Hot rolled coils (HRC)

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Hot rolling is a metalworking process that occurs above the recrystallization temperature of the material. After the grains deform during processing, they recrystallize, which maintains an equiaxed microstructure and prevents the metal from work hardening. The starting material is usually large pieces of metal, like semi-finished casting products, such as slabs, blooms, and billets. If these products came from a continuous casting operation the products are usually fed directly into the rolling mills at the proper temperature. In smaller operations the material starts at room temperature and must be heated. This is done in a gas- or oil-fired soaking pit for larger workpieces and for smaller workpieces induction heating is used. As the material is worked the temperature must be monitored to make sure it remains above the recrystallization temperature. To maintain a safety factor a finishing temperature is defined above the recrystallization temperature; this is usually 50 to 100 °C (122 to 212 °F) above the recrystallization temperature. If the temperature does drop below this temperature the material must be re-heated before more hot rolling. Hot rolled metals generally have little directionality in their mechanical properties and deformation induced residual stresses. However, in certain instances non-metallic inclusions will impart some directionality and workpieces less than 20 mm (0.79 in) thick often have some directional properties. Also, non-uniformed cooling will induce a lot of residual stresses, which usually occurs in shapes that have a non-uniform cross-section, such as I-beams and H-beams. While the finished product is of good quality, the surface is covered in mill scale, which is an oxide that forms at high-temperatures. It is usually removed via pickling or the smooth clean surface process, which reveals a smooth surface.[4] Dimensional tolerances are usually 2 to 5% of the overall dimension. Hot rolling is used mainly to produce sheet metal or simple cross sections, such as rail tracks. Specifications: Type Standard No Grade Description Hot rolled low carbon steel JIS G3131 SPHC SPHD SPHE Suitable for manufacturing of cold formed parts DIN 1614 (EN10111) StW22 (DD11) STW23 (DD12) StW24 (DD13) Common structure steel JIS G3101 SS 330 SS 400 SS 490 SS 540 For common structure of construction, bridges, ships&vessels and auto mobiles DIN 17100(EN10025) St 33 (S185) St 37-2 (S235JR) St 37-3 (S235JO) St 44-2 (S275JR) St 50-2 (E295) St 52-3 (S355JO) Weldable structure steel JIS G3106 SM400A SM400B SM400C SM490A SM490B SM490C SM490YA SM490YB SM520B SM520C For structures requiring fine weldability used in buildings bridges, ships & vessals, autombiles, petroleum tanks and construction machines NSC Welten590RE Weldable high strength steel plate, used for presure vessel, oil tank, construction, machine mining machine and pressure water pipe Mechanical structure steel DIN 17200 C22 C35 S20C S35C For mechanical structures machined and heat treated before use JIS G4501 Fine grain structure steel DIN 17102 StE255 StE355 Fine grain structure steel suitble for welding Strip steel for steel tube JIS G3132 SPHT1 SPHT2 SPHT3 For welded tube

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