Magnesium alloy extrusion deforming processing method

Technical Field

The invention belongs to the field of extrusion deformation of the magnesium alloy, in particular relates to a magnesium alloy extrusion deforming processing method.

Background Art

Magnesium alloy has a close-packed hexagonal crystal structure, low symmetry, its axial ratio (c/a) value to 1.623, close to the ideal dense platoon value 1.633, less slippage is at room temperature, the plastic deformation is poor. In all of the magnesium alloy to in deformation mode, it is comparatively easy for the extrusion deformation, the productivity of large is easy to form, after deformation performance is also of the material is greatly increased. Plastic is wrought magnesium alloy one of the important mechanical performance index, which determine the material, parts and component of the plastic working forming property and performance. My deformed magnesium alloy material of research and development is still at the initial stage, the lack of high-performance magnesium alloy plate, rod and section, now National defense and military industry, aerospace use high performance magnesium alloy material is still dependent on imported, civilian products which have not yet carried out vigorously development. Therefore, research and development of good performance, various specifications of the wrought magnesium alloy material is very important.

At present, industrial production of the extrusion by the deformation of the magnesium alloy is extruded one-way extrusion, the magnesium alloy is usually extrusion temperature of the blank the 350-450 [...] , extrusion speed is usually 1m/min -2.5m/min, this kind of one-way extrusion mode with the extruded extrusion temperature is directly proportional to speed, the lower the extrusion temperature, the slower extrusion speed, if the extrusion temperature is reduced and the speed is slowed down, the shaping effect of the magnesium alloy will be affected, leading to the occurrence of a crack of the material, to affect the product quality. See Figure 9, now discloses the most advanced of the magnesium alloy for ECAE one-way extrusion deformation mode (  channel   angular   extrusion Equal) of equal diameter angle extrusion, this is a kind of using pure grain refinement of the shearing deformation of large plastic deformation processing method, to be extruded magnesium alloy blank 13, through the extrusion die 12 is bent into a 90 degrees with the diameter of the extrusion channel 14 is extruded, the magnesium alloy blank in a extrusion rod 11 under the pressure of the, by the unidirectional equal diameter extrusion channel one end to the other-end motion, make the magnesium alloy blank through one-way such as the diameter of the extrusion channel 90 degree corner, , subjected to shear deformation, the magnesium alloy crystal grain refinement, the extrusion is the mechanical performance of the magnesium alloy material, however, as this kind of extrusion mode is a one-way only radial channel extrusion manner, such as, extrusion ratio is 1, the extrusion temperature the 300-350 [...] , extrusion speed is 0.6-1.2m/min, each extrusion thereof after a time, the size of the magnesium alloy crystal grains half of the extent of refinement can not be achieved, the multi-pass extrusion only can be magnesium alloy crystal grain refinement to a relatively small size. If the crystal grain is 210 the magnesium alloy   m technical ECAE deformation of the extruded blank, the eight channel extrusion, the grain size of the magnesium alloy can be attained only if the 10   m the following, the method can realize the magnesium alloy crystal grain refinement to the minimal extent, however, by employing the multi-pass extrusion processing result in the production efficiency and reduce; and because the ECAE technique for extrusion speed of 0.6-1.2m/min, each of the relatively long extrusion time, likewise lead to the production efficiency and reduce, if enhancing the extrusion speed of the one-way extrusion, will decline in the quality of the product. Therefore, in the industrial production need to improve the production efficiency, it is clear that the technical ECAE.

Content of the invention

A purpose of this invention is to to the deficiency of the prior art, provides a magnesium alloy extrusion deforming processing method, which adopts the two-way radial extrusion deformation, not only can greatly improve the refining effect of the crystalline grain of magnesium alloy, the magnesium alloy material comprehensive mechanical performance is improved, but also can realize low-temperature extrusion state the extrusion speed is not reduced under, magnesium alloy extrusion deformation to improve the production efficiency of the processing.

Another purpose of this invention is to provide a magnesium alloy can be realized bi-directional radial extrusion deformation extrusion die.

The purpose of this invention is realized as follows: first of all the magnesium alloy homogenization treatment of the blank, the two-way extrusion radial flow reducing forming die, in the mould after the heating mould and evenly spread lubricant extrusion passage cavity, and then through the homogenizing treatment of the magnesium alloy blank is heated in the mould that is heated in the extrusion channel cavity, its magnesium alloy blank temperature is 230 the the [...] -450 [...] , the mold temperature high-temperature magnesium alloy blank than the 50-100 the [...][...] , the two in opposite directions through the extrusion die of the movement of, at the same time with 1.5m/min -2.5m/min extrusion speed, 2.5 MPa -5 MPa extrusion pressure, respectively from the magnesium alloy of the blank to the magnesium alloy of the two ends of the blank to the two-way constant-speed extrusion, the magnesium alloy blank is made of the central part to the mould to squeeze and channel of the radial, cross-sectional area is smaller than the sectional area of the extrusion channel extrusion deformation changes the diameter die space channel.

