Microstructure tailoring of Ti-15Mo alloy fabricated by selective laser melting with high strength and ductility
Microstructure tailoring of Ti-15Mo alloy fabricated by selective laser melting with high strength and ductility
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DOI：
10.1016/j.msea.2021.141962
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发表时间：
2021-08-27
期刊：
影响因子：
6.4
通讯作者：
Niu, Yan
中科院分区：
文献类型：
--
作者：
Chen, Jian;Liao, Xingyu;Niu, Yan
本文对Ti-15Mo合金的选区激光熔凝(SLM)工艺进行了系统的研究，重点研究了其致密化、显微组织和力学性能。在低扫描速度下，球孔的形成主要是由于残余气体带来的气孔。在高扫描速度下，由于能量密度不足，会出现未熔合(LOF)缺陷，这对延性非常不利。由于温度梯度的不同，在XY面上观察到了胞晶向等轴晶的转变，而在XZ面上主要由沿熔池边缘辐射的柱状晶组成。由于保留了合理的omega相、较高的位错密度、较细小的晶粒、孪生诱发塑性和织构取向的变化，使经SLM处理的Ti-15MO获得了较高的抗拉强度(840.41 Mpa)和高伸长率(32.37%)的更好的组合，这一结果高于迄今的报道。随着应变的增加，孪晶变得更致密、更粗，当应变为10%时，不同应变的孪晶宽度平均为7微米，15%应变时为4微米，20%应变时为2微米。
In this study, selective laser melting (SLM) of Ti-15Mo alloy was systematically investigated, especially in its densification, microstructure and mechanical properties. At low scanning speed, the formation of spherical holes are mainly due to gas porosity brought about by residual gases. At high scanning speed, the lack of fusion (LOF) defects are presented because of the insufficient energy density, which is very detrimental to the ductility. Owing to the difference of the temperature gradient, the transition from the cellular crystals to equiaxed crystals has been observed in XY plane while the XZ plane are mainly consist of columnar crystals which are radiating along the edge of the molten pool. As a result of the retention of a reasonable level of omega phase, high dislocation density, finer grains, the twinning-induced plasticity (TWIP) and the changes of texture orientation, the Ti-15Mo samples processed by the SLM achieve a greater combination of high tensile strength of 840.41 MPa and a high elongation of 32.37%, which are higher than those reported so far. The twins become denser and thicker with increasing strain, and the average of twin widths with various strains were calculated to 7 mu m at strain of 10%, 4 mu m at strain of 15% and 2 mu m at strain of 20%.