热处理工艺对CuAlMn形状记忆合金力学性能影响的研究

Study on the Effect of Heat Treatment Process on Mechanical Properties of CuAlMn Shape Memory Alloys

对采用真空中频感应炉熔炼出的CuAlMn形状记忆合金进行热锻、热轧和伴随中间退火的多道次冷拔加工后,制得直径为2 mm的线材。用普通热处理和循环热处理两种工艺对线材分别进行热处理,并对线材的组织和抗拉强度、超弹性、硬度进行了测试。结果表明:普通热处理时,随淬火温度的升高,晶粒尺寸由213μm增加至547μm,抗拉强度、维氏硬度分别由771 MPa、264降低至618 MPa、246,但会略微提高材料的超弹性,最大超弹性应变为2.5%;循环热处理时,随循环次数的增加,晶粒会发生异常长大,对应线材的抗拉强度和维氏硬度分别由348 MPa、240降低至302 MPa、226,超弹性应变由4%增加至10%,循环5次后,加载至10%应变后卸载,变形能完全恢复,表现出极佳的超弹性。

The CuAlMn shape memory alloy melted by vacuum medium frequency induction furnace was processed by hot forging,hot rolling and multi pass cold drawing with intermediate annealing,and the wires with diameter of 2 mm were fabricated.The wires were heat treated by normal heat treatment and cyclic heat treatment respectively,and the microstructure,tensile strength,super-elasticity and hardness of the wires were tested.The results show that with the increase of quenching temperature during normal heat treatment,the grain size increases from 213μm to 547μm.The tensile strength and Vickers hardness decrease from 771 MPa and 264 to 618 MPa and 246,respectively,but the superelasticity of the material is slightly improved with the maximum super-elastic strain of 2.5%.During cyclic heat treatment,the grains grow abnormally with the increase of cycle.The tensile strength and Vickers hardness of the corresponding wire decrease from 348 MPa and 240 to 302 MPa and 226,respectively,and the super-elastic strain increases from 4%to 10%.After 5 cycles,the deformation completely recovers after loading to 10%strain and then unloading,showing excellent super-elasticity.