【摘要】 业已证实,淬火硼钢中硼向奥氏体晶界的偏聚,是在冷却过程中发生的一种非平衡的晶界偏聚。本文通过解变温扩散方程,导出了非平衡晶界偏聚的理论公式,建立了晶界贫硼区宽度与淬火加热温度、冷却速度以及非平衡晶界偏聚扩散激活能与扩散常数之间的关系,理论预言与实验结果较好地吻合。根据实验结果和理论分析,提出这种非平衡晶界偏聚的机制,是在冷却过程中,过饱和空位或双空位带着硼原子向晶界(空位阱)迁移的结果。基于这种非平衡晶界偏聚的新概念,可以较完满地说明影响硼钢淬透性的众多复杂因素。更多还原

【Abstract】 It has been demonstrated that the boron segregation at austenite grain boundaries in quenched steel is a non-equilibrium grain boundary segregation phenomena occurred during cooling. In this paper, by way of resolving nonisothermal diffusion equation, a theoretical formula for non-equilibrium grain boundary segregation has been derived, and the relationship among width of boron depleted zone, quenching temperature, cooling rate, activation energy and diffusion constant of non-equilibrium grain boundary segregation has been established. The theoretical prospects agreed with experimental results satisfactorily.From experimental results and theoretical analysis, an atomic model for nonequilibrium grain boundary segregation has been suggested, based on the moving of boron atoms along with supersaturationies vacancies or divacancies to grain boundaries (sink of vacancy) during cooling. In light of this new idea of nonequilibrium grain boundary segregation, the complicated effects of boron on hardenability of steel can be explained unambiguously.更多还原