Investigation on friction stir welding of aisi 321 stainless steel

Abstract

AISI 321 stainless steel is an austenitic alloy, stabilized with titanium, making it resistant to intergranular attack caused by chromium carbide precipitation. It is characterised by high corrosion resistance and in general atmospheric corrosive environments, it exhibits excellent resistance to most oxidizing agents, general foodstuffs, sterilizing solutions, dyestuffs, most organic chemicals. It has excellent resistance to intergranular corrosion and has good weldability. As a result, AISI 321 stainless steel is used widely in aerospace industry for the fabrication of components such as jet engine parts, exhaust ducts, flanges and piston engine exhaust manifolds. newlineIn Traditional welding methods there is a downside with regard to melting and metal solidification which can lead to weld defects like cracks. In this scenario, Friction Stir Welding (FSW) promises to be an alternative method for joining of materials, with the process having comparatively less peak temperatures 70 80% of the melting temperature of the base material and thereby producing sound joints. FSW is a new welding technique that is a prospective method for producing full thickness welds in a single welding pass and also eliminating fumes and reducing distortion, and thus preventing solidification defects. To join High Melting Temperature (HMT) materials such as steels and titanium, FSW process is used. The present study involves in the selection of FSW process parameters which have an important effect on the weld joint strength of AISI 321 stainless steel. Design of Experiments (DoE) was used to study the effects of FSW process parameters on the attributes of the welded joints. Regression model was developed and used towards the optimization of FSW process parameters for predicting the maximum UTS in the friction stir welded AISI 321 stainless steel joints. newline