TiN, which is ubiquitous in Ti-bearing steel, has a critical influence on both the mechanical properties and the welding process of steel, and therefore researche on the precipitation behavior of TiN in molten steel bath is of great significance. In this paper, Ti-bearing peritectic steel was taken as the study object and FactSage was adopted to explore how the precipitation behavior of typical inclusions in steel was affected by the steel composition. Furthermore, microsegregation models were used to analyze the precipitation process of TiN at solidification front, and the calculation results were finally verified by scanning electron microscope (SEM). Research showed that a multitude of dispersed particles of high melting oxide MgAl₂O₄ or MgO always existed in molten steel after magnesium treatment. In consideration of the segregation and enrichment of solute elements at the solidification front, the Ohnaka microsegregation model was employed to compute the precipitation during solidification. In the event of the solid fraction reaching 0.95 or more, the concentration product of [Ti][N] at the solidification front exceeded the equilibrium concentration product, then TiN began to precipitate. MgO or MgAl₂O₄ cores were generally found in TiN particles of peritectic steel after the magnesium treatment, which was consistent with the thermodynamic calculation results. Moreover, the average size of TiN particles was reduced by approximately 49%. This demonstrated that Mg-rich high melting inclusions were formed after the magnesium treatment, by which the heterogeneous nucleation of TiN was promoted it; therefore, favorable nucleation sites were provided for further refining the high-temperature ferrite phase.

含Ti钢中普遍存在的TiN对钢的力学性能和焊接工艺均具有至关重要的影响，因此研究TiN在钢水熔池中的析出行为具有重要意义。本文以含钛包晶钢为研究对象，采用FactSage方法研究了钢中典型夹杂物的析出行为如何受到钢成分的影响。此外，采用微观偏析模型对TiN在凝固前沿的析出过程进行了分析，最后通过扫描电镜（SEM）对计算结果进行了验证。研究表明大量分散的高熔点氧化物MgAl ₂ O ₄颗粒镁处理后，钢水中始终存在MgO或MgO。考虑到凝固前沿溶质元素的偏析和富集，采用Ohnaka微偏析模型来计算凝固过程中的沉淀。如果固体分数达到0.95或更高，则在凝固前沿的[Ti] [N]浓度积超过平衡浓度积，然后TiN开始沉淀。MgO或MgAl ₂ O ₄镁处理后，包晶钢的TiN颗粒中普遍发现有核，这与热力学计算结果一致。此外，TiN颗粒的平均尺寸减少了约49％。这表明镁处理后形成了富含镁的高熔点夹杂物，从而促进了TiN的异质成核。因此，提供了有利的成核位点以进一步细化高温铁素体相。