退火工艺对冷轧工业纯钛带卷各向异性的影响

力学性能各向异性是影响工业纯钛板带材成形性能的主要因素之一。为制备低各向异性工业纯钛带卷,采用室温拉伸试验和电子背散射衍射技术表征了经不同工艺退火后冷轧工业纯钛的力学性能、显微组织和织构,分析了退火工艺对工业纯钛带卷力学性能各向异性的影响规律。结果表明,退火温度固定时,延长退火时间,TA1钛带纵向屈服强度降低程度大于横向,导致其各向异性升高,而退火超过一定时间后其各向异性趋于稳定,700 ℃时钛带纵横向屈服强度差值的稳定值为82 MPa,610 ℃时的稳定值为58 MPa;退火时间固定时,在所研究温度范围内,退火温度越高,钛带各向异性越显著。织构分析表明,延长退火时间或/和升高退火温度,TA1钛带的棱锥织构增强、基面织构减弱,导致室温拉伸时纵横向{1010}<1120>柱面滑移的施密特因子差值增大,从而表现出更明显的力学性能各向异性。

Effect of annealing process on mechanical anisotropy of cold rolled commercial pure titanium coil

Anisotropy of mechanical properties is one of the major factors affecting the formability of commercial pure titanium sheet and strip. In order to fabricate commercial pure titanium coil with low anisotropy, the mechanical properties, microstructure and texture of cold rolled commercial pure titanium after annealing with different parameters were characterized by using room temperature tensile tests and EBSD technique. And the influence of annealing process on anisotropy of mechanical properties of commercial pure titanium coil was analyzed. The results show that at fixed annealing temperature, with prolonging annealing time, the yield strength of TA1 strip in rolling direction (RD) descends more rapidly than that in transverse direction (TD), resulting in the increase of anisotropy of mechanical properties . When annealing arrived at a certain duration, the anisotropy of mechanical properties tends to be stable. The stable value of difference in yield strength between RD and TD is 82 MPa when annealed at 700 ℃, but it becomes 58 MPa at 610 ℃. For fixed annealing time, the higher the annealing temperature, the higher the anisotropy of mechanical properties, within the study temperature range. Texture analysis indicates that with prolonging annealing time or/and increasing annealing temperature, the intensity of pyramid texture increases, while that of the basal texture decreases, which leads to the increase of the difference in Schmid factor for {1010}<1120> prismatic slip between RD and TD when stretched at room temperature, therefore causes more obvious anisotropy of mechanical properties.