Researchers from Fort Wayne Metals, Texas A&M University, and NASA Glenn Research Center reported on a new class of iron-based shape-memory alloy cables in “Superelastic Fe-based Shape Memory Alloy Cables,” a presentation at the ASM International SMST 2019 conference in May.
A new class of Fe-based SMA cables was examined as a candidate to provide high-performance per cost unit, design flexibility, and damage resistance for industrial applications, and to show that favorable wire properties can be scaled into larger assemblies. So far, NiTi SMA cables have been studied in detail and have shown better flexibility and strain-recovery properties than similar diameter monolithic SMA bars. However, the inherent material cost and difficulties in welding and joining of NiTi SMA cables may limit their use at scale in some applications.
In this work, the researchers developed an inexpensive Fe-Mn-Al-Ni SMA cable. Cables were fabricated into a simple 1×7 construction with an individual wire diameter of 0.5 mm. Abnormal grain growth heat treatments were performed to generate large grains, and nano-sized precipitates formed in the matrix after precipitation heat treatments at 200°C for three hours.
Microstructural features of the wires were investigated using electron backscatter diffraction (EBSD) and scanning electron microscopy. Grain growth methods and crystallographic texture in these Fe-based SMA cables were discussed in the presentation.
Tensile cyclic tests were performed at room temperature until failure, to determine critical stress for stress-induced martensitic transformation (CSSIM), stress hysteresis, superelastic strain, and irrecoverable strain. Results were compared against similarly constructed NiTi and stainless-steel cables.
Authors:
Hande Ozcan, Albert Patrick, Peter Miller, Dr. Ji Ma, Prof. Ibrahim Karaman, Texas A&M University, College Station www.tamu.edu
Dr. Jeremy E. Schaffer, Fort Wayne Metals Research Products Corporation, Fort Wayne, Indiana www.fwmetals.com
Dr. Ronald D Noebe, NASA Glenn Research Center, Cleveland www.nasa.gov/centers/glenn
SMST (Shape Memory and Superelastic Technologies) Conference and Exposition
May 13 – 17, 2019, at the Bodenseeforum in Konstanz, Germany.
https://www.asminternational.org/web/smst-2019
https://www.asminternational.org/web/smst/home
