Study On Extrusion Process Parameters And Deformation Mechanism Of AM50 Alloy Tube

The effect of extrusion ratio , pre-pressing before extrusion , heat treatment after extrusion on mechanical properties and microstructure of isothermal extruded AM50 alloy tube was studied in this paper. Numerical modeling was also used in process of extrusion deformation. The structural design of mould could be optimized according to numerical simulation results, taking a role of instructor in practical produce. The optimal mould angle to achieve least deformation force and distribution of material inner stress and strain can be pre-estimated using numerical simulation, on which the optimization of mould structure design can be based. The results of experiments show that when extrusion ratio λ=12, preferable mechanical properties can be obtained by combining effects of strain hardening and dynamic recrystallization; After T6 treatment before extrusion plus T6 after extrusion, the optimal mechanical properties was got ; It is more effective through T6 treatment before extrusion than T6 after extrusion. After treatments, mechanical properties can be improved by the β-Mg₁₇Al₁₂ phase dispersedly precipitated on grain boundary. Results of the orthogonal experiments show that the cryogenic treatment is the most remarkable factor that influence the elongation of AM50. After cryogenic treatment, finer and more equaled grains of Mg alloy can be achieved with more dispersedly precipitation of the β-Mg₁₇Al₁₂ particles on grain boundary. Consequently tensile strength was enhanced and elongation of the casts can be increased remarkably(35.5%). Properties of manufacture design can be greatly improved by combining extrusion process numerical simulations,experimentation,mechanism analysis, which can shorten the period of design and build up competitive ability of market.