Study On Pulsed YAG Laser Welding Process Of A304 Stainless Steel

With the advancement of science and technology, our laser technology becomes moremature, with the advantages of good welding quality, high welding efficiency, beautifulappearance and easy operation. Stainless steel has good corrosion resistance and weldability.Therefore, laser welding of stainless steel is the focus of the study. This paper studies on theprocess, weld joint microstructure, mechanical properties and corrosion resistance of use laserwelding technology to weld A304 stainless steel.First, we weld A304 stainless steel in three output of the laser. When P=1600W,V=3mm/s in continuous laser ,the sample was penetration and exist holes. When P=1600W,V=3mm/s in sine pulse laser, all the sample did not penetration, but the sample of penetration of2.9 mm not has holes. When the mean power=1600W, peak power=3200W, duty=50%,welding speed=5mm/s is the best process of square wave pulses of laser welding. The hole atthe fusion caused by the uneven vibration of the liquid pool, the holes of at the bottom of theweld is due to rapid solidification of liquid metal at the bottom of the pores, some metal vaporlate overflow, thus forming a pore. Therefore, the better welding process is square wave pulseof laser welding, mean power=1600W, peak power=3200W, duty=50%, weldingspeed=5mm/s, pulse frequency=100Hz, pure argon shielding gas, flow of gas= 30L/min, theamount of defocus=0, with a smaller weld width, no welding defects, weld uniform, mainlycomposed of columnar crystals.Second, the use of micro-hardness test microstructure of welded joint under differentwelding processes, the results showed that the most hardness of the fusion zone, second, thecentral area of the weld and the base metal,the hardness of the weld have something to theorganization of the weld and the main content of alloying elements.Further, study on the welded joint for corrosion in electrochemical experiments of A304stainless steel laser. Electrochemical experiments use Tafel testing techniques and corrosivemedia use the mass fraction of 3.5%NaCl and 10%HCl. The results showed that the mostcorrosion resistance is the base metal in both electrolyte solutions, the corrosion resistance ofwelded joint is considerable in two electrolyte solutions. The second, the corrosion potentialare between -0.2v～-0.3v in 3.5%NaCl, the corrosion potential of the base metal is -0.092v,their corrosion resistance is far greater than the corrosion resistance in 10%HCl.