Researches On The Homogenization And Thermal Deformation Of ZM61

Along with the development of the research and manufacture, the magnesium alloys are used in many fields, just as vehicle, electronic products and military industry. Magnesium has hcp crystal structure and little slip system, so its plastic deformation is difficult. The main deformation of magnesium alloys is die-casting and traditional plastic processing is limitedly in magnesium. However, plastic processed magnesium alloys are highly improved in the microstructure and properties compared with die-casting products. So the development of plasticity procsseing is significant theoretical meaning and engineering value for the magnesium alloys.In this paper, ZM61 alloy studied by ourselves was chosen to investigate the homogenization and thermaldeformation. The variation of microstructure of ZM61 was discussed under different heat treatment with microscopic examination, SEM, EDS and DTA.Then we get the curve of micro hardness with temperature and time, also the parameter of heat process were carefully studied; Homogeneous level of alloy which had been treated was innovatively judged by the variance of micro hardness distribution; The regularities of distribution of alloying agent were analyzed to provide the attestation in secession by SEM. Final, the better uniformity of the process for ZM61 magnesium alloy is identified.Hot compression tests of ZM61 magnesium alloy after homogeneous annealing were performed on Gleeble-1500 at deformation temperature ranged in 300～390℃and strain rates 0.001～0.1s^-1. The results show that the stress and strain curve of ZM61 magnesium alloy has a typical feature of continuous dynamic recrystallization; first the flow stress rapidly emerged working hardening and reached a peak, then gradually softened and emerged steady-state flow when reached greater stain. The material constants of ZM61 magnesium alloy in the hot compressive deformation are calculated, Q=201.86kJ/mol;A=1.1915×1015s-1;α=0.020756mm2/N; n=4.3159, the flow stress equation was established. Meanwhile the microstructure is changed in the hot compressive deformation. The grain is refined and dynamic recrystallization is fully completed with increase of deformation. Dynamic recrystallization is accelerated with increase of temperature, but at the same time the grain is easy to grow coarse. The grain is refined with increase of the deformation rate, but dynamic recrystallization can't be fully completed when the deformation rate is too high. The average dynamical recrystallized grian is decreased with reduction of deformation temperature and increase of strain rate. The equation of d and Z is established, d =12788·Z^-2,12.Tacking the factors such as resistance of compression, microstructure evolvement etc. it is considered that the good deformation condition is temperature of 300³30℃with strain rate 0.001～0.1s^-1 and the lower strain rate is preferred...