Thermal Stresses and Distortion Developed in Mild Steel DH36 Friction Stir-Welded Plates: An Experimental and Numerical Assessment

Abstract

Welding processes involve localized heating which in turn give rise to thermal stresses and distortion. Friction stir welding (FSW) is a solid state joining process where temperatures below melting are experienced. Nonetheless, some degree of thermal heating and consequently thermal stresses develop at the joint. This study aims to quantify the stresses developed in friction stir welding of mild steel DH36 plates, through an experimental and numerical investigation. The temperatures and transient strains developed during FSW, are experimentally measured and used to validate thermo-elastoplastic numerical models. These models are used to investigate the evolution of thermal stresses and distortion for different welding parameters.

Keywords:

• Friction stir welding (FSW)
• Mild steel DH36
• Numerical modeling
• Thermal distortion
• Thermal gradients
• Thermal stresses

ACKNOWLEDGMENTS

The authors would like to acknowledge the project partners, in particular Dr. Alex Galloway the project coordinator and Mr. Athanasios Toumpis, for providing the necessary macrographs and Mr. Stephen Cater for providing testing facilities at TWI. The authors would like to thank Dr. Norman McPherson for sharing information related to distortion measurements of friction stir-welded plates.

Notes

*Referenced to support points.

Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/uths.