Rotary Piercing Technique Of AZ31B Magnesium Alloy Seamless Tube

With the increasing demand for lightweight infrastructure materials,high performance magnesium alloy pipes have broad application prospects in aerospace and fluid pipeline fields.However,due to the limitation of magnesium alloy’s own performance and the short time of rolling technology research,the rolling process of large-size magnesium alloy seamless tubes still needs to be further studied.Therefore,in this paper,the research process is the first process of seamless magnesium alloy pipe production-cross rolling piercing and the research object is AZ31 B magnesium alloy.In order to provide guidance for the further improvement of magnesium alloy seamless tube rolling technology,with the combination of hot compression test and numerical simulation,the hot deformation behavior,microstructure evolution and process parameters optimization of magnesium alloy ingot piercing process during cross rolling were studied in this paper.In this paper,the stress-strain curves obtained from thermal compression tests are compared with the microstructural evolution under the same process parameters,and the influence rules are analyzed.And then discussed the nucleation mechanism during deformation and the effect of dynamic recrystallization on grain size.At the same time,according to the curve data,the constitutive equation,flow stress prediction model and hot deformation processing diagram of AZ31 B magnesium alloy during rolling process were fitted.Thus the processing window parameters during the rolling process of magnesium alloy were obtained,and the results were used as physical parameters of AZ31 B magnesium alloy in DEFORM-3D software simulation.The piercing process of AZ31 B magnesium alloy seamless tube during cross rolling was simulated by DEFORM-3D software,and the temperature parameters of the roll and the workpiece were set respectively,then equivalent stress distribution and wall thickness stability of magnesium alloy seamless tubes after perforation were analyzed.Finally,the simulation results are verified by experiments.The results show that the axial and longitudinal structures of the magnesium alloy seamless tubes obtained at 500℃ tend to be more uniform,while the wall thickness and width are more stable,and their performances are improved.