Properties of the Casting Nonferrous Alloys

All non-ferrous alloy elements have their inherent characteristics, and all kinds of alloys have their own characteristics. Therefore, engineering technicians and operators in Sieg-Huao engaged in the production of non-ferrous die-casting parts must understand and master its characteristics, formulate appropriate smelting and casting processes, and strictly follow the process operation, so as to produce high-quality and qualified castings. Today we will talk about the properties of the casting nonferrous alloys.

1. Easy to oxidize. Some alloy elements, such as aluminum, magnesium and titanium, are active elements, which are easy to oxidize and form oxides in smelting. These oxides will enter into the casting mold, form oxide inclusions in the casting and make the castings obsolete. This should be taken into account in the preparation of smelting and casting processes for such alloys. For example, coating agent is added to reduce oxidation during smelting. Remove slag with flux before pouring; Designed to enter the casting system smoothly to prevent secondary oxidation; Set up filter screen and other measures. 

2. Easy to inhale. Non - ferrous alloys have the characteristics of inhalation during smelting, especially aluminum and copper alloy. The serious result of gas-filled casting is the rise of riser, forming a cavity in the casting and causing the casting parts to be scrapped. Needle holes may appear in minor castings. The source of gas is water and water vapor in the air. Therefore, the raw materials and tools used in the smelting process must be dry and melt rapidly in a micro-oxidation atmosphere. The degassing and refining shall be carried out before pouring, and can be cast only after the pre-furnace inspection is qualified.

3. Easy to shrink. The linear shrinkage and bulk shrinkage of nonferrous alloys are large. Therefore, the shrinkage scale is different when making the model process. Only when the foundry nozzle and the cold iron are used together can the satisfactory effect be achieved. 

4. Big thermal crack tendency. Due to the large shrinkage of non-ferrous alloys and the low thermal strength during solidification, the casting is blocked during solidification and contraction, that is, cracks are generated and the casting is scrapped. Technical measures must be taken. For example: lower casting temperature; Increase the riser; Increase or thicken the cooling iron to increase the cooling speed; Reduce core strength and increase yield. 

5. Segregation. Due to the large density difference between elements in nonferrous alloys, it is easy to produce uneven components, resulting in segregation. Therefore, it is necessary to thoroughly stir the alloy before pouring.

6. Thick grain. Aluminum alloy, magnesium alloy and zinc alloy all tend to have large grain size, so the alloy needs to undergo metamorphic treatment before pouring.