Effect of scanning strategies on residual stress and mechanical properties of Selective Laser Melted Ti6Al4V
Effect of scanning strategies on residual stress and mechanical properties of Selective Laser Melted Ti6Al4V
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DOI：
10.1016/j.msea.2017.11.103
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发表时间：
2018-01-18
期刊：
影响因子：
6.4
通讯作者：
Mumtaz, Kamran
中科院分区：
文献类型：
--
作者：
Ali, Haider;Ghadbeigi, Hassan;Mumtaz, Kamran
在选择性激光熔化（SLM）工艺期间，可能形成大的温度梯度，从而产生弹性变形的失配，这可能导致增材制造的金属结构内的高水平残余应力。快速熔池凝固导致SLM处理的Ti6 Al 4V形成马氏体微观结构，其延展性通常低于热加工等效物。目前SLM构件可以采用后处理热处理来消除内部残余应力和提高塑性，本文研究了扫描策略（扫描矢量长度和扫描矢量旋转）和再扫描策略对SLM Ti6 Al 4V构件残余应力形成和力学性能的影响。90 °交替扫描策略使得SLM Ti6 Al 4V部件的残余应力累积最低，该部件使用调制Nd-YAG光纤激光器在标准和改良的雷尼绍平台上构建。扫描策略与机械性能没有任何直接相关性。用150%能量密度的再扫描导致残余应力降低33.6%，但对机械性能的影响是有害的，并且样品过早失效。该研究是基于详细的实验分析沿着与有限元模拟的过程中，使用ABAQUS了解的基础物理过程。
During the Selective Laser Melting (SLM) process large temperature gradients can form, generating a mismatch in elastic deformation that can lead to high levels of residual stress within the additively manufactured metallic structure. Rapid melt pool solidification causes SLM processed Ti6Al4V to form a martensitic microstructure with a ductility generally lower than a hot working equivalent. Currently post-process heat treatments can be applied to SLM components to remove in-built residual stress and improve ductility.This study examined the effect of scanning strategy (scan vector lengths and scan vector rotation) and re scanning strategy on residual stress formation and mechanical properties of SLM Ti6Al4V parts. 90 alternating scanning strategy resulted in the lowest residual stress build-up for SLM Ti6Al4V parts built on both the standard and modified Renishaw platforms using a modulated Nd-YAG fiber laser. Scanning strategy did not show any direct correlation with mechanical properties. Re-scanning with 150% energy density resulted in 33.6% reduction in residual stress but the effect on mechanical properties was detrimental and samples failed prematurely. The study was based on detailed experimental analysis along with Finite Element simulation of the process using ABAQUS to understand the underlying physics of the process.