LASER-WELDING OF A NI-RICH TINI SHAPE-MEMORY ALLOY - MECHANICAL-BEHAVIOR

A Nd:YAG laser was used for joining a pseudoelastic Ti-51.5 at.% Ni sh ape memory alloy. Tensile tests on sheet metal of 0.5 mm thickness wer e performed at temperatures of -40 degrees C, +20 degrees C and 110 de grees C, representing the martensitic, pseudoelastic and austenitic co ndition, respectively. Laser-welded specimens exhibited an ultimate te nsile strength of about 820 MPa not affected by the test temperature. This value corresponds to 80% of the ultimate tensile strength of the base material which was also tested in its martensitic, pseudoelastic and austenitic condition. Therefore, the full use of stress-induced ma rtensite formation on welded components is ensured. However, for a com prehensive understanding of microstructural changes resulting from las er-welding investigations of the 0.6 mm weld were carried out by optic al and transmission electron microscopy. Their results will be present ed and discussed with respect to the tensile tests. Observation of fra cture surfaces of ruptured specimens by scanning electron microscopy c onfirmed the ductile behavior of laser-welded joints.