Orientation gradient on surface of non-oriented electrical steel annealed by γ →α transformation

• 作 者: Jin-hua Wang Ping Yang Wei-min Mao Feng-e Cui
• 机 构: School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 1
• 出 处: 钢铁研究学报（英文版）
• 发表日期: 2020年1期
• 关键词: Electrical steel Texture Phase transformation Thermal stress Oxide scale

The microstructures and textures of the non-oriented electrical steel sheets under various annealing conditions were investigated.The orientation gradient in the interior of grains appeared on the surface of steel sheets after α → γ → α transformation in various atmospheres.The orientation gradient that appeared on the surface was inherited into the center of the steel sheet in H2 atmosphere,while that appeared only in the grains of the surface layer during γ → α transformation with N2 atmosphere.The thin oxide scale was generated in various atmospheres containing traces of O2 and H2O.The formation mechanism of orientation gradient is related to the thermal stress caused by the difference of thermal expansion coefficients between the oxide scale and the thin ferrite on the surface.The combined effect of phase transformation stress and thermal stress caused the plastic deformation of the thin ferrite grains on the surface in the initial stage of γ → α transformation,and then the orientations of the thin ferrite grains gradually rotated and caused the orientation gradient in the interior of grains.