Study On Cold Straightening Technology And Experiment Of AZ31 Magnesium Alloy Medium And Heavy Plate

Magnesium alloy has many advantages,such as rich reserves,high specific strength,high specific stiffness,good thermal conductivity and so on.Magnesium alloy has gradually become another rapidly developing metal material in addition to traditional metal materials such as iron and steel.Magnesium alloy sheet is a high-order product of the development of magnesium alloy processing and manufacturing technology.in the production history of magnesium alloy sheet,rolling is used as the main method to prepare magnesium alloy sheet.However,the rolled magnesium alloy sheet is easy to produce bending,winding and other shape defects in cooling,shearing,transportation and various processing processes,which seriously affects the quality and later use of magnesium alloy sheet,so the sheet must be straightened.At the same time,because the magnesium alloy sheet is straightening out,The deformation of the plate is complex in the process of continuous deformation,and the edge crack of the plate is enlarged in the process of continuous deformation.It is necessary to shear the edge of the plate in the actual production,so as to greatly reduce the yield of the product and increase the production cost of the product.In view of this situation,on the basis of classical straightening theory,combined with the mechanical properties of magnesium alloy sheet,this paper reveals the straightening principle of magnesium alloy sheet.Through theoretical calculation,finite element simulation and experimental verification,The effects of different plastic deformation rates on the flatness,residual stress and edge cracks of magnesium alloy sheet during cold straightening are analyzed,and the effective reduction is obtained on the premise of ensuring the flatness after correction.After low correction,the residual stress of the plate and the optimum plastic deformation rate of reducing the edge crack are obtained,the main conclusions are as follows:(1)Under the condition that the other straightening process parameters remain unchanged,when the magnesium alloy sheet with low,medium and high plastic deformation rate is used to straighten the magnesium alloy sheet with theinitial curvature value satisfying the straightening condition,the straightening purpose can be achieved.(2)The flatness is the best when the low plastic deformation rate is used for straightening;(3)After straightening with three different plastic deformation rates,the residual stress is the coexistence of tensile stress and compressive stress,whether along the straightening direction or perpendicular to the straightening direction.The residual stress value is lower than that before straightening.(4)After straightening with low plastic deformation rate,the surface residual stress of magnesium plate is the smallest and the distribution is the most uniform.(5)The crack extension at the edge of the sheet is the smallest after the process of straightening with low plastic deformation rate,and the crack extension at the edge of magnesium alloy sheet tends to increase in the process of straightening with medium and high plastic deformation rates.