Electron beam welding of Fe–Mn–Al–Ni shape memory alloy: Microstructure evolution and shape memory response

P Krooß,J Günther,L Halbauer,A Buchwalder,M Vollmer,R Zenker,T Niendorf,H Biermann

doi:10.1142/s1793604717500436

P Krooß, J Günther + Show 6 more

Open Access

https://doi.org/10.1142/s1793604717500436

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Abstract

The present study reports on the impact of abnormal grain growth (AGG) on the microstructural evolution following electron beam (EB) welding of Fe–Mn–Al–Ni shape memory alloy (SMA). Polycrystalline sheet-like material was EB-welded and a cyclic heat treatment, studied in previous work, was conducted for inducing AGG and a bamboo-like microstructure, respectively. Optical and electron microscopy were carried out to characterize the prevailing microstructure upon cyclic heat treatment. For characterization of the functional properties following AGG, a load increase test was conducted. The current results clearly show that good shape memory response can be obtained in Fe–Mn–Al–Ni SMA upon EB welding and subsequent post-heat treatment. These results further substantiate the potential use of conventional processing routes for Fe–Mn–Al–Ni SMA.

Highlights

Shape memory alloys (SMAs) attracted a lot of attention during the last decades due to their unique functional material properties.[1,2] With Ni–Ti being the most studied and employed shape memory material, numerous industries like aerospace, energy harvesting and biomedical request these materials as they are well suited for both damping and actuation applications
Fe-based shape memory alloy (SMA) are of highest relevance, due to the fact, that alloying elements are cheap and processing routes from steel industry are supposed to be well suited for manufacturing of these alloys
Omori and coworkers proposed a cyclic heat treatment, leading to abnormal grain growth (AGG) in Cu–Al–Mn and Fe–Mn–Al–Ni SMAs, resulting in a so-called bamboo-like microstructure, which is characterized by grain boundaries having a predominant alignment perpendicular to the loading

Summary

Introduction

Shape memory alloys (SMAs) attracted a lot of attention during the last decades due to their unique functional material properties.[1,2] With Ni–Ti being the most studied and employed shape memory material, numerous industries like aerospace, energy harvesting and biomedical request these materials as they are well suited for both damping and actuation applications. Microstructural analyses of the fusion zone and base material were carried out using optical and scanning electron microscopy in order to characterize secondary phase fractions being present after welding.

Results

Conclusion