Methods of overlapping closed joints in friction stir welding of thin wall structures made of aluminium alloys

Abstract

Three methods of completing closed (circular and annular) welded joints in welding the 1570C alloy of an Al–Mg–Sc system with a thickness of 11 and 35 mm (using the output wedge, a tool with a moving tip, friction welding) are discussed. The range of double stirring (the beginning to end of the welded joint) has a heterogeneous microstructure and mechanical properties. The distributions of the hardness of the weld metal after the first and second stirring cycle are similar if the working length of the tip is the same, and greatly differ if the working length of the tool used for the second pass is variable (as in welding with a moving tip). The ratio of the tensile strength of the welded joint and the parent metal is not lower than 0.9, which is higher than in arc welding. It is shown that the three methods of completing the closed joints can be used in practice.

Keywords:

• Friction welding with mixing
• output orifice removal
• Al–Mg–Sc alloy
• microstructure
• mechanical properties
• heterogeneous

Notes

Selected from Svarochnoe Proizvodstvo, 2015, 68 (10) 23–28.