Effect of welding condition on microstructures of weld metal and mechanical properties in Plasma-MIG hybrid welding for Al 5083 alloy

Abstract

The effect of welding condition on microstructure and mechanical property of Plasma-MIG Hybrid Weld between Al 5083 plates(thickness : 10mm) was investigated. 1 pass weld without any defects such as puckering, undercut, and lack of fusion was obtained by 150~200A of plasma current and 5~7mm of welding speed. Gas porosities and shrinkage porosities were existed in the weld near fusion line. As welding speed and plasma current were decreasing, the area fraction of porosity was increasing. The hardness of the weld is increasing as welding speed. On the basis of microstructural analysis, Mg segregated region near dendrite boundaries tends to increase with the welding speed. In the result of hardness test, Distribution of hardness in fusion zone showed little change with the plasma current. However, when the welding speed increased, hardness in weld metal markdly increased. It could be considered that effect of heat input to growth of the dendritic solidification structures. Based on tensile test, tensile properties of weld metal was predominated by area fraction of porosities. Consequently, tensile properties can be controlled by formation site and area fraction of porosity.

Remanufacturing the AA5052 GTAW Welds Using Friction Stir Processing

“…This could be explained by the noticed fine-grain structures and the existence of magnesium. In fact, the hardness increases due to the fine co-axial dendritic structure, intermetallic compounds, the precipitates forming, and the high cooling rate in the weld metal region [7,13]. As a result of the interaction between the grain growth and precipitates' existence in the HAZ, hardness has moderately reduced.…”

“…Nonetheless, a few techniques, such as using pulsed current welding, the arc manipulation technique, and torch vibration for refining the microstructure of fusion zones, have been investigated. Despite the promising laboratory results, using such a method may increase the complications during manufacturing [12][13][14][15][16][17][18][19].…”