Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5455904 | Materials Science and Engineering: A | 2017 | 10 Pages |
Abstract
The microstructure and microhardness of Ni-base superalloy IN-738LC fabricated by laser solid forming (LSF) with the preheating was investigated. The results showed that with the increase of the preheating temperature (T0) (25 °C, 800 °C, 900 °C and 1050 °C), the total crack length decreased significantly, the segregation of Ti and Al worsened, and the volume fraction of equiaxed grain increased, as well as the size of blocky carbides, γ-γⲠeutectic and γⲠparticles. The high-angle grain boundaries, at which the continuous liquid film can be easily formed, were found to be susceptible to cracking. Both the concentration of Ti and Al and the increase of dendrite spacing contribute to the growth of carbides and γ-γⲠeutectic in the interdendrite while the size of the γⲠphases was largely affected by preheating. It was interesting to find that γⲠphase exhibited a bimodal distribution in the bottom of the deposit with the preheating at 1050 °C. The average microhardness of the deposits without preheating and with preheating at 800 °C and 900 °C is about at the same level, while the deposit with preheating at 1050 °C has the lowest average value. The crack-free deposit can be obtained when T0 was up to 1050 °C, and its room temperature tensile properties are superior to cast IN-738LC alloy.
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Physical Sciences and Engineering
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Authors
Jianjun Xu, Xin Lin, Pengfei Guo, Yunlong Hu, Xiaoli Wen, Lei Xue, Jianrui Liu, Weidong Huang,