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Control of residual stress in metal additive manufacturing by low-temperature solid-state phase transformation: An experimental and numerical study
Additive Manufacturing ( IF 11.0 ) Pub Date : 2021-04-27 , DOI: 10.1016/j.addma.2021.102016
Wei Chen , Lianyong Xu , Yongdian Han , Lei Zhao , Hongyang Jing

Directed energy deposition (DED) technology commonly known as additive manufacturing (AM), is a rapid prototyping method for fabricating metallic functional components with minimum finishing operations. However, excessive tensile residual stress (RS) is often a potential source of structural failure due to the fact that it can cause surface/subsurface cracking of DED parts. In this work, the RS properties in DED specimens made of the low-temperature transformation (LTT) pre-alloyed powders was investigated. A DED model coupling the finite element (FE) and thermo-mechanical-metallurgical (TMM) analysis was constructed, and was experimentally validated by thermographic system and X-ray diffraction (XRD) stress measurements. An additional set of RS prediction for the DED specimen, using increased inter-track idle time was developed to reveal the effects of thermal history on TMM evolution behavior and RS distribution. The combination of experiment and predictive simulation provided an insight into the non-linear thermo-metallurgical evolution and the formation mechanism of compressive RS during DED of LTT alloy, and showed the great potentiality of LTT powder in minimizing the RS in DED parts by the austenite-to-martensite transformation on cooling.



中文翻译:

低温固态相变控制金属增材制造中残余应力的实验和数值研究

定向能量沉积(DED)技术通常称为增材制造(AM),是一种用于以最少的精加工操作来制造金属功能部件的快速成型方法。但是,由于过大的拉伸残余应力(RS)可能会导致DED零件的表面/亚表面开裂,因此通常是导致结构破坏的潜在原因。在这项工作中,研究了由低温转变(LTT)预合金粉末制成的DED样品的RS特性。建立了耦合有限元(FE)和热机械冶金(TMM)分析的DED模型,并通过热成像系统和X射线衍射(XRD)应力测量进行了实验验证。DED标本的另一组RS预测,利用增加的磁道间空闲时间来揭示热历史对TMM演变行为和RS分布的影响。实验和预测模拟的结合为LTT合金DED期间的非线性热冶金演变和压缩RS的形成机理提供了见识,并显示了LTT粉末在使奥氏体使DED零件中的RS最小化方面具有巨大的潜力。冷却时马氏体转变为马氏体。

更新日期:2021-04-30
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