Seamless Steel Pipe Can Be Welded Under High Temperature And Pressure
Hot-rolled seamless steel pipe: Hot rolling is relative to cold rolling, cold rolling is carried out under the recrystallization temperature of the rolling, and hot rolling is above the recrystallization temperature of the rolling. Can damage the ingot casting structure, refine the grain of steel, and eliminate the defects of microstructure, so that the steel structure is dense, mechanical properties improved. This improvement is mainly reflected in the rolling direction, so that the steel to a certain extent is no longer isotropic body; pouring the formation of bubbles, cracks and loose, but also under high temperature and pressure welding.
1. After hot rolling, non-metallic inclusions (mainly sulfides and oxides, as well as silicates) inside the steel are pressed into sheets, resulting in stratified (interlayer) phenomena. Stratification makes the performance of the steel in the thickness direction greatly deteriorated, and there may be tearing when the weld shrinkage occurs. The local strain induced by the weld shrinkage often reaches several times the yield point strain, much larger than the load caused by the load; 2. The residual stress caused by the uneven cooling. Residual stress is in the absence of external force under the internal self-balanced stress, a variety of cross-section of hot-rolled steel have such residual stress, the general steel cross-sectional size, the greater the residual stress. Although the residual stress is self-balanced, but the steel components under the action of external forces still have a certain impact. Such as deformation, stability, fatigue and other aspects may have an adverse effect. 3. Hot-rolled steel products, for the thickness and width of this is not good control. We are familiar with the thermal expansion and contraction, because the beginning of the hot rolled out even if the length of the thickness of the standard, the final cooling or there will be a certain negative difference, the wider the width of the gap, the thicker the more obvious the performance. So for large steel, for the steel width, thickness, length, angle, and the edge can not be too precise requirements.
Seamless steel pipe hot rolling and cold rolling (dial) seamless steel pipe two categories.
Hot-rolled seamless steel pipe is divided into general steel pipe, low and medium pressure boiler steel pipe, high pressure boiler steel pipe, alloy steel pipe, stainless steel pipe, oil cracking pipe, geological pipe and other steel pipe.
In addition to the general steel pipe, low pressure boiler steel pipe, high pressure boiler steel pipe, alloy steel pipe, stainless steel pipe, oil cracking pipe, other steel pipe, but also includes carbon thin-walled steel pipe, alloy thin-walled steel pipe, Stainless steel pipe, shaped steel pipe. Hot-rolled seamless pipe diameter is generally greater than 32mm, wall thickness of 2.5-75mm, cold-rolled seamless pipe diameter can be 6mm, wall thickness to 0.25mm, thin-walled tube diameter to 5mm, wall thickness less than 0.25mm, Cold rolling than the hot-rolled high dimensional accuracy.
General use of seamless steel pipe: 10,20,30,35,45 and other high-quality carbon steel 16Mn, 5MnV and other low-alloy structural steel or 40Cr, 30CrMnSi, 45Mn2, 40MnB alloy steel such as hot-rolled or cold rolled. 10,20 and other low-carbon steel seamless pipe is mainly used for fluid pipeline. 45,40Cr and other carbon steel made of seamless pipe used to manufacture mechanical parts, such as cars, tractors force parts. Generally use seamless steel pipe to ensure strength and flattening test. The hot-rolled steel pipe is delivered in a hot-rolled state or a heat-treated state; cold-rolled steel is delivered in a heat-treated state.
Steel pipe weight calculation formula: [(outer diameter - wall thickness) * wall thickness] * 0.02466 = kg / m (weight per meter).