LNG储罐9%Ni钢TIP-TIG立焊接头组织及性能  

Microstructure and properties of TIP-TIG vertical welded joint of 9%Ni steel for LNG storage tank

作　　者：郭鹰 杨尚玉 Guo Ying;Yang Shangyu(Offshore Oil Engineering Co.,Ltd.,Tianjin 300461,China)

机构地区：[1]海洋石油工程股份有限公司,天津300461

出　　处：《焊接》2022年第8期50-58,共9页Welding & Joining

摘　　要：文中将新型TIP-TIG全自动焊技术用于液化天然气(LNG)储罐内罐的焊接,通过电子显微镜、能谱分析、X射线衍射等测试手段,对比研究了TT焊、SMAW焊接头显微组织、力学性能和低温冲击韧性。结果表明,TT焊接头具有强度高低温韧性好的优点,这主要归因于TT焊热输入小、焊接过程稳定、焊接工艺参数波动小,使得焊接接头成形良好、熔合比小,焊缝组织主要为晶粒细小的奥氏体,元素脱溶析出较少,析出相也是Mo含量较高的富Mo相,这种晶间析出相阻碍位错滑移,具有一定析出强化的作用,较少的析出相避免了因为夹杂物引起应力集中而形成孔洞形核,提高了接头韧性。随着该焊接方法自动化程度的提高,未来可替代SMAW成为LNG储罐立焊缝焊接新技术。The demand for clean energy in China will be further increased during the‘14th Five-Year Plan’period.Liquefied natural gas(LNG)is an important part of the national energy strategy.LNG storage tanks are one of the major infrastructures,and the welding technology of storage tank is the key to ensure the safety and service life of facilities.In this paper,the new TIP-TIG automatic welding technology was used to weld the inner tank of storage tank.The microstructure,mechanical properties and low-temperature impact toughness of TT welding and SMAW welded joints were compared and studied by means of electron microscopy,energy spectrum analysis and X-ray diffraction.The results show that the TT welded joint has the advantages of high strength and low temperature toughness,which is mainly due to the small heat input of TT welding,stable welding process and small fluctuation of welding process parameters,resulting in good forming of welded joint and small fusion ratio.The microstructure of joint is mainly austenite with fine grains,and the element desolventizing precipitation is less.The precipitated phase is Mo-rich phase with high Mo content,which hinders dislocation slip,and has a some precipitation strengthening effect.Less precipitates avoid the formation of hole nucleation caused by gravitational concentration caused by inclusions and improve the toughness of the joint.With the improvement of automation,this welding method can replace SMAW and become a new welding technology for vertical seam of LNG storage tank.

关 键 词：9%NI钢 TIP-TIG焊 焊条电弧焊 显微组织 低温韧性 

分 类 号：TG444.74[金属学及工艺—焊接]