时效对GH4090合金弹簧丝微观结构及力学性能的影响

Effects of aging process on microstructure and mechanical properties of GH4090 superalloy spring wires

为制备高强度耐高温的高温合金弹簧,以固溶冷拉的GH4090高温合金弹簧丝为母材,在550~750℃范围内进行了时效处理。研究了时效工艺对GH4090高温合金弹簧丝的微观组织结构的影响,分析了γ′强化相对其纯扭力学性能的影响。结果表明,当时效温度在650℃以下时,随着时效温度的升高,γ′相的含量增加,但尺寸变化不大,室温抗扭强度提升。当时效温度大于650℃时,γ′相明显粗化,体积分数降低,室温抗扭强度逐渐下降。另外,二阶时效处理可以获得更细化和更高体积分数的γ′相、从而表现出更高的抗扭强度与硬度。650℃×8 h(50℃/h速率冷却)+550℃×8 h (空冷)的二阶时效工艺可以合理有效地调控微观组织结构,使GH4090合金弹簧丝表现出优良的综合力学性能。室温抗扭强度达到1 373.4 MPa,并且在500℃的测试温度下保持较高抗扭强度。

To develop superalloy springs with high strength and good thermostability, aging processes were carried out in solution cold-drawn GH4090 superalloy spring wires at temperatures of 550-750 ℃. The effects of aging processes on the microstructure of GH4090 superalloy spring wires were investigated. The effects of the size and volume fraction of the γ′ phase on the torsional mechanical properties were also revealed. The results show that when the aging temperature is below 650 ℃, the volume fraction of the γ′ phase and the torsional strength increase with increasing aging temperature, but the change of particle size of the γ′ phase is not significant. When the aging temperature is above 650 ℃, the γ′ phase coarsening appears, and the volume fraction and the torsional strength decrease gradually with increasing aging temperature. In addition, compared with the one-step aging treatment, the higher volume fraction and finer γ′ phase can be obtained by the two-step aging treatment, which enhances the higher torsional strength and hardness in GH4090 superalloy spring wire. The aging process, 650 ℃ for 8 h(50 ℃/h cooling) +550 ℃ for 8 h(air cooling), can efficiently optimize the microstructure and achieve good mechanical properties in GH4090 superalloy spring wire. The high torsional strength(1 373.4 MPa) can be achieved in GH4090 superalloy spring wires at room temperature, which also shows high torsional strength at the elevated temperatures of 500 ℃.