Chemical and mechanical property test of gravity casting

Chemical composition of aluminum gravity casting alloy

The chemical composition of aluminum gravity casting alloy is key essential for the quality of a gravity cast product. Apparently, the main content of the aluminum gravity casting alloy is aluminum. However it is not that the higher contact of aluminum casting alloy, the higher quality of the aluminum cast product. Generally, there should be several certain elements of certain content mixed into the aluminum alloy so as to achieve casting ability and the mechanical property of the aluminum gravity cast product poured by the very mixed alloy. The alloyed other elements have their different function effecting the various features of the casting alloy. For example, the silicon can improve the fluidity of aluminum casting alloy. However when it reaches a certain content rate, the more silicon adds, the fragile the gravity cast product is. There is a setoff curve of fluidity and fragileness by increasing silicon content. Besides, the magnesium and titanium can increase the strength of the gravity cast product, however they are much more expensive than commercial aluminum like titanium, and while more titanium is added, the aluminum gravity cast product becomes extreme hard, which is difficult for post manufacturing process like machining.

As talked above, certain elements are added to improve the casting ability while achieving special mechanical property for final gravity cast product. But for commercial reason and most important engineering purpose, the content of the other alloying elements is always limited into a certain range. Then the detection of the chemical composition of the aluminum casting alloy before pouring is key essential for the success of a batch of gravity casting. Commonly, spectrometer is widely used for on spot chemical composition analysis, which is easy and swift to carry out the chemical composition of a testing specimen. Besides, simple testing solution is used to detect some certain element by dipping some drop of such solution of a mirror polished surface of the specimen. However such means is economical but not precise enough to cover other elements which are not sensitive to or don't react with the solution.

Mechanical property of aluminium gravity casting

The common mechanical property of aluminum gravity cast product applied in practice are hardness, tension and pressure. The former two property are not only affected by the chemical composition of the aluminum alloy used for the part, but also the post heat treatment for the gravity cast part. The chemical composition is the essential factor for the hardness, tension and strength For example the magnesium is the critical element for quenching. Once the alloying temperature is out of control and increases to unallowed high, the magnesium element can be turned out, then the aluminum cast products are hard to quench to certain hardness say above HRC90.

Besides, the gravity cast products can also be heat treated to improve mechanical property especially the hardness. For most aluminum cast hardware's, they should be processed by heat treatment such as T5 and T6. Certain aluminum cast products after T6 heat treatment can reach a hardness above HRC100. However the heat treated aluminum cast products will also increase its fragileness. In order to achieve the desired point at the hardness and fragileness setoff curve, certain testing equipments like hardness machine, intension testing machines should be applied for the purpose.

HH gravity casting foundry is processing aluminum alloying and heat treatment in house to guarantee the chemical composition of the aluminum gravity casting products, and gathered rich experience in heat treatment of aluminum cast products. Besides ,we introduced necessary mechanical detection machines to guarantee the high grade quality of our aluminum gravity cast products.