Influence of ageing treatment on the thermophysical characteristics and mechanical properties of forging wire Ni-rich NiTi alloy for superelastic applications

The Influence of the Soaking Temperature Rotary Forging and Solution Heat Treatment on the Structural and Mechanical Behavior in Ni-Rich NiTi Alloy

“…The hot working applied during the thermomechanical processing is important to set up the homogenization of the microstructure by the reduction in the solidification grain texture, and when a suitable reheating temperature is adopted, it is more effective than a simple annealing treatment for homogenization with 24 to 48 h. The literature indicates that this process is usually performed at a temperature range from approximately 800 °C to 950 °C [ 1 ], but the material needs processing in a temperature of at least 800 °C to function in such a way as to significantly decrease critical stress for the dynamic recrystallization to take place [ 7 , 8 , 9 ]. However, there are few works in the literature that detail the procedures to adopt rotary forging for thermomechanical-process geometries in the bar and wire forms of the NiTi alloys [ 4 , 8 , 10 ]. Rodrigues [ 11 ] highlights in his study thermomechanical processing via multi-step rotary forging, which uses some intermediate heat treatments in order to reheat to a suitable temperature for hot mechanical work, i.e., before each deformation step, a high austenite plasticity is required.…”

The influence of aging treatment on the microstructural and mechanical behavior by ultra-micro hardness tester in Ni-rich NiTi alloy

“…When stress is applied to the austenite field, the induced-stress martensite is formed, but after unloading, the deformed material reverts to austenite. [18][19][20][21] Therefore, this study aimed to evaluate the superelastic development, the influence of aging treatment, and correlate the resulting phase at room temperate in Ni-rich NiTi alloy thin bars produced by rotary forging.…”