Influence of heat treatment on the fatigue life of a laser-welded NiTi alloy wire

• Published in: Materials characterization Vol. 58; no. 3; pp. 262 - 266
• Main Authors: Yan, X.J., Yang, D.Z., Liu, X.P.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 01.03.2007; Elsevier Science
• Subjects: Applied sciences; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Fatigue; Heat treatment; Joining, thermal cutting: metallurgical aspects; Laser welding; Materials science; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; NiTi alloy; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Physics; Precipitate; Solidification; Welding; Fatigue; Heat treatment; Precipitate; NiTi alloy; Laser welding; Fatigue life; Mechanical properties; Surface treatments; Surface alloying; Wire; Precipitates; Heat treatments; Welded joints; Precipitation; Lasers
• ISSN: 1044-5803; 1873-4189
• DOI: 10.1016/j.matchar.2006.05.001

The influence of heat treatment on the rotating–bending fatigue of a laser-welded superelastic NiTi alloy wire was investigated. In comparison with the as-welded and annealed at 500 °C for 1 h specimens, the specimen annealed at 400 °C for 1 h shows the best fatigue resistance. The difference of fatigue life in the heat-treated materials is attributed to the different Ti 3Ni 4 precipitate size. Heat treatment to produce smaller coherent precipitates (10 nm) improves the fatigue resistance of the laser-welded NiTi alloy wire. When the Ti 3Ni 4 precipitates become coarse, the fatigue resistance decreases.