Rotating-bending fatigue of a laser-welded superelastic NiTi alloy wire

The rotating-bending fatigue of a laser-welded superelastic NiTi alloy wire was investigated. In comparison with the base metal, the welded specimens show significantly reduced numbers of cycles to failure when strain amplitude remains above 0.4%. This is mainly caused by coarse-grained and dendritic microstructure in the welded joints. Both the welded and unwelded specimens can be loaded up to 106 cycles without failure if the strain amplitude remains below 0.4%.