Study On Hot Deformation And Ageing Precipitation Behavior Of The Spray Deposited Al-Zn-Mg-Cu Alloy

In this paper, we studied the spray forming Al-Zn-Mg-Cu alloy through isothermal compression experiment, The deformation and deformation behavior of the deposited alloy is studied systematically, The effects of deformation temperature and strain rate as well as deformation extent on the alloy flow stress were investigated mainly,the basis of it we established the constitutive equation. The deformation mechanism and the ageing characteristic of the spray formed and forged alloy were studied through SEM and OM, which offers basis for forged alloy forming parameters and theories. Subsequently,the paper analyzed the heat treatment of the extruded pipe,test the room temperpture mechanical property,and we obtain the optical heat treatment process.The compression testing results show that the curve shapes of true stress-true strain of two alloys were similar and both of them apperred work hardening and flow sofening stage of balance. It is found that the spray formed alloy exhibits an excellent deformation compared to the as-cast alloy. The stresses of two alloys decreased with the increase of temperature or the decrease of strain rate. But it caused macro-cracking with the increase of temperature and strain rate.It is found that deposited alloy exhibit excellent deformation at 420℃,0.01s^-1. The hyperbolic sine function,with the curve of true-stress-true strain steady data,which fitted for the spray formedalloy.The microstructure observation indicates that alloy deformation is mainly dynamic recovery in low temperature and dynamic recrystallization(DRX) with the increase of temperature.The DRX of the spray formed alloy occurs in deformation,which related with temperature,strain rate and deformation. the degree of DRX is increased with increasing of testing temperature and strain,decreasing of strain rate, With DEFORM software ,we studied the temperature and stress distribution, we get the final densifying process: deformation temperature 420±5℃,holding time 6h,forging rate 0.3⁰.4mm/s. The defect were disappear entirely, second phase became more homogenous, after densifying, homogeneous distribution in alloy.After extrusion aluminum alloy tube ,we studied solution and ageing treatment and got the final optimization of the alloy heat treatment process ;two-step solid solution using 470℃×1h +485℃×1h and aging temperature 120℃,14h.