预时效工艺对Ti-3.5Al-5Mo-6V-3Cr-2Sn-0.5Fe钛合金组织与性能的影响

Effect of Pre Aging Microstructure on the Mechanical Properties of Ti-3.5Al-5Mo-6V-3Cr-2Sn-0.5Fe

摘要:

对Ti-3.5Al-5Mo-6V-3Cr-2Sn-0.5Fe钛合金分别进行单级和双级时效热处理,对比研究双级时效工艺对高强β钛合金组织与性能影响。单级时效温度为550℃,双级时效工艺采用在400℃预时效之后再进行550℃下的再时效处理。研究结果表明,合金在400℃预时效时析出了ω相,随着预时效时间的延长,ω相最终转变为α相。相比单级时效而言,合金经双级时效后其次生α相显微组织得到明显细化,其原因主要是因为预时效阶段为后续较高温度下次生α相的形核与长大提供了更多的形核质点。双级时效工艺可以大幅提高合金的强度及硬度,但是塑性略有下降。

Abstract:

The microstructure evolution and mechanical properties of Ti-3.5Al-5Mo-6V-3Cr-2Sn-0.5Fe alloy after single and duplex aging treatment were studied. The Single aging temperature was 550℃, the duplex aging was pre-aged at 400 ℃ then re-aged at 550℃. The results showed that when the alloy pre-aged at 400℃, the ω phase was precipitated. As the pre-aging time prolonged, the ω phase finally changed to the α phase. Duplex aging was effective to yield the α phase fine dispersion, and the pre precipitated isothermal ω phase provided more uniform nucleation position for precipitation of α phase than single aging so as to improve the alloy tensile strengthen greatly. During pre aging, the isothermal ω phase could precipitate sufficiently so as to provide more advantageous nucleation position to precipitate very fine α phase of acicular style, and the strengthening effect was the same with that of duplex aging.