β相区加热TA15钛合金热变形显微组织演化

摘要

The microstructure, phase transition and texture evolution of TA15 titanium alloy afterβ phase region heating through hot deformation under different process parameters and water quenching were investigated by OM, XRD and EBSD. The results indicate that the microstructure is mainly composed ofα′ martensite phase transformed from flatted and elongatedβ grains and clearβ grain boundaries. There are some tiny grain boundaryα grains distributed along originalβ grain boundaries through hot deformation below the phase transition point. Al and V elements were dissolved inα′ martensite phase formed by the shear mode, and resulted in crystal lattice contraction and the diffraction peak moving to high-angle. The grain orientation distributions are similar owing to the crystal orientations between martensiteα′ and originalβ complying with the Burgers orientation relationship. The grain orientations of material are enhanced with increasing temperature and strain rate. The average grain size is less than 7μm andα′ grains inherit the misorientation of parentβ grains when the peaks of the number fraction locate at 10°, 60° and 90°.%采用OM、XRD和EBSD研究经过β相区加热，在不同工艺参数下热变形水冷淬火后TA15钛合金的显微组织、相变和织构演化规律。结果表明：显微组织主要由被压扁、拉长的原始β晶粒转变的α′马氏体相及清晰β晶界组成，相变点以下温度变形的显微组织中出现沿原始β晶界分布的细小晶界α相晶粒；通过切变方式形成α′马氏体相固溶了Al和V元素，且晶格点阵收缩，衍射峰向高角度方向偏移；α′马氏体与原始β的晶体取向间满足 Burgers 位向关系，显微组织的晶粒取向分布也类似，且随着变形温度和应变速率的提高，材料的晶粒取向性增强；显微组织的晶粒尺寸均在7μm以内，α′晶粒继承母相β晶粒的取向差，在10°、60°和90°附近出现峰值。