Chemical composition
Chemical composition performance depends largely on carbon steel and carbon steel microstructure. In the annealed or hot-rolled state, with increasing carbon content of the steel increases strength and hardness, ductility and toughness and fall. Weldability and cold-formed deteriorated. Therefore, structural steel pipe, often limit the carbon content. Carbon steel elements and the residual impurity elements such as manganese, silicon, nickel, phosphorus, sulfur, oxygen, nitrogen, carbon steel also affects performance. Sometimes these effects reinforce each other, and sometimes against each other. For example: ① sulfur, oxygen, nitrogen can increase the hot brittleness of steel, and can reduce the amount of manganese or partially offset the thermal brittleness. ② residual elements manganese, nickel and outside to reduce the impact toughness of steel, an increase of cold brittleness. ③ lower intensity except sulfur and oxygen, the other impurity elements are to increase the strength of steel in different degrees. ④ almost all of impurity elements can reduce the ductility and weldability. Hydrogen in the steel can cause many serious defects, such as white spots, dots segregation, hydrogen embrittlement, cracks and other surface bubbling and weld heat-affected zone. To ensure the quality of steel, the steel must be reduced as much as possible the content of hydrogen (see stress corrosion cracking and hydrogen embrittlement). Deoxy into the residual elements such as aluminum, can reduce the aging tendency of low-carbon steel, grain refinement can also improve the steel toughness at low temperatures, but not too much margin. Residual elements in the charge brought in such as nickel, chromium, molybdenum, copper, etc., while high levels can improve the steel hardenability, but requires a high plasticity of special steel, such as deep drawing steel, it is unfavorable.
Hunan Great Steel Pipe Co.,ltd would like to introduce more knowledge of carbon steel pipe for you.
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