Friction Stir Processing as a Novel Technique to Achieve Superplasticity in Aluminum Alloys: Process Variables, Variants, and Applications

Abstract

This article provides an overview of the potential for superplasticity of aluminum alloys using friction stir processing (FSP). FSP is a variant of friction stir welding (FSW), and FSP is an effective technique to alter the metallurgical and mechanical properties of the material, which results in superplastic properties at high strain rate and low temperature. This makes FSP as an attractive and cost-effective method to produce superplastic materials. A detailed summary of previously reported superplasticity in all aluminum alloys using FSP is tabulated in this review. It reveals the influence of tool design, machine variables, number of passes, active cooling, grain size, superplastic temperature, strain rate, and elongation on the superplastic properties of FSP aluminum alloys. Variants of FSP to achieve superplasticity at optimized conditions are proposed based on dual rotation of tool and additional cooing during the process. Applications of superplastic forming in aerospace and automotive are discussed. The direction of research in friction stir-processed superplasticity is covered in future scope.