The steel of load-bearing structure should be selected according to the importance of the structure, load characteristics, connection methods, working temperature and other different conditions. The steel of load-bearing structure should be open hearth or oxygen converter No. 3 steel (boiling steel or static steel), 16Mn steel, 16Mnq steel, 15MnV steel or 15MnVq steel. The quality shall meet the provisions of the current standards "Technical Conditions of ordinary carbon Structural Steel", "Technical Conditions of low alloy Structural Steel" and "Technical Conditions of Carbon Steel and ordinary low alloy Steel Plate for Bridge" respectively.
Production and classification of steel
The concept of steel: Steel is the ingot, billet or steel that has been pressed into the various shapes, sizes and properties that we want.
Steel is an essential material for national construction and the realization of the four Modernizations, widely used, wide variety, according to the different section shape, generally divided into profiles, plates, pipes and metal products four categories, in order to facilitate the organization of steel production, ordering supply and do a good job of management, and divided into heavy rail, light rail, large steel, medium steel, small steel, cold-formed steel, High quality section steel, wire, medium thickness steel plate, thin steel plate, electrical silicon steel sheet, strip steel, seamless steel pipe, welded steel pipe, metal products and other varieties.
Most steel processing is through pressure processing, so that the processed steel (billet, ingot, etc.) produce plastic deformation. According to the steel processing temperature is different to cold processing and hot processing two.
The main processing methods of steel are:
Rolling: The metal billet through a pair of rotating roll gap (various shapes), due to the compression of the roll to reduce the section of the material, the length of the pressure processing method, this is the most commonly used production of steel production, mainly used to produce profiles, plates, pipes. Cold rolling, hot rolling.
Forging: A pressure process that uses the reciprocating force of a hammer or the pressure of a press to change the blank to the desired shape and size. Generally divided into free forging and die forging, commonly used for the production of large profile, billet and other materials with large cross-section size.
Drawing: is already rolled metal billet (type, tube, products, etc.) through the die hole drawing into a cross-section to reduce the length of the increase of processing method mostly used for cold processing.
Extrusion: is to put the metal in a closed extrusion, one end of the pressure, so that the metal from the specified die hole extrusion to have the same shape and size of the finished product processing method, mostly used in the production of non-ferrous metal materials.
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