Grain structure and texture control of additive manufactured nickel-based superalloy using quasi-continuous-wave laser directed energy deposition
Grain structure and texture control of additive manufactured nickel-based superalloy using quasi-continuous-wave laser directed energy deposition
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DOI：
10.1016/j.addma.2023.103520
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发表时间：
2023-03
影响因子：
11
通讯作者：
Hui Xiao;Yanqin Li;W. Xiao;C. Liu;P. Xie;Lijun Song
中科院分区：
文献类型：
--
作者：
Hui Xiao;Yanqin Li;W. Xiao;C. Liu;P. Xie;Lijun Song
采用准连续波激光定向能量沉积（QCW-DED）技术对镍基高温合金的晶粒组织和织构进行控制。采用实验和数值模拟相结合的方法，研究了不同脉冲频率下QCW-DED的凝固组织特征和凝固机制。QCW-DED大大改变了凝固条件，并引入了熔池的周期性重熔。高脉冲频率有利于柱状枝晶的外延生长，这是由于倾斜的线状熔池边界、柱状晶向等轴晶的转变（CET）受到抑制以及熔池的高频重熔。结果，获得了由规则的锯齿形晶粒组成的高强度织构。由于半圆形的熔池边界、促进的CET和有限的熔池重熔效应，低脉冲频率抑制了枝晶的外延生长，形成了由等轴或错取向晶粒组成的随机织构。这项工作提供了一个可控的加工窗口，定制的晶粒结构和纹理使用QCW-DED。
The quasi-continuous-wave laser directed energy deposition (QCW-DED) process was proposed to control the grain structure and texture of additive manufactured nickel-based superalloy. The microstructure characteristics and solidification mechanisms of QCW-DED under different pulse frequencies were investigated by means of experiment and numerical simulation. The QCW-DED greatly modifies the solidification conditions and introduces the periodical re-melting of molten pool. The high pulse frequency promotes the epitaxial growth of columnar dendrites due to the slant-line-like molten-pool boundary, the inhibited columnar to equiaxed transition (CET) and the high-frequency remelting of molten pool. As a result, a high-intensity texture composed of regular zigzag grains was obtained. Owing to the semicircular molten-pool boundary, the promoted CET and the limited molten-pool remelting effect, the low pulse frequency inhibits the epitaxial growth of dendrites and develops a random texture composed of equiaxed or misoriented grains. This work provides a controllable processing window for tailoring the grain structure and texture using QCW-DED.