Mechanical properties of 5083, 5059 and 7020 aluminium alloys and their joints welded by MIG

The article presents the research results on the mechanical properties of aluminum alloy 7020 and its MIG welded joints. For comparison alloy 5083 - the most currently used in shipbuilding alloy was chosen as well as 5059 -the new high-strength alloy. Besides the native material alloys there were investigated their joints welded by MIG -the same method as alloy 7020. Welding parameters used for the connection of the sheets made of 7020, 5083 and 5059 alloys were presented. Metallographic analysis showed the correct construction of structural bonded joints. The arc welding method - MIG is the most common method of joining aluminum alloys used in shipbuilding. It replaces the TIG method of providing equally high quality of joints with a much higher performance. The research was carried out using a static tensile test in accordance with the requirements of the Polish Standard PN-EN 10002:2004. Flat samples cut perpendicular to the direction of rolling were used. The research was conducted at the temperature of + 20 centigrade. The 7020 alloy has higher strength properties then alloys: 5083 and 5059. The yield stress is higher by 14.8% compared to 5083 alloy, and by 11.7% compared to the alloy 5059. Plastic properties of an alloy 7020 are the lowest, but with reserves meet the requirements of classification societies. The joints welded by MIG of 7020 alloy have higher strength properties then joints of alloys: 5083 and 5059. Plastic properties of alloy 7020 compared to 5083 alloy are smaller and at the same level as the connector alloy 5059.