20CrMn钢双辊薄带振动铸轧第二相粒子析出行为研究

Study on Precipitation Behaviors of Second Phase Particles in Twin-roller Strip Vibratory Cast-rolling Processes of 20CrMn Steels

在自主研发的双辊薄带振动铸轧机上进行了20CrMn钢的振动、非振动铸轧对比实验。对所得铸轧板坯进行了拉伸测试、断口形貌观察、粒子能谱分析,结果显示振动能抑制大尺寸粒子的形成从而促进小尺寸粒子的均匀析出,进而提升铸轧板坯的力学性能。结合初步的第二相粒子动力学分析,提出振动对铸轧板坯中第二相粒子析出的影响机理为:振动对熔池区钢液的扰动作用使合金元素分布均匀,从而抑制其在钢液凝固阶段因局部富集而以大颗粒结晶相析出,并促进其在轧制阶段脱溶析出为小尺寸第二相粒子;合金元素分布于对基体有明显强化效果的小尺寸第二相粒子中,提高了合金元素的使用效率,极大地强化了铸轧板坯的综合力学性能。

The vibration and non-vibration cast-rolling experiments of 20CrMn steels were carried out on a twin-roller strip vibratory cast-rolling mill. The obtained slabs were subjected to tensile test, fracture morphology observation and energy spectrum.The results show that the vibration may suppress the formation of large-sized particles and promote uniform precipitation of small-sized particles, thereby improving the mechanics properties of the strips.Combined with the preliminary second-phase particle dynamics analysis,the mechanism of the influences of vibration on the precipitation of the second phase particles in the strips were proposed as follows.The vibration disturbs the molten steels in the molten pool areas to make the alloy elements evenly distributed, thereby inhibiting the precipitation of the large-grain crystal phase in the solidification stages of the molten steels due to local enrichments, and promoting the desolvation and precipitation in the form of small-sized second phase particles in the rolling stages. The alloying elements are distributed in the small-sized second phase particles which have obvious reinforcing effects on the matrix, improving the use efficiency of the alloying elements and greatly strengthening the comprehensive mechanics properties of the cast-rolling slabs.