520JJ steel, Q345B plate recognition and the recognition and of course playing the guitar room projectors and small electric blanket electric blanket a good identity with the molten steel is poured, after cooling pressed flat like steel. Steel is a flat plate, rectangular, can be directly rolled or cut from wide strip from. Divided by the thickness of the steel plate, sheet <4 mm (thinnest 0.2 mm), 4 to 60 mm thick steel plate, thick steel plate from 60 to 115 mm. Divided by rolling steel plate, hot-rolled and cold points. Sheet width of 500 to 1500 mm; thickness of 600 to 3000 mm in width. Divided by steel sheet, ordinary steel, high quality steel, alloy steel, spring steel, stainless steel, tool steel, heat-resistant steel, bearing steel, silicon steel and industrial iron sheets, etc.; according to professional use points, there are drums with boards, enamel plates, bulletproof panels; divided by the surface for coating, galvanized sheets, tin plate, lead-plated sheets, plastic composite steel and so on. Thick steel plate and sheet steel steel roughly the same. In all aspects of products, in addition to varieties bridge plate, boiler plate, automobile manufacturing steel, pressure vessel steel plate and pressure vessel steel and other purely multilayer thick, but some varieties of steel, such as automobile beam steel (thickness of 2.5 to 10 mm), the pattern steel plate (thickness of 2.5 to 8 mm), the variety of stainless steel plates, the same heat-resistant steel and other thin cross. Also, the sheet material as well as one that not all plates are the same, the material is not the same, the steel sheet used in the place, not the same. Boiling steel is a steel deoxidation incomplete, only a weak amount of deoxidizer for deoxidizing the molten steel, the higher the oxygen content of the molten steel when the molten steel into the ingot mold, a large number of carbon-oxygen reaction gas, resulting in the boiling liquid steel , boiling steel thus named. Low boiling steel carbon content, because they are not ferrosilicon oxygen, silicon steel is also low (Si <0.07%). http://www.sdgcgg.com boiling steel outer layer is in the boiling liquid steel caused by violent agitation crystallization conditions, so the surface clean, compact, good surface quality, good ductility and stamping performance, no large concentration of shrinkage, less cutting head, finished product rate, and simple boiling steel production process, less ferroalloy consumption, low cost of steel. Boiling steel is used extensively for the manufacture of various stamping parts, construction and engineering structures and some of the less important parts of the machine structure. But boiling steel core part of impurities, segregation is more serious, the organization is not dense, uneven mechanical properties. At the same time due to the large steel gas content, so low toughness, greater sensitivity to cold brittle and aging, welding performance is also poor. It is not suitable for the manufacture of boiling steel to withstand impact loads, welded construction work at low temperatures and other important structures. Steel exports grew rapidly. Stimulate domestic steel market supply and demand imbalance export. January to June, China's total exports of steel 30.69 million tons, up 12.6 percent; steel imports 6.83 million tons, down 1.8%, imports of steel billets and ingots 320,000 tons, an increase of 50%. The equivalent of crude steel billet, the cumulative net export 25.06 million tons, an increase of 17.3%, accounting for 6.4% of crude steel production. From the export price, the January-June exports of wire rod average $ 624.3 / t, down 18%; plate $ 835.2 / ton, down 2.8%. The yield strength quenched and tempered alloy steel after quenching hardenability about 800MPa, impact toughness at 800kJ / m2 core hardness up to 22HRC ~ 25HRC. If the cross-sectional size larger without hardenability, performance was significantly reduced. Improve the strength of steel is one of the main purpose of adding alloying elements. To improve the strength, we should try to increase the resistance to dislocation motion. Metals strengthening mechanisms are mainly solid solution strengthening, dislocation strengthening, fine grain strengthening, second phase (precipitation and dispersion) strengthening. Strengthening the role of alloying elements, took advantage of these enhanced mechanisms. With the development of science, technology and industry, the material put forward higher requirements, such as high strength, high temperature, high pressure, low temperature resistance, corrosion resistance, abrasion and other special physical and chemical properties of the requirements, carbon steel has not completely meet the requirements. Carbon steel major deficiencies in the performance of the following aspects: low hardenability. Under normal circumstances, the maximum water quenching steel hardenability diameter of only 10mm-20mm. Strength and yield strength is relatively low. Such as ordinary carbon steel Q235 steel σs is 235MPa, and low-alloy structural steel 16Mn of σs was 360MPa or more. 40 steel σs / σb is only 0.43, far below the alloy. Tempering stability. Since tempering stability is poor, making quenched steel, high strength required in order to ensure a lower tempering temperature, so that the toughness of steel is low; in order to ensure good toughness, high tempering temperature strength and low, so the level of mechanical properties of carbon steel is not high. Can not meet the specific performance requirements. Carbon in anti-oxidation, corrosion resistance, heat resistance, low temperature resistance, wear resistance and other aspects of special electromagnetic often poor, can not meet the needs of special use properties. Common non-carbide-forming elements are: Ni, Co, Cu, Si, Al, N, B, etc. Basically they are soluble in the ferrite and austenite. Common carbide forming elements are: Mn, Cr, W, V, Nb, Zr, Ti, etc. (according to the degree of stability of the formation of carbides in order of the strong and weak), are part of the solid solution in the matrix phase in the steel , a portion of cementite to form an alloy, a new alloy to form a high carbon compound content is available.