Effect of heat treatment on microstructures and mechanical properties of Inconel 718 additively manufactured using gradient laser power

作者：Xu, Luming; Chai, Ze; Peng, Bo; Zhou, Wei^*; Chen, Xiaoqi^*

来源：Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing , 2023, 868: 144754.

DOI：10.1016/j.msea.2023.144754

• Laser powder deposition
• Gradient laser power
• Inconel 718
• Heat treatment
• Laves phase
• Microstructure

To achieve high-performance nickel-based superalloys by laser powder deposition for applications in the aviation industry, post-heat treatments are always indispensable. We prepared two typical as-deposited microstructures by constant laser power deposition (CLP) and gradient laser power deposition (GLP), respectively. A systematic research on the room-temperature microstructural evolution, hardness, tensile property and fracture morphology of Inconel 718 after three kinds of heat treatments is performed. The as-deposited microstructure and segregation ratio (SR) can significantly influence the microstructure evolution. The as-deposited GLP samples with fine discrete Laves phases and a low SR can achieve a relatively uniform element distribution and gamma '' and gamma ' phase precipitation after standard solution treatment plus aging (STA), while CLP samples with coarse long-chain Laves phases and high SR require a high-temperature homogenization plus STA (HSTA) heat treatment to achieve the uniform element distribution. Differences in heat treatments have a greater impact on the fracture mechanism. With the transformation of heat treatments from direct aging, STA to HSTA, the fracture mode of both CLP and GLP samples transforms from a ductile transgranular fracture mode to a mixed mode of transgranular and intergranular fractures.

• 单位
  上海交通大学; 南阳理工学院