(钢铁研究总院,北京 100081)
摘 要: 研究了β锻造的Ti-22Al-25Nb合金在固溶+时效热处理过程中微观组织的转变规律,并对不同固溶温度+800 ℃时效处理合金的室温和650 ℃拉伸性能进行了测试和分析。结果表明:合金经β锻造后的组织由少量α2颗粒、大量O相板条和B2相基体组成。在固溶处理过程中,组织中的O相板条发生溶解,数量减少,形状变短、变粗。在980 ℃以上固溶处理时,基体B2相发生明显的再结晶。固溶+时效处理后,细小的二次O相板条再次从B2基体中析出,并最终形成一种具有短棒状或颗粒状的初生α2/O相+细小的二次O相板条+B2相基体组成的组织。随着微观组织中初生α2/O相数量的减少、二次O相板条数量增加,合金室温和650 ℃抗拉强度升高,伸长率降低。
关键字: Ti2AlNb;金属间化合物;热处理;拉伸性能
properties of β-forged Ti-22Al-25Nb alloy
(Central Iron and Steel Research Institute, Beijing 100081, China)
Abstract:Microstructure evolution of the β-forged Ti-22Al-25Nb alloy during subsequent solution plus aging heat treatment was investigated. The tensile properties of the alloy with different heat treatments at room temperature and 650 ℃ were tested. It is found that after β-forging the microstructure is composed of a large number of O phase laths, a few a2 particles and B2 matrix. During solution treatment, the O phase lamellae in the microstructure solves, the volume fraction of O lamellae decreases, and the shape becomes short and coarse. The recrystallization of B2 matrix grains happens when the solution temperature is above 980 ℃. During aging treatment, the fine O phase lamellae precipitates from B2 matrix and the microstructure with the primary α2/O particles or short bar, the secondary fine O phase and the B2 matrix forms. The test results of the tensile properties exhibit that when the volume fraction of the primary α2/O particles decreases and that of the secondary fine O phase lamellae increases, the tensile strength of the alloys at RT and 650 ℃ rises and the RT ductility drops.
Key words: Ti2AlNb; intermetallic compounds; heat treatment; tensile properties