Heterogeneous nucleation is an effective way to promote the dispersion and precipitation of second-phase particles in steel and refine the grain size of the solidification structure. Not only refining as-cast structure grain size, but TiN in ferritic stainless steel can also pin grain boundaries and restrain the overgrowth of grains during rolling. The interface characteristics between TiN and heterogeneous phases (high-melting inclusions and ferrite phase) were studied based on the wetting angles between molten steel with different compositions and TiN substrate, and on the matching degree between TiN and ferrite lattice. It was found that, for the molten steel with the same composition, the wetting angle with the TiN substrate was significantly smaller than the contact angles with the other three substrates, while the wetting angle between ferrite phase and TiN was the smallest. The lattice matching was compared among MgAl₂O₄, TiN and δ matrix by means of a high-resolution transmission electron microscope, which revealed that a coherent or semi-coherent interface was formed between the crystal plane (400) of MgAl₂O₄ and the crystal plane (200) of TiN, as well as between the crystal plane (200) of TiN and the crystal plane (110) of δ matrix, with a lattice misfit of 5.1% and 3.4%, respectively. Finally, these two characteristics between TiN and ferrite phase were both explained from the perspective of interfacial energy. The microstructure refinement mechanism from high temperature to room temperature can be better reflected by the proposed wetting–lattice misfit theory.

异相成核是促进第二相颗粒在钢中分散和沉淀并细化凝固组织晶粒尺寸的有效方法。不仅精炼铸态组织的晶粒尺寸，铁素体不锈钢中的TiN还可钉扎晶粒边界并抑制轧制过程中晶粒的过度生长。基于不同成分的钢水与TiN基体的润湿角，以及TiN与铁素体晶格的匹配程度，研究了TiN与非均相（高熔点夹杂物和铁素体相）之间的界面特性。结果发现，对于具有相同成分的钢水，与TiN基体的润湿角明显小于与其他三个基体的接触角，铁素体相与TiN的润湿角最小。比较了MgAl中的晶格匹配通过高分辨率透射电子显微镜观察₂ O ₄，TiN和δ矩阵，发现MgAl ₂ O ₄的晶面（400）和晶面（200）之间形成了相干或半相干的界面TiN的晶格失配以及晶格失配分别为5.1％和3.4％，以及TiN的晶面（200）和δ矩阵的晶面（110）之间。最后，从界面能的角度解释了TiN和铁素体相之间的这两个特性。提出的润湿-晶格失配理论可以更好地反映从高温到室温的微观结构细化机理。