Effect Of Heat Treatment On Microstructure And Properties Of 7055 Aluminum Alloy

7055 aluminum alloy is a kind of 7xxx aluminum alloy,which belongs to super high strength aluminum alloy.7055 aluminum alloy has a series of characteristics such as high specific strength,small density,good weldability and good plastic deformability(processability),etc.It is widely used in the field of aerospace and navigation,and is indispensable in the aerospace industry of countries around the world.Important material.In this paper,the two-stage solid solution and two-stage aging of 7055 aluminum alloy in extruded state are studied,and the following conclusions are drawn:The test results show that the prolonged solution time within a certain range,the number of second phases in 7055 aluminum alloy shows a gradually decreasing trend,almost all the fine second phases are dissolved,the undissolved rough second phase is obviously reduced,the second level When the solution temperature is 480 ?,the low-melting phase is fully dissolved,and as the temperature increases,the solution effect no longer increases;the hardness value shows a trend of increasing first and then decreasing.In the second solution treatment,it is 480 ? ×40 min It can reach the maximum value of 185.6 HV at the time;the tensile strength and elongation both increase first and then decrease with the increase of the second solution temperature,and the change of electrical conductivity gradually decreases with the increase of temperature;tensile fracture The fracture mechanism gradually changes from mixed fracture to transgranular fracture with the increase of secondary solid solution temperature.After single-stage aging,the grains of the alloy are elongated along the extrusion direction.With the increase of aging time,the second phase precipitated in the matrix is dispersed;the hardness peaks at 8h and 24 h of aging time;with the aging time When prolonged,the strength of the alloy first increased and then decreased;when the single-stage aging was 8h,the tensile strength,yield strengthand elongation of the alloy were 627.1MPa,560.5MPa and 10.1%,respectively.With the extension of the second-stage aging,the number of particles in the second phase showed a decreasing trend.The tensile strength,elongation and yield strength all increased first and then decreased with the extension of the aging time.The tensile strength reached the peak point at 20 h.The maximum value was 15.4% at 24h;with the extension of aging time,the fracture mode transitioned from intergranular fracture to transgranular fracture mode.Through comparison,it can be concluded that the best solution heat treatment process is 450?×60min + 480?×40min,and the aging heat treatment process is 120?×8h + 160?×20h.