Effect of friction welding conditions and aging treatment on mechanical properties of A7075-T6 aluminium alloy friction joints

Abstract

This article describes the effect of friction welding conditions and aging treatment on the mechanical properties of type 7075-T6 aluminium alloy (A7075) friction welded joints. A7075 was joined by using a continuous drive friction welding machine with an electromagnetic clutch in order to prevent braking deformation during as rotation speed decreases. That is, it was welded by using the ‘Low Heat Input Friction Welding Method’ (LHI method) developed by the authors, in which heat input is lower than in the conventional method. The maximum joint efficiency at a friction pressure of 30 MPa was approximately 25%, and that at 90 MPa was approximately 64%. These joints were made without forge pressure. The low joint efficiency was due to the existence of non-joined regions at the welded interfaces. However, the welded joint had approximately 82% joint efficiency when the friction time was 0·5 s at a friction pressure of 90 MPa with a forge pressure of 180 MPa. The welded joint softened at the welded interface and its adjacent region. It had approximately 90% joint efficiency after aging for 730 days at room temperature (natural aging). It also had approximately 95% joint efficiency after aging for 48 h at 393 K (120°C), and had no softened region at the welded interface. The heat input of the welded joint with the LHI method could be decreased to approximately 50% of that with the conventional method. The LHI method has several advantages for A7075 friction welding; less heat input than with the conventional method, and light post-weld processing (machining, etc.) because the flash can be minimised.

Friction welding technique and joint properties of thin-walled pipe friction-welded joint between type 6063 aluminum alloy and AISI 304 austenitic stainless steel

“…Actually, the joint, which was made by the solid-state joining methods [23,24] as well as fusion welding methods [25][26][27], had changed in joint strength by heat treatment. Furthermore, the friction-welded joints had also changed in strength through heat treatment [28]. However, the material used in this study was A6063, and it had the H18 work hardening treatment.…”

Comparing bond formation mechanism between similar and dissimilar aluminium alloy friction welds

“…3,4 Longer friction times, which technically equate to higher burn-off lengths, raised the joint strength in AA 7075 welds only up to a certain limit, after which there was stabilisation. 5 Simulation studies reported higher friction pressures lead to larger axial shortening whereas longer friction times lead to linear rate in axial shortening. 6 Both friction pressure and friction time needed to be ideal for a strong joint for particulate reinforced AA 7005 alloy.…”

Effect of friction pressure on joining phenomena of friction welds between pure titanium and pure copper

“…[2][3][4][5][6][7][8][9][10][11][12][13] The authors also clarified the joining mechanism during the friction welding process and the mechanical properties for several joints made from dissimilar materials. [14][15][16][17][18] In addition, it was also indicated that the joining phenomena of dissimilar materials were affected by the differences between the yield stress of both base materials at a temperature on the weld interface during the friction process and the friction pressure to make the joint.…”