Abstract： One aluminum alloy forearm connecting rod with surface copper plating cracked after suffering unidirectional down stress for three months. The fracture reasons of aluminum alloy rod were comprehensively analyzed by means of chemical composition analysis, macroscopic and microscopic fracture analysis, high-magnification metallographic examination, mechanical property test, and microhardness measurement. The results showed that the aluminum alloy rod cracked due to the fatigue breakage under bending stress. Fatigue cracked linearly from the surface. The material itself had crack defects before copper plating, and the copper plating further penetrated into the substrate material. The unidirectional stress in work further accelerated and caused fatigue cracking.
2020, Vol. 38 
