Track: Manufacturing

Abstract

Different industries have increased interest to utilize shape memory alloy, nitinol, due to its abilities like morphing, superelasticity, high corrosion resistance, and biocompatibility. On the other hand, Ti-6Al-4V has high tensile strength and toughness, high corrosion resistance, good biocompatibility, and low specific weight. For these reasons, Ti-6Al-4V gets a lot of attention from industries like aircraft and medical engineering. Joints of these two widely different alloys should then offer unique advantages for highly specialized applications. However, problems related to the joining of dissimilar metals like nitinol to Ti-6Al-4V have restricted the widespread use of these alloys. Differences in metallurgical properties and coefficient of thermal expansion, as well as the tendency to form brittle intermetallic phases during welding, lead to cracks in the welds. This mismatch related to the thermal and mechanical properties between dissimilar metals results in the weakening of the overall quality of the joint between these two metals. Therefore, knowledge on joining nitinol to Ti-6Al-4V should be expanded in relation to dissimilar metal joints to overcome these problems, and future solutions can be found. In this study, the shape memory effect and superelastic properties of nitinol are discussed, and how these might get affected during the welding of nitinol to Ti-6Al-4V are presented. An attempt is made to friction weld Nitinol to Ti-6Al-4V using friction welding technique. Both metals start to form flash indicating a positive response to the friction welding cycle and a narrow strip of intermixed zone seen to have formed at the weld interface.