变形温度对固溶态Fe-Mn-Si基合金形状记忆效应的影响

Effect of deformation temperature on shape memory effect of solution treated Fe-Mn-Si based alloys

采用OM、XRD和SQUID研究了在77~293 K变形时固溶态Fe-17Mn-5.5Si-9Cr-5.5Ni-0.12C合金的形状记忆效应和微观组织随变形温度的演化规律。结果表明：当变形温度在223~293 K之间时,固溶态Fe-17Mn-5.5Si-9Cr-5.5Ni-0.12C合金的奥氏体屈服强度与应力诱发ε马氏体临界应力的差值△σ0.2从293 K的26 MPa迅速增加至223 K的105 MPa,即奥氏体抵抗塑性变形的能力随变形温度的降低而显著提高,所以其形状回复率从293 K的42%显著提高至223 K的72%;当进一步降低变形温度至77 K时,△σ0.2仅缓慢增加至125 MPa,即奥氏体抵抗塑性变形的能力缓慢提高,所以其形状回复率仅小幅提高至81%。

Evolution of shape memory effect and microstructure with different deformation temperatures was investigated by OM,XRD and SQUID for solution treated Fe-17Mn-5. 5Si-9Cr-5. 5Ni-0. 12 C alloy subjected to deformation at 77-293 K. The results show that △σ0. 2,the difference between austenitic yield strength and critical stress of stress-induced ε martensitic transformation,dramatically increases to105 MPa at 223 K from 26 MPa at 293 K when the deformation temperatures are in the range of 223-293 K. This result indicates that the resistance of plastic deformation of austenite is enhanced remarkably with decreasing the deformation temperature. Thus,the shape recovery ratio increases observably to 72% at 223 K from 42% at 293 K. When the deformation temperature further decreases to 77 K,△σ0. 2increases slowly to 125 MPa. This suggests that the plastic deformation resistance of austenite is improved slightly with further decreasing the deformation temperature to 77 K from 223 K and therefore the shape recovery ratio is only increased to 81%.