An Updated Index Including Toughness for Hot-Cracking Susceptibility
An Updated Index Including Toughness for Hot-Cracking Susceptibility
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DOI：
10.1007/s11661-022-06612-6
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发表时间：
2022-02
期刊：
影响因子：
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通讯作者：
Guannan Tang;Benjamin J. Gould;Abigail Ngowe;A. Rollett
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文献类型：
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作者：
Guannan Tang;Benjamin J. Gould;Abigail Ngowe;A. Rollett
热裂纹是基于激光的增材制造中可能发生的主要缺陷之一。在固化的最终阶段，当半固态基质积累了由热收缩引起的过度负（拉伸）压力时，热裂纹开始。本研究提出了一种新的量化上述过程中的趋势：我们估计的体积变化所带来的热变形从能量守恒的角度来看，并结合联合收割机晶粒长大和液体回流引起的晶间体积变化，推导出一个判据热裂纹萌生。在此基础上，我们提出了两个基于先前工作的修改索引，即：（1）和（2）。这里，T是温度，是半固态区域的固相分数，是收缩因子，是固相线温度附近的材料韧性。评价这些指标对实验数据表明，热裂纹敏感性与第二个指标密切相关，确实是材料的高温韧性的函数。
Hot cracking is one of the major defects that can occur in laser-based additive manufacturing. During the terminal stage of solidification, hot cracking initiates when the semi-solid matrix builds up excessive negative (tensile) pressure induced by thermal contraction. This study presents a new quantification of the trends in the above process: we estimate the volume change brought by thermal deformation through a perspective of energy conservation and combine it with the intergranular volume change induced by grain growth and liquid backflow to derive a criterion for hot-cracking initiation. Based on this, we propose two modified indexes that build on prior work, namely: (1)and (2). Here, T is temperature,is the solid fraction of the semi-solid region,is the shrinkage factor andis the material toughness near the solidus temperature. Evaluating these indexes against experimental data reveals that hot-cracking susceptibility is strongly correlated with the second index and indeed is a function of material high-temperature toughness.