材料期刊网

对具有不同屈服强度的薄板坯连铸连轧工艺生产的Nb、Ti复合微合金化热轧板卷059和066进行了全面的组织分析，研究了其强化机制。组织分析表明，两板卷的主要组织均为铁素体组织，但具有高屈服强度的059板卷铁素体呈现出非多边形铁素体特征，其晶粒明显细于066板卷，并具有高的位错密度。两板卷中的析出物特征相同，其中复合型的星形析出物较多，它们的平均尺寸140~150nm, 消耗了钢中50%的Nb。强化机制研究表明，铁素体晶粒细化强化是两板卷的主要强化机制，占总屈服强度的43~46%；无论是低屈服强度还是高屈服强度板卷，析出强化效果微弱，只占总屈服强度的4~6%。位错强化与晶粒细化强化是059板卷具有高屈服强度的原因。

The experimental steel is a kind of Nb、Ti complex microalloyed steel produced by using thin slab casting and direct rolling process. Comprehensive microstructural analyses were conducted and strengthening mechanisms were studied for its two hot rolled coils: coil 059 with higher yield strength and coil 066 with lower yield strength. The results show that both coils mainly consist of ferrite microstructure. The ferrite of coil 059 presents non-ploygonal ferrite morphology which is with finer grain size and higher dislocation density. Both coils have the same precipitation characters. A large number of complex star-like precipitates exist in both coils, which have an average size of 140~150nm and account for 50% Nb of the total. Ferrite grain refinement strengthening is the first mechanism contributing 43~46% to total yield strength. Precipitation strengthening effect is weak, whether in coil 059 with higher yield strength or in coil 066 with lower yield strength, which only accounts for 4~6% of total yield strength. Dislocation strengthening and grain refinement strengthening makes coil 059 with the higher yield strength.