优特钢小方坯高拉速压下工艺的研究与应用  

Application and research on reduction technology of billet under high casing speed

作　　者：王郢 赵新宇 王向红 桂仲林 WANG Ying;ZHAO Xinyu;WANG Xianghong;GUI Zhonglin(Zenith Special Steel Group,Zenith Steel Group Co.,Ltd.,Changzhou 213011,Jiangsu,China)

机构地区：[1]中天钢铁集团有限公司中天特钢有限公司,江苏常州213011

出　　处：《钢铁》2025年第1期92-99,共8页Iron and Steel

基　　金：2022年江苏省“双创人才”资助项目(JSSCRC2022380)。

摘　　要：高拉速是连铸的研究重点、热点之一。目前小方坯高拉速研究普遍集中在螺纹钢上,国内外优特钢小方坯的拉速均为3.0 m/min(折合160 mm×160 mm断面)以下。首次以帘线钢小方坯3.5 m/min拉速为研究对象,研究高拉速轻压下参数对小方坯帘线钢低倍组织和碳偏析指数的影响。研究发现,帘线钢C82DA拉速从2.0 m/min提高至3.5 m/min,两相区长度从8.0 m增加至14.3 m,在没有轻压下的状态下,中心碳偏析指数平均值从1.18(2.0 m/min)增加到1.29(3.5 m/min),中心偏析控制难度大幅增加。当拉速提高后,由于铸坯截面的温度变高、温差变大,零塑性温度带(ZDT)离铸坯表面更近,更容易因压下应力产生压下裂纹,因此,高拉速压下裂纹的敏感性远高于低拉速情况。拉速为3.5 m/min时,首辊压下心部的固相率越低,铸坯心部的碳偏析指数越低,但当首辊压下位置固相率低于0.3时,易形成严重的压下裂纹,并且在裂纹内会出现碳的正偏析,同时在铸坯心部会出现碳的负偏析;而首辊压下位置固相率高于0.45时,铸坯中心碳偏析指数平均值会达到1.13左右,偏析值偏高。因此,高拉速下,合理的压下范围应该在固相率fs为0.3~0.8内,其中心碳偏析指数平均值可以控制在1.06以内。High casting speed is one of the research focuses and hotspots in continuous casting.At present,the research on high casting speed of small billets is generally focused on hot rolled ribbed bars.The casting speed of special steel made by billets at home and abroad is below 3.0 m/min(equivalent to 160 mm×160 mm section).It took the 3.5 m/min casting speed of cord steel billets as the research object for the first time,and studied the influence of parameters under soft reduction on the macrostructure and carbon segregation ratio of cord steel billets under high casting speed.The study finds that casting speed of cord steel C82DA increases from 2.0 m/min to 3.5 m/min,and the length of the two-phase zone increases from 8.0 m to 14.3 m.The average central carbon segregation ratio increases from 1.18(2.0 m/min)to 1.29(3.5 m/min)without soft reduction,indicating a significant difficulty in controlling central segregation.As the casting speed increases,the zero plasticity temperature(ZDT)band becomes closer to the surface of the casting due to the increased temperature and temperature difference of the casting section.This makes it easier for internal cracks to occur due to reduction stress.Therefore,the sensitivity of internal cracks at high casting speed is much higher than at low casting speed.When the casting speed is 3.5 m/min,the lower the solid phase ratio of center under the first roll,the lower the carbon segregation ratio of casting center.However,when the solid fraction at the first roll position is lower than 0.3,it is easy to form internal cracks,and positive carbon segregation will occur inside the cracks.At the same time,negative carbon segregation will occur in the casting core.When the solid fraction at the first roll position is higher than 0.45,the average carbon segregation ratio at the center of the casting will increase to 1.13.Therefore,at high casting speed,a reasonable reduction range should be within the range of fs=0.3-0.8,and the average central carbon segregation ratio can be controlled with

关 键 词：小方坯 高拉速 中心偏析 轻压下 压下裂纹 碳偏析指数 零塑性温度 连铸 

分 类 号：TF777[冶金工程—钢铁冶金]