Optimization of the friction-stir-welding process and tool parameters to attain a maximum tensile strength of AA7075–T₆ aluminium alloy

Abstract

High-strength, precipitation-hardening AA7075 alloy is used extensively in aircraft primary structures. The friction-stir-welding (FSW) process is an emerging solid-state joining process in which the material that is being welded does not melt and recast. The FSW process and tool parameters play a major role in deciding the joint strength. In this paper an attempt has been made to establish an empirical relationship between the FSW process and tool parameters (tool rotational speed, welding speed, axial force, shoulder diameter, pin diameter, and tool material hardness) and the tensile strength of the joint. Statistical tools such as design of experiments, analysis of variance, and regression analysis are used to develop the relationships. The developed empirical relationship can be effectively used to predict the tensile strength of FSW joints at the 95 per cent confidence level. A sensitivity analysis is also carried out and compared with the relative impact of input parameters on tensile strength in order to verify the measurement errors on the values of the uncertainty in estimated parameters.

A study to estimate the tensile strength of friction stir welded AA 5059 aluminium alloy joints

“…This may be due to insufficient coalescence of transferred material. At highest axial force, the plunge depth of the tool into the work pieces is higher which results in lower tensile strength [18]. When rotational speed is compared with the welding speed, rotational speed is marginally more sensitive to changes in tensile strength.…”

Friction Stir Welding of Dissimilar Materials Aluminum AL6061-T6 to Ultra Low Carbon Steel

“…The practical approach is to use a non-consumable rotating tool consisting of two parts: a shoulder and a pin. Rotational speed, traverse speed, and vertical pressure on the plates during welding are the main process parameters [7].…”

Effectiveness of cold metal transfer process for welding 7075 aluminium alloys

“…Additionally, it could be concluded that CMT process achieved mechanical characteristics comparable to FSW and LBW since these processes use low heat input as well. 25,35,[39][40][41][42][43][44] We should mention here the advantages of CMT in comparison with other welding processes with respect to its higher welding speeds, simplicity and easy automation, low skill required for operation, availability, cost and economic issue. When the joints are loaded in tension, the WM constitutes the weakest area where all the strain concentrates.…”