Electrochemical Corrosion Behavior Of Friction Stir Welding Weld Of Aluminum Alloy

Friction stir welding (FSW) was invented at The Welding Institute (TWI) of UK in 1991 as a solid-state joining technique that unites thermal and mechanical aspects to produce a high quality joint. Because it is a solid state joining process that no melt metal emerges during welding, and it can avoid many defects in fusion welding techniques, FSW has been used on many alloys that are typically difficult to be welded, many advantages of friction stir welding make FSW extremely attractive for the joining of aerospace aluminum alloys. In a relatively short duration after invention, quite a few successful applications of FSW have been demonstrated. Meanwhile, many researchers have devoted to systematically investigating the technology and the mechanical properties of FSW joints, the electrochemical corrosion behaviours have been studied relatively scarcely.In the ambient temperature solution of 0.2M NaHSO3 and 0.6M NaCl, by static weight loss experiment (gravimetric test) and potentiodynamic polarization curve, the electrochemical corrosion behavior of friction stir welding weld of 5083 aluminum alloy and 6082 aluminum alloy were comparatively investigated.At the tool rotation rate of 300 r/min, the traverse speed of 160 mm/min and 3 tool tilt, the corrosion potentials of the 5083 FSW weld were more positive than those of MIG weld and parent material, meanwhile, the corrosion rate and the corrosion current density were less than those of MIG weld and parent material, Rp (polarization resistance) of the FSW weld was larger than that of MIG weld and parent material. Scanning electron microscope(SEM) observation showed that a few shallow pits presented on the surface of the FSW weld, however, a large number of deeper pits emerged on the surfaces of MIG weld and parent material.At the tool rotation rate of 1200 r/min, the traverse speed of 200 mm/min and 3 tool tilt, the corrosion potentials of the 6082 FSW weld were more positive than those of MIG weld and parent material, meanwhile, the corrosion rate and the corrosion current density were less than those of MIG weld and parent material, Rp (polarization resistance) of the FSW weld was larger than that of MIG weld and parent material. Scanning electron microscope(SEM) observation showed that a few shallow pits presented on the surface of the FSW weld, however, a large number of deeper pits emerged on the surfaces of MIG weld and parent material.At the tool rotation rate of 800 r/min, the traverse speed of 160 mm/min and 3 tool tilt, the corrosion potentials of the dissimilar weld were more positive than those of MIG dissimilar weld and two parent materials, meanwhile, the corrosion rate and the corrosion current density were less than those of MIG dissimilar weld and two parent materials, Rp (polarization resistance) of the FSW weld was larger than that of MIG dissimilar weld and two parent materials. Scanning electron microscope(SEM) observation showed that a few shallow pits presented on the surface of the FSW dissimilar weld, however, a large number of deeper pits emerged on the surfaces of MIG dissimilar weld and two parent materials.