What is the difference between cast iron valves and cast steel valves?

The main difference between cast iron and iron steel valves is the different carbon content, carbon content directly affects the strength and plasticity of steel. Carbon steel, also known as carbon steel, carbon content WC less than 2% of the iron-carbon alloy. Carbon steel in addition to carbon generally also contains a small amount of silicon, manganese, sulfur, phosphorus According to the use of carbon steel can be divided into carbon structural steel, carbon tool steel and free cutting structural steel three categories. Carbon structural steel is divided into building structural steel and machine structural steel two kinds of carbon content 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 the phosphorus, sulphur content of carbon steel can be divided into ordinary carbon steel (phosphorus, sulphur, higher), Carbon steel (containing phosphorus, sulfur lower) and steel (containing phosphorus, sulfur lower) General carbon steel in the higher carbon content is the higher the hardness, strength is also higher, but lower plasticity.

Cast Iron

Cast iron is an iron-carbon alloy containing more than 2% carbon.

Cast iron can be divided into

1, grey cast iron 2, white cast iron 3, malleable cast iron 4, ductile iron 5, creep cast iron 6, alloy cast iron

Generally what we call cast iron valves, with ductile cast iron, grey cast iron iron by spheroidal treatment to obtain, precipitation of graphite is spherical, referred to as ductile iron. Than ordinary grey cast iron has higher strength, better toughness and plasticity;

Cast steel

Steel used for pouring castings. 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. Carbon as the main alloying element and contains a small amount of other elements of cast steel. Carbon less than 0.2% for casting low carbon steel, carbon 0.2% to 0.5% for casting medium carbon steel, carbon greater than 0.5% for casting high carbon steel. With the increase of carbon content, cast carbon steel strength increases, hardness increases. Cast carbon steel has high strength, plasticity and toughness, low cost, in heavy machinery used in the manufacture of parts to withstand large loads, such as steel mill stand, hydraulic press base, etc.; in railway vehicles used in the manufacture of large force and impact parts such as rocking pillows, side racks, wheels and hooks and so on;

From the above material characteristics, cast iron is more rigid than cast steel, brittle than cast steel, cast steel and cast iron has better plasticity and toughness, so cast iron is generally used in the lower pressure pipeline, but also can only be applied to the pipeline at room temperature above, because of the pressure or temperature increases on the instructions of the valves will have a certain amount of deformation of cast iron valves is unfavourable compared to the cast iron valves cast steel valves can be Apply in the pressure or temperature is relatively high in the pipeline.

Application of cast iron valves

For example, we often see the delivery of water pipelines with the valve, the valve will be sprayed with black paint, this type of valve is cast iron valves.