Research On Semi-solid Joining And Forming Of Aluminum Alloy And Aluminum Composite

To make it come true that the semi-solid joining between the semisolidthixotropic alloy] and the semisolid rheological aluminum matrix compositesreinforced with particles with loads under some certain temperature conditions toget semi-solid joint with excellent connection performance and to get semisolidjoining and forming parts with semi-solid die forging forming process are maingoals of this research.The experiment material is7075aluminum alloy. With the strain induced meltactivation process, the thixotropic alloy can be produced. By analyzing themicrostructure of7075thixotropic aluminum alloy that produced under thecondition of different heat treatment temperature and different holding time, it isdetermined that better semi-solid organization can be obtained in the conditions thatthe heat treatment temperature is600℃with holding time of45minutes and thatthe heat treatment temperature is615℃with holding time of15minutes.By the mechanical stirring,7075aluminum alloy and SiC particles are used asmatrix material and reinforced material to obtain the rheological slurry of aluminummatrix composites reinforced with particles. By observing metallographicmicrostructure and analyzing the distribution of the reinforcing particles incomposite materials under the conditions of different mixing temperature and time,it is determined that the available rheological composite material can be prepared inthe process that mixing temperature is620℃with the stirring time is10-15minutes.According to the experiment request, the best process parameters aredetermined that preparing for semi-solid aluminum alloy and semi-solid aluminummatrix composites. Under the protection with argon gas, the thixotropic aluminumalloy is produced by the strain induced melt activation process; the rheologicalslurry of aluminum matrix composite material by mechanical stirring. While putingthe prepared thixotropic into the casting mold, pouring the rheological slurry upon it,and under the rapid loading, semisolid connection is completed and semisolid jointparts are obtained. By changing the connection process parameters, more joints canbe produced. Analyzing the connection performance of joint parts by shear tests, it isachieved that the average shear strength of semisolid joint parts can be up to200MPa. By observing metallographic microstructure and comparing with mechanicalproperty tests, it is explored what is the formation mechanism of semi-solidconnection interface.It is respectively produced that are die forging forming tests with the thixotropic aluminum alloy, the rheological aluminum matrix composite materialand the semisolid connection parts. By analyzing the mechanics properties offorming parts, it is proved that the semisolid joints have better comprehensiveproperties.