The Influence Of Heat Treatment Proess On The Corrosion Behavior Of 6082 Aluminun Alloy

The addition of Cu,Mg to Si in aluminium alloy with improper mass ratio or improper heat treatment may cause intergranular corrosion susceptibility of 6xxx alloy which itself has no intergranular corrosion.In this paper,6082 aluminum alloy is used as research material,scanning electron microscope?SEM?and its own energy spectrometer,optical microscope?OM?,transmission electron microscopy?TEM?and electron back scattering diffraction test results with electron backscattered diffraction?EBSD?and analytical means such as vickers hardness tester were employed.The influence of heat treatment proess on the corrosion behavior of 6082 aluminun alloy were investigated by intergranular corrosion test and Vickers hardness measurement method.The result shows:The hardness curve of 6082 aluminum alloy reached its peak at 200?,showing a trend of rising first and falling later,and the hardness curves are different with the different solid solution treatment temperature in the previous period.The corrosion depth curve and corrosion rate curve of 6082 aluminum alloy reached their peak value at 200?and both present a downward trend after rising first.In the previous period,the preaging treatment temperature and the corrosion depth curve are different,but the maximum corrosion depth is similar;the rate of corrosion and the percentage of corrosion are different,and the maximum corrosion rate was 15.23%.The larger"Mg atoms state of aggregation"appeared during the aging treatment of6082 aluminum alloy without tempering conditions on the grain boundary will have a trace of partial phenomenon,until 150?×1 Hr artificial aging treatment resulted in the distortion of the dislocation line and the matrix co-lattice,indicating that this was the beginning of the G.P region.In the determination of hardness,intergranular corrosion depth and corrosion rate,there is a tendency of accelerating upward.175?×1Hr Artificial Aging Treatment is the beginning stage of segregation of alloy elements in 6082 Aluminum Alloy.The segregation amount covers almost the entire grain size,which is indicated by the increase of hardness and the acceleration of intergranular corrosion.During the artificial aging treatment at 200?×1Hr,the phenomenon which is similar to"mole stripe"phenomenon is caused by the regular distribution of dislocations and other defects,representing the peak of intergranular corrosion.In the artificial aging treatment of300?×1Hr-400?×1Hr,the second grainy phase increases with the increase of aging temperature,the alloy elements in the grainy phase accumulate further,and the order degree of the atoms increases further.With the increasing of aging temperature,some grains revert to recrystallization,which leads to the movement of grain boundaries and sub-grain boundaries.The second phase short rod-like particles can not be seen in the new grain boundaries,which is similar to the untempered state.It is indicated that the corrosion of intergranular is decreasing with the accumulation of the second phase.The corrosion velocity of the matrix is obviously faster than that of the aging treatment.The crack is forming in a network,and developing along the intergranular boundary of Mg₂Si and the matrix,extending into the intragranular at the same time.The corrosion depth curve of 6082aluminum alloy also shows the same trend as the hardness curve.