高纯钽板异步轧制及后续退火过程中微观组织及织构演变研究

Study on microstructure and texture evolution during asymmetrical rolling and subsequent annealing of high pure tantalum plate

采用1.2的轧速比对高纯钽板材进行异步轧制,获得了变形量分别为60%、70%和80%的异步轧制钽样品。采用电子背散射衍射(EBSD)对样品进行显微组织分析,研究了异步轧制过程中高纯钽板沿整个板厚方向的微观组织及织构演变规律。结果表明:变形量为60%时,钽板近表面区域的晶粒主要为{100}(〈100〉//ND,ND为板法向)和{110}(〈110〉//ND)取向,而中心区域的晶粒主要为{111}(〈111〉//ND)取向。随着变形量的增大,轧制变形组织逐渐变得均匀,同时沿板厚方向的织构分布也愈发均匀。当变形量为80%时,形成了γ织构(〈111〉//ND)与θ织构(〈100〉//ND)交替、均匀分布的现象。这种特殊的织构变化与异步轧制过程中沿厚度方向引入的剪切变形有关。对上述不同变形量的异步轧制高纯钽板的退火微观组织的对比研究发现,80%变形量样品表现出更为细小均匀的再结晶组织。80%变形量的样品经1 200℃退火30 min后,获得了平均晶粒尺寸为53.4μm的再结晶组织,同时{111}取向的晶粒与{100}取向的晶粒均匀分布。

The rolling speed ratio of 1. 2 is used for asymmetrical rolling（ ASR） of high pure tantalum plate. The reduction rate is 60%,70% and 80%,respectively. Electron backscatter diffraction（ EBSD） is used to analyze the microstructure of the samples,and the effect of ASR on the microstructure evolution and texture transformation of high purity tantalum sheet along the thickness direction is studied. The results show that with the increase of deformation,the strength of γ texture reduces,and the strength of through-thicknessγ texture gradually decreases,and finally γ texture and θ texture alternates and distributes evenly. The special texture changes are related to the shear deformation introduced through thickness during the ASR process. After annealing at 1 200 ℃ for different time,the average grain size of 80% deformed samples after annealing at 30 min is only 53. 4 μm,while the grains of { 111} orientation and{ 100} orientation are uniformly distributed.