Research On Effective Activating Flux Of A-TIG Welding For Duplex Stainless Steel

Duplex stainless steel which has good mechanical properties and excellent corrosion resistance is widely used in petroleum and natural gas transportation,marine engineering,chemical industry and other industries.As a common method of stainless steel welding,TIG welding has the shortcomings of shallow weld penetration,low welding productivity,complex process and high manufacturing cost in thick plate welding.A-TIG welding method can improve the shortcomings of traditional TIG welding process,improve manufacturing efficiency and reduce manufacturing costs.In this thesis,2205 duplex stainless steel material was used to develop A-TIG welding activating flux.First,seven kinds of single-component activating flux were selected for surface cladding test to study the weld forming effect and arc shape of uncoated and coated active flux TIG welding under the same welding parameters.Among the seven selected single-component active flux,TiO₂,CaF₂,SiO₂ and MgO have obvious effect on changing weld formation.Finally,TiO₂,CaF₂,SiO₂ and MgO were determined as the basic components of the multi-component composite activating flux.Secondly,the orthogonal test was used to design the multi-component composite activating flux for the four basic components,and the order of the four single-component activator was defined.The range analysis method and variance analysis method were used to process the data of weld forming parameters and optimize the processing to obtain the best combination mode.The results show that the primary and secondary order of the effect of four kinds of single-component activating flux on weld penetration is SiO₂,MgO,CaF₂ and TiO₂.The composite activator DS-17?40%SiO₂,20%CaF₂,10%MgO,30%TiO₂?was designed by comprehensive analysis.The experimental results show that the activating flux can increase weld penetration significantly.Finally,in the 2205 duplex stainless steel welding process test,the tensile properties,microstructure and microhardness of the conventional TIG welding and A-TIG welding joints were tested.The results show that the tensile strength of the conventional TIG welded joint is similar to that of the A-TIG welded joint,and is also similar to that of the parent metal.The fracture belongs to ductile fracture.The microstructure of the two welded joints did not change significantly.The microhardness of the weld zone and HAZ of the two joints are higher than those of the base metal.Through comprehensive analysis,2205 duplex stainless steel can obtain deep and narrow weld effect,save energy and production efficiency under the condition of coating activating flux DS-17?40%SiO₂,20%CaF₂,10%MgO,30%TiO₂?under the same heat input.