Tensile and fatigue properties of flanged NiTi pins from laser produced ball pins

The application of commercialized mechanical and adhesive joining of shape memory alloys in superelastic cycling is limited by their discontinuous joint, poor heat and corrosion resistance. The objective of this work was to adapt a laser-based free form heading to a two-step process chain for fabricating a flanged pin with continuous NiTi alloys, and to identify the influence of the process conditions and post heat treatment on the tensile and fatigue properties under superelastic cycling. The results showed that the delay time of the process chain controlled the flange geometry accuracy. Despite similar tensile properties, different laser parameters resulted in varying functional and structural fatigue under superelastic cycling. Regardless of improved tensile strength by within 16 %, the post heat treatment of the flanged pin may reduce its structural fatigue by up to 50 %. These findings provided opportunity for the flanged NiTi pin in the micro systems demanding superelastic cycling.