高强韧耐候桥梁钢Q690qNH的不预热焊接试验  

Non-preheated Welding Test of Q690qNH High Strength and Toughness Atmospheric Corrosion Resisting Steel for Bridge

作　　者：周文浩[1] ZHOU Wenhao(Hunan Valin Xiangtan Iron and Steel Co.,Ltd.,Xiangtan 411101,China)

机构地区：[1]湖南华菱湘潭钢铁有限公司,湖南湘潭411101

出　　处：《金属材料与冶金工程》2022年第2期59-64,共6页Metal Materials and Metallurgy Engineering

基　　金：长株潭国家自主创新示范区专项(2018XK2301)。

摘　　要：通过优化成分设计,采用低Si减少焊接热影响区(HAZ)粗晶区的M/A组元以提高韧性,合理匹配Ni、Mn、Cu元素的含量,促使HAZ软化区生成M/A组元以抑制软化,开发了优化高强韧耐候桥梁钢Q690qNH的HAZ组织的技术;同时采用调质工艺,开发出的Q690qNH耐候桥梁钢板组织均匀,具有良好的强韧性和低屈强比匹配。并对开发钢种进行了不预热焊接的斜Y型坡口焊接裂纹试验、焊接热影响区最高硬度试验和焊接工艺评定试验。结果表明,开发的32 mm厚度的高强韧耐候桥梁钢Q690qNH能够实现不预热焊接:斜Y试样检查面均未出现裂纹;焊接热影响区最高硬度为HV345,小于HV350的要求,且相对于母材的硬度,热影响区的硬化倾向较小,未有明显的软化区;使用15 kJ/cm热输入量的药芯焊丝电弧焊和30 kJ/cm热输入量的埋弧焊,焊接接头的拉伸强度与母材相当,-20℃冲击功均在100J以上,6a弯心直径下180°冷弯不开裂,能够满足桥梁建造对焊接性能的要求。开发钢已在白沙长江特大桥中少量使用。By better composition design,including low Si design to reduce the M/A component in coarse-grained zone of weld heat affected zone(HAZ)for improving toughness,and reasonably matching the contents of Ni,Mn and Cu elements to promote the formation of M/A component in HAZ softening zone for inhibiting softening,the technology to optimize HAZ microstructure of high strength,high toughness and weather resistance bridge steel Q690qNH was developed.At the same time,by quenching and tempering process,the Q690qNH weather-resistant bridge steel plate was developed with uniform structure and good matching of strength,toughness and low yield ratio.Then non-preheating welding Y-groove cracking test,HAZ maximum hardness test and welding procedure evaluation test of the developed steel were carried out.Results show that the developed 32 mm thickness steel plate of Q690qNH high strength and toughness atmospheric corrosion resisting steel for bridge has good weldability without preheating.No crack appears on the inspection surface of Y-groove sample.The maximum hardness of the HAZ is HV345,less than the required HV350,and compared with the hardness of the base metal,the hardening tendency of the HAZ is less,and meanwhile no obvious softening zone appears.Using the welding method of flux cored are welding with 15 kJ/cm heat input and submerged are welding with 30 kJ/cm heat input,the tensile strength of the welded joints are equivalent to that of the base metal,the impact energies of -20℃ are above 100 J,and the cold bending of 180°under the bend center diameter of 6a shows no erack,which can meet the welding performance requirements of bridge construction.The developed steel has been used in Baisha Yangize River Bridge.

关 键 词：耐候钢 Q690qNH 不预热焊接 热影响区 可焊性 

分 类 号：TG113.25[金属学及工艺—物理冶金]