Development Of Special High Silicon Stainless Steel Non-punching Argon-argon Arc Welding Wire

High silicon austenitic stainless steel has become an important material for producing sulfuric acid equipment because of its corrosion resistance to high temperature and strong oxidizing medium.However,the weldability of high silicon stainless steel is poor,and it is easy to produce welding joints that are easy to fracture,poor impact toughness,and the corrosion rate of welding joints is far lower than that of the base metal.Therefore,in view of the weldability problem of high silicon stainless steel,the alloy system is optimized,and the idea of transitioning to the austenite phase zone and ferrite phase zone in the cladding metal and purifying the structure to reduce the alloying elements of inclusions is adopted to design the tig free welding wire.The microstructure,mechanical properties and corrosion resistance of the cladding metal in the three alloy systems were detected and analyzed to explore the influence of alloying elements on the microstructure and properties,and finally determine the optimal addition element and content.The main conclusions are as follows:(1)It is found that Nb element plays an important role in improving microstructure,refining grain size and increasing hardness in cladding metals,and also affects the grain boundary aggregation of σ With the increase of Nb element content,a certain amount of component segregation occurs in the microstructure,and the precipitated niobium carbide is distributed along the grain boundary in a long chain form from block to block,and the content increases,resulting in poor impact toughness and reduced corrosion resistance of welded joints.When the Nb content is 0.5%,the comprehensive performance is better,the impact absorption energy is 23.4 J,the corrosion rate is 0.3641 mm/a,but it still can not meet the actual production needs.(2)The addition of Ni reduces the amount of σ phase in the cladding metal and changes the shape of σ phase from large block to small round block.When Ni content is 2%,the comprehensive properties are best matched,the impact absorption energy is 26.9 J,the corrosion rate is 0.4948 mm/a,and there is no intergranular corrosion.However,when the Ni element is 3%,σ phase precipitates at the junction of the three grains,and the impact toughness and corrosion resistance of the cladding metal deteriorate.(3)Element A can refine the microstructure of the cladding metal,promote the formation of equiaxed crystals,and reduce dendrite.When element A is added 0.2%,the comprehensive performance is the best,the impact absorption energy of the cladding metal is 44.2 J,the corrosion rate is 0.2895 mm/A,no intergranular corrosion phenomenon.However,the content should not be too much,reaching 0.3% will cause coarse structure,so that the impact toughness and corrosion resistance of the cladding metal decline.(4)After comprehensive optimization of the three components,2%Ni +0.2%A was determined as the optimal formula of tig free wire coating.Under this formula,the impact absorption energy of the cladding metal was about 50 J,the corrosion rate was 0.9 mm/ A,and the mechanical properties and corrosion resistance were in line with the actual production conditions,which could be put into operation later.