9Ni钢TIP-TIG焊接接头低温韧性研究  

Study on Low Temperature Toughness of 9Ni Steel Welded Joint for LNG Storage Tank

作　　者：杨尚玉 郭鹰 YANG Shangyu;GUO Ying(Offshore Oil Engineering Co.,Ltd.,Tianjing 300462,China)

机构地区：[1]海洋石油工程股份有限公司,天津300462

出　　处：《电焊机》2023年第6期29-35,共7页Electric Welding Machine

摘　　要：为研究TIP-TIG(TT)焊接技术在液化天然气(LNG)储罐用9Ni钢焊接中的应用价值,根据国标对9Ni钢埋弧焊(SAW)和TT焊接接头进行了低温夏比冲击韧性试验和裂纹尖端张开位移(CTOD)试验,并对接头进行了微观组织及CTOD试样断口分析。结果表明,TT焊缝和热影响区平均低温冲击吸收能量远高于SAW,低温冲击韧性更好。TT焊缝和热影响区CTOD特征值分别为0.455 mm和0.744 mm,SAW焊缝区和热影响区为0.621 mm和0.391 mm,CTOD特征值远高于常用工程标准要求,CTOD试样断口均为韧窝,断裂形式为韧性断裂。TT焊接时,送丝机的推拉振动送丝功能实现了对熔池的搅拌,使得焊缝金属成分更加均匀,细化了晶粒,也减少了焊接过程中气孔的产生;另一方面,TT焊接时采用钟摆型摆动方式,焊枪摆动也有助于晶粒的细化,从而提高焊接接头的低温韧性。将TT焊接技术运用到9Ni钢的焊接中,相比传统的弧焊方法,不仅能够获得高品质的焊接接头,还可以解决清根、大量打磨的问题,节省材料和人工成本,从而实现高效高质量焊接。To study the application value of TIP-TIG(TT)welding technology in 9Ni steel welding of Liquefied Natural Gas storage tanks,in this paper,the charpy impact toughness test and crack tip opening displacement(CTOD)test were carried out on the welded joints of SAW and TT of 9Ni steel according to national standard.The microstructure and fracture of CTOD sample were analyzed.The results show that the average low-temperature impact energy absorption of TT weld and heat-affected zone is much higher than that of SAW,and the low-temperature impact toughness is better.The average CTOD eigenvalues of TT weld and heat affected zone are 0.455 mm and 0.744 mm respectively,and SAW weld zone and heat affected zone are 0.621 mm and 0.391 mm respectively.The CTOD eigenvalues are far higher than the requirements of common engineering standards.The fracture of CTOD samples are all ductile pits,and the fracture form is ductile fracture.TT welding,the push and pull vibration wire feeding function of wire feeder to achieve the mixing of molten pool,making the weld metal composition more uniform,refine the grain,but also reduce the production of porosity in the welding process;On the other hand,TT welding adopts pendulum swing mode,the swing of welding gun is also conducive to grain refinement,thus improving the low temperature toughness of welding joints.TT welding technology applied to 9Ni steel welding,compared with the traditional arc welding method,not only can obtain high-quality welding joints,but also can solve the problems of root cleaning and large amount of grinding,save considerable welding material quantity and labor cost,so as to achieve efficient and high-quality welding.

关 键 词：9NI钢 TIP-TIG焊接 埋弧焊 低温韧性 CTOD试验 

分 类 号：TG457.1[金属学及工艺—焊接]