Magnesium alloy squeeze casting forming technology is an advanced technology, is an ideal near net forming technology, especially suitable for the production of high-end precision parts, has great practical value and application potential in the fields of automobile, motorcycle, aerospace and so on. Extrusion casting can be abbreviated as extrusion casting. Its performance is close to that of forging, but its cost performance is much higher than that of forging. Therefore, this process has partially replaced the conventionaland die-casting process for industrial production of aluminum alloy, magnesium alloy and its composite parts.
The mold temperature of magnesium alloy squeeze casting is 200 ℃ ~ 300 ℃, the filling pressure is 50N / mm2 ~ 150n / mm2, the mold coating is graphite, and the melt pouring temperature is 30 ℃ ~ 140 ℃. If the extrusion pressure is high, the die wall thickness should be increased to bear the applied force.
The mechanical properties of AZ91 parts produced by different processes are shown in Figure 1, and the quality indexes of magnesium alloy parts produced by different casting methods are shown in Table 1. It can be seen from the listed properties that the squeeze casting magnesium alloy parts have the best mechanical properties, especially plasticity. The surface of magnesium alloy extruded parts is much better than that of die casting, and there are almost no casting defects, even if there are, it is much lighter than that of die casting.
Some magnesium alloys with poor casting properties can be formed by squeeze casting, which has important practical significance. In addition, the melting point and solid solubility of alloy elements of magnesium alloy will change under pressure. Therefore, htm1 magnesium alloy developed by high tech metals R & D Ltd. in the UK has good properties, and has good creep resistance and mechanical properties at 180 ℃ (Figure 2).
Magnesium alloy squeeze casting technology has many advantages. It has made some progress in substituting magnesium for aluminum, plastic and steel, but the total amount of substitution is still very small. One of the reasons is that the raw materials used are not easy to obtain, the technology is monopolized by foreign countries, the equipment is complex, and the production cost is high. Only AZ91D, AM50A and AM60B magnesium alloy can be used in squeeze casting. Although China is the world’s largest producer of raw magnesium with a production capacity of more than 820kt / A, the squeeze casting of magnesium alloy parts has not yet started, so it is urgent to strengthen the research and development of the technical materials and equipment to promote the development of magnesium alloy industry.