On the microstructure evolution and strengthening mechanism of GH4099 Ni-based superalloy fabricated by laser powder bed fusion

• Published in: Materials today communications 2024-08, Vol.40, p.109734, Article 109734
• Main Authors: ZHANG, Keqing, CHEN, Chaoyue, XU, Songzhe, HU, Tao, LI, Xia, CAO, Zhuohan, LI, Xiaopeng, PANWISAWAS, Chinnapat, KE, Linda, WANG, Jiang, REN, Zhongming
• Format: Article
• Language: English
• Subjects: Cellular structure; GH4099 superalloy; Laser powder bed fusion; Strengthening mechanisms
• ISSN: 2352-4928; 2352-4928
• DOI: 10.1016/j.mtcomm.2024.109734

Establishing the connection between multi-scale heterostructures and mechanical performance is a hot topic in laser additive manufacturing (LAM) research. The role of cellular structures is commonly simplified or neglected in the analysis of strengthening mechanisms, due to unclear evolution patterns. This work systematically investigated the microstructure evolution and strengthening mechanisms of GH4099 Ni-based superalloy processed by laser powder bed fusion (L-PBF) additive manufacturing. The results indicate that increasing the scanning speed led to a decrease in the average grain/cell size and texture strength. However, based on statistical analysis of a large number of cell sizes, it was found that increasing the scanning speed only refined a portion of the cellular structures. The localized coarsening of the cellular structure resulted in a deterioration of mechanical performance. The mechanical properties show that as the scanning speed increases from 1100 mm/s to 1700 mm/s, the yield strength rises from 510.12 ± 10.5 MPa to 555.17 ± 1.3 MPa, while the elongation decreases from 33.25 ± 4.5 % to 20.1 ± 4.6 %. Through the analysis of strengthening mechanisms, it is evident that both grain and cellular structure play a crucial role in the variations of strength and ductility. This study introduces a new perspective on achieving customized mechanical performance by regulating multi-scale microstructures during the LAM process. [Display omitted] •The influence of scanning speed on laser powder bed fusion (L-PBF) GH4099 was systematically investigated.•The homogenous distribution of cell size can be improved by the control of scanning speed.•Local coarsening of the cellular structure at the HAGB (high-angle grain boundary) led to decreased ductility.•Both grain and cellular structure played a positive role in contributing to strength.