Hot-rolled strip, the English name Hot-rolled strip, also known as hot-rolled steel, commonly known as a hot plate. Hot Strip width is less than or equal to 600mm, and a thickness of 0.35-200mm steel strip having a thickness of 1.2-25mm. Classified into structural steel hot-rolled steel, mild steel, welded steel bottle, then you need to re-locate the steel according to various steel products, and then check the density and composition of the particular steel. Hot-rolled steel low hardness, easily processed, good ductility. The relatively low intensity of hot-rolled steel, surface quality and almost (oxidation \ finish low), but plastic, generally plate, cold rolled sheet, high strength, high hardness, high surface finish, usually thin, can be used as punching with the board. Cold-rolled steel sheet due to the difference between a certain degree of hardening, low toughness, but can achieve better yield ratio for cold-formed spring piece and other parts, and because the yield point closer to the tensile strength, so that during use of hazardous no predictability in the load exceed the allowable loads on accident-prone. 1) cold working surface without the use of cold rolled scale, good quality. Hot rolled steel sheet ligation work surface oxide, thickness have under poor. 2) hot-rolled steel toughness and surface roughness of the poor, lower prices, and cold rolled sheet extension is good, there is toughness, but more expensive. 3) rolled into cold-rolled and hot-rolled steel to the recrystallization temperature of distinguishing points. 4) cold-rolled: generally used for the production of cold-rolled strip, its high rolling speed. Hot-rolled steel plate: temperature and the temperature of hot rolling forging close. 5) hot rolled steel plated surface is not as dark brown, not plated cold rolled plate surface is gray, from the smoothness of the surface can be distinguished after plating, the smoothness of cold rolled plate above the hot rolled steel plate. Available brands, supply and use criteria and standard grades of national standards fairly standard role and use of foreign material category perform standard grades Standard grades suitable for the manufacture of cold forming parts of low-carbon steel coil Q / BQB302 SPHC JISG3131 SPHC SPHD SPHD SPHE SPHE SAE1006 / SAE1008 SAE1006 / SAE1008 XG180IF / 200IF XG180IF / 200IF general structural steel GB / T912-1989 Q195 JISG3101 SS330 for buildings, bridges, ships, vehicles and other general building Q235B SS400 SS400 SS490 ASTMA36 SS540 size, shape and weight tolerances Thickness (mm) Width (mm) Length (mm) roll inside diameter (mm) 1.5 ~ 4.0 800 ~ 1600 2000 ~ 2500 (or C) sheet and strip thickness Φ580 tolerances shall comply with the provisions of Table 2. Table 2 Nominal thickness (mm) thickness tolerance (mm) width direction after slice thickness deviation (mm) after rolling direction slice thickness deviation (mm)> 1.5-2.6 ± 0.10 ≤0.05 ≤0.05> 2.6-3.0 ± 0.12 ≤0.05 ≤ 0.05> 3.0-4.0 -0.17 ~ + 0.12 ≤0.05 ≤0.05 1.3 steel irregularities shall not exceed 12mm. Roughness measurement unit length 1000mm.1.4 camber plates and sheets every two meters shall not exceed 4mm. 1.5 steel sheet and strip width tolerances shall comply with the provisions under the table. Width tolerance (mm) thickness range (mm)> 2.0-2.8> 2.8-3.5 trimming 0 ~ + 30 ~ + 5 is not trimming +20 (target +10) 1.6 coil side of the head and tail should not exceed overflow 40mm, Central overflow edge, tower height should be no more than 30mm.1.7 Coil weight per volume should be 5-25 tonnes. Mechanical Properties Nominal thickness Yield strength (Mpa) Tensile Strength (Mpa) Elongation A50mm% 180 ° bending test> 1.5-2.5 ≤290 ≥310 ≥38 D = 0a> 2.5-3.0 ≤290 ≥300 ≥38 D = 0a > 3.0-4.0 ≤290 ≥300 ≥40 D = 1 / 2a: 1, listed in Table tensile test, bending test is applied to the sample two longitudinal tensile test uses L0 = 50 mm, b = 25 mm test Sample 3, bending test sampling program should be in accordance with JIS Z 2204 sample on the 3rd, The test method should be carried out in accordance with JIS Z 2248 4, hardness tests to perform in accordance with JIS Z 2245 5, the target value of the hardness of HRB 60 ± 8. The book provides the actual value of the warranty, but not as acceptance requirements. 3.3 3.3.1 Surface quality steel or steel surfaces allowed to have inclusions, cracks, corrosion and other defects on the use of harmful, does not allow parking spots. There are not allowed to affect the performance of molding defects, such as minor abrasions no handle, light yellow film after pickling, slight pitting, scratches, roll marks and indentation, color and slight crease-free feel like. [1] 3.3.2 no chance of defects due to the strip cut, allowed defect delivery, but a defective portion does not exceed 6% of the total length of the coil. 3.3.3 refers oiled steel coated with electrostatic anti-rust oil has certain anti-rust properties, painted light oil oiled, painted in oil, heavy oiling, indicated by the demand side in the contract. Oiled product under normal transportation, storage, etc. The supplier shall ensure that no rust within three months. Hot rolling their main product material, performance can be divided into: ordinary carbon steel, low alloy steel, alloy steel. Their different uses can be divided into: cold forming steel, structural steel, automotive steel, corrosion-resistant structural steel, mechanical structural steel, welding gas cylinders and pressure vessel steel, pipeline steel and so on.