Effect Of Mn Content On The Homogenization And Hot-rolled Microstructure Evolution Of Twin-roll Casting 6061 Aluminum Alloy Plate

6061 aluminum alloy has high strength,excellent corrosion resistance and weldability.It is used in transportation,construction,aviation,aerospace and other fields.6061 aluminum alloy has great potential in automotive applications,which can reduce weight and fuel consumption.6061 aluminum alloy has great potential in automotive applications,which can reduce weight while reducing fuel consumption.Twin-roll casting has the advantages of short process,high efficiency and energy saving,and it is a promising plate preparation process.However,the 6061 plates prepared by the twin-roll casting process also has some obvious disadvantages,such as element segregation,coarse second phase,acicular ?-Fe split matrix and poor mechanical properties.In order to solve the above problems,in this experiment,the twin-roll casting 6061 aluminum alloy plate was homogenized and then hot rolled to research the influence of different Mn contents on the iron-rich phase transformation,morphology and distribution of 6061 aluminum alloy and its influence on recrystallization.(1)After the twin-roll casting 6061 aluminum alloy plate is homogenized and annealed,with the increase of Mn content,the grain size,the second phase and the iron-rich phase all changed.With the increase of Mn content,the grain size decreases and stabilizes after reaching a certain level.When the Mn content is 0.69%,the grain size is the smallest,in the thickness direction,the grain sizes at the edge and centre are43?m and 51?m.With the increase of Mn content,the second phase area and hardness difference between the edge and the centre of the alloy increase,the uniformity of the plate becomes worse.In addition,the second phase of the net-like edge of the alloy is melted,the second phase becomes rounded.The transformation degree of the iron-rich phase is estimated by counting the aspect ratio of the iron-rich phase.When the Mn content is 0.69%,the aspect ratio of the iron-rich phase accounts for 50.5% in the range of 0.8-1,the phase transition of the iron-rich phase is the most complete.(2)Twin-roll casting 6061 aluminum alloy plate is hot rolled,the grains are refined,the coarse second phase is broken,recrystallization occurs,and the mechanical properties change accordingly.With the increase of Mn content,which the Particle Stimulated Nucleation(PSN)effect occurs,the amount of recrystallization in the alloy increases.When the Mn content is 0.69%,the recrystallization in the alloy is the most.With the increase of Mn content,the mechanical properties change.When the Mn content is 0.46%,the comprehensive mechanical properties of the plate are the best.At this time,the tensile strength,yield strength and elongation are 197.36 MPa,157.89 MPa,6.23% respectively.