Research Process 7B50 Aluminum Solid Solution With High Saturation

The solution behavior of7B50aluminum alloy has been investigated by means of mechanical property test, microstructure analysis and dynamic resistance analysis and the optimum single and progressive solution process has been established. The CCT curve which conducting quenching process has been measured by dynamic resistance analysis. Follow results can be involved:(1) The re-dissolution of the precipitate promoted with the increasing of solution temperature. The precipitation dissolved completely when the temperature reached480℃; Increasing temperature has no effect on improving oversaturation degree of the alloy when the temperature is above480℃, and the alloy overburned and recrystallization degree improved significantly. When solution time is under1h, the solution degree could be promoted with the increasing of solution time. When solution time is above1h, the solution degree keep constant while recrystallization degree improved evidently. The best single-stage solution treatment is480℃/1h. The tensile strength of the alloy reached604MPa and the elongation reached10.4%.(3)Investigated two-stage solution process including low temperature long time and high temperature short time, which decreasing the recrystallization degree and increasing mechanical property. The tensile strength reached614MPa while elongation reached11.3%after470℃/1h+485/15min solution treatment.(4)CCT curves of7B50show that the initial and end temperature of phase transformation decreased when cooling rate increased. and it mainly happened in the temperature range of238-462℃. The critical cooling rate which restrain phase transition between from7.16℃/s to10.4℃/s. CCT curves can conclude that water quench at room temperature should be taken and the transfer time must be less than30s. When reducing hardening stress is needed, room temperature water quenching should be taken after60℃water quenching for20s。...