Microstructure evolution of 316L stainless steel during solid-state additive friction stir deposition
Microstructure evolution of 316L stainless steel during solid-state additive friction stir deposition
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DOI：
10.1080/14786435.2021.2011980
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发表时间：
2021-12-10
影响因子：
1.6
通讯作者：
Fabijanic, Daniel
中科院分区：
文献类型：
--
作者：
Beladi, Hossein;Farabi, Ehsan;Fabijanic, Daniel
采用固态添加剂搅拌摩擦沉积技术对316L不锈钢进行了三维打印。用五参数晶界分析表征了组织、织构和晶界分布。在整个沉积层厚度上，块体组织非常细小(类似于0.7微米)，由等轴晶以及由高角度和低角度边界段划分的亚晶组成。沉积层的取向差角分布与原始组织有很大的不同，Sigma 3退火孪晶界的相对面积因严重的塑性变形而显著减小。整体织构还表现出与面心立方金属相关的强烈剪切成分，这表明组织细化主要是通过渐进的亚晶旋转进行的，即所谓的连续动态再结晶。与原始材料相比，晶界面上的各向异性明显降低，在(111)和(110)晶面上出现两个中等的各向异性峰。高角度移动界面的迁移可能是由随后沉积时的热循环以及相邻晶粒之间的位错梯度引起的，略微增强了低能(111)取向的强度，但牺牲了(110)高能晶界。
Solid-state additive friction stir deposition was employed to three dimensionally print a 316L stainless steel. The microstructure, texture and grain boundary distribution were characterised using five-parameter boundary analysis. The bulk microstructure was exceptionally fine (similar to 0.7 mu m) throughout the thickness of the deposited layers, consisting of equiaxed grains along with sub-grains delineated by high and low angle boundary segments. The misorientation angle distribution of the deposited layers was considerably different from the as-received microstructure, exhibiting a significant reduction in the relative areas of Sigma 3 annealing twin boundaries due to their distortion by severe plastic deformation. The overall texture also exhibited strong shear components associated with FCC metals, suggesting that the microstructure refinement largely took place through progressive subgrain rotation, known as continuous dynamic recrystallisation. The grain boundary plane distribution revealed significantly lower anisotropy compared with the as-received material, showing two moderate peaks at the (111) and (110) orientations. The migration of high-angle mobile boundaries, which may have been induced by thermal cycle upon subsequent deposition along with the dislocation gradients between adjacent grains, slightly enhanced the intensity of low energy (111) orientations at the expense of (110) high-energy boundaries.