Common defects of LFC castings

LFC castings,Carbon steel castings,iron castings

LFC casting quality than traditional sand casting surface finish, dimensional accuracy and internal quality, no coarse sand casting generally often occur, up boxes, boxes and partial dislocation core and other defects. However, due to process characteristics of EPC itself, cause the appearance of foam in the vaporized decomposition products accompanied by the diffusion of metal from the liquid crystal is injected into the solidification, the cooling process, the casting defects These casting defects Quality has a very significant impact.

Throughout the EPC process in the process, including white mold forming and pouring the entire process, resulting in a series of physical and chemical changes, could cause defects in these changes, the reaction process, for casting defects, the paper discusses on the factors play a key role in these defects and countermeasures.

1 Carbon steel castings defects disappear by carbon steel casting is the most common form of defect, defect carbon decomposition characteristics and appearance of its manifestations thermal decomposition products concerned, including the surface by carbon castings, castings increase the volume of carbon, carbon and increase local casting casting surface decarburization.

Carbon steel castings increased hydrogen seriously affect the mechanical properties of castings, such as the reduction of area, elongation decreased, poor ductility and toughness; hardness increased gradually increasing carbon surface, to the subsequent machining difficult, and to cast welding performance.

Measures to prevent the growth of carbon defects: ① try to look for the appropriate choice of materials. ② coating to maximize breathability. ③ minimize the appearance of the materials used. ④ increase degree of vacuum casting.

2 cast iron for iron castings wrinkled surface, the surface wrinkled skin is the most common defects. The following measures to eliminate such defects. ① Select the appropriate casting foam. ② improve pouring temperature and casting speed. ③ improve the pumping capacity and vacuum. ④ Select the appropriate gating system in accordance with the foam-type gasification characteristics. ⑤ improve the permeability of the mold.

3 LFC cast iron black carbon black cast iron deficiencies are the most common form of defect, the performance of the cast iron side or top (sometimes including the cross-section) appears black inclusions defects. Waste carbon defects accounted for the largest proportion in the cast is particularly prominent. Measures to prevent the carbon black and prevent surface defects similar to the method wrinkled, requires the use of a lower density material pattern, pouring temperature higher and higher permeability of the coating.