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用拉伸实验研究了退火温度(θ_(an))和应力应变循环对Ti-50.8Ni-0.3Cr合金超弹性(SE)的影响.结果表明,随θ_(an)升高,应力诱发马氏体(M)相变的临界应力σM先降低后升高,随后趋于稳定,分别在450和600℃达到最小值(311 MPa)和最大值(583 MPa).残余应变在θ_(an)=350—590℃之间变化不大,始终保持在较低的水平;当θ_(an)高于590℃时,残余应变则急剧升高.随着应力-应变循环次数(N)增加,350和590℃退火态合金由部分非线性超弹性逐渐转变为完全非线性超弹性,而650℃退火态合金由部分非线性超弹性逐渐转变为线性超弹性.此外,随N增加,590和650℃退火态合金的能耗作用逐渐下降,并趋于稳定,而350℃退火态合金的能耗作用基本保持不变.要使Ti-50.8Ni-0.3Cr合金获得良好的SE,退火温度应低于再结晶温度.
The effect of annealing temperature (θ an) and stress-strain cycle on the superelasticity (SE) of Ti-50.8Ni-0.3Cr alloy was studied by tensile test. The results show that with the increase of θ an, The critical stress, σ M, of the bulk (M) decreases first and then increases and then stabilizes, reaching the minimum (311 MPa) and the maximum (583 MPa) at 450 and 600 ° C. The residual strain at θ an = 350-590 ℃, while the residual strain increases sharply when θ an is higher than 590 ℃ .When the stress-strain cycle number (N) increases, 350 and At 590 ℃, the as-annealed alloys gradually change from partially nonlinear super-elastic to completely non-linear super-elastic, whereas the as-annealed alloys gradually transform from partially nonlinear super-elastic to linear super-elastic at 650 ℃ .In addition, The energy dissipation effect of Ti-50.8Ni-0.3Cr alloy is gradually decreased and tends to be stable, while the energy consumption effect of the alloy annealed at 350 ℃ remains basically unchanged.To obtain a good SE for Ti-50.8Ni-0.3Cr alloy, the annealing temperature should be lower than that of Crystallization temperature.