High-frequency linear friction welding of aluminum alloys

Highlights: • Linear friction welding (LFW) was performed at 250 Hz (five times as high as conventional LFW frequency.) • Sound welds were obtained for 6063 and 5052 Al alloys with joint coefficient > 80%. • Joint strength was higher at shorter processing time with less heat effect for the 6063 Al alloy. • Refined grains and remaining precipitates contributed to the high joint strength of 6063 Al alloy at a short processing time. • High-frequency LFW is promising for the welding of precipitation-hardening aluminum alloys with less heat effect. We developed High-Frequency Linear Friction Welding (HFLFW) operating at 250 Hz, which is larger than conventional LFW methods, to realize welding aluminum alloys. In order to establish the fundamental HFLFW process for the welding of Al alloys, the relationship between the mechanical properties and microstructure of the HFLFW joint was investigated for both 6063 and 5052 Al alloys, which have different strengthening mechanisms. Sound welds were achieved for both 6063 and 5052 Al alloys. The change in the shape of flash with increasing process time indicated that the material flow in the joint was largely affected by the material properties such as proof stress at high temperature and thermal conductivity. Further, the hardness increased and refined grains were observed at the interface of the 6063 Al alloy joints welded in the low-heat-input condition, which led to a higher joint strength at a shorter process time. The size of the refined grains was about 100 nm, as observed by transmission electron microscopy. Our findings reveal that a high frequency is effective and HFLFW is a promising process for the welding of precipitation-hardening aluminum alloys with a high joint strength owing to the less heat effect during the process.