A TEM Study of Weakly Overaged Precipitates in AA 6082
MetadataShow full item record
New models for modeling the material properties for aluminium alloys that can take intoconsideration the geometry of the needle shaped precipitates, that can be found in 6xxxalloys are being developed. The background for this thesis is to help find needed experimentaldata to calibrate and develop these model further. In this thesis the chosen materialto study was from an extruded plate of AA6082 aluminium, which is a relevant materialin for example the automobile industry.Three different tempered cases has been studied in depth with Transmission ElectronMicroscopy, tensile tests and hardness curves. A hardness curve was made to find T6which is the first case. The second case was weakly over aged at 185 ◦C after reachingT6 until it reached ≈ 70% of peak hardness. The third case was over aged at 200 ◦Cafter reaching T6 until it also reached ≈ 70% peak hardness. It has been made crosssection area and length distributions of the precipitates for the three cases using a TEM.The tensile tests were done to relate the contributions of the different particle parameterssuch as length, cross section area and density to the mechanical properties of the material.It was found in the tensile tests that the over aged materials experienced increasedinitial work hardening rate as compared to T6. The distributions showed that the materialover aged at 200 ◦C had wider and shorter precipitates compared to the material over agedat 185 ◦C. It was also found that the over aged materials has a significantly lower particledensity compared to T6.