Failure analysis on cracking of die-forged connecting rod of 7A09 alloy

doi:10.13251/j.issn.0254-6051.2020.01.045

Abstract

Abstract: The causes of cracking failure of die-forged connecting rod of 7A09 alloy were studied by means of fracture morphologies, macrostructure, microstructure, hardness, chemical composition. The results show that the cracks are originated from the specimens surface, and gradually extended to the interior along the grain boundaries. Simultaneously, there are grain boundary broadening and remelting eutectic microstructure in the cracked specimens, which roughly can be judged the burnt microstructure.It is concluded that the overburning owing to temperature being out control during heat treatment is the main cause of cracking of die-forged connecting rod of 7A09 alloy, and results in the decrease of hardness and grain boundary strength. And the relevant improvement measures are put forward.

Key words: 7A09 aluminum alloy, cracking, failure analysis, over-burning

CLC Number:

TG142.2

Liu Yanmei, Zhao Meilan, Feng Hui, Bai Yaru, Li Yan, Wang Tiegang. Failure analysis on cracking of die-forged connecting rod of 7A09 alloy[J]. HTM, 2020, 45(1): 234-238.

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