焊接工艺对LNG储罐用高锰钢焊接接头组织和性能的影响

The effect of welding processes on the microstructure and properties of welded joints of high manganese steel for LNG storage tanks

为了推动新型国产低温高锰钢及相应焊材在LNG储罐国产化中的应用,利用扫描电子显微镜、光学显微镜并通过常温拉伸、弯曲、低温冲击以及显微硬度等试验,研究了熔化极气体保护焊(GMAW),埋弧焊(SAW)和焊条电弧焊(SMAW)3种不同的焊接工艺对LNG储罐用低温高锰钢焊接接头组织和性能的影响。结果表明,3种焊接工艺的热影响区组织为奥氏体与少量夹杂物颗粒,熔合线附近晶粒粗大且狭长,焊缝组织为柱状晶。硬度最低值均位于焊缝中心,拉伸试验断裂位置均为焊缝部位。3种焊接工艺焊接接头抗拉强度分别为839.2,863.8,675.2 MPa,拉伸和弯曲性能均能满足要求。-196℃时的焊缝冲击吸收能量值分别为123,100,83.7 J,冲击断口均为韧性断裂。在焊接低温高锰钢时应严格控制热输入,从而保证低温高锰钢的焊接质量。

In order to promote the application of new domestic low-temperature high-manganese steel and corresponding welding consumables in the localization of LNG storage tanks,the effects of three different welding processes,i.e.,gas metal arc welding(GMAW),submerged arc welding(SAW)and shielded metal arc welding(SMAW)on the microstructure and mechanical properties of welded joints of high manganese steel for LNG storage tanks were investigated by scanning electron microscopy,optical microscopy and through tests such as tensile testing,bending test,impact toughness test and microhardness test.The results show that the microstructure of the heat affected zone of the three welding processes is composed of austenite and a small amount of inclusion particles.The grains near the fusion line are coarse and narrow,and the microstructure of the weld seam is columnar crystals.The lowest hardness values are all located at the center of the weld seam,and the fracture positions in the tensile test are all at the weld seam.The tensile strength of three welding processes welded joints is 839.2,863.8,675.2 MPa.The tensile and bending properties can meet the requirements.The-196℃impact energy of submerged arc welding seam is 123,100,83.7 J.The impact fracture surface is ductile fracture.The welding heat input of low-temperature high manganese steel should be strictly controlled so as to ensure welding quality of low-temperature high manganese steel.