.6082-t6 Aluminum Alloy Mixing Friction Welded Microstructure And Mechanical Properties Study

Lightweight is a critical factor that decides the whole performance of high-speed railway. Although aluminum rolling stock produces effective lightweight, the performance of the welding joint will be considerably reduced due to fusion welding. It seriously influence the safety of high-speed railway. The friction stir welding is characterized with the excellent properties of the welding joint and low welding stress and distortion, and has been applied in the aluminum alloy rolling stock of high-speed railway. In this paper, the performances and the properties of 6082-T6 aluminum alloy by friction stir welding were studied with a view to Friction Stir Welding for high-speed train in China in the manufacture of aluminum alloy body provide a theoretical and experimental basis.Using friction stir welding of 3mm thick of 6082-T6 aluminum alloy plate welding. Micro-structural analyses show that, dynamic recrystallization occurred and small equiaxed grains formed in weld nugget. Thermo-mechanical affected zone affected that the role of thermo-mechanical was weaker than the weld nugget zone, forming the grain deformation. Heat affected zone, subject only to frictional heat effects, that is the weakest parts of the joints. Friction Stir Welding of mechanical properties showed that tensile fracture occurred in the weld center position and heat affected zone at the junction of the softening zone or heat-affected zone, the tensile strength of welded joints has reached 70% of the base material。S-N fatigue test results show that the aluminum alloy friction stir welded joints fatigue performance superior to the same level of welded joints fatigue performance.Beijing 625 gantry using friction stir welding of 30mm thick 6082-T6 aluminum alloy welded on both sides. Its forward side and back side have been able to clearly distinguish, forward lateral weld nugget zone and transition zone boundaries clearly than the back side, there a number of onion-ring appearance; The tensile strength of welded joints 197.07 MPa, is 65.6% of the tensile strength of base metal; Welded joint tensile test show that the fracture site mostly in the weld center region, rather than the base metal region. Base metal alloy FSW joints fatigue crack source is incomplete penetration site, Fatigue crack growth the fracture mainly affected by the original parent material fatigue resistance of dendrite morphology, quasi-cleavage and dimple a combination of. Crack growth in fracture crack extension area mainly affected by the dislocation pileup formation of micro-crack accumulation effects. Fatigue fracture and tensile fracture are significantly different that the tensile fracture surface of the plastic is dimple majority, while the majority of brittle tearing of fatigue fracture.