Influence of Joining Method for Mechanical Properties of 5083, 5059 and 7020 Aluminum Alloys Joints

Abstract

The paper presents the research results on the mechanical properties of aluminum alloy 7020 and its FSW and 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 FSW and MIG – the same methods 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.Friction Stir Welding (FSW) – a new technology can be successfully used for butt welding of different types of aluminum alloy sheets. FSW method can be an alternative to traditional arc welding methods, especially MIG, which is the most common method of joining aluminum alloys used in shipbuilding. The research was carried out using a static tensile test in accordance with the requirements of the Polish Standards PN-EN ISO 4136:2011 and PN-EN ISO 6892-1:2010. Flat samples cut perpendicular to the direction of rolling were used. The research was conducted at the temperature of +20 oC.Friction stir welded joints of tested alloys have higher strength properties as compared to MIG welded joints. The 7020 alloy has higher strength properties then alloys 5083 and 5059. The yield stress is higher by 14.8% as compared to alloy 5083, and by 11.7% as compared to the alloy 5059. Plastic properties of alloy 7020 are the lowest, but with reserves meet the requirements of classification societies. The joints welded by FSW of alloy 7020 have the highest strength properties of all researched joints – higher then alloys 5083 and 5059 joints welded by FSW and joints of all alloys welded by MIG.