ã€China Aluminum Industry Network】 Aluminum alloy ingots, whether they are ingots or ingots, often suffer from porosity and porosity defects in their production. Swelling and looseness, like twin sisters, often accompany each other and cause many problems for aluminum processing. A circular hole in the aluminum alloy ingot structure is called a blowhole. It is a bubble defect in which the gas precipitated during the cooling and solidification of the metal liquid remains in the ingot. Looseness is caused during the solidification process of the aluminum alloy ingot structure. Due to the aluminum alloy in the liquid state and the solidification state, the volume is not compensated for in the shrinkage to produce a dispersion hole. The main factor of pore formation: In the dissolved melt gas is saturated, there is a large amount of non-metallic inclusions in the solution, the gas floating slowly in the casting process, the bubble will stay in the ingot to produce pores. Wire Mesh Fence,Square Wire Mesh ,Welded Wire Mesh Panel Jiangrui Wire Mesh Products Co., Ltd. , http://www.hstemporaryfence.com
The cause of the pores:
1. Raw materials are moist, oily, and watery.
2. Furnace overhaul or repair. Incomplete drying after long-term shutdown.
3. The melt is overheated in the furnace.
4. The smelting time is too long.
5. The tool is completely dry at the end.
6. The quality of the lubricant is not good.
7. The gas moisture is too large.
Looseness is generally divided into two types: one is the loosening generated between the shrinkage, and the other is the loosening formed by removing the dissolved gas at the end. The main factors for the formation of porosity and the gas content of the melt are related to the size, shape, and structure of the overlying band during ingot formation.
There are several reasons for analyzing looseness:
1. The gas content in the melt is too high.
2. The melt is overheated.
3. The oven is not complete. Suspension time is too long.
4. The strength is low but the casting speed is too fast.
5 casting temperature is too low.
6. Tools and refined gases. Solvents such as wet or incomplete.
7. Funnel flow is not uniform.
8. The high magnesium alloy does not cover well.
Aluminum alloy ingot porosity and porosity is one of the more common defects, aluminum alloy melting and casting technology (process specification); are developed around the pore and loose defects. How to solve the problem of stomatal and loose defects?
Take several measures:
1. It is the delivery of solid material to liquid material (shortening the smelting time)
2. Control chemical composition impurity content (reduce non-metallic inclusions)
3. It is to strengthen refining and degassing 4. It is to change the original small ingot specifications to large ingots (to reduce the casting speed and change the oversize dimension) to avoid losses.
From the above cases, although the incident has passed for more than 30 years, it has provided invaluable data and lessons for our exploration and development of aluminum processing.
summary:
1. The use of liquid feed reduces the residence time of the metal in the furnace, allowing the gas in the furnace to be released and decomposed under the effect of unsaturation.
2. Strengthen the control of component impurities and effectively reduce the increase of non-metallic inclusions.
3. Effective degassing refining.
4. Casting temperature upper limit.
5. Decrease the casting speed Change the structure of the liquid transition zone so that the remaining gas has sufficient floating space.
6. The establishment of smelting process technology is not static. Under special circumstances, decisive use of plans to prevent product quality defects.