The effect of annealing temperature on microstructure and mechanical properties of dissimilar laser welded superelastic NiTi to austenitic stainless steels orthodontic archwires. (September 2020)

• Record Type: Journal Article
• Authors: Asadi, Saeed; Saeid, Tohid; Valanezhad, Alireza; Watanabe, Ikuya; Khalil-Allafi, Jafar
• Is Part Of: Journal of the mechanical behavior of biomedical materials. Volume 109(2020)
• Publication Date: 2020-09
• Subjects: Orthodontic archwire -- NiTi -- Stainless steel -- Laser welding -- Annealing; Biomedical materials -- Periodicals; Biomedical materials -- Mechanical properties -- Periodicals; Biomedical materials; Biomedical materials -- Mechanical properties; Periodicals; Electronic journals; 610.28
• DOI: 10.1016/j.jmbbm.2020.103818
• Languages: English
• ISSNs: 1751-6161

Abstract

Abstract: Annealing after welding is a common operational process to improve the mechanical properties of metallic joints through releasing residual stresses in the weld zone. In this study, the effect of post weld annealing on the microstructure and mechanical properties of dissimilar laser-welds for orthodontic archwires of NiTi alloy to austenitic stainless steel has been investigated. In order to do this, the laser-welded wires were annealed at temperatures of 100, 200, and 300 °C for 1 h and then they were quenched in water. Results show that annealing at 100 °C does not affect the microstructure and mechanical properties of joints but post weld heat treatment at 200 °C ends in an increase in the tensile strength to an order of 1.91 times of the strength of as welded (non-heat-treated) joints. Also, precipitation and increase of intermetallic compounds, such as Cr2 Ti, and Fe2 Ti, at the weld zone during heat treatment at 300 °C, results in a reduction in the mechanical properties of joints. Therefore, post-weld annealing is an effective process on improving mechanical properties of dissimilar joints of these two alloys. However, a suitable heat-treatment temperature is needed in order to achieve desired results. Graphical abstract: Image 1