Study On Microstructures And Properties Of AZ31 Magnesium Alloy FSW Joint

Lightweight technology of rail passenger car at home and abroad is an important direction. As the lightest metal materials for industrial applications, Magnesium alloy is the lightweight material of choice. Magnesium alloy in the high-speed train application, first of all to solve the problem of magnesium alloy is the connection issue.This article is about AZ31 magnesium alloy plate FSW welding with butt-joint. It is adopted that the best processing parameters. AZ31 magnesium FSW welds is study on the microstructure and mechanical properties, including tensile properties, bending performance, the impact of performance, micro-hardness distribution, and observing the impact of the fracture surface. The conclusion of the paper is as follows:1. AZ31 magnesium alloy FSW joint is in good shape, smooth surface, no fash, groove.2. AZ31 magnesium alloy FSW joint microstructure analysis showed that the weld nugget organization is small, uniform. Thermo-mechanically affected zone organizations is smaller partly and clear distortion. HAZ organizations someone is small, someone is big, not even. Base metal is typical rolling organizations.3. FSW joint tensile strength is 215.34MPa. Base mental tensile strength is 241.29MPa FSW joint strength factor is 0.89. FSW joint extension percentage is 8.3%. Base metal extension percentage is 15.2%. Tensile rupture is mixed pattern, tough rupture and brittle rupture.4. AZ31 magnesium alloy FSW joint weld nugget hardness decreased significantly, it has been softened.5. The bending angle of normal bend test is 64°. Cracks appear in the heat affected zone. The bending angle of root bend test is 56°. Cracks appear inter the weld nugget and thermo-mechanically affected zone.6. The FSW joint absorbed the impact energy higher than base mental. Impact rupture is mixed pattern, tough rupture and brittle rupture. The plastic fracture of weld nugget and heat affected zone is more obvious than base metal.