Welding and Joining of NiTi Shape Memory Alloys: A Review

NiTi is an increasingly applied material in industrial applications. However, the difficultiesfaced when welding and joining is required, limits its broader use in the production ofcomplex shaped components. The main weldability problems associated with NiTi are:strength reduction, formation of intermetallic compounds, modification of phase transformationand transformation temperatures, as well as, changes in both superelastic andshape memory effects. Additionally, NiTi is envisaged to be joined to other materials, in dissimilarjoints with more complex problems depending on the other base material. Thus,intensive research in welding and its effects on the joints performance has been conductedsince the early stages of NiTi. This paper presents a detailed review of welding and joiningprocesses applied to NiTi, in similar and dissimilar combinations considering both fusionand solid-state processes. Since laser is the most studied and applied welding process, aspecial section is devoted to this technique