TT自动焊在X7Ni9钢制LNG储罐内罐环焊缝焊接上的应用研究  

Application of TT automatic welding in circumferential seam welding of X7Ni9 steel LNG storage tank inner vessels

作　　者：周聪 路兴才 赵龙一 谌康 ZHOU Cong;LU Xingcai;ZHAO Longyi;SHEN Kang(PipeChina Engineering Technology Innovation Co.,Ltd.,Tianjin 300450,China)

机构地区：[1]国家管网集团工程技术创新有限公司,天津300450

出　　处：《压力容器》2025年第1期1-9,共9页Pressure Vessel Technology

基　　金：国家管网集团课题(GWHT20220034157BG1)。

摘　　要：为提高LNG储罐内罐环缝焊接质量,对LNG储罐内罐X7Ni9钢环缝TT焊接工艺展开研究,采用双J型窄坡口设计与单面焊双面成型技术,揭示TT自动焊接头低温韧性优良的机理。使用光学显微镜和扫描电镜对焊接接头进行金相组织观察,并对焊接接头进行了无损检测和拉伸、弯曲、冲击、硬度、CTOD及XRD测试。结果表明:焊缝成型良好且性能优良,抗拉强度均值为743 MPa,弯曲试验证明焊缝无缺陷。在-196℃温度下,上表面焊缝冲击韧性均值为152.1 J,侧向膨胀量均值为1.82 mm;根部焊缝冲击韧性均值为164.2 J,侧向膨胀量均值为1.58 mm;上表面热影响区冲击韧性均值为233.1 J,侧向膨胀量均值为2.05 mm;根部热影响区冲击韧性均值为175.3 J,侧向膨胀量均值为1.71 mm。焊缝CTOD值为0.465 mm,热影响区CTOD值为0.734 mm,具有良好的低温韧性,其原因是焊缝组织以奥氏体为主,晶粒细小,组织纯净,逆转奥氏体含量高。研究开发的TT自动焊工艺用于LNG储罐环缝焊接,实现了工程示范应用,为下一步推广应用提供支撑。To improve the welding quality of circumferential seams in LNG storage tank inner vessels,this study focuses on the tandem TIG welding process for X7Ni9 steel circumferential seams.A double-J narrow groove design and single-sided welding with double-sided formation technology were applied to investigate the mechanism behind the excellent cryogenic toughness of tandem TIG welded joints.Microstructure analysis was performed using optical microscopy and scanning electron microscopy.Non-destructive testing and mechanical evaluations,including tensile,bending,impact,hardness,crack tip opening displacement,and X-ray diffraction tests,were conducted.Results showed that the welds exhibited excellent formation and performance.The average tensile strength reached 743 MPa,and bending tests confirmed defect-free welds.At the temperature of-196°C,the impact toughness values were 152.1 J for the upper weld surface with a lateral expansion of 1.82 mm,164.2 J for the root weld with 1.58 mm lateral expansion,233.1 J for the upper heat-affected zone with 2.05 mm lateral expansion,and 175.3 J for the root heat-affected zone with 1.71 mm lateral expansion.The crack tip opening displacement values were 0.465 mm for the weld and 0.734 mm for the heat-affected zone,demonstrating outstanding cryogenic toughness.This is attributed to the fine-grained austenitic microstructure,high purity,and abundant reversed austenite content in the weld.The developed tandem TIG welding process has been successfully applied in engineering demonstrations,providing a foundation for its broader use in LNG storage tank manufacturing.

关 键 词：LNG储罐 TT焊 组织性能 低温韧性 

分 类 号：TH49[机械工程—机械制造及自动化] TE972[石油与天然气工程—石油机械设备] TG146.15[一般工业技术—材料科学与工程]