Low-cost high-plasticity wrought magnesium alloy and its preparation method

Abstract

The invention belongs to magnesium alloy design field, and relates to a low-cost high-plasticity wrought magnesium alloy. The magnesium alloy is made from the raw materials with components as follows: between 0.10% and 1.00% by mass of tin, between 0.10% and 3.00% by mass of aluminum, between 0.10% and 1.00% by mass of manganese, and commercially pure magnesium and inevitable impurities in balance. The magnesium alloy is prepared by the steps of: melting magnesium and aluminum, adding tin and then adding microalloyed element manganese, stirring, refining, casting to form ingots followed by homogenized heat treatment, and extruding to obtain a corresponding profile; or directly extruding to obtain a corresponding profile without homogenization. The invention is characterized by controlling the content of the high-cost raw material tin through using the raw material aluminum that is low in cost and low in melting point to obtain a low-cost high-plasticity wrought magnesium alloy.

What we claimed is: 
     
         1 . A low-cost high-plasticity wrought magnesium alloy, characterized in that it is made from raw materials with components as follows: between 0.10% and 1.00% by mass of tin, between 0.10% and 3.00% by mass of aluminum, between 0.10% and 1.00% by mass of manganese, and commercially pure magnesium and inevitable impurities in balance, wherein the commercially pure magnesium, aluminum and tin all have a purity of 99.00% or more; and manganese is added in the form of 4.00% magnesium-manganese intermediate alloy. 
     
     
         2 . The low-cost high-plasticity wrought magnesium alloy according to  claim 1 , characterized in that the aluminum is in an amount of 1.00% by mass, the tin is in an amount of 1.00% by mass, and the manganese is in an amount of 0.30% by mass. 
     
     
         3 . A method of preparing the low-cost high-plasticity wrought magnesium alloy according to  claim 1 , comprising the steps of:
 (1) smelting ingots: weighing out raw materials according to the components in  claim 1 , smelting the commercially pure magnesium and the commercially pure aluminum at a temperature between 720° C. and 740° C. under protection of a protective gas, increasing the temperature to 740° C. after all components are molten, adding commercially pure tin that has been preheated to 150° C. and magnesium-manganese intermediate alloy that has been preheated to 300° C. to 400° C. after the temperature is stable, adding a refining agent and fully stirring for 3 min to 6 min, allowing the melt to stand at 720° C. for 10 min to 20 min, removing the dross on the surface, and casting at a temperature of 660° C. to an iron mold that has been preheated to 250-350° C. to give ingots; and   (2) extruding: preheating the magnesium ingots at 250° C. to 350° C. for 2 h after skin layer removing, coating a magnesium alloy lubricant, extruding at 250° C. to 350° C. with an extrusion ratio of 20:1 to 80:1 at an extrusion speed of 0.50 to 3.00 m/min.   
     
     
         4 . The method of preparing a low-cost high-plasticity wrought magnesium alloy according to  claim 3 , characterized in that the aluminum is in an amount of 1.00% by mass, the tin is in an amount of 1.00% by mass, and the manganese is in an amount of 0.30% by mass in the raw materials. 
     
     
         5 . The method of preparing a low-cost high-plasticity wrought magnesium alloy according to  claim 3 , characterized in that the extruding temperature in step (2) is controlled at 300° C. 
     
     
         6 . The method of preparing a low-cost high-plasticity wrought magnesium alloy according to  claim 3 , characterized in that following step (1), homogenization is performed before extruding, wherein the homogenization is performed by covering the magnesium ingots obtained from step (1) with graphite, homogenizing at 410° C. to 500° C. for 24 h, and subsequently water quenching to obtain homogenized magnesium ingots. 
     
     
         7 . The method of preparing a low-cost high-plasticity wrought magnesium alloy according to  claim 3 , characterized in that the protective gas is carbon dioxide supplemented with 0.5% to 1.5% of sulfur hexafluoride. 
     
     
         8 . The method of preparing a low-cost high-plasticity wrought magnesium alloy according to  claim 3 , characterized in that the refining agent is hexachloroethane