电工钢柱状晶热、冷轧时晶界作用分析

ANALYSIS ON GRAIN BOUNDARY EFFECTS OF COLUMNAR GRAINED ELECTRICAL STEEL

利用XRD和EBSD研究了长轴分别平行于轧向(RD)、横向(TD)和轧面法向(ND)的柱状晶样品在热轧、冷轧及退火过程中的组织、织构演变规律,并分别从几何诱导和取向诱导两个方面分析了晶界的交互作用.结果表明,热轧时由表面摩擦剪切作用引起的组织和织构梯度直接影响并遗传给后续冷轧及退火样品.热轧后,不同样品的初始晶粒形状各向异性差异消失,形成相同的各向异性晶界组织,但晶体学各向异性发生改变,导致随后冷轧、退火组织及织构的变化均不同于直接冷轧的柱状晶样品.研究中特别关注了对磁性能有利的{100}取向区域与晶界的关系.

Columnar grains show their special characteristics of morphological and crystallographic anisotropies, and thus markedly influence the microstructure and texture evolution during rolling and annealing process in electrical steel. The rolling and annealing microstructure and texture of three columnar grained samples with the long axes arranged along different directions were investigated by means of XRD and EBSD techniques, and the effects of columnar grain boundaries were analyzed from the view point of geometry-induced interaction and orientation-induced interaction. The results indicated that, prominent microstructure and texture gradients caused by the surface shearing during hot rolling inherited to subsequent cold rolling and annealing in columnar grained samples. The difference in morphological anisotropy of initial columnar grain boundaries in the three samples were eliminat- ed after hot rolling, while a same type structure of anisotropic grain boundaries was formed. However, the crystallo- graphic anisotropies of the samples were changed before cold rolling, and it caused that the evolution of the micro- structure and texture during subsequent cold rolling and annealing was different with directly cold rolling process in previous work. This feature produced a graded microstructure and texture relationship between hot rolled sampies and finally annealed samples. In this work, it mainly focused on the {100}-oriented regions at grain boundaries, because the { 100} texture was most beneficial to the magnetic property of electrical steel.