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What is the difference between Hot-rolled and cold-rolled
Issuer:Huanyulongfei Issue time:2008-10-7 Read£º144 times
Hot-rolled and cold-rolled steel is making process for steel; their organization and performance will be more effected by different processing, most of steel are processed by hot rolled, cold rolled is only use for small product and thick sheet. I. Hot Rolled Advantages: You can damage the steel ingot casting, steel refinement of grain, and the elimination of the defect microstructure, so that the organization because dense, mechanical properties will be improved. This improvement is mainly reflected in the direction of rolling along, so that the steel to a certain extent, is no longer isotropic body; air bubbles formed when casting, cracks and loose, but also in high temperature and pressure were welded together. Shortcomings: 1. After hot-rolled, the steel inside the non-metallic inclusions (mainly sulphide and oxide, and Portland) was pressure into a thin, the emergence of stratified (laminated) phenomenon. Stratified so that the thickness of steel along the direction of the tension of the significant deterioration of performance, and may shrink in the weld when torn between layers. Weld-induced contraction of the local emergency response time to reach the yield point several times, much greater load caused by the strain; 2. Uneven cooling caused by the residual stress. Residual stress in the absence of external force under the internal equilibrium since the stress, a variety of cross-section of hot-rolled steel have this type of residual stress, the general size of the greater cross-section steel, and also thegreater the residual stress. Although the residual stress from the equilibrium, but in the steel members of Properties under the external force or have a certain influence. Such as deformation, stability, anti-fatigue, and so on may have an adverse effect. II. Cold Rolled Cold rolled is cold drawing, cold-formed, such as cold drawing the cold steel strip or processed into various types of steel under normal temperature. Advantages: fast forming, high-yield and does not damage the coatings, can cause a variety of forms of cross-section, in order to meet the needs of the conditions of use; cold-rolled steel products can generate a lot of plastic deformation, thus increasing the yield of steel Point. Shortcomings: 1. Although the molding process has not been heat-compressed plastic, but the section still exists residual stress, and local buckling of steel as a whole will inevitably have an impact on the properties; 2. The general pattern of cold-rolled steel for the opening section, making cross-section of the free To reverse a lower stiffness. Bending at the time prone to reverse, when under pressure prone to buckling of bending and torsion, torsion poor performance; 3. Thickness of cold-rolled steel into smaller pieces of plate convergence in the corners and no thickening, and are subject to local Concentrated load capacity of the weak. III. Hot-rolled and cold-rolled The main difference is: 1, cold-rolled steel into a section to allow local buckling, which can make full use of the bar after the buckling of the bearing capacity; and hot-rolled steel section does not allow local buckling occurred. 2, hot-rolled steel and cold-rolled steel residual stress generated by different reasons, the section on distribution are very different. Cold-formed steel section of the residual stress distribution is the type of bending, but steel bar or hot-section steel welding residual stress distribution on the film is based. 3, hot-rolled steel free of torsional stiffness than the cold-rolled steel, so the torsional properties of hot-rolled steel are superior to cold-rolled steel.
