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为了解NiTiNb形状记忆合金的高温松弛性能,进行了高温下的松弛试验。由应力松弛与蠕变的关系,推导得到松弛曲线表达式。通过实验数据回归,发现松弛曲线表达式与实验结果吻合良好,并得到了表征材料抗松弛性能的材料松弛特征系数和剩余应力比。结果表明,温度越高,初始应力越大,应力松弛越明显;当温度在300～400℃,初始应力在260～360MPa时,NiTiNb的应力松弛很小;在高温下NiTiNb的抗松弛性能优于NiTiFe,更适合于高温下使用。
To understand the high temperature relaxation properties of NiTiNb shape memory alloys, relaxation tests at high temperatures were performed. From the relationship between stress relaxation and creep, the relaxation curve expression is deduced. By regression of experimental data, it is found that the relaxation curve expression is in good agreement with the experimental results, and the relaxation characteristic coefficient and the residual stress ratio of the material are obtained. The results show that the higher the initial temperature, the more obvious the stress relaxation. When the temperature is between 300 and 400 ℃ and the initial stress is between 260 and 360 MPa, the stress relaxation of NiTiNb is very small. The relaxation resistance of NiTiNb is better than that of NiTiNb NiTiFe, more suitable for high temperature use.