What Is the Difference between Cast Iron Valves and Cast Steel Valves?

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The main difference between cast iron and iron steel valves is the different carbon content, which directly affects the strength and plasticity of the steel. Carbon steel, also called carbon steel, is an iron-carbon alloy with a carbon content of less than 2% WC. In addition to carbon, carbon steel generally contains a small amount of silicon, manganese, sulfur, and phosphorus. Carbon steel can be divided into three types: carbon structural steel, carbon tool steel, and free-cutting structural steel. Carbon structural steel is divided into two types: architectural structural steel and machine-made structural steel. According to the carbon content, carbon steel can be divided into low carbon steel (WC ≤ 0.25%), medium carbon steel (WC0.25%-0.6%) And high carbon steel (WC>0.6%) According to phosphorus and sulfur content, carbon steel can be divided into ordinary carbon steel (containing phosphorus and sulfur), high-quality carbon steel (containing phosphorus and sulfur). Advanced high-quality steel (lower phosphorus and sulfur) Generally, the higher the carbon content of 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 containing more than 2% carbon

Cast iron can be divided into 1, gray cast iron 2, white cast iron 3, malleable cast iron 4, nodular cast iron 5, vermicular cast iron 6, alloy cast iron.

Generally speaking, the cast iron valve we use is nodular cast iron, which is obtained by spheroidizing the molten iron of gray cast iron. The precipitated graphite is spherical, referred to as ductile iron. It has higher strength, better toughness, and plasticity than ordinary gray cast iron;

Cast Steel Globe Valve

Cast steel: steel used for casting castings. A type of casting alloy.

Cast steel is divided into 3 types: cast carbon steel, cast low alloy steel and cast special steel; cast carbon steel. Cast steel with carbon as the main alloy element and a small number of other elements. Casting low carbon steel with carbon content less than 0.2%, casting medium carbon steel with carbon content 0.2% to 0.5%, casting high carbon steel with a carbon content greater than 0.5%. As the carbon content increases, the strength of the cast carbon steel increases, and the hardness increases. Cast carbon steel has high strength, plasticity and toughness, and low cost. It is used in heavy machinery to manufacture parts that bear large loads, such as rolling mill racks and hydraulic press bases. It is used to manufacture heavy stress on railway vehicles. Parts subject to impact such as bolsters, side frames, wheels, and couplers, etc.;

From the above material characteristics, cast iron is stronger than cast steel, and its brittleness is also greater than cast steel, and cast steel globe valve has better plasticity and toughness than cast iron, so cast iron is generally used In the pipeline with lower pressure, it can only be applied to the pipeline at normal temperature, because the increase in pressure or temperature means that the valve will have a certain amount of deformation, which is unfavorable for the cast iron valve, compared with the cast steel valve cast steel The valve can be used in pipelines with relatively high pressure or temperature.

The application of cast iron valves: For example, we often see valves used to transport tap water pipes. The valves are sprayed with black paint on the surface. These valves are cast iron valves.