Research Of Influence Of C, Cr, Ni, RE And Heat Treatment On Memory Effect Of Fe-Mn-Si SMA

The shape memory alloy is a new kind of functional materials,the main characteristic of this material is the shape memory effect. Compared with others alloys, Fe-based shape memory alloy have such advantages as high strength, better plasticity, easy processing, low cost and so on. So they become the focus of recent research.In this paper, 15 kinds different compositions of Fe-based Shape Memory Alloys(SMA) were prepared by melting rough stock such as common scrap and pig iron in medium frequency induction furnace in atmosphere. By means of bend tests, Influences of different composition of SMA on SME were studied. Tensile properties of the alloys were also researched. On this basis, the influence of C, Cr, Ni and RE on shape memory effect and tensile properties were investigated, and several kinds alloy compositions with better compositive performances were optimized. Microstructures of optimum alloys were observed by means of optical microscope, XRD and so on. The influence of tempering and quenching temperature on SME were investigated. Corrosion resistance of optimum alloys has also been studied.The results shown that the tensile strengh decreased continually with C content increasing, but the SME increased first and then dropped over 0.2wt.% C content; with the increase of Cr content, the tensile strengh and the SME increased stability and then dropped over 10wt.% Cr content; Adding Ni was harmful to tensile strengh and the SME; When RE content was 0.1wt.%, tensile strengh was the best but SME worst. Optimum alloys content were Fe-15Mn-5Si-10Cr-0.2C, Fe-15Mn-5Si-10Cr-0.2C-2Ni and Fe-15Mn-5Si-10Cr-0.2C-0.2RE. Tempering and quenching experiment shown that optimum tempering temperature of three alloys were 500℃, 700℃and 600℃, respectively. Optimum quenching temperatures were at 650℃. The corrosion tests indicated that, the optimum corrosion resistance of alloy was Fe-15Mn-5Si-10Cr-0.2C-2Ni in HCl solution. However, corrosion weight rate of three alloys have slightly difference in NaCl and NaOH solution. The best corrosion resistance was in NaOH solution, and then in NaCl solution, worst in HCl solution for the three alloys.