Substructure Evolution Of 6082 Aluminum Alloy During Hot Deformation And Its Effect On Mechanical Properties

6082 aluminum alloy is a medium strength aluminum alloy with good formability,weldability and corrosion resistance.The components can be prepared by hot die forging and have excellent mechanical properties,which is of great significance for the wide application of 6082aluminum alloy in rail transportation and other fields.Under the conditions of different thermal deformation,the use of thermal deformation and solid solution aging heat treatment process of combining the study of trace Zr addition and thermal deformation under the condition of different grains and the evolution law of structure,system structure of precipitation phase and grain group in the subsequent heat treatment in the process of evolution,through quantitative statistics of phase,the number of points,the dislocation density,organization characteristics,such as The contribution of microstructure to strength was analyzed,and the principle of microstructure optimization for improving mechanical properties of 6082aluminum alloy forgings was revealed.The main conclusions are as follows:（1）When 6082 aluminum alloy is deformed at 500℃at 0.05～0.3s^-1 strain rate,the grain size of the deformed microstructure is similar with the strain rate.With the increase of strain rate,the subcrystal volume fraction and dislocation density increase,and the dynamic recovery mainly occurs during the thermal deformation process.（2）The substructure can promote the precipitation ofβ″phase.In the subsequent heat treatment process,the substructure acts as a favorable nucleation point to induce nucleation of the precipitated phase.The precipitated phase diameter decreases with the increase of dislocation density,and the spacing becomes smaller and the quantity density increases.The calculation of strengthening model shows that precipitation strengthening results are best when the contribution of subcrystal volume fraction and dislocation density to precipitation strengthening is linear,that is,thermal deformation with （?） quarter 0.3 s^-1,yield strength of forging reaches 331.4 MPa after 550℃/1 h solution plus 180℃/12 h artificial aging heat treatment.The elongation was 9.9%.（3）By analyzing the true stress-strain curve,it is found that when the strain rate is between 10^-3 and 10^-1 s^-1,the dynamic softening effect is greater than the work hardening,and the deformation process is dominated.When the strain rate is 1 s^-1,the work hardening is greater than the dynamic softening.The flow stress is related to deformation temperature and strain rate,and the peak stress decreases with the increase of deformation temperature and the decrease of strain rate..（4）The main recrystallization mechanism during hot deformation is continuous dynamic recrystallization.The substructure increases with the increase of strain rate and the decrease of temperature,and the recrystallization decreases with the increase of strain rate and the decrease of temperature.After Zr alloying,the recrystallization ratio of 6082aluminum alloy decreases by 29.7%at 500℃/10^-3 s^-1,and the addition of Zr is beneficial to the delay of dynamic recovery and the inhibition of dynamic recrystallization during hot deformation.（5）The microstructure characterization of isothermal compression samples before and after heat treatment shows that the static recrystallization results in a large decrease in the proportion of subgrains,dislocation density and deformation energy storage,and the inhibition of Zr on recrystallization is reflected in increasing the recrystallization temperature of the alloy.The hardness value increases with the increase of strain rate,and the hardness value of the deformed sample at 500℃is higher than that at 550℃,that is,the hardness value of the deformed sample at 500℃/1 s^-1 is 124.3 HV after heat treatment.