THE EFFECT OF MEDIA TEMPERATURE ON THE CORROSION BEHAVIOR OF MIG WELDED AA 6061-T6 JOINTS

Abstract

The purpose of the present paper isto identify theinfluences ofMetal inert gas joiningmethod on the behavior of AA 6061 -T6 joints’ regarding corrosion. Many experiments have been performed to test the rate of the corrosion of this alloy. Metal inert gas (MIG) welding processhas been performedonplates having a thicknessof 6mm to producemultiple buttwelding connectionswithmeasurements of (100 *50* 6)mm,withmarginalangle of single and twofold V of 70⁰byfiller metal having symbol ER- 4043 and Argon as a protecting gas. The connected pieces are examined byX-ray radiography.The welded joints were treated by heat, the joints heated for half an hour in the stove to 150 C° then cooled in the air to releasethe connecting stresses.Numeroussampleswere providedfor the corrosion examination inmeasurements of (15*15*3) mm agreeing to ASTM G71-31 from the weld joint and the base metal, then the microstructure was examined. The corrosion test was achieved by potentiostatic polarization measurements in 3.5%NaCl seawater at various temperatures (25, 50, 75°C). It was found that the corrosion rate for the base metal decreases as the media temperature increasesbecause the increasing temperature prevents the oxygen from dissolving in the water and accelerates the chemical reaction between the metal and the oxygen forming aprotective layer. Besides, the results of the corrosion rate for the weld joints showed a noticeable decrease for the same reason and for the change in the microstructure during the welding.