摘要
以Ti微合金化热成形钢连铸坯为研究对象,通过SEM、EDS、OM等手段对铸坯试样中的大尺寸TiN进行了形貌观察,发现铸坯试样中存在数十微米级的TiN夹杂物,其形貌不同于常规的矩形块状结构,而是呈现出了条状、树枝状、异形块状等形貌。首次利用Aspex对热成形钢铸坯厚度方向不同位置进行微观扫描统计分析,发现大尺寸的TiN夹杂物分布具有明显的规律性,由铸坯表面至凝固中心TiN的面密度和粒度尺寸呈现增加的趋势;利用物相法确认原奥氏体晶界,发现TiN夹杂物在原始奥氏体晶界和晶内均有析出,并且其形貌和粒度无明显规律性。同时,在Ti、N活度积及相关作用系数基础上,对固液两相凝固前沿动态活度积进行了热力学计算,确认了热成形钢铸坯中的TiN夹杂物是在两相区析出的,并阐述了TiN夹杂物分布规律的形成原因。
Ti microalloyed hot formed steel continuous casting slab was studied as the research object.The morphology of large-sized TiN in the slab samples was observed through SEM,EDS,OM,and other methods.It was found that there were TiN inclusions in the slab samples at the scale of tens of micrometers,which were different from the conventional rectangular block structure,exhibited strip,dendritic,irregular block shaped morphology.For the first time,Aspex was used to conduct microscopic scanning statistical analysis on different positions in the thickness direction of hot-formed steel slab.It was found that the distribution of large-sized TiN inclusions has obvious regularity,and the surface density and size of TiN from the slab surface to the solidification center show an increasing trend.By using the phase method to confirm the original austenite grain boundaries,it was found that TiN inclusions precipitated both at the original austenite grain boundaries and within the grains,and their morphology and particle size showed no obvious regularity.At the same time,based on the TiN activity product and related action coefficients,more accurate thermodynamic calculations were conducted on the dynamic activity product of solid-liquid two-phase solidification front,confirming that TiN inclusions in hot-formed slab precipitate in the two-phase zone,and elaborating on the relevant reason of TiN inclusion distribution law in detail.
作者
李岩杰
李哲
程翠花
张大勇
贾宁
李红斌
张岩
LI Yanjie;LI Zhe;CHENG Cuihua;ZHANG Dayong;JIA Ning;LI Hongbin;ZHANG Yan(Technical Center of Tangsteel Company HBIS Group,Tangshan 063000,Hebei,China;School of Metallurgy and Energy,North China University of Science and Technology,Tangshan 063210,Hebei,China)
出处
《连铸》
北大核心
2025年第3期91-98,共8页
Continuous Casting
关键词
TiN夹杂物
连铸坯
分布规律
动态活度积
热成形钢
TiN inclusion
continuous casting slab
distribution pattern
dynamic activity product
hot formed steel
