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The State Of Stainless Steel Casting Parts After Processing
Stainless Steel Casting Parts, is a variety of stainless steel production of steel products in general, mainly used for a variety of media corrosion conditions. Stainless steel casting material is 304, which is 1Cr19Ni9Ti, the general microstructure is austenitic, machined castings will appear on the surface of small black spots and lead to scrap in batches, according to the black spots of the form we divided the black spots into two Class, one is irregular black spots, the other is close to the circular rules of the rules of the black spots, such black spots are more particularly visible after polishing, welding almost impossible.
The following specific analysis of the causes of black spots, whether irregular black spots or rules black spots defects, are traces of oxygen elements, other components, including carbon, manganese, silicon, chromium and so on. Carbon sources are few, the added stainless steel raw materials and alloys without carbon, the only possible may be due to dewaxing is not clean, wax high temperature carbonization adhere to the shell, after pouring and oxygen, silicon and other elements combine to form a complex Carbide or multiple oxide inclusions. Production practice, irregular black spots occurred near the riser near, this is because the oxidation of small particles of small particles easy to float. This part of the black point of the solution can certainly be perfect dewaxing process is not conducive to dewaxing castings can be set dewaxing hole, in addition to ensure that the temperature and pressure of dewaxing in strict accordance with the implementation of the process file, should be able to successfully resolved.
Another part of the cause of the black spots can be judged as follows: first, deoxygenation failure or the effect is not complete, a large number of free oxygen and manganese manganese in the molten steel (possibly from the ferroalloy may also come from lining or slag) Other elements such as chromium and other complex formation of complex oxide slag, because the circular surface should be said that the spherical surface energy is minimal, so the formation of a large number of spherical oxide particles, due to the impact of time or molten steel viscosity has to float to the surface, The molten steel containing the spherical oxide slag is solidified into a casting to form a black dot defect.
The biggest advantage of stainless steel casting parts is that the die-casting has a high dimensional accuracy and surface finish, so it can reduce the machining work, only in the parts require a higher part of the remaining margin can be a little processing, and even some cast only Polished, polished margin, no mechanical processing can be used.