On the effects of selective laser melting process parameters on microstructure and thermomechanical response of Ni-rich NiTi

Any variation in the processing parameters of selective laser melting fabrication could impact the performance of the final product. This study is concentrated on the effects of laser power and scanning speed alteration on the microstructure, transformation temperatures, texture, and shape memory response of Ni50.8Ti49.2. In this regard, multiple samples were systematically fabricated to demonstrate that careful selection of process parameters can lead to fabrication of parts with distinctive features and behaviors. The samples processed with low laser power showed significantly higher strain recovery and lower mechanical hysteresis compared to those processed with high laser power. It was demonstrated that the samples fabricated with same energy level, using a combination of different processing parameters each displayed unique responses. The sample fabricated with a laser power of 100 W and scanning speed of 125 mm/s exhibited almost perfect superelasticity with a recovery ratio of 96% and strain recovery of 5.77% in the first cycle. The corresponding stabilized superelastic response demonstrated full strain recovery of 5.5% after 10 cycles. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.