Short Proess Preparation Technology And Micostructure And Properties Of High Performance Magnesium Alloy Sheet

Mg alloy with high specific strength,specific stiffness,excellent vibration resistance,and other advantages has great application prospect in transportation and electronic domain.However,traditional commercial Mg alloy sheet producing process is very complex,high cost and poor plasticity at room temperature.Therefore,it is necessary to develop a short process for high proformance Mg alloy sheet to lower its cost and extend its application field.In this paper,ZK60 Mg alloy and AZ31 Mg alloy of the wrought magnesium alloys are studied by electromagnetic stirring-solution treatment-extrusion-hot rolling to produce thin sheet to determine the whole short process of high proformance Mg alloy thin sheet.Firstly,Mg alloy ingot was product by using electromagnetic casting to study the influence of electromagnetic stirring paramenters on properties of Mg alloy.It was found that the effect of grain refinement becomes more obvious when the current of electromagnetic stirring increases.When the electromagnetic stirring parameter was 6Hz-150 A,the tensile strength of ZK60 magnesium alloy was 204 MPa,the elongation is 8.2% and the hardness was66.8HBW,meanwhile the tensile strength and elongation of the AZ31 magnesium alloy were192 MPa and 10.9%.Secondly,solid solution treatment was employed for ZK60 and AZ31 Mg alloy.Solid solution treatment after electromagnetic stirring,the content of the second phase increased in the matrix after solid solution treatment.However,when the solution temperature was over high,the trend of grain growing becomes obviously.The best solution processing parameter for ZK60 magnesium alloy was 400°C×10h,and the electromagnetic stirring parameter was6Hz-150 A,meanwhile the tensile strength was 226 MPa,the elongation was 9.2% and the hardness was 70.2HBW.It was found that the most important factor affecting the alloy mechanical properties was the solution temperature according to orthogonal test.The optimum solution temperature of AZ31 magnesium alloy was 410°C,and the electromagnetic stirring parameter was 6Hz-150 A.Under such conditions,the tensile strength,elongation can reach219 MPa,14.5%,respectively.Two kinds of Mg alloy ingots were carried out pipe shape extruding experiments after solid solution treatment,and then microstructure and properties of extruded pipe were analysized,in which it was found that grain was refined and dynamic recrystallization appears.After aging treatment(170°C×10h)for ZK60 magnesium,the second phase precipitated,and the tensile strength,the elongation,the hardness were 307 MPa,10.5%,78.9HBW,respectively.With the increase of the solid solution time,the mechanical properties of the as-extruded AZ31 magnesium alloy tend to decrease.But when the solid solution time was 10 h,the grain growed up,and the optimum process parameter was 400?×6h,at this time,the tensile strength was273 MPa and the elongation was 26.3%.Finally,both kinds of Mg alloy pipes were spreaded and rolled to obtain thin Mg alloy sheets.The dynamic recrystallization occurred during the hot rolling process,and twins can be observed inside the grains.With increasing the rolling temperature,the grain gradually growed up while the mechanical properties of the castings decrease.When the rolling temperature was300°C,the mechanical properties of ZK60 magnesium alloy reached the maximum value,which the tensile strength was 370 MPa,the elongation was 14.1%,and the hardness was108.3HBW.When the rolling temperature was 400°C,the tensile strength of AZ31 magnesium alloy was 286 MPa,and the elongation was 27.2%.