The main difference between the valve of cast iron and iron steel is the difference in carbon content. The carbon content directly affects the strength and plasticity of the steel. Carbon steel is also called carbon steel and contains carbon iron with a carbon content of less than 2%. Carbon steel generally contains a small amount of silicon, manganese, sulfur, and phosphorus in addition to carbon. Carbon steels can be classified into three types: carbon structural steels, carbon tool steels, and free-cutting structural steels. Carbon structural steel is divided into building structural steel and machine-made structural steel. According to carbon content, carbon steel can be divided into low carbon steel (WC ≤ 0.25%) and medium carbon steel (WC 0.25% - 0.6%). And high-carbon steel (WC 0.6%) can be divided into ordinary carbon steel (higher phosphorus and sulfur content), high-quality carbon steel (lower phosphorus and sulfur content), and high grade according to phosphorus and sulfur content. High-quality steel (lower phosphorus, sulfur content) The higher the carbon content in general carbon steel, the higher the hardness and the higher the strength, but the lower the plasticity.
Cast iron: Cast iron is an iron-carbon alloy with a carbon content of 2% or more
Cast iron can be divided into: 1, gray cast iron 2, white cast iron 3, malleable cast iron 4, ductile iron 5, vermicular cast iron 6, alloy cast iron
Generally speaking, we call the cast iron valve, which uses nodular cast iron and obtains gray cast iron molten iron after balling treatment. The precipitated graphite is spherical, which is referred to as ductile iron for short. Higher strength, better toughness and plasticity than ordinary grey cast iron;
Steel used to cast the casting. A kind of casting alloy. Cast steel is divided into cast carbon steel, cast low alloy steel and cast special steel 3 categories; cast carbon steel. Cast steel with carbon as the main alloying element and a small amount of other elements. Containing less than 0.2% of carbon for the casting of low-carbon steel, carbon 0.2% to 0.5% for the casting of carbon steel, carbon containing more than 0.5% for the casting of high-carbon steel. As the carbon content increases, the strength of cast carbon steel increases and the hardness increases. Foundry carbon steel has high strength, plasticity and toughness, and has a low cost. It is used in heavy machinery to manufacture parts that can withstand large loads, such as rolling mill stands, hydraulic press bases, etc.; it is used on railway vehicles to produce large forces. Impact parts such as bolsters, side frames, wheels and couplers;
From the above material characteristics, cast iron is more rigid than cast steel, brittle than cast steel, and cast steel has better ductility and toughness than cast iron, so cast iron is generally used in low pressure pipelines, At the same time can only be applied to the normal temperature of the pipe above, because the increase in pressure or temperature shows that the valve will have a slight amount of deformation, is not favorable for cast iron valves Relative to the cast iron valve Cast steel valve can be used in the pressure or temperature is relatively high In the pipeline.
The application of cast iron valves: For example, we often see the valves used to transport tap water pipes. The valves are painted with black paint on them. These valves are cast iron valves.