Desenvolvimento e caracterização de liga Fe-Mn-Si-Cr-Ni com efeito de memória de forma
Simon, Rafael Wagner
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The shape memory effect represents a physical property of materials with great potential applications in several sectors of Industry. In metallic materials, it’s a phenomenon associated to martensitic transformation and its reversion process in which the material, after being deformed over its elastic limit, can reestablish its original form through heat treatment. It’s really worthwhile to explore this feature because it allows the fabrication of joints and pipe coupling joints without the use of welds. The stainless Fe-Mn-Si-Cr-Ni alloys which this property are potentially eligible for this application and thus have attracted attention of researchers because they’re a cheap economical alternative and easy to be produced when compared to copper and Nickel-Titanium alloys with shape memory shape effect. However, these stainless alloys still feature discrete values of shape recovery and limited corrosion resistance. Besides that, the fabrication processes of this alloys reported in literature involve the production through induction vacuum furnaces that add great cost to the final product and imply few engineering applications. In this regard, the present work aimed to contribute to the study of Fe-Mn-Si-Cr-Ni alloys with shape memory effect and creating and characterizing an alloy obtained by fusion in inductions furnace without controlled atmosphere, assessing the different conditions of material processing when in terms of microstructure, mechanical properties, degree of shape recovery and corrosion resistance. The fusion of the alloy has generated an ingot with a high level of non-metallic inclusions and a certain amount of interdendritic porosity as well as the formation of secondary phases in the microstructure. The homogenization treatment has dropped some of the secondary phases, but the air cooling generated precipitation in grain boundaries. In the heat-treated condition, the alloy featured better results in terms of shape recovery and corrosion resistance.