Slide 1: Aluminum Welding
Some of the factors that affect the welding of aluminum are * Aluminum Oxide coating * Thermal conductivity * Thermal expansion Coefficient * Low melting temperature Melting point of Aluminum oxide is nearly 1926 ° C. As the aluminum oxide film becomes thicker, it will start absorbing moisture from the air. Moisture is a source of hydrogen which is the cause of porosity in aluminum welds. Hydrogen can come from oil, paint, dirt, base metal, oxide, etc. Hydrogen will enter the weld pool and is soluble in molten aluminum. Hydrogen is rejected during solidification. Prior to welding, aluminum oxide film must be removed. If not, it may lead to reduction in ductility, lack of fusion and weld cracking. Aluminum has a thermal conductivity which is about six times as fast as steel, which means more heat has to be put into aluminum even when the melting point is less than half that of steel. Source: http://everlastgenerators.com/wordpress/welders/aluminum-welding/
