Characterization of residual stresses and microstructural features in an Inconel 718 forged compressor disc
(1. Commercial Aircraft Engine Co., Aero Engine Corporation of China, Shanghai 201108, China;
2. Shenzhen Wedge Central South Research Institute Co., Ltd., Shenzhen 518045, China;
3. Key Laboratory of Neutron Physics and Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621999, China;
4. School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai 200092, China;
5. State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China)
2. Shenzhen Wedge Central South Research Institute Co., Ltd., Shenzhen 518045, China;
3. Key Laboratory of Neutron Physics and Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621999, China;
4. School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai 200092, China;
5. State Key Laboratory of Metal Matrix Composites, Shanghai Jiao Tong University, Shanghai 200240, China)
Abstract: Residual stress plays an important part in fabricating commercial aero engine Inconel 718 components for their fatigue properties, reliability and durability. Due to the limitation of Chinese neutron diffraction instrument and lack of test practice and specifications, there is little systematic research on the residual stress of forged compressor disc. X-ray diffraction and neutron diffraction methods were used to measure the residual stress of Inconel 718 forged discs at the surface and in the interior, respectively. Scanning electron microscope and transmission electron microscope were used to characterize the microstructural features. The residual stress state at the disc is in near-surface compression, balanced by tension within the disc core. However, the surface residual stress of disc depends more on the rough machining than on the forging process. Also, the dislocation densities increase with decreasing distance to the surfaces of disc, and the residual stress accelerates dislocation generation and dynamic recrystallization.
Key words: neutron diffraction; X-ray diffraction; residual stress; Inconel 718; compressor disc