节镍型奥氏体不锈钢轧板表面脱皮缺陷特征与成因  

Characteristics and formation mechanism of surface peeling defects on rolled plates of a nickel-saving austenitic stainless steel

作　　者：王巍 张壮 张力萍 段才锋 尚广浩 张家泉[1] WANG Wei;ZHANG Zhuang;ZHANG Li-ping;DUAN Cai-feng;SHANG Guang-hao;ZHANG Jia-quan(School of Metallurgical and Ecological Engineering,University of Science and Technology Beijing,Beijing 100083,China;Henan Xinjinhui Stainless Steel Industry Co.,Ltd.,Xuchang 461000,Henan,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]河南鑫金汇不锈钢产业有限责任公司,河南许昌461000

出　　处：《中国冶金》2022年第6期139-146,154,共9页China Metallurgy

基　　金：国家自然科学基金资助项目(U1860111)。

摘　　要：节镍型奥氏体不锈钢热轧板和冷轧板常见的表面脱皮缺陷对后续产品合格率有着极大的影响。采用金相显微镜、扫描电镜和电子背散射衍射等手段,观察并分析该脱皮缺陷处的宏观形貌、微观组织及元素成分,探究脱皮缺陷的形成原因。结果表明,热轧板脱皮缺陷表面及纵截面存在明显的嵌入型Cr、Mn金属氧化物,其化学组成与其常见氧化铁皮高度一致。此外,在热轧板脱皮缺陷纵截面EBSD扫描中发现有残余铁素体组织,轧制过程中该处两相组织热塑性差异可能导致微裂纹产生及后续高温氧化,从而表现为热轧板常见的氧化型脱皮缺陷。冷轧板脱皮缺陷来源于热轧板的隐性缺陷,其异常成分与中间包覆盖剂、结晶器保护渣等外来夹杂物基本一致,这些夹杂物在浇注过程卷入铸坯内部且多在冷轧过程得以暴露,并表现为夹杂型脱皮缺陷,形貌上包括直线型脱皮和剥落型脱皮。通过改进连铸中间包与浸入式水口工艺,可有效降低这类不锈钢轧材表面的脱皮缺陷比例。The frequently observed surface peeling defects on the hot and cold-rolled plate of a kind of nickel-saving austenitic stainless steel have an extremely influence on the qualification rate of the final products.The macroscopic morphology,microstructure and element composition of the peeling defects were observed and analyzed by means of metallographic microscope,scanning electron microscope and electron backscattered diffraction,respectively,to explore the cause of peeling defects.The results show that there are obviously embedded Cr and Mn metal oxides on the surface and longitudinal section of peeling defects of the hot-rolled plate,and their chemical composition is highly consistent with their common iron oxide scales.In addition,the residual ferrite structure is found in the longitudinal section of the peeling defect of the hot-rolled plate by EBSD scanning.The thermoplastic difference between ferrite and the matrix austenite phase during rolling might lead to local micro-cracks and oxide embedding,which grows into the oxidative peeling defect frequently observed on the hot-rolled plate.The peeling defect of cold-rolled plate comes from the hidden defect of hot-rolled plate.The abnormal composition of the peeling defect of the cold-rolled plate is basically consistent with the exogenous inclusion such as tundish covering flux and mold protective flux,which is involved into the liquid steel during the casting process and could mostly be exposed during the final cold rolling process.The latter could be defined as inclusions induced peeling defects,which appears as linear peeling and spalling peeling.Through the improvement of continuous casting tundish and submerged nozzle process,the proportion of peeling defects on the surface of this kind of stainless steel rolled sheets could be effectively reduced.

关 键 词：节镍型不锈钢 轧板 脱皮缺陷 氧化铁皮 夹杂物 

分 类 号：TG335[金属学及工艺—金属压力加工]