Researchers from Fort Wayne Metals, Indiana; and NASA Glenn Research Center, Cleveland, will report on the results of a study in which a large-scale plasma-arc-melted NiTi20Hf ingot was subjected to a hot forging and rolling process, during the ASM International IMAT 2020 conference to be held in Cleveland in September.
The NiTi20Hf shape memory alloy has been previously shown to be an ideal material for actuation at elevated temperatures. High work output, high activation temperatures and stable actuation responses are among the key properties that have made this alloy an optimum choice.
From an alloy production/conversion standpoint, most thermo-mechanical processing has been limited to extrusion of round billets. Extrusion has many processing benefits, such as large cross-sectional area reductions at high strain rates, which can be beneficial for crack-susceptible or difficult-to-process material. However, the cost of extrusion and limited output geometry can be a barrier to production scale-up or product innovation.
In this study, a large-scale plasma arc melted NiTi20Hf ingot was subjected to a hot forging and rolling process to create thin strip material. The alloy was forged from a round ingot to a pseudo-flat bar, followed by a multi-step rolling and annealing process to form strips with a thickness of 0.56 mm. The resulting materials microstructure and property characterization will be discussed.
Title:Forging and Hot Rolling of High Temperature Actuator Alloy NiTi20Hf
Authors: Dr. Kyle Fezi, Fort Wayne Metals, Columbia City, Indiana
Mr. Glen S Bigelow, Dr. Othmane Benafan, NASA Glenn Research Center, Cleveland, Ohio