Another purpose of the present invention is realized as follows: the female die of the extrusion die is provided with a two-way extrusion channel, the middle section of the two-way extrusion passage are symmetrically provided with at least two radially extending channel of the cavity, the cavities and the two-way channel is vertical to the axis of the extrusion passage and oppositely, two-way extrusion the sectional area of the channel is greater than the die cavity and the sectional area of the channel; two die are respectively formed by two-way of the lower die extrusion channel inserted into the two ends of the two-way extrusion channel in opposite directions to form a clearance fit with the die cavity.

Because of using the above scheme, the two-way extrusion radial flow reducing forming the extrusion die, the two in opposite directions through the extrusion die of the movement of, respectively the two ends of the magnesium alloy of the blank from the two-way constant-speed extrusion, the middle part of the magnesium alloy blank is made the radial direction of the extrusion channel to the cavity die extrusion deformation changes the diameter die space channel. The extrusion method to make the magnesium alloy in the process of forming the metal flow when the original crude large crystal grain is elongated to become elongated streamlined organization, most of the streamline crushing phenomenon the grain region, the re-crystallization nucleation [...] area, extrude and deform only one time, it can make the processing of the magnesium alloy has extremely prominent grain refining effect. The AZ31 magnesium alloy extrusion deforming, for example, by homogenization treatment prior to extrusion the grain size is 350 the AZ31   m of magnesium alloy, only after a time of extrusion, can be grain size refinement to the 6.5  m, its grain refining effects than existing ECAE technique, refer to the following table 1:

Table 1 grain refining effects comparison table

The extrusion method is through the extrusion die of the movement of the two in opposite directions, from the magnesium alloy of the blank at the same time the two ends of the two-way constant-speed extrusion, although each of the male die of the extrusion speed is 1.5m/min -2.5m/min, but because of the male die of the movement of the two in opposite directions respectively from the two ends of the magnesium alloy blank two-way extrusion, the magnesium alloy blank extrusion time is shortened, its extrusion speed equivalent to one-way extrusion 2 times, thereby increasing magnesium alloy extrusion deformation of the production efficiency of the processing. And because the extrusion method is to make the magnesium alloy blank is made of the middle part of the radial direction of the extrusion channel to the cavity die, the extrusion channel sectional area is smaller than the sectional area of the channel extrusion deformation changes the diameter die space , in the process of extruding the metal in the process of flowing the internal organizations and certain directivity of small grain size, the grain is elongated or even break, increases the recrystallizaiton shape nucleus rate , refining the grain, even when the extrusion temperature is lower than 300 the under the state of [...] , its extrusion speed is not reduced, in order to still 1.5m/min -2.5m/min extrusion speed of extrusion, magnesium alloy is completely dynamic re-crystallization, through this kind of dynamic re-crystallization process, the organization of the magnesium alloy is thinner, the average diameter of crystal grains is greatly reduced (as shown in Figure 4, Figure 5, Figure 6 and Figure 7 shown).

At the same time, but also because the extrusion method can realize low-temperature extrusion molding industrial production, in improving the efficiency of the industrial production, extrusion of the magnesium alloy material has high tensile strength, high yield strength, the mechanical property of the good-extensibility, can be used for the metal material of high field of the mechanical property requirements, such as aerospace, military and other fields. According to the National standard GB228-2002 standard, the AZ31 magnesium alloy by extrusion after the extrusion method of the present invention the extrusion and the use of traditional extrusion method extrusion extrusion, is processed into a standard tensile tensile test sample, can be seen through the contrast to adopt this invention the AZ31 extrusion extrusion method for comprehensive mechanical performance of the round bar is superior to the traditional AZ31 of extrusion extrusion method for comprehensive mechanical performance of the round bar, refer to the following table 2, 3:

Table 2 AZ31 the extruding method of the present invention the mechanical property of the rod

Table 3 traditional extrusion method is the AZ31 rod mechanical performance

The embodiment of Figure and with the further description of this invention. Should be understood that, these embodiment is used for explaining the invention, and is not limiting of the present invention, in this invention the idea of this invention is on the premise that the simple modification of the extrusion method, all belong to the scope of the invention claimed.