(中国科学院 金属研究所钛合金研究部， 沈阳 110016)
摘 要: 测试了两种温度固溶后锻态Ti-6.9Al-3.6Zr-2.7Sn-0.7Mo-0.6Nb-0.21Si(BT18y)钛合金棒的室温拉伸性能。 利用金相显微镜、 透射电镜和扫描电镜研究了该合金的室温拉伸塑性与显微组织的关系。 结果表明： 经920 ℃、 2 h空冷处理的材料为细晶等轴组织， 变形时晶粒间的协调性好， 具有优良的室温拉伸性能， 塑性尤其突出； 经1 020 ℃、 2 h空冷处理的材料为具有晶界α相的粗晶片层组织， 在拉伸变形时， 同时要求相邻晶粒之间、 晶粒内部的相邻α片束团之间相互协调， 增加了塑性变形的阻力， 但残余β相使得材料保持了一定的塑性。 多个视角观察表明： α片束团表现出了方向性， 与拉伸轴夹角较小的片束具有良好的拉伸性能， 与拉伸轴夹角较大的片束内的β相中间层是拉伸时裂纹的优先形成区。
关键字: Ti-6.9Al-3.6Zr-2.7Sn-0.7Mo-0.6Nb-0.21Si钛合金； 热处理； 显微组织； 室温拉伸塑性
（ Titanium Alloy Laboratory, Institute of Metal Research, Chinese Academy of Science, Shenyang 110016, China）
Abstract: Tensile properties of forging Ti-6.9Al-3.6Zr-2.7Sn-0.7Mo-0.6Nb-0.21Si titanium alloy after two types of heat treatments were tested at room temperature. Optical microscope, transmission electron microscope (TEM) and scanning electron microscope (SEM) were used to investigate the relationship between microstructures and room-temperature tensile plasticity. The microstructure of the sample solutionized at 920 ℃ for 2 h followed by cooling in air is fine equiaxed structure. Compatibility among grains is easy during deformation, so it has good tensile properties at room temperature, especially better tensile plasticity. The sample solutionized at 1 020 ℃ for 2 h followed by cooling in air possesses a coarse and lamellar structure with continuous grain boundary α phase. In the tensing process, coordinations among adjacent grains and among α colonies in grains are needed at the same time, so the plastic deformation becomes difficult. But β phase interlayer makes the material maintain some plasticity. α colony has anisotropy. The one that has small included angle to the tensile direction possesses better tensile properties. β phase interlayer in the one that has big included angle to the tensile direction is vulnerable area in the material, and cracks arise in this place firstly while tensing.
Key words: Ti-6.9Al-3.6Zr-2.7Sn-0.7Mo-0.6Nb-0.21Si titanium alloy; heat treatment; microstructure; room-temperature tensile plasticity
