The tensile deformation behavior of laser repaired Inconel 718 with a non-uniform microstructure
The tensile deformation behavior of laser repaired Inconel 718 with a non-uniform microstructure
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非均匀微观结构激光修复Inconel 718的拉伸变形行为
DOI：
10.1016/j.msea.2017.01.110
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发表时间：
2017-03-14
期刊：
影响因子：
6.4
通讯作者：
Lin, Xin
中科院分区：
文献类型：
--
作者：
Sui, Shang;Chen, Jing;Lin, Xin
激光修复技术是在激光增材制造技术的基础上，为节省时间和经济成本而应用于损伤部件的修复。由于激光沉积区的存在，激光修复后的零件的显微组织和力学性能与原锻件不同。采用数字图像相关（DIC）方法，对LRed和变形后的Inconel 718的拉伸变形行为进行了比较。研究了LRed Inconel 718的显微组织和失效机理。结果表明，LRed Inconel 718试样可分为两部分：激光沉积区（LDZ）和衬底区（SZ）。激光沉积区由沿沉积方向外延生长的柱状枝晶组成，y′′相聚集在枝晶间Laves相周围。基体区组织为等轴晶，δ相和y′相均匀分布。说明LRed Inconel 718的显微组织不均匀。由于LRed合金中Laves相的存在和y′′相的不均匀分布，使得LRed合金的变形相容性不如变形后的Inconel 718。结果，应变集中在激光沉积区，导致大部分塑性变形集中在该区域。由于局部应力集中，硬脆的Laves相滑动并分裂成更小的部分。在Laves相与y基体的界面处形成微观孔洞并结合在一起导致LRed Inconel 718断裂。
Laser repairing technology, based on laser additive manufacturing technology, has been used in repairing damaged components for saving time and economic cost. Due to the existence of laser deposited zone, the microstructure and mechanical properties of laser repaired (LRed) components are different from original wrought parts. In this paper, the tensile deformation behavior of LRed Inconel 718 was compared with that of wrought Inconel 718 by using digital image correlation (DIC) method. The microstructure and the failure mechanism of LRed Inconel 718 were also investigated. The results showed that the LRed Inconel 718 sample could be divided into two parts: laser deposited zone (LDZ) and substrate zone (SZ). The laser deposited zone consisted of columnar dendrite growing epitaxially along the deposition direction, where the y" phases gathered around the interdendritic Laves phases. However, the microstructure of the substrate zone was equiaxed grain with the uniform distribution of delta and y" phases. It means that the microstructure of the LRed Inconel 718 was non-uniform. The deformation compatibility of the LRed Inconel 718 was inferior to that of the wrought Inconel 718 because of the existence of the Laves phases and the heterogeneous distribution of the y" phases. As a result, strain concentrated in the laser deposited zone resulting in that most plastic deformation was clustered in this region. The hard and brittle Laves phases slipped and broke up into smaller parts due to local stress concentration. Microscopic holes formed at the interface of the Laves phases and the y matrix and combined together to cause the fracture of the LRed Inconel 718.