退火处理工艺下Ti40合金蠕变组织研究

摘要

The creep experiment of Ti40 alloy after annealing treatment of 600 ℃ × 4 h/AC was carried on at the temperature from 500 ℃ to 600 ℃ with the stress of 250 MPa.The experimental results indicate that the Ti40 alloy shows better creep resistance when the creep temperature is not exceeding 520 ℃.When the creep temperature is above 535 ℃,the alloy shows worse creep resistance and can not meet the service requirement.During the steady-state stage of creep,there is a dynamic equilibrium of jam-packed dislocation and dislocation climbing motion inside the grains of Ti40 alloy.When the alloy is stepping into the tertiary creep,there are decomposition and tangle of dislocation which result in stress concentration.The stress concentration at grain boundaries eventually leads to the formation of creep pores.%对Ti40合金进行600℃×4 h/AC退火处理,并测试合金在500～ 600℃温度范围内250 MPa应力下的蠕变性能.实验结果表明,蠕变应力为250 MPa的条件下,当蠕变温度不超过520℃时,合金蠕变性能较好,当蠕变温度升高到535℃时,合金蠕变性能急剧恶化,不能满足使用要求.Ti40合金蠕变稳态阶段是位错滑移塞积和攀移释放应力的动态平衡.当蠕变进入第三阶段,出现主位错的分解与合并以及位错之间的交割和缠结.在蠕变过程中,位错的缠结和塞积导致应力集中,最终在晶界处形成蠕变空洞.