Hot-rolled steel ingot casting can damage tissue, grain refining of steel, and eliminate defects in the microstructure, and thus the steel dense tissue improve the mechanical properties. This improvement is mainly reflected in the rolling direction, so that the steel is no longer certain extent isotropic; pouring bubbles formed cracks and porosity, but also in under the action of high temperature and pressure welding. Multiple passes through the tension reducer rolling and active control makes the dimensional accuracy, especially steel tube roundness and wall thickness accuracy) than similar seamless. The production of the world's developed countries fluid pipe, through furnace heating the weld microstructure and maternal and mechanical properties can be reached complete agreement in addition. Boiler tube seamless pipe has taken a large number of processes, along with the development of society, the domestic thermal rolled seamless steel pipe gradually replacing the situation has been formed. 4540Cr such as carbon steel seamless pipe used in the manufacture of mechanical parts, such as automobiles, tractors and the force components. General seamless steel pipe to ensure the strength and flattening test. Hot-rolled steel thermal rolled condition or disposition state delivery; cold to heat treatment delivery.
Pipe tension reducing the overall process is the pipe heated to 950 degrees Celsius, and then by tension reducing mill (reducing mill tension seamless steel pipe detection method reinspection total 24 times) rolled into various diameter and waste pipe wall, seamless pipe is at ambient temperature, after cold-drawing, bending, drawing and other cold working of the plate or strip processed into various types of steel. Forming speed, high yield, and does not damage the coating, can be made into a variety of cross-sectional form, in order to adapt to the conditions of use; cold-strained steel has undergone great plastic deformation, thereby increasing the yield point of steel. This process uses hot-rolled steel produced by the high-frequency welded pipe with the ordinary substantive differences, to ensure the quality of mother pipe welding conditions. Freedom of thermal rolled steel and cold-strained steel high torsional stiffness ratio, so the hot-rolled steel torsional performance than cold-strained steel. Seamless steel pipe and welded pipes between plain between, according to the equipment needed to produce the pipe. Superior quality welded pipe, seamless cost less than pure, an ideal alternative to hot-rolled seamless pipe is relative to the purposes of seamless pipe seamless pipe is below the temperature of recrystallization rolling, The hot-rolled seamless tube is above the recrystallization temperature for rolling.
