Aluminum Casting Defects and Analysis
Aluminum Casting Defects and analysis of defects in oxide slag characteristics: distribution
of oxide slag over the upper surface in Aluminum Casting, casting no ventilation in the corner position.
A. fracture often isolated and off-white or yellow, or by x-ray and found in mechanical processing, but also in the alkaline cleaning, pickling, or anodized found
Reason: 1. Charging dirty, back to the use of excessive charging 2. Gating system of the poor design 3. Alloy fluid slag is not cleaned 4. Gating improper operation, into the slag 5. Refining standing after modification lack of time
Prevention: 1. Charge shall be subject to blowing sand, back to the appropriate use of lower furnace 2. Gating system design to improve and enhance their ability to block Java 3. Adopt appropriate flux to the slag 4. Gating time should be smooth and should to slag 5 . refined pouring liquid alloy should be standing before a certain time
B. Stomatal characteristics of bubble defects: three casting wall pores were round or oval, with smooth surface oxide is generally bright, and sometimes the oil was yellow.
Surface pores, bubbles can be found through the sand, the internal pore through X-ray bubbles or bubble machining holes found in the X-ray film on black
Reason: 1. Pouring alloy is not stable, involved in gas 2. Type (core) sand mixed with organic matter (such as litter, grass-roots horse manure, etc.) 3. Mold and sand core poor ventilation 4. Cold iron surface shrinkage 5. the poor design of gating system
Prevention: 1. The right to master casting speed, avoid getting involved in gas. 2. Type (core) sand shall not be mixed with organic impurities to form the material to reduce gas evolution 3. To improve the (core) sand of the exhaust capacity of 4. Correct use and handling of cold iron 5. Improve the of gating system
C. Characteristics of shrinkage defects: Aluminum Casting shrinkage generally produce flying near the riser, including the roots of Heavy Runner site, the wall thickness of switching offices and a large flat thin-walled office.
Cast when the fracture is gray, light yellow to pale yellow after heat treatment or dark gray on the x-ray film showed a filament was cloudy serious shrinkage by X-ray, fluorescent and other low-fold inspection method to find the
Metal Halide LampReason: 1. Riser feeding effect and poor in 2. Charge too much gas content 3. In the vicinity of hot runner 4. Sand too much water, not dry sand core 5. Alloy coarse grains 6. Castings in the mold poorly located 7. pouring temperature is too high, pouring too fast
Prevention: 1. Pouring molten metal from the riser to improve the riser design 2. Furnace should be clean and free from corrosion 3. Riser casting shrinkage office setting, placing the cold iron cold iron or combined with the riser 4. Control of sand moisture , and the sand core drying 5. to take measures to refine grain products 6. to improve the position of the casting in the mold pouring temperature and casting speed reduced
D. Crack defect characteristics: 1. Foundry crack. Development the grain boundaries, often accompanied by segregation, is a high temperature in the formation of shrinkage cracks in the volume and shape of large alloy castings prone to more complex 2. Heat cracks: As the burning or overheating caused by excessive heat, often was transgranular crack. Often produces stress and thermal expansion coefficient of the larger alloy Zhang cooling-off drama.
Reasons: 1. Castings unreasonable structural design, there are sharp corners, wall thickness changes over the poor 2. Sand mold (core) yield of bad 3. Cast local overheating 4. Pouring temperature is too high 5. Removed from the mold casting early 6. heat hot or burning, excessive cooling rate
Prevention: 1. Improved casting structural design, to avoid sharp corners, seek uniform thickness, smooth transition 2. To increase the sand mold (core) measures concession of 3. Ensure that all parts of casting solidification or solidification at the same time, improving the design of gating system 4. appropriate to reduce the pouring temperature 5. control the type mold cooling time. 6. Castings by thermal deformation correction method. 7. Properly controlling the
Grinding machine temperature, the lower quenching rate
Aluminum Casting Defects and Analysis
By: zll10417
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