The Effect Of Welding Wire Component On Microstructure And Properties Of X100 Pipeline Steel Submerged Arc Welding

With the increasing demand for oil and gas,high level pipeline steel-X100 came out.The current production of X70,X80 pipeline steel submerged-arc welding wire have been unable to meet the mechanical properties and welding technology of X100 pipeline steel welded joints.Therefore,a new submerged-arc welding wire was needed to meet the welding technology and the mechanical properties requirements of X100 pipeline steel welded joints.In this topic,from the microstructure of X100 pipeline steel welded joints,for meeting the demand of mechanical properties,changed the alloy elements composition,made composition design for welding wire,and confirmed the optimal design of wire:Mn-Ni-Cr-Mo.By choosing H08C,AH60Q and making X100 welding wire for X100 pipeline steel and matching sintered flux,carried out experiments and analysis.From the result of research of the effect of welding wire component on microstructure and properties,the main conclusions were obtained:(1)The microstructure of X100 welding wire,H08C welding wire and AH60Q welding wire are acicular ferrite and granular bainit.Ti and B affect the microstructure of deposited metal of X100 welding wire,TiN and Ti2O3 could be nucleation core of granular bainite,and refine the microstructure of deposited metal;B could prevent the forming of proeutectoid ferrite,was conducive to the formation of acicular ferrite,and refine grain.The degree of disorder of acicular ferrit:X100,H08C and AH60Q,and X100 welding wire obtained better microstructure.(2)The microstructure of deposited metal of X100 welding wire,H08C welding wire and AH60Q welding wire was acicular ferrite,granular bainite,and a little M-A.X100 welding wire obtained better microstructure.Cr and Nb could delay precipitation and growing of proeutectoid ferrite,and promote the forming of acicular ferrite,and refine grain.(3)The alloy elements composition design of X100 welding wire was as below:C:0.01-0.05%,Mn:1.4-2.1%,Si:0.1-0.3%,Mo:0.2-0.4%,Ti:0.05-0.1%,B:0.003-0.005%,Cr:0.1-0.4%,Cu:0.2-0.3%,Ni:0.3-0.6%,Nb:0.03-0.08%,P,S<0.005%.X100 welding wire obtained better tensile strength,the tensile strength reached 732 Mpa,and the yield strength was 653 Mpa,and the low impact energy was 33J(-20℃),met the demand of deposited metal mechanical properties.