关键词: 6.5 % Si无取向硅钢, 稀土, 微观组织, 有序度, 拉伸

Abstract: The effects of yttrium（Y） on microstructure, elevatedtemperature tensile properties and fracture mechanism of 6.5 %  Si non-oriented electrical steel were investigated by means of microstructure characterization, high-temperature tensile test and fracture analysis. The results showed that the doping of Y introduced composite Y rich precipitates (YS/YP) in the melt. YS and YP precipitates were qualified for heterogeneous nucleation agents, which thus raised the nucleation rate and refined the solidification microstructure. The hot rolling microstructures were inhomogeneous through the thickness. Three distinct layers characterized by equiaxed grains, a mixture of equiaxed and elongated grains and completely elongated grains were detected at the surface, subsurface and center layers, respectively. After annealing, the hot rolling microstructures were transformed into equiaxed structures. The annealing microstructure of the experimental steel doped with Y was significantly refined. After aging at  500 ℃, the experimental steel doped with Y showed a lower ordering degree and a ductile fracture morphology at  300 ℃. The tensile ductility approached as high as 20.2 %. On the contrast, the experimental steel undoped with Y fractured brittlely and the tensile ductility was only 2.1 %. The results verified that the doping of Y in 6.5 % Si non-oriented electrical steel could improve the intermediate temperature ductility by refining the microstructure and lowering the ordering degree. 

Key words: 6.5 % Si non-oriented electrical steel, rare earth, microstructure, ordering degree, tensile test