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以Ueshima的正六边形横断面枝晶模型为原型,采用有限差分方法建立了钢凝固过程伴随δ/γ相变的两相区溶质微观偏析模型,浅析了冷却速率10℃/s非平衡凝固条件下,钢的脆性温度区内各溶质元素的偏析特点,并定量给出不同P、S含量下,脆性温度区临界断裂应变和临界断裂应力随C含量的变化规律。结果表明,C、P、S偏析对连铸坯凝固前沿裂纹敏感性影响显著,钢液P、S初始含量的增加显著降低脆性温度区临界断裂应变,小幅提高钢在fs=1.0处的临界断裂应力,而且引起脆性温度区内固相分率和相组成的显著变化,抗拉强度下降。
Taking the hexagonal cross-sectional dendrites model of Ueshima as a prototype, a two-phase solute microsegregation model with the δ / γ phase transformation during the solidification of steel was established by using the finite difference method. The effects of non-equilibrium solidification at a cooling rate of 10 ℃ / s , The segregation characteristics of each solute element in the brittle temperature region of steel were quantitatively analyzed. The variation rules of the critical fracture strain and the critical fracture stress with C content were quantitatively given under different P and S contents. The results show that the segregation of C, P and S has a significant influence on the susceptibility of the front slab to solidification. The increase of the initial P and S contents in the molten steel significantly reduces the critical strain at the brittle temperature, and slightly increases the critical fracture at fs = 1.0 Stress, but also caused a significant change in solid fraction and phase composition in the brittle temperature zone, with a decrease in tensile strength.