Effects of tool wear on friction stir welded joints of Ti–6Al–4V alloy

Abstract

Tool wear behaviour on microstructure and mechanical properties of friction stir welded zones of Ti–6Al–4V alloy was evaluated. SEM examination, EDS analysis and X-ray diffraction results indicated that severe wear of the tool is indicated by the presence of WC-Co particles in the stir zone at rotational speed of 630 rev min⁻¹ and travel speed of 8 mm min⁻¹. Micro-hardness, tensile tests and fractographical examinations also reflected that these particles make the material more brittle and reduce the mechanical strength by 40%. However at travel speed of 22 mm min⁻¹, tool wear is less, hardness distribution is more uniform and enhanced ductility and strength is achieved.

Keywords:

• Friction stir welding
• Titanium alloys
• Microstructure
• Mechanical properties