Proposal of easy disassembling technology using friction stirring of butt joint ADC12 aluminum alloy / SS400 steel

Though multi materials are jointed strongly to ensure the strength during using, end of life of multi materials need to be disassembled in each material to reuse and recycle. In this study, the method of reduce the joint strength of dissimilar metals after end of life of product was investigated. Butt-joined ADC12 alloy and SS400 steel was fabricated by friction stir welding (FSW) as 1st pass. Then, under the conditions that prevent the joining, FSW for disassembling was conducted as 2nd pass on those joints. Here, we define this FSW conducted to disassemble dissimilar metals as friction stir disassembling (FSD). By conducting three-point bending test of test pieces, fracture load of test pieces conducted FSD was lower than that of test pieces without FSD. All the test pieces conducted FSD were fractured at joint interface. Result of observing test pieces by digital microscope shows that FSD has the effect on forming defects at the joint interface of ADC12 alloy / SS400 steel and internal area of ADC12 alloy. By conducting FSD, formed defects at joint interface reduced the fracture load and lead to easy disassembling.