X80管线钢埋弧焊缝组织特征及其控制的试验研究  

Experiment study of microstructure property and its control of submerged arc welding seam of X80 pipeline steels

作　　者：张敏[1] 姚成武[1] 周永欣[1] 王为波[1] 

机构地区：[1]西安理工大学材料科学与工程学院,陕西西安710048

出　　处：《中国石油大学学报（自然科学版）》2006年第5期88-92,97,共6页Journal of China University of Petroleum(Edition of Natural Science)

基　　金：陕西省教育厅自然科学基金资助项目(01JK134)

摘　　要：从贝氏体强化针状铁素体基体角度出发,采用降低碳元素、提高锰元素含量,并添加镍元素以增加贝氏体转变区和高温铁素体转变区的分离程度的技术路线,进行Mn-Ni-Mo-Ti-B合金系X80级(σs≥551 MPa)管线钢埋弧焊丝的试验研究。焊缝的力学性能测试以及SEM、TEM显微组织观察结果表明,对于所研究的焊缝,过高的锰元素含量因提高冷裂纹敏感指数(Pcm)而细化焊缝金属原奥氏体晶粒尺寸,增加贝氏体形核质点,减少了晶内形核的针状铁素体含量,焊缝韧性下降。镍元素对Pcm贡献较小,且镍元素使焊缝金属基体易于交叉滑移,因而合适的镍元素含量有利于提高焊缝的强韧性。针状铁素体片以夹杂物为核心呈放射状生长,夹杂物周围的局部合金元素(Mn,Ti等)贫乏区提高铁素体相变温度,有利于针状铁素体在该区优先形核。另外,夹杂物周围不存在镍元素的贫乏区。Based on the design of strengthening acicular ferrite using bainite, the Mn-Ni-Mo-Ti-B alloy system submerged-arc welding wire for X80 （the yield strength of σs≥551 MPa） pipeline steel was fabricated according to the technological route, which is to increase the degree of separation betwecn the bainite transition region and high-temperature ferrite transition region by reducing the eontent of carbon element, raising the content of Mn element, and adding Ni element. The results of mechanics performance test of weld metal, and micrcscopic analysis by scanning electron microscope （SEM）, transmission electron microsoope （TEM）, respectively, indicate that excessive content of Mn is disadvantageous to the intragranular nucleated acicular ferrite. The cold cracking sensitivity index （Pcm） of weld metal increases with Mn content increasing, the austenite grain of weld metal is thinner when the Pcm Of weld metal is higher. Thereby, the austenite grain boundaries increases, which is effective for the formation of bainite nucleation and is disadvantageous to the content of acicular ferrite. Ni element has light contributions to Pcm, and makes the matrix of weld metal apt to alternate slip. Thereby, the adequate content of Ni element is beneficial to the toughness of weld metal. The laths of acicular ferrite nucleated at inclusions grow radially, and the depletion of alloying elements such as Mn and Ti may increase the driving force for ferrite transformation, which will lead to form acicular ferrite preferentially in the region. In addition, there is not depletion of Ni element around the inclusions.

关 键 词：高强度管线钢 焊缝 贝氏体 针状铁素体 强韧性 

分 类 号：TG401[金属学及工艺—焊接]