Ti40合金550℃热暴露组织和性能演化规律的分析与讨论

Analysis and Discussion of Mechanical Properties and Microstructure Developments for Ti40 Alloy Thermal Exposed at 550℃

对Ti40合金锻态和热处理态在550℃热暴露不同时间的组织和性能进行了研究。结果表明:该合金在热暴露过程中析出物较少,并且大都分布在晶界,这些晶界析出物是合金热稳定性能降低的主要原因;通过组织模拟和分析,对Ti40合金550℃热暴露组织和性能划分了3个阶段,每个阶段对应析出物不同的形成和长大阶段;热暴露末期,出现性能的不稳定和与硬度不匹配的主要原因是析出物沿晶界形成析出物带;最后指出,Ti40合金要使用到更高温度,适当调整合金目前的热处理工艺和成分是可行的方法。

Microstructures and mechanical properties of Ti40 alloy after hot-rolled, heat treatment and thermal exposure at 550 ℃ for different times were studied. The results show that there is only a little precipitation during thermal exposure, which mostly distributes on grain boundaries. The main reason of deterioration of mechanical properties is due to the precipitated phases distributing on grain boundary. By simulating and analyzing for the microstructures, the thermal exposure process of Ti40 alloy at 550 ℃ can be divided into three stages, and every stage is defined by the shapes of precipitated phases. In the last stage, the main reason of non-matched mechanical properties between strength and hardness is due to the formation of continuous precipitated zone along the grain boundary. Lastly, it is pointed out that the adjustments of heat treatment and composition are feasible methods to use for Ti40 at higher temperatures.