂金属构件快速成形,但其局部快速熔化凝固易形成显著热梯度与非均匀组织,从而引入高残余应力。扫描策略是调控热输入与热场分布,进而影响残余应力的关键工艺参数。研究以SLM 316L不锈钢为对象,研究双向线性、条纹和棋盘三种扫描策略对残余应力场的影响规律,揭示扫描路径对热累积行为、凝固方式、晶粒取向及熔池边界演变的调控机制。结果表明,双向线性扫描表面残余应力幅值较高,最大峰值为123 MPa;与之相比,条纹扫描可使残余应力峰值降低约63%(最大峰值为45.5 MPa),棋盘扫描降低约84%(最大峰值为19.6 MPa),应力分布均匀性明显改善。文章深入阐述了扫描策略-热场-组织-残余应力之间的耦合机理,为SLM 316L构件的残余应力优化与可靠性提升提供理论依据与工艺指导。

     

    Abstract: Selective laser melting (SLM) enables the rapid fabrication of complex metallic components. However, significant thermal gradients and heterogeneous microstructural evolution are tend to be generated by the localized rapid melting and solidification processes involved in SLM, thereby introducing high residual stresses within the components. The scanning strategy, as a key process parameter, is recognized to play a critical role in regulating heat input and thermal field distribution, thus influencing the formation and release of residual stresses. The research focused on SLM 316L stainless steel, studying the influence patterns of three scanning strategies, namely bidirectional linear, stripe, and checkerboard, on the residual stress field. The regulatory mechanisms of scanning paths on thermal accumulation, solidification behavior, grain orientation, and melt pool boundary evolution are elucidated. The results show that residual stresses are relatively high under bidirectional linear scanning, with a maximum peak of 123 MPa. In comparison, stripe scanning reduces the peak residual stress by approximately 63% (with a maximum peak of 45.5 MPa), while chessboard scanning reduces it by about 84% (with a maximum peak of 19.6 MPa). Both strategies significantly improve stress distribution uniformity. The coupling mechanisms among scanning strategy, thermal field, microstructure, and residual stress are thoroughly examined in this study, with theoretical support and process guidance provided for optimizing residual stress and enhancing the reliability of SLM-fabricated 316L components.

     

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