Brief introduction of low carbon equivalent gray cast iron

Gray cast iron has low cost, low price and wide application. It has always accounted for a large proportion in the output of all cast iron castings. In the s, the total output of gray cast iron castings accounted for about half of the total output of casting metals. Until now, gray cast iron is mainly used in machine tool bed, base, leather pulley, gearbox, cover, rainbow body Hand wheel and other parts with low stress, shock absorption and wear resistance, and China is a large developing country with machinery, automobile and construction as pillar industries. Gray cast iron plays an important role in China’s development and construction. However, generally speaking, the production and application of gray cast iron in China lags behind that in developed countries, which is mainly reflected in:

1) The quality of gray cast iron castings produced is low;

2) Poor equipment, casting production process and technology;

3) High energy consumption;

4) The economic benefit of producing gray cast iron is poor.

The manufacturing process of cast iron in western developed countries is obviously more advanced than that in China. At the same time, the products manufactured are mainly high-quality gray iron castings with high added value and high-tech content. Therefore, we must strive to improve the level of producing gray iron.

According to the different forms of carbon in cast iron, cast iron can be divided into gray cast iron, hemp cast iron and white cast iron. According to different forms of graphite, cast iron can be divided into malleable cast iron, screw cast iron, nodular cast iron and gray cast iron. Gray cast iron refers to cast iron with flake graphite, which is mainly composed of iron, carbon, magnesium, sulfur, phosphorus, etc, Gray cast iron has high carbon content (therefore, it can also be regarded as the matrix of carbon steel plus flake graphite. Grey cast iron can be divided into low carbon equivalent grey cast iron and high carbon equivalent grey cast iron according to different carbon equivalent, but there is no clear division between them. High carbon equivalent grey cast iron generally refers to a kind of cast iron with carbon equivalent near its eutectic point. The increase of carbon equivalent makes this kind of cast iron Gray cast iron has better casting process performance, shrinkage porosity and shrinkage cavity are reduced, casting stress is also reduced, and has better wear reduction performance; Low carbon equivalent gray cast iron has the high strength that high carbon equivalent gray cast iron does not have. At the same time, it has good wear resistance and heat resistance. It is widely used in industrial production. However, the reduction of carbon equivalent makes the hot crack tendency, shrinkage tendency and white cast tendency of gray cast iron very serious. At the same time, the hardness of gray cast iron is high and the brittleness is large, The processing performance is very poor. Therefore, it is a very meaningful subject to maintain the carbon equivalent of gray cast iron at a low level to ensure its high strength, try to improve its comprehensive properties, and then give full play to the characteristics of low carbon equivalent gray cast iron.

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