| Austenitic stainless steel is of excellent properties and has been widely applied. It is easy to realize automation of welding production for stainless steel during submerged- arc welding, and the production efficiency is very high. Sintered flux is a kind of submerged-arc welding flux with superior properties which is environment friendly and energy saving, but at present, the categories of China’s flux are too simple, especially the sintered flux suitable for a particular stainless steel is less and develops slowly,as a result that the production of sintered welding flux and its technology gap is larger compared with abroad, so these cannot achieve the actual production requirements for stainless steel. The paper based on the common problems during the submerged-arc welding of stainless steel has provides a new flux component with superior properties according to the component and ratio of the flux. The paper mainly has studied the processing properties of the flux as well as the mechanical properties of the welded joint after the preparation of the sintered flux. The results are as follows.With the content of Ca F2 increases, the slag detachability of sintered flux improves when the content of Ca F2 ranges from 10% to 20%. When the content of Ca F2 ranges from 20% to 25%, the slag detachability of sintered flux gradually decreases with the Ca F2 content increases. Analogously, the slag detachability of sintered flux improves with the content of Al2O3 increases when the content of Al2O3 ranges from 15% to 20%. When the content of Al2O3 ranges from 20% to 25%, the slag detachability rates of sintered flux tend to change slowly and get into the stable stage which has the most excellent slag detachability. The slag detachability of sintered flux decreases with Al2O3 content increases when the Al2O3 content ranges from 25% to 30%.When the Mg O content ranges from 16% to 28%, the slag detachability of sintered flux decreases gradually with Mg O content increases,but when the Mg O content ranges from 16% to 20%, the slag detachability is not the best considering the emergence of the phenomenon of slag viscosity. When Al2O3 content ranges from 24% to 28%, the slag detachability of sintered flux decreases with the content of Mg O increases. When the content of Al2O3 is 20%-25%, the weld bead has no undercut, welding ripples is fine, the surface is smooth and lustrous, the back of the slag shell is bright, and the welding ability is the best. When the content of Mg O is 20%-24%, the weld surface is smooth, no pitting, good colour and lustre,the weld width and the height are uniform, the formation of weld joint is perfect on both arc-retreating place and arc- starting place, no adverse phenomenon such as undercut, also the formation ability of the welding joint is superior and stable.When the content of Ca F2 is less than 20%, the welding process is stable and the arc stability is perfect; When the content of Ca F2 is more than 20%, the arc stability decreases and then the phenomenon of broken arc and unstable arc emerge. For sodium sodium-silicate flux and potassium sodium-silicate flux, the average moisture absorption rates are, respectively, 0.3321 and 0.2219. Due to the microstructure of sodium sodium-silicate flux is special that its moisture absorption ability is better than potassium sodium-silicate flux, and the absorption of moisture resistance is poor. After the sintered flux going though submerged-arc welding, the tensile strength and the impact energy of the weld metal at the welding line are, respectively, more than 590 MPa and 27 J, which meet the national standard requirements. In the process of welding metallurgic, some compounds that composed of S, Si, O etc. emerge and these phenomena are not conducive to the mechanical property of welding joint.The final formula of sintered flux is: 15%-20%Ca F2, 20%-25%Al2O3, 20%-24%Mg O, 5%Ca O, 10%Ti O2, 5%Mn O. |
PDF Full Text Request