Research For The Protectant On The Stainless Steel Of Weldability

TIG welding has been widely used in the industrial production. TIG weldingprocess on the back of the issue of protection has become increasingly prominent. Thisprotection method is often used by back filled with argon protection, Ceramic linerprotection, mixed-gas protection etc. However, these methods have some limitations,such as argon protection production efficiency is low、serious waste、cannot solve thedefects in the weld patching with argon protection. Thus macking the weld patching ata security risk. The ceramic liner protect inconvenience. The protectant of stainlesssteel is simple and flexible to use、and have good operability. Simply coating to theback of the weldment, and not need the protection of argon, get non-oxidize, showinga silver-white metallic luster and good forming on the back of weld line.This article has been studied in304Stainless Steel for TIG welding ofself-control protectant. Systemmatic studied the effect of the welding current, weldingspeed, smear thickness of the protectant on weld shape, determine the optimalparameters. Use a tensile test to testing the mechanical properties of the joints, andresearch the joints for corrosion test. The results shows that, the protectant can play agood protective effect of304Stainless Steel for TIG welding. Can get non-oxidize,showing a silver-white metallic luster and good forming on the back of weld line.After the protectant coating, the greater the current, the smaller the surface tension ofthe molten pool of metal, facilitating the flow of the molten pool of metal, thusincreasing the welding current can eliminate the phenomena of forming width uneven,rough and sagsandcrests of the root surface of weld. When the current is too large, theone hand, the pressure of the arc of the weld pool increased, on the other hand the bathof the molten pool size and longer existence time, will cause the weld shape variation,also make the weld line oxidation increases. The welding speed is affected the weldshape by molten pool size of the bath and existence time. This is mainly due to lowerwelding speed, the protectant can promote the full flow of molten pool, this effectdiminished when the welding speed is larger. With the increase in the thickness of theprotectant applied, the better the effect of weld shape. When the welding current is20A, welding speed is160mm/min, smear thickness of the protectant is4mm, the jointforming is the best. Tensile and corrosion experiments shows that, the mechanicalproperties of welded joints accord with the requirements. The weldment serious corrosion of uncoated protectant, and less corrosion of smear protectant. Shows thatuse the protectant can effectively improve the corrosion resistance of the joints.Applied research in the welding of stainless steel thin-walled tube of theprotectant, expand the scope of the use of protectant, break through the limitations ofthe stainless steel tube welding needs filled with argon protection, Save the weldingcost, greatly improve the efficiency of the welding.