管线钢大电流双面高速埋弧焊接用焊丝研制

介绍了石油、天然气输送管线用埋弧焊丝的特征及高韧性焊丝成分设计原则，分别采用92kg高频感应炉实验室冶炼。500kg中频感应炉半工业性冶炼和300t顶吹氧气转炉工业化大生产冶炼、进行焊丝研制。对所研制的焊丝配合烧结焊剂SJ101，进行了无坡口双面埋弧焊试验，测试了焊缝成分、冲击韧度、金相组织、硬度和接头抗拉强度，用扫描电镜分析了冲击断口形貌及夹杂物组成，透射电镜分析了焊缝金属的微观结构，俄歇试验分析了B、Ti、N在焊缝中的分布。结果表明，B在原奥氏体晶界偏聚，可抑制先共析铁素体在晶界析出，弥散分布的细小夹杂物有助于针状铁素体的生成，配合降低S、P、气体元素和杂质含量，可使焊缝金属具有高的韧性，焊缝硬度在HV185～HV214之间，与母材平均硬度HV190为同一水平。焊缝金属横向抗拉强度高于母材。

Development of Wire for Large Current Double Side Submerged Arc Welding of Pipe Steel

In this paper,the characteristics of wire for submerged arc welding of oil and gas pipe line and the principles for the design of chemical compositions of high toughness welding wire are discussed.Steels of wire are smelted in high frequency induction furnace,medium frequency induction furnace,and top oxygen blown converter respectively.Matching the agglomerated flux SJ101,these wires are used for double side submerged arc welding.The chemical compositions,impact toughness,microstructure of weld metal and hardness and tensile strength of welded joint are investigated.The fractured surfaces of impact specimens are analyzed by scanning electron microscope,the microstructures of weld metal are analyzed by transmission electron microscope,and the distributions of B,Ti,N are examined by Auger spectrum analysis.It is indicated that B segregates in the boundary of original austenite grains,that is beneficial for the restriction proeutectoid ferrite.Uniformly distributed particles are helpful for the produce of acicular ferrite.These factors,combined with low content of S,P,gas elements and impurity,result in high toughness of weld metal.The hardness of weld metal is between HV185 and Hv214,which is in the same level with the average hardness,HV190,of base metal.The transverse tensile strength of weld metal is higher than that of base metal.