Effect of heat input on microstructure, mechanical properties and corrosion behavior of 5083-H321 aluminum alloy welded joint using P-MIG process

In this research, effects of heat input on microstructure, mechanical properties and corrosion behavior of 5083-H321 aluminum alloy welded joints using pulsed MIG process are investigated. AA5083 aluminum alloy is extensively used for many applications in the marine industries. Due to the environmental conditions and the presence of sea water in service, the corrosion behavior of this alloy, particularly the weld zone, has been studied by researchers. Due to lower heat input and the smaller heat-affected zone (HAZ), pulsed MIG welding process is used. The results showed that an increase in the heat input leads to a decrease in the cooling rate and an increase in the primary dendrite arm spacing in the weld metal. In the HAZ, grain size increases due to recrystallization and grain growth, with increasing the heat input. The results of tension and microhardness test show decreasing the mechanical properties in the HAZ. The weld metal in all samples exhibits a less resistance to pitting corrosion than the base metal and increasing the heat input do not have noticeable effect on the corrosion behaviors of the weld metal. However, by increasing the heat input, corrosion diagrams of the HAZ shift to the low currents which indicates an improvement in the corrosion behavior, due to the slower cooling rate and further dissolution of β phase.