Study On High Temperature Precipitation Behavior And Microstructure And Properties Of High Mn4343/3003/4343composite Brazing Plate

With the development of science and technology,it is imperative to lightweight vehicles,to reduce weight by reducing the thickness of composite materials,composite plate strength and corrosion resistance will be reduced,Therefore,lightweight,high strength,corrosion resistant composite plate is the latest development trend,and the 4343/3003/4343 composite brazing plate is one of them.The high Mn3003 aluminum alloy as the matrix of brazing plate composite material has the most influence on the microstructure and properties of the composite plate.Therefore,the research of the 3 series aluminum alloy has been a hot topic in the field.At present,the research on the influence of domestic and foreign researchers on the structure and properties of composite panels has been reported.However,few researches have been done on the high temperature precipitation behavior of composite panels during processing and the mechanism of their influence on the structure and properties of composite panels.With the help of conductivity meter,universal tensile testing machine,scanning electron microscope,optical microscope,transmission electron microscope,energy dispersive spectroscopy and Image-Pro Plus software testing equipment,research of new high Mn4343/3003/4343 composite plate in a uniform and brazing process on precipitation behavior and its effect,microstructure and properties of composite plate and different homogenization system.To provide a theoretical basis and guidance for industrial production and technology development.The main results of this paper are as follows:(1)Hot rolling,cold rolling and annealing have little effect on the precipitation morphology of high Mn 3003 aluminum alloy.However,homogenization has a great influence on the precipitation behavior of the precipitated phase of the high 3003 alloy.It mainly includes: the low temperature phase(<400?),the Mn diffusion rate is small,and the precipitation is difficult.In the middle and high temperature stage(400-550 ?),the Mn diffusion capacity increased due to the increase of temperature,and the Mn containing phase increased continuously from the matrix,and the quantity of the precipitated phase began to grow.At high temperature(550-600?),the solid solubility of the matrix increased,and theprecipitated phases mainly occurred coarsening and partial dissolution,accompanied by the decrease of the number of precipitates and the increase of the size.In the heat preservation stage,the precipitation phase is coarsened by two mechanisms of Ostwald ripening and atomic long range diffusion,and the size is increasing and the number is reduced.(2)Different homogenization treatments have different microstructure and properties,which are mainly due to the comprehensive effect of precipitation morphology,and the effect of the number density on recrystallization is greater than that on the size.With the increase of the heating rate,the yield strength of composite plate increases gradually,at200 ? /h for 71.8MPa;The yield strength of the composite plate increases first and then decreases with the increase of homogenization temperature,and the maximum yield strength of the composite plate is 64.2MPa at 600 ?;At the thermal insulation stage,the yield strength of the composite plate increases gradually,and the thermal insulation 24 h is 68 MPa.The heating rate has the greatest influence on the yield strength of the composite plate.(3)Compared with before brazing,after brazing,the skin and core materials of the composite plate interact with each other.The Si particles of the skin alloy disappear,on the one hand,change into Al-Si eutectic microstructure;on the other hand,a dense layer of precipitate zone is formed at the edge of the core alloy.BDP is an important factor affecting the corrosion resistance of composite panels.(4)During the brazing process,the core of the core material has no obvious precipitation behavior due to the prior homogenization treatment.The number density and size are almost unchanged.When the temperature exceeds 560?,the excessive temperature leads to the dissolution of fine precipitates.The core material alloy edge,the temperature from room temperature to 570?,due to the diffusion phenomenon of Si elements,in the edge of the core material to precipitate a large number of Al-Mn-Si,the number density increases and the size decreases;when the temperature exceeds 570?,influenced by the matrix solid solubility,the resolution rate of the Mn phase is greater than the precipitation rate,the quantity density decreases,and the size increases slightly.