Effect of load cycling on the phase transformations in Ni–Ti wires for civil engineering applications

Tensile tests were conducted in order to evaluate the cyclic behaviour of superelastic Ni–Ti wires for civil engineering applications. Different load–unload cycling frequencies, maximum elongation and pre-strain levels were tested. Phase transformation temperatures were determined by using electrical resistivity method and differential scanning calorimetry. No variation on energy dissipation was observed with increase of frequency, although an increase in cycling amplitude increased energy dissipation. By lowering the pre-strain level, a different hysteresis behaviour was obtained. The transformation temperatures were determined for specimens with different load histories, leading to similar results.

► Tensile tests were conducted on superelastic Ni–Ti wires. ► Phase transformation temperatures were determined by ER and DSC. ► No variation on energy dissipation was observed with increase of frequency. ► Energy dissipation increased with cycling amplitude. ► Transformation temperatures for specimens with different load histories were similar.