Domestic high-precision seamless steel pipes generally improve the performance of materials by adding metal alloys. After cold-drawing, seamless steel pipes need stress annealing to eliminate the residual stress of materials, improve the structure material and improve the material plastics, so as to prevent the fracture of seamless steel pipes.


At present, stainless steel seamless steel pipes in our country are made of ordinary 45 # or 20 # 27SiMn steel, which improves the metal strength after cold stretching, but at the expense of metal plasticity and toughness. Precision cold-drawn seamless steel tube is of high dimensional accuracy and high strength. On the basis of market, it must guarantee the deformation within a certain range to maximize the performance of materials and reduce the negative impact of materials.


The deformation of seamless steel tube is too small to meet the requirements of surface finish and dimension accuracy, and can not meet the strength index members; the deformation is too large, the ductility and toughness of seamless steel are reduced too much, and the grains are pulled too long, forming fiber structure, metal will produce obvious anisotropy. The cold-drawn seamless steel tube is elongated in the axial direction parallel to the grain direction to increase its strength; the radial tensile seamless steel tube is perpendicular to the grain length direction, but its strength is low, while the maximum hydraulic stress exists in the radial direction of the seamless steel tube, which makes the deformation too large to give full play to the performance of the Cold-drawn Tube with negative effect.