Research Of Submerged Arc Weld Wire For X80 High Class Pipeline Steel

The development tendency of oil gas pipeline (especially for natural gas pipeline) is improving the pipe strength level, so as to reduce the construct and transferring cost to maximum extent. Now X80 class steel is used as the priority class steel for high pressure natural gas transferring pipeline. Because of its excellent mechanical properties and good weldabilty, X80 pipeline steel has comprehensive applying perspective. The pipeline in the 2nd West-East Pipeline Project built in 2008 in our country is the the longest distance pipeline with the largest diameter, and the consumped X80 is at most in the world. The main line is 4918 kilometers long, and all are built byΦ1219mmX80 pipe. The submerged arc weld wire used in the developmet of the pipe was demanded to have high strength and good low temperature toughness. For satisfying the construction of west gas transferring to east project pipeline, the submerged arc weld wire for X80 class steel was developed.The development target of the submerged arc welding wire was based on the Technical Specification of X80 LSAW Line Pipe for the 2nd West-East Pipeline Project. The primary composition of the X80 submerged arc welding wire was designed by analyzing the composition and mechanical properties of X80 pipeline steel, as well as the acting mechanics for the alloy elements being in the weld. Based on the try-out results of small oven steel in laboratory, the alloy system and the main elements alloy content range were determined. The production technology of the steel for X80 pipeline steel submerged arc weld wires was researched by using the 210t converter, and the alloying and deoxidating process for low carbon, low silicon and phosphorus steel was optimized, so as to realize high commercial production. the composion of the steel in mass production for X80 class pipeline submerged arc welding wire is homogenous, which has low content of the inclusion, and it is very clean.When the welding speed is 1.65m/min, The X80 hot rolled strip sheets made by Wu Steel, Bao Steel, Ma Steel, Tai Steel and Shou steel all can be welded by the developed X80 class pipeleine submerged arc weld wire matching with the sintered flux F80 developed by Bai Ji Petroleum Steel Pipe Co., Ltd. The tensile strength, impact absorbed energy and Vickkers hardness of the joints all satisfied the demand of"Technical Specification of X80 LSAW Line Pipe for the 2nd West-East Pipeline Project". The microstrucutre of the deposited metal and the weld of pipes are main acicular ferrite, and the non-metal inclusions are the nucleating centres for acicular ferrite. The addition of Zr can improve the proportion of the acicular ferrite in weld. The developed submerged arc weld wire has passed the identification of PetroChina Company Group, and it is successful used in the 2nd west-east gas pipeline project.