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依据固体与分子经验电子理论(EET),计算了渗碳体的价电子结构,确定了含V、Mn渗碳体的稳定结构分别为θ-(Fe_(2.75)Mn_(0.25))C、θ-(Fe_(2.5)V_(0.5))C。计算θ-Fe_3C、θ-(Fe2.5V_(0.5))C和θ-(Fe_(2.75)Mn_(0.25))C的比饱和磁化强度MS分别为167.19、111.20和146.32A·m~2/kg。制备的不同V含量的未冷拉70和80级帘线钢的MS计算误差在0.18%~6.22%,与振动样品磁强计(VSM)的实测值符合较好。建立了渗碳体溶解的4阶段模型,得出了渗碳体溶解对未冷拉帘线钢MS的影响规律。帘线钢冷拉后MS的巨变表明:铁素体中Fe原子的平均原子磁矩和原子状态发生重大改变;计算发现其原子状态根据钢的成分与应变量,会从甲种(A)变成乙种(B)甚至丙种(C)杂化状态。
The valence electron structures of cementite were calculated based on the empirical electronic theory of solids and molecules (EET), and the stable structures of the cementite containing V and Mn were determined as θ- (Fe 2.75 Mn x 0.25) C, θ - (Fe_ (2.5) V_ (0.5)) C. The calculated saturation magnetization MS of θ-Fe_3C, θ- (Fe2.5V_ (0.5)) C and θ- (Fe_ (2.75) Mn_ (0.25)) C were 167.19,111.20 and 146.32A · m ~ 2 / kg . The calculated MS errors of uncoated 70 and 80-grade cord steel with different V content ranged from 0.18% to 6.22%, which were in good agreement with the measured values of vibrating sample magnetometer (VSM). A 4-stage model of cementite dissolution was established, and the influence of cementite dissolution on MS of uncooled cord steel was obtained. The dramatic changes of MS after cold drawing of the cord steel indicate that the average atomic moment and atomic state of Fe atoms in ferrite change greatly. Calculations show that the atomic states change from A (A) to A Into B (B) or even C (C) hybrid state.