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Magnesium alloy extrusion are in thermal state, extrusion method has a positive extrusion method, also can use reverse extrusion method, but the vast majority of extrusion magnesium material is about more than 90% of the magnesium alloy extrusions with forward extrusion process. Magnesium alloy pipe, bar, shape, line of production available single acting extruder, can also be used double action extrusion press, useful horizontal extruder, useful also vertical extrusion machine, can by forward extrusion machine, also can use reverse extrusion machine. In general, the extruding machine used for extruding aluminum can be used for extruding magnesium material, but the billet heating furnace can not be directly used as a general purpose, so as to prevent the burning of magnesium ingot. The extrusion parameters of aluminum and magnesium alloys are also very different.

Positive extrusion is product flow direction and axial compression mobile aspects consistent process (see photo), squeeze the heated billet is pushed into the extrusion cylinder, extrusion axis in the main piston under the action of force extrusion cylinder of magnesium alloy outflow hole die, and ingot with extrusion process and slow moving forward and billet surface and extrusion intense friction to the inner wall of the cylinder liner.

The advantages of forward extrusion are many, flexible, and can produce all kinds of extrusion products, equipment structure, tooling and equipment and production operation is more simple than other extrusion method. However, the main disadvantage is in the extrusion in the process of billet during extrusion cylinder to move and generate great friction, the l flow uneven because of, geometric wastes and under extrusion conditions are the same, forward extrusion method of extrusion pressure than anti extrusion of 30% to 40%. Magnesium and magnesium alloy during extrusion easy and tool and die bonding, friction condition than that of aluminum and aluminum alloy worse; magnesium alloy ingot heating, temperature is not easy to be uniform, so during extrusion, only in make sure the temperature uniform and sufficient lubrication conditions, in order to obtain uniform flow.

Magnesium and magnesium alloy extrusion temperature of 300 DEG C to 450 DEG C, according to alloy composition, shape of the article to determine specific extrusion temperature and extrusion ratio 10: 1-100: 1. If the pre extrusion billet, extrusion ratio larger. Magnesium alloy welding performance is far better than aluminum alloy. Therefore, pipe production in addition to the individual situation, should adopt the extrusion punch pins or hollow ingot, commonly used magnesium alloy extrusion process parameters are shown in Table 1.

Magnesium alloy extrusion speed is not fast, for example, AZ31 alloy extrusion speed should not be more than 6063 aluminum alloy 1/3. For the same alloy, the extrusion speed of the hollow section bar can be 1 /3~1/5 for the solid shape. After uniform treatment, the extrusion pressure can be significantly decreased, with a diameter of 98mm, long 150mm billet extrusion Mg-3%Al alloy diameter 44mm, wall thickness of 1.5mm tube, the effect of uniform annealing on extrusion pressure is shown in table 2.

Commonly used magnesium alloy extrusion conditions see (Table 1), the shape of the extruded product is shown on the right side of the table, using 12.5MN single forward extrusion machine, ingot billet diameter 152.4mm.

Of magnesium alloy extrusion speed and temperature should be strictly controlled, temperature if more than the solidus temperature will produce hot crack, surface of a serious decline in the quality, speed more than once limit value, will produce large amounts of heat, the temperature rise. The relationship between the mechanical properties of the magnesium alloy round bar and the die temperature (Table 2), the temperature is too high, the strength of the performance of the overall decline. Magnesium alloy extrusion, available oil with flake graphite mixture lubrication and lubrication can reduce extrusion pressure, but may be contaminated products in the surface, and even lead to cracks and bubbles.

Magnesium alloy can only in the air resistance furnace heating, the peak temperature in the magnesium alloy for 470 DEG C, magnesium alloy extrusion maximum speed up to 20m / min, but about one fourth of the aluminum alloy, straightening magnesium material need heated to 150 DEG C to 250 DEG C. Typical of magnesium alloy extrusion process: ingot heating, the first extrusion, cutting intermediate billet, heating, the second extrusion, artificial aging, tensile straightening, cut head and tail and specimen, and type of car straight, manual straightening, inspection and cut finished and print, oxidation colouring, finished inspection, packaging, warehousing. The relationship between the mechanical properties of the magnesium alloy round bar and the die temperature (Table 2).

The ingot is by semi continuous casting, usually after homogenization treatment, can reduce the pressure of 20%~25%. Uniform system is generally 350 degrees x 12h. Ingot before extrusion to wagon and boring, to ensure the uniformity of wall thickness of the product, small size and special requirements of the product can be extrusion billet.

The sawing of magnesium and magnesium alloy, should be equipped with good dust suction equipment, should clean up the sawdust class. Heating furnace resistance should be placed in the refractory brick tank, the workshop should have fire extinguishers and D level fire extinguishing equipment.