Dissimilar friction welding of NiTi shape memory alloy and steel reinforcing bars for seismic performance

Abstract

Integration of NiTi superelastic bars with steel reinforcing bars is a promising path for increasing the seismic performance of reinforced concrete structures. Welding of NiTi alloy to steel is however not straightforward with standard welding techniques. Friction welding is investigated for performing this dissimilar junction using both regular friction (forced controlled) and milling (position-controlled) machines. When adequate shortenings and forging forces are selected, the welds can withstand the tensile strength of the steel rebars. Failure actually occurs in the heataffected zone of the steel bars. The intermetallic (IM) layer at the welded interface should be kept thin and cracks should be limited in the steel layer next to the interface in order to avoid early brittle interfacial cracking.

Feasibility of using superelastic shape memory alloy in plastic hinge regions of steel bridge columns for seismic applications

“…This method circumvents the limitations of conventional fusion welding, enabling the creation of robust and efficient welds between NiTi SMA alloy and steel. 26 The successful implementation of friction welding in SMA-steel hybrid systems could pave the way for more resilient and innovative seismic design solutions.…”

“…Friction welding, by controlling parameters such as friction time, compressive force, and rotational speed, allows for the efficient joining of dissimilar materials with varying mechanical and thermal properties. This method circumvents the limitations of conventional fusion welding, enabling the creation of robust and efficient welds between NiTi SMA alloy and steel 26 . The successful implementation of friction welding in SMA‐steel hybrid systems could pave the way for more resilient and innovative seismic design solutions.…”

Comparative study on weld characterisation and corrosion performance of laser-welded NiTinol

“…The fabrication of NiTinol components is problematic, because of poor machinability and formability [11], and heat sensitivity of the alloy. Different reported joining techniques for NiTinol have different limitations [12][13][14][15][16]. From the available literature, it is clear that laser welding is a mostly preferred and promising method of joining NiTinol [17][18][19][20] because of the superior characteristics of the process.…”