热装工艺对含铌微合金钢铸坯再加热奥氏体晶粒细化影响  

Effect of hot charging process on austenite grain refinement in reheating process of as-cast Nb bearing steel

作　　者：何倩 刘华松[1] 刘珂 徐国栋 郑宏光 张家泉[1] HE Qian;LIU Hua-song;LIU Ke;XU Guo-dong;ZHENG Hong-guang;ZHANG Jia-quan(School of Metallurgical and Ecological Engineering,University of Science and Technology Beijing,Beijing 100083 China;Baoshan Iron and Steel Co.,Ltd.,Shanghai 201900,China;Shougang Group Co.,Ltd.,Beijing 100041,China)

机构地区：[1]北京科技大学冶金与生态工程学院,北京100083 [2]宝山钢铁股份有限公司,上海201900 [3]首钢集团有限公司,北京100041

出　　处：《连铸》2018年第4期5-10,共6页Continuous Casting

摘　　要：组织细化是控制连铸坯表面裂纹、提升轧材性能的重要手段。针对连铸坯表面裂纹问题,采用热模拟试验的方法,首先获得模拟铸坯进加热炉之前的奥氏体组织,进一步研究了含铌低碳钢SCX400在冷却-加热过程中的晶粒细化潜力。研究结果发现进行一次γ→α→γ相变处理,当铁素体析出量超过85.9%时,最终粗大的奥氏体边缘处出现了许多尺寸为40μm左右的细小晶粒,混晶现象严重,推测是由于Nb（C,N）钉扎原奥氏体晶界,粗大的初始晶粒得到保留;而通过多次γ→α→γ相变可以有效细化奥氏体晶粒,从而对热装热送过程中的表面裂纹控制及最终产品性能的提升产生积极影响。Microstructure refinement is an important method to control the surface cracks of continuous casting billets and to improve the properties of rolled products. In order to solve the defects of crack in surface of continuous casting bil- let, we acquired the anstenite grain in low carbon steel SCX400 containing niobium, which can be used to simulate the state before transferring to the heating furnace. Then, the grain refining potential in the process of cooling-heating was investigated. Experimental result shows that after one γ→α→γ, phase transformation, when the ferrite precipitation ex- ceeds 85.9%, many fine grains appear at the edge of the coarse austenite grain, whose size is about 40 μm at the end, and the phenomenon of mixed grain is serious. It may result from the influence of Nb （C, N）, because they prevent aus- tenite grain from growing and leave the big original austenite. It also shows that multiple γ→α→γ, phase transitions can effectively refine the austenite grain, which has a positive impact on surface cracks control and the final product perfor- mance in the hot charging process.

关 键 词：热装工艺 奥氏体晶粒 细化 相变 

分 类 号：TF777[冶金工程—钢铁冶金] TG142.1[一般工业技术—材料科学与工程]