Nitinol 60形状记忆合金高温变形特性研究

High Temperature Deformation Characteristics of Nitinol 60 Shape Memory Alloy Based on Processing Map

采用Gleeble-3500热模拟试验机对轧态Nitinol 60形状记忆合金进行等温恒应变速率拉伸试验,基于动态材料模型的加工图技术,研究了该合金在650~850℃和0.01~1 s^(-1)范围内的高温变形特性,并优化了其适宜的高温变形参数范围。结果表明,加工图中失稳区位于低温、高应变速率区,范围为650~776℃、0.075~1 s^(-1),对应的失稳现象为局部塑性流动。加工图中有2个η峰值区,范围分别为690~750℃、0.01~0.026 4 s^(-1)和750~838℃、0.01~0.050 5 s^(-1),η最大值分别达到了0.36和0.38,对应的变形机制均为动态再结晶,这2个区域为Nitinol 60合金适宜的热拉伸变形工艺参数范围。

The hot tensile deformation of Nitinol 60 shape memory alloy was conducted with Gleeble-3500 thermal simulation machine at 650- 850℃ and0.01-1s-1. The processing maps were constructed and hot working parameters were optimized based on the generated processing map. The results show that there exists a single unstable region at 650-776℃,0.075-1 s-1 associated with flow localization in the processing map. The optimized hot working conditions correspond to 690-750℃,0.01t0.026 4 s with peak efficiency of 0. 35 at 720 ℃,0.01 s 1, and750-838℃,0.01-0.050 5 s 1 with peak efficien- cy of 0.38 at 810 ℃,0.01 s 1. microstructural observation indicates that the main deformation mecha- zatlon