M100大型电渣重熔板坯表面裂纹成因与控制  

Cause and control of surface crack on M1o0 large-scale electroslag remelting slab

作　　者：李健[1] 赵刚 柴锋[1] 张友鹏 罗小兵[1] 潘涛[1] LI Jian;ZHAO Gang;CHAI Feng;ZHANG Youpeng;LUO Xiaobing;PAN Tao(Institute for Structural Steels,Central Iron and Steel Research Institute Co.,Ltd.,Beijing 100081,China;Iron&Steel Research Institute of Angang Group Corporation,Anshan 114009,Liaoning,China)

机构地区：[1]钢铁研究总院有限公司工程用钢研究院,北京100081 [2]鞍钢钢铁研究院,辽宁鞍山114009

出　　处：《中国冶金》2024年第8期69-82,共14页China Metallurgy

摘　　要：M100钢是一种采用电渣工艺生产的高强度船体结构用钢,其在电渣重熔过程中产生的表面裂纹会对产品的成材率和表面质量产生不利影响。针对M100大型电渣板坯出现的表面裂纹问题,利用残余应力、低倍组织、裂纹形貌、微观组织分析及硬度测试等方法,对电渣板坯表面裂纹特征及形成机理进行了研究。结果表明,电渣板坯表面裂纹多沿粗大柱状晶晶界分布,其断口呈典型的沿晶断裂特征;裂纹处存在明显氧化现象,表明裂纹主要产生于电渣板坯凝固冷却阶段。对电渣板坯表面裂纹形成机理进行了分析,发现表层金属在结晶器较大冷却强度作用下,所形成的粗大马氏体柱状晶晶间结合力弱,受马氏体相变瞬间产生的组织拉应力作用而开裂,是试验电渣板坯产生表面沿晶裂纹的主要原因。基于表面裂纹形成机理,提出了将结晶器冷却水流量由130 m^(3)/h降低至80 m^(3)/h的工艺优化措施并进行了工业试验,验证电渣板坯主要由马氏体和贝氏体混合组织组成,平均硬度较优化前的电渣板坯降低约40HV10,表面未发现裂纹,表明所采取的结晶器冷速优化措施合理有效。研究结果可为马氏体型合金钢大型板坯电渣生产中表面质量的控制提供参考。Mioo steel is a high strength ship structure steel produced by electroslag process,and the surface cracks generated during the electroslag remelting process can have adverse effects on the yield and surface quality of the product.In order to solve the surface cracking problem of M1oo large-scale electroslag remelting slab,the charac-teristics and formation mechanism of surface cracks on electroslag slab were investigated using the methods of resid-ual stress,macrostructure,crack morphology,microstructure and hardness analysis.The results show that most of the surface cracks on electroslag slab distribute along the coarse columnar crystal grain boundaries,their fracture ex-hibit the typical feature of intergranular fracture.And there is obvious oxidation phenomenon at the cracks,indica-ting that the cracks are mainly generated in the solidification and cooling stage of electroslag slab.The formation mechanism of surface crack on electroslag slab is analyzed,the intergranular bonding force of coarse martensite co-lumnar crystals which is formed under a rather large cooling intensity by crystallizer is weak,it caused cracks along grain boundaries under the instantaneous tensile stress produced by martensitic transformation,and it is the main reason for surface intergranular cracks on the experimental electroslag slab.Based on the formation mechanism of surface cracks,the process optimization measure of reducing the crystallizer cooling water flow rate from 130 m^(3)/h to 80 m^(3)/h was proposed and tested industrially.It is verified that the microstructure of electroslag slab is mainly composed of mixed martensite and bainite,whose average hardness is reduced by about 40HV10 compared with the pre-optimization electroslag slab.And no crack is found on the surface,which indicates that the adopted optimiza-tion measure for the cooling rate of crystallizer is reasonable and effective.The research results can provide reference for the control of surface quality in the electroslag production of large martensitic alloy ste

关 键 词：M100钢 电渣板坯 表面裂纹 结晶器冷却强度 组织应力 

分 类 号：TF142[冶金工程—冶金物理化学]