Prediction of Friction Stir Welding defect-free joints of AISI 304 austenitic stainless steel through axial force profile understanding

Abstract

Friction Stir Welding (FSW) joints of AISI 304 austenitic stainless steel (304 SS) using position controlled mode were investigated in order to understand and relate axial force behavior to welding quality. Joints were produced using two tools and four combinations of specific parameters. The results showed coherence between the axial force profiles and the low-magnification overviews of the welded joints. For defect-free joints, only a natural oscillation on axial force occurred after tool plunge. In contrast, abnormal or abrupt oscillations were directly associated with common welding defects, such as voids and nugget collapse.

Conditions for void formation in friction stir welding from machine learning

“…17,[23][24][25][26][27][28][29] It was also suggested that the peak temperature had to be within 80-90% of the solidus temperature of the alloy to avoid the void formation. 25 Diverse experimental studies such as ultrasonic 30 and radiographic 31 detections of voids and theoretical analysis of forces 26,32,33 were undertaken to understand the origin of void formation. Although progress made in the previous work to identify the important variables such as temperature, strain rate, torque, and maximum shear stress on the pin that affect the void formation, no rigorous mechanistic explanation, or criterion for the void formation have emerged.…”