Crack characteristics analysis and mechanisms in GH3536 alloy manufactured by laser powder bed fusion

• Published in: Engineering failure analysis 2024-08, Vol.162, p.108382, Article 108382
• Main Authors: Lu, Junwen, Zheng, Hao, Ji, Xiaochao, Guan, Yi, Wang, Zhonglai, Cheng, Jian, Zhang, Wei
• Format: Article
• Language: English
• Subjects: Crack mechanism; Laser powder bed fusion; Microstructure; Superalloy; Thermal stress
• ISSN: 1350-6307; 1873-1961
• DOI: 10.1016/j.engfailanal.2024.108382

[Display omitted] •Thermal stress in the heat-affected zone was identified as primary crack driver in GH3536 LPBF alloy.•Local severe grain disorientation was confirmed as a crucial factor for crack occurrence.•Inconsistent deformation coordination among carbides and matrix leads to dislocation aggregation and crack initiation. The presence of cracks poses a significant challenge in the application of laser powder bed fusion (LPBF) for manufacturing high Ni-base superalloys. The crack characteristics of LPBF-fabricated GH3536 superalloy are investigated in this paper, with a focus on analyzing the generation and expansion mechanism of micro-cracks through an investigation into the evolution of the molten pool, thermal stress and micro-characteristics. The findings suggest that thermal stress serves as the primary driving force for both crack initiation and propagation, with a predominant concentration of thermal stress observed in the heat-affected zone located at the periphery of the molten pool. Grain disorientation is another crucial factor influencing both the initiation and propagation of cracks. The difference in orientation between adjacent grains at the crack exceeds 40°, with the crack primarily originating from large angle grain boundaries (LAGBs) and propagating along them. Furthermore, there exists inconsistency in terms of elastic modulus and deformation coordination between carbides (Mo2C, (Ni, Cr) Mo3C6) particles, and matrix. This inconsistency results in two normal partial stresses acting in different directions, leading to dislocation aggregation and crack nucleation.