低焊接裂纹敏感性高强钢Q550CFD的组织性能研究  

Microstructure and Mechanical Properties of High Strength Q550CFD Steel with Low Welding Crack Susceptibility

作　　者：镇凡 张宽 郭志龙 曲锦波 

机构地区：[1]江苏省(沙钢)钢铁研究院,江苏张家港215625 [2]沙钢集团有限公司钢板总厂,江苏张家港215625

出　　处：《热加工工艺》2013年第3期160-164,167,共6页Hot Working Technology

摘　　要：以低焊接裂纹敏感性高强钢Q550CFD为试验材料,测试了该低碳贝氏体钢变形奥氏体的连续冷却转变行为,制定了CCT曲线,并研究了以5℃/s冷却到不同终冷温度(550～680℃)后缓冷(0.1℃/s)至室温时的组织转变规律。在此基础上,通过工业化试验,分析了不同冷却工艺条件下钢板的组织性能。试验结果表明,不同的终冷温度可得到两种具有不同马氏体/奥氏体(MA)组元分布的组织,一种出现在贝氏体铁素体(BF)条间,并与之一同形成粒状贝氏体;一种则在晶界处单独存在,含有该类MA组织的钢冲击韧性较低。通过回火处理,存在于晶界处的MA组织得到分解,冲击韧性可以得到提高。The continuous cooling transformation （CCT） behavior of Q550CFD high strength steel with low welding crack susceptibility was simulated and the CCT diagram was constructed. The microstructure evolution during cooling under the cooling rate of 5℃/s, at 550 -680℃, and followed by a slow cooling to room temperature was investigated. On the basis of that, by the industrial trials , the effects of accelerated cooling rate on the microstructure and mechanical properties were analyzed. The results show that two different types of microstructure, one is granular bainite（GB） consisting of bainitic ferrite（BF） and martensite/austenite（MA） constituent, and the other is GB plus coarse block-like MA phase, can be generated by different finish cooling temperatures （FCT）. The plates with the microstructure of GB and coarse MA generally have lower strength and poor toughness, which can be improved by tempering.

关 键 词：低焊接裂纹敏感性 Q550CFD 粒状贝氏体 马奥岛 终冷温度 

分 类 号：TG142.41[一般工业技术—材料科学与工程]