连铸-热轧区段X80钢中碳氮化物析出与固溶的实验研究

针对连铸-热轧区段的工艺技术界面，在传热研究的基础上通过热模拟实验研究了典型大板坯生产流程连铸、辊道输送、堆冷、加热等单元内X80钢中碳氮化物的析出与固溶行为. 结果表明，在连铸和输送过程中，Ti(C, N), (Ti, Nb)(C, N)和NbC先后析出，加热结束尚有少量(Ti, Nb)(C, N)未完全固溶；输送过程中不同冷却速率对碳氮化物的析出影响显著，以6.0℃/min辊道冷却至750或600℃，析出的碳氮化物分布密度较大，平均当量直径较小，部分碳氮化物沿奥氏体晶界分布，碳氮化物形成元素在钢中呈过饱和状态；以0.3℃/min堆冷却至400℃，碳氮化物充分析出，粒子的分布密度较小，平均当量直径较大；加热过程的热履历影响铸坯中碳氮化物的行为，但对加热结束后碳氮化物的存在状态无显著影响；冷却速率是导致碳氮化物沿奥氏体晶界析出的根本原因.

Experimental Study on Precipitation and Dissolution of Carbonitrides in X80 Steel in Continuous Casting-Hot Rolling Region

As for the techno-interface of continuous casting-hot rolling region, the precipitation and dissolution of carbonitrides in X80 steel were studied during continuous casting, roller conveying, stack cooling and heating units in typical slab process flow by hot simulation experiment based on the study of heat transfer. The results showed that Ti(C, N), (Ti, Nb)(C, N) and NbC were precipitated in turn in continuous casting and conveying. A few (Ti, Nb)(C, N) particles were not dissolute totally after heating. The precipitation of carbonitrides was effected significant by cooling rate in conveying. When slab was conveyed at 6.0℃/min rate and then cooled down to 750 or 600℃, the distributing density of carbonitride particles was higher, and their average equivalent diameter smaller, some carbonitride particles were distributed along the austenitic grain boundaries and the elements related to the carbonitride particles were supersaturated. When slab was conveyed at 0.3℃/min rate and then cooled down to 400℃, the distributing density of carbonitride particles was lower, and their average equivalent diameter bigger, the carbonitride particles precipitated fully. The behavior of carbonitrides in slab was affected by thermal course in heating. The status of carbonitrides was affected insignificant by thermal course after heating. The basic reason of carbonitride particles distributed along the austenitic grain boundaries was cooling rate.