Precision tube production process is more tedious, the status of the production is also good, the performance is more superior, in use is also constantly to give play to the role of come out well, so if precision tube in a way this may be a good steel type.
Precision steel tube: hot rolling is relative to the case of cold rolling, cold rolling is below the recrystallization temperature of rolling, and hot rolling is carried out above the recrystallization temperature rolling. Advantages side impact door beams can destroy the ingot casting organization, grain refining of steel, and eliminating the defects of the microstructure, which makes steel group is close-grained, mechanical performance is improved. This improvement is mainly manifested on along the rolling direction, so that the steel to a certain extent, is no longer isotropic body; Pouring formed bubbles, cracks and loose, can also be used in high temperature and pressure are welded together.
Faults after hot rolling, steel internal non-metallic inclusions (mainly sulfide and oxide and silicate) was pressed into thin slices, appear statified phenomenon (sandwich). Layered make steel along the thickness direction tensile performance is much worse, and may in the weld shrinkage occurs when torn between the layers. Weld shrinkage induced local beam impact tubes strain often reach the yield point several times as much, much bigger than the load caused by the strain; The residual stress caused by uneven cooling. Residual stress is without external force within the phase equilibrium under the action of stress and all sorts of cross section of hot rolled steel has this kind of residual stress, the general steel section size, the greater the residual stress.
Although the residual stress is the phase equilibrium, but the performance of the steel members under the action of external force still has certain influence. Such as the deformation, stability, fatigue resistance, etc, are likely to produce adverse effect. Hot rolled steel products, the thickness and edge width is bad control. We know heat bilges impact beam tubes cold shrink, because the beginning of the hot rolled out even the length, thickness, standard, finally will appear certain negative difference after cooling, the negative difference edge width is wider, the thicker the thickness of the more obvious. So for large steel, the steel edge width, thickness, length, Angle, and sideline couldn't request too precise.