Agglomerated Flux with MgO-CaF₂-Al₂O₃-SiO₂ Slag System Used for Pipeline Steels

A new type of agglomerated flux for submerged arc welding for X60,X65 grade pipeline steels was prepared.The slag system was MgO-CaF2-Al2O3-SiO2.The influences of different factors on technical properties and diffused hydrogen content,the mechanical properties and microstructure were studied when the basicity was 23,the composition was Al2O3 17%-23%,CaF2 16%-24%,MgO 31%-43%,SiO2 9%-16%,CaCO3 5%-13%,MnO 0%-9%,TiO2 1% and others 5%,the flux showed good removability of slag and favorable welding formation.The diffused hydrogen content was 2.59mL/100g,which reached the level of low hydrogen.This flux matched with a suitable welding wire could meet the need of mechanical properites and low temperature charpy toughness at -20℃ for the welding need of X60 and X65 grade pipeline steels.