冷轧辊钢锻后探伤缺陷的原因分析与优化  

Cause analysis and optimization on abnormal flaw detection in cold roll steel after forging

作　　者：于彬 申同强 郭保善 李昭澎 李鑫 Yu Bin;Shen Tongqiang;Guo Baoshan;Li Zhaopeng;Li Xin(Xingtai Iron&Steel Corp.,Ltd.,Xingtai 054027,China)

机构地区：[1]邢台钢铁有限责任公司,河北邢台054027

出　　处：《锻压技术》2023年第11期40-45,共6页Forging & Stamping Technology

摘　　要：邢台钢铁有限责任公司利用具有保护气氛的抽锭式电渣炉生产Ф600 mm的9Cr3Mo冷轧辊钢锭,并锻造成Φ440 mm×1700 mm×4215 mm规格的辊坯,锻造后经超声波探伤发现辊径中心有连续缺陷,直径为Φ4~Φ5 mm,范围长度约为330 mm。采用化学成分分析、金相检验、断口宏观微观检测及酸洗检测等手段对该冷轧辊钢内部探伤缺陷情况进行了全面分析。结果表明,经酸洗后,9Cr3Mo冷轧辊钢心部存在密集的纵向微裂纹,似材料疏松缺陷。进一步检测发现,裂纹附近无脱碳层,周围组织为均匀的球化退火组织,夹杂物无明显异常,无化学成分偏析,排除了电渣锭组织疏松缺陷。而后,对缺陷的特点进行了分析,判定此缺陷为在锻造过程中因心部透烧不充分、材料塑性较低而导致的锻造形变时的拉伸裂纹。最后,通过优化锻造加热过程中每火次间的保温时间和增加操作机抱钳预热的措施,保证了冷轧辊钢心部的锻造温度,避免了此类锻辊的探伤缺陷情况。9Cr3Mo cold roll steel ingot of Ф600 mm was produced in Xingtai Iron&Steel Corp.,Ltd.by using a pulled-ingot type electroslag furnace with protective atmosphere,which was forged into a roll blank with the specification of Ф440 mm×1700 mm×4215 mm.Then,after forging,the continuous defects with the diameters of Ф4-Ф5 mm and the range length of about 330 mm were found in the center of roller diameter by ultrasonic flaw detection.Furthermore,the internal flaw detection of the cold roll steel was analyzed comprehensively by chemical composition analysis,metallographic examination,macro-microscopic examination of fracture and pickling examination.The results show that after pickling,there are dense longitudinal micro-cracks in the center of 9Cr3Mo cold roll steel,which looks like loose material defects.However,it is found that there is no decarbonized layer near the crack by further inspection,the surrounding structure is the uniform spheroidized annealed structure,and there are no obvious abnormalities in the inclusions and no segregation of chemical composition,which rules out the defect of loose structure for electroslag ingot.Then,the characteristics of the defect were analyzed,and it is determined that the defect is a tensile crack during the forging deformation due to insufficient penetration of the core and low material plasticity during the forging process.Finally,by optimizing the holding time between each fire during the forging and heating process and increasing the preheating of manipulator clamp,the forging temperature of the cold roll steel core is ensured,and the abnormal flaw detection of such forging rolls is avoided.

关 键 词：9Cr3Mo冷轧辊钢 裂纹 锻造形变 锻造温度 保温时间 预热 

分 类 号：TG316.1[金属学及工艺—金属压力加工]