Metallurgical analyses on Al-Mg alloy pop rivets used in the electric cabinet

•The failure reasons of the Al-Mg pop rivets in the electric cabinet were studied.•SEM, EBSD, fatigue tests and ICP-AES were used to analyze the failure mechanisms of the samples under different states. One of the rivets connecting the frame and cover plate was broken unexpected in use. To analyze the fracture mode of this Al-Mg alloy pop rivet and prevent the similar events, scanning electron microscopy observation and chemical composition tests were carried out. Fatigue tests were performed to further find out the cause of failure of the Al-Mg alloy pop rivets. The failed rivets showed obvious fatigue fracture characteristics, whereas no corrosive medium could be tracked. The fatigue limit of Al-Mg alloy pop rivets was about 400 N. The stress concentration generated during riveting process and the maximum external forces beyond fatigue limit of aluminum rivets led to the initiation of plastic deformation zone. The low content of Mn and the possible existence of crevice between rivet core and rivet body may promote the initiation of plastic deformation zone. Under the action of continuous external load, the fatigue crack continued to expand, and finally caused the fracture of pop rivet. The effect of corrosive medium on cracking can be eliminated.