Study On Corrosion Resistance Of Aluminum Alloy Composite Welded Joints By Welding Process

5083 aluminum alloy,is a kind of Al-Mg alloy,which has the good performance of fusion welding,cold processing and corrosion resistance,so that it's widespread used to the field of the vehicle engineering,marine engineering,aerospace and so on.It's gradually faced with the severe problem of the corrosion along with the alloy and it's welding components widely used.This thesis describes the testing which is potentiodynamic polarization curve test method of the corrosion resistance of 5083 aluminum alloy coupons(10mm thick),being processed plate welded joints using compounded heat sources of YAG laser and MIG arc under the different laser processing parameters and in the experimental conditions which is simulated to the seawater by 3.5% NaCl solution.The tests were performed using metallographic microscope to observe the micro-structure,and we analyze the cause of formation through the tools of the high-speed camera and simulation software.The results show that the internal defections,the uniformity of grains and the distribution of stress are different obviously because of the various processing parameters.The electrochemical stabilities are diverse under the interaction of mentioned justly,which results in optimal phenomenon using steel brush grinding processing,the chemical etching method secondly,but the surface of original state being the worst in terms of the corrosion resistance of welding joints.The corrosion resistance of welding joints decreased along with the enhancement of the laser power and the shielding gas flow,which are altered to various parameters.Then,the trends of the property of corrosion resistance were first increased and then decreased with the increase of welding current,welding speed,and the distance between laser and wire,which are altered to various parameters.The corrosion resistance was fluctuated over the various of the defocusing distance.In conclusion,the pre-treated to the 5083 aluminum alloy coupons is the steel brush grinding processing,and the procedure parameters are P=3.0kW,I=200A,U=20.8V,DLA=3mm,v=1.0m/min,?f=-2mm,fg?=20L/min,where the P is laser power,the I is welding current,the U is welding voltage,the DLA is the distance between laser and wire,the v is laser scanning speed,the ?f is defocusing distance,and the fg? is the shielding gas flow.Above all the parameters are the optimal welding process which causes to the highly corrosion resistance significantly.