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采用OM和铁素体测量仪研究了铸态Fe-18Mn-5.5Si-9.5Cr-4Ni合金的微观组织随退火温度的改变及其对合金形状记忆效应的影响.结果表明,在773-1173 K之间退火处理能进一步提高合金的形状记忆效应.经973 K退火30 min后,合金的可恢复变形量达到了6.4%,比训练4次的常规Fe-14Mn-5Si-8Cr-4Ni合金高1.2%.当铸态合金在低于1173 K退火30min后,δ铁素体仍为条状,变形时能使应力诱发ε马氏体以区域化的方式形成,合金具有良好的形状记忆效应;当退火温度高于1273 K时,δ铁素体将固溶到奥氏体中,体积分数减少.当退火温度进一步升高到1423 K时,δ铁素体的体积分数显著增加,形态由条状演变为岛状.条状δ铁素体体积分数的减少和岛状δ铁素体的形成导致δ铁素体不能有效分割奥氏体晶粒,合金的形状记忆效应显著下降.
The microstructure of as-cast Fe-18Mn-5.5Si-9.5Cr-4Ni alloy with annealing temperature and its effect on the shape memory effect of the alloy were studied by using OM and ferrite meter.The results show that in the range of 773-1173 K Annealed at 973 K for 30 min, the recoverable deformation of the alloy reaches 6.4%, which is 1.2 higher than that of conventional Fe-14Mn-5Si-8Cr-4Ni alloy with 4 times of training %. When the as-cast alloy is annealed at below 1173 K for 30 min, the δ-ferrite is still in the form of strip and the stress-induced ε-martensite can be formed in a regionalized manner during deformation. The alloy has a good shape memory effect. When the annealing temperature is higher than 1273 K, δ ferrite will dissolve into the austenite and the volume fraction decreases. When the annealing temperature is further increased to 1423 K, the volume fraction of δ ferrite increases significantly, Evolved into island shape.The decrease of the volume fraction of strip δ ferrite and the formation of island δ ferrite led to the fact that δ ferrite could not effectively separate the austenite grains and the shape memory effect of the alloy decreased significantly.