Study On Hot Extrusion Forming Process Of Magnesium Alloy Conical Shell

Under the current situation,competition among countries has led to rapid development in the aerospace filed and it has become the highlight for countries.And whether it has the ability to move freely into space is the key criterion for measuring international competitiveness.With the gradual upgrading of China's world status,improving aerospace technology level has vital significance to our country.High-performance missiles,rockets and other weapons and equipment is applied to open up China's space region,which is an important bearing parts,it is necessary to carry out research on it.At present,the material of these typical products is mainly aluminum alloy,in order to further lightweight,we choose magnesium alloy instead of aluminum alloy,and it is also fit in with the current trend of lightweight.In the past,the processing methods mainly used the traditional methods were casting,machining and plastic forming process which was based on spinning,but the processing methods have their limitations,the product reliability is low,and the mechanical properties and the quality of the ribs are also difficult to meet the requirements.First of all,this paper starts with choosing the materials,the extruded ZK61M magnesium alloy with excellent mechanical properties was selected,in order to study the hot deformation behavior of the extruded ZK61M magnesium alloy,the hot compression experiment was carried out by using Gleeble-3800 thermal simulator under the condition that the temperature was 300?450? and the strain rate was 0.001?0.5 s-1.The influence of deformation temperature and strain rate on flow stress is analyzed,and the deformation activation energy of cast magnesium alloy and extruded magnesium alloy is studied and compared,and the acuuracy of the constitutive equation is verified by simulation.The results show that the flow stress of the alloy is negatively correlated with the deformation temperature,positively correlated with the strain rate,and the stress-strain curve has the characteristics of dynamic recovery and recrystallization.It is also found that,the same processing state of magnesium alloy materials,if the composition is similar,the deformationactivation of the material can be basically similar,such as extruded ZK61M,magnesium alloy similar to its composition is basically around 120 KJ·mol-1.The deformation activation energy Q=122.685 KJ·mol-1 and Stress index n=4.13652 of extrusion ZK61M magnesium alloy are calculated by Arrhenius constitutive equation,which provides theoretical guidance for the hot processing parameters and preparation o Mg-Zn-Zr extruded magnesium alloys.Then,a new process of composite extrusion-punching-necking is proposed,in order to obtain reliable process parameters,the whole process of the process is simulated by numerical simulation,the influence of deformation temperature and extrusion speed on the forming results is studied emphatically,and the parameters are optimized by 9 groups of virtual orthogonal experiments,taking the forming load and deformation uniformity as the evaluation indexes.The primary and secondary factors affecting the forming results are judged,and the best combination of process parameters is obtained.Finally,the necking results of magnesium alloy materials under different wall thicknesses are studied and analyzed by simulation software,and under the guidance of the reasonable process scheme,the shrinkage parts of the forging product of magnesium alloy cone shell is verified according to the existing conditions,the samples in accordance with the shape and wall thickness of the forging product is tested,and it is satisfied with the prediction of the simulation,which provides a new idea for the lightweight quantification of magnesium alloy conical shell.