Failure analysis of an aluminum alloy material framework component induced by casting defects

2017 2nd International Seminar on Advances in Materials Science and Engineering

Li, Bo^1 ; Hu, Weiye^2

Shanghai Institute of Special Equipment Inspection and Technical Research, 915 Jinshajiang Road, Shanghai

200062, China^1

Aerospace Materials Physical and Chemical Analysis Institute, Nanjing Chenguang Corporation, CASTC, 1 Zhengxue Road, Nanjing

210022, China^2

关键词: Aluminum alloy materials;    Chemical composition analysis;    Eutectic particles;    Fracture surfaces;    Intergranular fracture;    Metallographic examination;    Optical microstructures;    Visual observations;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/231/1/012097/pdf
DOI  :  10.1088/1757-899X/231/1/012097

来源: IOP

【 摘 要 】

Failure analysis on a fractured radome framework component was carried out through visual observations, metallographic examination using optical microscope, fractog-raphy inspections using scanning electron microscope and chemical composition analysis. The failed frame was made of casting Al-Si7-Mg0.4 aluminum alloy. It had suffered a former vi-bration performance tests. It was indicated that the fractures were attributed to fatigue cracks which were induced by casting porosities at the outer surfaces of frame. Failure analysis was carefully conducted for the semi-penetrating crack appearing on the framework. According to the fractography inspected by scanning electron microscope, it was indicated that numerous casting porosities at the outer surface of the framework played the role of multiple fracture sources due to some applied stresses. Optical microstructure observations suggested that the dendrite-shaped casting porosities largely contributed to the crack-initiation. The groove-shaped structure at roots of spatial convex-bodies on the edge of casting porosities supplied the preferred paths of the crack-propagation. Besides, the brittle silicon eutectic particles distrib-uting along grain boundaries induced the intergranular fracture mode in the region of the over-load final fracture surface.