论文部分内容阅读
以硼质量分数为0.0045%、氮质量分数为0.0039%的低碳含硼钢为研究对象,通过对实验钢在凝固过程中BN析出和长大的热力学与动力学进行分析,并结合实验研究了冷却条件对BN析出与长大行为的影响.结果表明:由于溶质元素B和N在凝固前沿的微观偏析,只有当凝固前沿的固相率大于临界值0.981时,BN才能在凝固前沿析出;在凝固前沿随着固相率的增加,B和N均具有明显的偏析.当固相率接近于1时,硼在剩余液相中的实际含量远高于氮元素的含量,氮的扩散是BN长大的限制性环节;钢液冷却速率的变化对B和N元素的偏析无显著影响,而生成BN的尺寸随着钢液冷速的增加而显著减小.
Based on the analysis of the thermodynamics and kinetics of precipitation and growth of BN during the solidification of the experimental steel, boron-containing steel containing 0.0045% boron and 0.0039% nitrogen was selected as the research object. Based on the experimental study The results show that due to the micro-segregation of solute elements B and N at the solidification front, BN can precipitate at the solidification front only when the solid fraction of the solidification front is larger than the critical value of 0.981. Solidification front with the increase of the solid fraction, B and N have significant segregation.When the solid fraction is close to 1, the actual content of boron in the remaining liquid phase is much higher than the nitrogen content, the diffusion of nitrogen is BN The change of the cooling rate of the molten steel has no significant effect on the segregation of the B and N elements, but the size of the generated BN decreases remarkably with the increase of the cooling speed of the molten steel.