A fully coupled thermo-mechanical numerical modelling of the refill friction stir spot welding process in Alclad 7075-T6 aluminium alloy sheets

Abstract

Refill friction stir spot welding (RFSSW) is a solid state joining technology that has the potential to replace processes such as the open-air fusion bonding technique and rivet technology in aerospace applications. Selection of proper RFSSW parameters is a crucial task which is important to ensure the mechanical strength of the joint. The aim of this paper is to undertake numerical modelling of the RFSSW process to understand the physics of the welding process, which involves large deformations, complex contact conditions and steep temperature gradients. Three-dimensional fully coupled thermo-mechanical models of RFSSW joints between Alclad 7075-T6 aluminium alloy sheets have been built in the finite-element-based program Simufact Forming. The simulation results included the temperature distribution and the stress and strain distributions in the overlap joint. The results of numerical computations have been compared with experimental ones. The numerical model was able to predict the mechanics of material flow during the joining of sheets of Alclad aluminium alloys using RFSSW. The predictions of the temperature gradient in the weld zone were in good agreement with the temperature measured experimentally. The numerical models that have been built are capable of simulating RFSSW to reduce the number of experiments required to set optimal welding parameters.

Experimental and Numerical Analysis of Refill Friction Stir Spot Welding of Thin AA7075-T6 Sheets

“…The refilling of the exit hole was accomplished, but no quantitative results were presented. Kubit et al [ 22 ] developed an axisymmetric thermo-mechanical model of refill FSSW. A temperature-dependent shear friction coefficient model is utilized to compensate for the incipient melting and tool slippage in the process.…”

The Influence of Tool Shape and Process Parameters on the Mechanical Properties of AW-3004 Aluminium Alloy Friction Stir Welded Joints

“…Especially in the case of the CR7, the brittleness might be caused by relatively low heat generation in the relevant joint, so the materials could not be stirred properly. Low heat input was studied not only in FSW but also in underwater welding as well as traditional friction welding, and in each process, it was found to cause the brittle structure of the joint produced [3,29,[58][59][60]. The results reveal that rotational speed may be a more important parameter than welding speed in improving welding conditions and, in addition, joint properties.…”

Review on joining processes of magnesium alloy sheets

“…The RFSSW process is shown in Fig. 4 [33]. The punch of RFSSW includes two parts: a pin and a sleeve.…”

“…3 The schematic of the UAFSSW [31] Fig. 4 RFSSW process [33] influence of different patterns on the welding effect. The shoulder profile is shown in Fig.…”