Stationary Shoulder Friction Stir Processing: A Low Heat Input Grain Refinement Technique for Magnesium Alloy

Abstract

Stationary shoulder friction stir processing (SSFSP) as a low heat input grain refinement technique is projected in this study. SSFSP can be considered as a variant of friction stir processing (FSP) with modified tooling system. It uses stationary shoulder tool and rotating probe, which helps to reduce heat input in great manner during process. Present work aims to refine grain size in thick AZ31B magnesium alloy using SSFSP without using external cooling at different tool rotational speeds (700–1300 rpm). The smooth surface with little flash without any defect was obtained in all the samples, which had confirmed the wide processing range of SSFSP. Probe-dominated stir zone (SZ) achieved for all rotational speeds, which confirmed smaller temperature gradient throughout the SZ thickness. SZ produced at the lowest rotational speed (700 rpm) exhibited reduction in grain size and subsequently enhancement in mechanical properties (hardness and tensile).