轧制方式对工业纯钛TA2轧板织构演变的影响

Effect of rolling mode on texture evolution of CP-Ti TA2 rolled sheets

摘要:

本文开展了轧制方式对工业纯钛TA2板的织构演变的影响研究。通过三种轧制方式,即等温轧制,差温轧制和反复弯轧,其中差温轧制的上辊温度高于下辊温度90℃,反复弯轧则是差温带异步轧制,并进行正弯和反弯变形。轧制后的三种钛材采用EBSD手段分析晶粒取向和织构变化。结果显示三种轧制方式获得钛板的变形织构出现明显差异,等温轧制变形织构与文献报道的典型的α-Ti轧制织构类似,差别仅在于主要峰位置的角度稍许偏移,其变形大晶粒和再结晶细晶取向沿<0001>//RD；差温轧制的变形织构为柱面织构,晶粒取向为<2-1-10>//RD。其主要原因是上下辊表面温度差异诱发材料厚向产生均匀一致的剪应变,这类似于等通道挤压变形的效果。而反复弯轧的织构同时存在基面织构与锥面织构等变形织构组分,但锥面织构占主导,其细晶取向除沿较强的<0001>//RD方向外,还有沿其他两个较弱的取向<2-1-12>//RD 和<2-1-13>//RD。

Abstract:

This paper reports the effect of the rolling mode on texture evolution in the commercially pure titanium (CP-Ti)TA2 sheets. For this purpose, total height reductions of 50% was imposed on the samples by three route modes: Route A is conventional rolling (CR), Route B is non-isothermal rolling(NWR) which CP-Ti sheets were rolled under a fixed temperature difference of 90-degree for the upper and lower rolls, respectively, Route C is repeated bending–unbending (RUB) where the sheets were bent by non-isothermal rolls with differential speed. Systematic analysis of the deformation characteristics refers to crystallographic orientation and texture component was performed using EBSD. The results indicate that the deformation characteristics significantly vary with the rolling modes. The texture of the CRed sheets is similar to those already reported for such rolled α-titanium, except that the center of the main peak is slightly shifted for a few degrees. And their small recrystallized grains and large deformed grains are oriented along <0001>//RD. However, prismatic texture formed in NWRed sheet and the grains’ orientation is <2-1-10>//RD. The texture and orientation changing are contributed to different temperatures for upper and lower rollers surface and thus induces intense shear strain uniformly throughout the sheet. NWR has a similar effect on shear deformation as equal channel angular extrusion. Basal texture and pyramidic texture are observed in the sheets processed by RUB, the priority was pyramidic texture. The finer grains exhibit a strong orientation of <0001>//RD, two weaker orientations of <2-1-12>//RD and<2-1-13>//RD.