Effect of tool rotational speed on mechanical properties and microstructure of friction stir welding joints within Ti–6Al–4V alloy sheets

Abstract

Friction stir welding of Ti-6Al-4V alloy sheets was successfully performed with a tungsten carbide (WC) tool, and the effect of the tool rotational speed on the microstructure and mechanical properties of the joints was evaluated. The microstructure was investigated using field emission scanning electron microscopy, electron backscattered diffraction and X-ray diffraction measurements. Tensile, Charpy impact and Vickers hardness tests were performed to evaluate the joints' mechanical properties. The process peak temperature of each welding condition was measured at the bottom of a specimen. Regardless of the welding conditions, the alpha (a) and alpha prime (a 0 ) phases were detected in the stir zone, whereas the base metal was composed of alpha (a) and beta (b) phases. The tensile strength and hardness of the stir zone increased as the tool rotational speed increased. The impact absorption energy was found to be equal to that of the base metal. Moreover, a phase transformation from the b to the a 0 phases occurred in the stir zone during friction stir welding and the evolution of the microstructure in the stir zone significantly affected the mechanical properties of the joints.

Experimental Investigation of Friction Stir Welding on 6061-T6 Aluminum Alloy using Taguchi-Based GRA

“…However, in this joining technique, the process parameters play a vital role in affecting the mechanical plus the metallurgical properties of the weldment [14][15][16][17]. The higher tool rotational and the lower traverse speeds are the source of producing adequate heat for joining the base metal and those are the highest statistical influence on hardness, tensile strength, and peak temperature relative to other parameters [18][19][20]. On the other hand, the tool pin profile is governing the material movement and significantly influence the flow of plasticized material.…”

Effects of a Post-Weld Heat Treatment on the Mechanical Properties and Microstructure of a Friction-Stir-Welded Beryllium-Copper Alloy

“…In particular, FSW is an effective technique for joining stain-less steel due to advantages such as low distortion and residual stress [15]. In recent days, studies about high strength steel [16], advanced high strength steel [17] and Ti-alloys [18] were performed. Murugan et al showed that friction stir welding condition can get sound joints without defects in copper and bronze plates [19].…”