Hunan Steel Industrial Zone, No.9 Xiangfu Road, Yuhua District, Changsha, China
After hot rolling, the non metallic inclusions in steel (mainly sulfide and oxide, and silicate) were pressed into thin slices, and there was a phenomenon of delamination (intercalation). The performance of the steel is greatly deteriorated along the thickness direction, and it is possible to be torn between layers when the seam is contracted. Weld shrinkage induced local strain to yield point strain often several times, much larger than the strain due to the load.
Residual stress caused by uneven cooling. Residual stress is in no external force under the action of internal self equilibrium stress and various section of hot-rolled steels have this kind of residual stress and general steel section size is larger, residual stress is larger. Although the residual stress is self balanced, but still have a certain influence on the steel structure under external force performance. Such as the adverse effect on the deformation, stability, anti fatigue, etc. may.
Hot rolled steel products, the thickness and width of this control is not good. Known as thermal expansion and contraction, due to start when hot rolled out even the length and thickness are standard, finally after cooling will appear some negative difference, the negative difference edge width is wider, and the thicker the thickness of the performance of the more obvious. So for the large steel for steel edge width, thickness, length, angle, and sideline didn't method requires very precise.