S355NL钢风电法兰锻件低温冲击韧性不良的原因  

Cause of Poor Low Temperature Impact Toughness of S355NL Steel Wind Power Flange Forgings

作　　者：张泽晨 曹铁山[1] 赵杰[1] 吕德超 程从前[1] ZHANG Zechen;CAO Tieshan;ZHAO Jie;LYU Dechao;CHENG Congqian(School of Materials Science and Engineering,Dalian University of Technology,Dalian 116024,China)

机构地区：[1]大连理工大学材料科学与工程学院,大连116024

出　　处：《机械工程材料》2025年第3期128-134,共7页Materials For Mechanical Engineering

摘　　要：某厂生产的某批次S355NL钢风电法兰锻件的−50℃冲击吸收能量较低且波动较大,通过对比不合格和合格法兰锻件的力学性能、断口形貌、显微组织,结合生产工艺分析了其低温冲击韧性不良的原因。结果表明:不合格法兰锻件冲击断口呈脆性断裂特征,纤维断面率几乎为0,在冲击过程中裂纹的扩展路径较平直,而合格法兰锻件冲击断口呈韧性和脆性混合断裂形貌,纤维断面率为60%,裂纹扩展路径更加曲折。正火温度偏高、在炉加热时间较长而导致的晶粒粗大、晶粒尺寸分布不均匀是S355NL钢风电法兰锻件低温冲击韧性不良的主要原因,组织中不均匀分布的珠光体也是法兰锻件韧性降低的原因之一。The impact absorbed energy at−50℃of a certain batch of S355NL steel flange forgings used in wind power from a factory were low and fluctuated significantly.The cause of poor impact toughness at low temperatures was analyzed by comparing the mechanical properties,fracture morphology,and microstructure of qualified and unqualified flange forgings and combining with the production process.The results show that the impact fracture of unqualified flange forgings was characterized by brittle fracture,the fiber section rate was almost 0,and the crack propagation path was relatively straight during the impact process.The impact fracture of qualified flange forgings was characterized by a mixture of ductile and brittle fracture morphology,the fiber section rate was 60%,and the crack propagation path was more tortuous.High normalizing temperature and long heating time in the furnace resulted in coarse grains and uneven grain size distribution,that was the main reason for poor temperature impact toughness of S355NL steel flange forgings.Uneven distribution of pearlite in the structure was another reason for the reduction of toughness of flange forgings.

关 键 词：S355NL钢法兰锻件 低温冲击韧性 显微组织 断口形貌 

分 类 号：TG142.41[一般工业技术—材料科学与工程]