A manufacturing process for shaft and pipe couplings of Fe-Mn-Si-Ni-Cr shape memory alloys

Abstract

It has been shown that rolling an Fe–15Mn–5Si–9Cr–5Ni (wt.%) alloy at 800 °C followed by annealing at 650 °C gives a structure – a high density of stacking faults and enough austenite hardness – that promotes the stress induced martensitic transformation instead of plastic deformation. After this thermo-mechanical processing, the material recovers around 95% of a 3% permanent deformation excursion. This work addresses the formability and weldability of sheets processed in that manner and how welding affects the mechanical and shape memory properties. Here, the designs and verification are presented for a new method for manufacturing couplings by forming and welding, and finally, the degree of shape recovery in couplings manufactured by this new method are evaluated. The results show that these couplings recover 83% of their diametrical expansion, which make them suitable for many industrial applications.