Machining of NiTi-shape memory alloys-A review

The emerging trends in the development of advanced smart materials with better unique properties under different environments for a particular application fascinate the researchers and industrialists. Nickel-Titanium based shape memory alloys are exotic materials due to their unique properties such as SME, SE, high damping characteristics, high corrosion and wear resistance and biocompatibility. This article presents an overview of machining processes that can be used to machine the NiTi and its surface induced characteristics such as microhardness, surface roughness, topography, induced layer, residual stress, fatigue and phase transformation. The surface integrity characteristics are discussed for machining of NiTi-SMAs under the category of traditional, non-traditional and micro-machining with the effect of input parameters such as cutting speed, feed, depth of cut, type of lubricant and type of coating material on cutting tool. The conventional machining of NiTi alloys are quite complicated due to high toughness, severe strain hardening, fatigue hardening and distinctive property of NiTi-SMAs such as pseudoelastic and shape memory effect. From this study, non-traditional process is significantly used to machine the NiTi-SMAs due to its better results on surface integrity characteristics. Consequently, future trends are also identified for machining the NiTi-SMAs and to improve the surface integrity characteristics.