The steam boiler is mainly constructed with steel material; include pressure part and non pressure part such as pipe, tube, plate, and structure. Steel can be classified by:
1. Manufacturing Method
Steel making method can be done by one of the following way: electric arc, acid open hearth, basic open hearth, basic oxygen, and acid bessemer
2. Percentage of Carbon
Properties of steel are influenced by composition of carbon. Higher carbon will make steel has high tensile strength, hardness, fatigue resistance, and harden ability. Lower carbon composition in steel will make it low ductility, toughness, weldability, formability and machinability.
3. Percentage of Alloy
Alloying elements are added to obtain specific properties like corrosion resistance, elevated temperature strength, hardness, toughness, and so on. Alloying material that can be added are Cr, Al, Mn, Mo, Ni, St, W, V, S and Cu.
4. Grain Size
The steel can be classified based on coarsening of grain size. They are fine grained and coarse grained. Fine grained can generate higher yield and tensile strength than coarse grained.
5. Hardenability
Hardenability in material is influenced by percentage of carbon and alloy. Low carbon and no alloy will make steel is non hardenability, this material is usually used for welding and cold working. Medium carbon and low alloy will make material be shallow hardening steel. High carbon and high alloy will make material be deep hardening steel.
6. Amount of Deoxidation
Deoxidation process in manufacturing of steel is a process to reduce entrapped gasses such as CO in solid ingot that causes inconsistency of material and blow holes in steel. The result of deoxidation process will causes steel can be classified into three types such as rimmed steel, killed steel and semi killed steel.
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