Hebei Hua Tuo Jia Ye Steel Trading Co., Ltd. URL: http:www.hbhtgt.net rolled seamless steel pipe: hot rolled phase for cold-rolled, cold-rolled rolling below the recrystallization temperature, and heat rolling conducted above the recrystallization temperature is in the rolling. Rolled seamless steel pipe advantages: can destroy the cast structure of the steel ingot, and refinement of the crystal grains of the steel, and eliminate the defects of the microstructure, so that the the steel organization compacting, improve the mechanical properties. This improvement is reflected in the rolling direction, so that the steel is no longer to a certain extent isotropic; pouring the formation of bubbles, cracks, and osteoporosis, under high temperature and pressure can also be welded together. Disadvantages: 1. After the hot rolled steel inside the non-metallic inclusions (mainly of sulfides and oxides, as well as silicates) is pressed into a sheet, stratified (laminated) phenomenon appears. The layering of the steel in the thickness direction by the pull performance deteriorated significantly, and may appear in the weld shrinkage interlayer tear. The local strain induced by weld shrinkage frequently reach several times the yield point strain, the strain is much greater than the load caused; 2. Residual stress caused by uneven cooling. The residual stress is the stress of internal self-phase equilibrium in the absence of external force, the hot-rolled steel of various cross-sectional has a residual stress such Usually steel sectional dimension is the greater, the greater the residual stresses. Residual stress is self-phase equilibrium, but the steel members in the performance external force or have a certain influence. Such as deformation, stability, anti-fatigue may adversely. 3 hot-rolled steel products, poor control of thickness and edge width. We are familiar with the thermal expansion and contraction, even if the beginning of the hot-rolled out are standard length, thickness, or there will be some negative final after cooling, this negative differential edge width wider the increasing thickness of the performance of the more obvious. So for large steel for steel edge width, thickness, length, angle, and sideline no law requires too precise. Seamless steel pipe [1] points hot-rolled and cold-rolled (dial) seamless steel pipe two categories. Hot-rolled seamless steel pipe divided into general steel tube, low and medium pressure boiler pipe, high pressure boiler pipes, steel pipes, stainless steel pipe, oil cracking pipe, geological steel pipes and other steel pipe. Cold-rolled (dial) seamless steel pipe Besides a general steel pipe, low and medium pressure boiler pipe, high pressure boiler pipes, steel pipes, stainless steel pipe, oil cracking pipe, other steel pipes, including thin-walled carbon steel pipe, alloy thin-walled steel pipe stainless steel thin-walled steel, special steel pipe. Hot-rolled seamless pipe outside diameter generally greater than 32mm, wall thickness 2.5-75mm rolled seamless steel pipe outside diameter to 6mm, wall thickness can be 0.25mm, thin-walled tube diameter to 5mm wall thickness of less than 0.25 mm, cold rolling the hot rolled high dimensional accuracy. General seamless steel pipes: 10,20,30,35,45 quality carbon the structural steel 16Mn, 5MnV low alloy structural steel or 40Cr 30CrMnSi, 45Mn2, 40MnB alloy steel hot-rolled or cold-rolled made. 10, 20, and other low-carbon steel seamless pipe for fluid pipes. 45,40 Cr, etc. made of carbon steel seamless pipe used in the manufacture of mechanical parts, such as automobiles, tractors, and the force components. General seamless steel pipes to ensure the strength and flattening test. Hot-rolled steel hot-rolled state or heat treatment delivery; cold-rolled to heat treatment delivery.