Domestic high-precision seamless steel pipes generally improve the properties of materials by increasing. After cold-drawn metal alloys and seamless steel tubes, stress relief annealing is needed to eliminate the residual stress of materials, improve the structure of materials, improve the plasticity of materials and prevent the failure of materials. The purpose of fracture failure of seamless steel tube.


At present, China's stainless steel seamless steel tubes are made of ordinary 45 # or 20 # 27SiMn steel, which increases the strength of cold-drawn metal; however, its price is the metal cost of plastics and toughness. Precision cold-drawn seamless steel tube with its high dimensional accuracy and high strength performance on the basis of the market, must ensure a certain range of deformation, in order to maximize the performance of materials, 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, which can not meet the strength index of components; the deformation is too large, the seamless plasticity of steel tube, the toughness is reduced too much, and the grains are too stretched to form fiber structure, so the metal can have obvious anisotropy. The axial elongation of the cold-drawn seamless steel tube increases parallel to the grain strength direction, while the radial tensile seamless steel tube is perpendicular to the grain in the slender direction, but the strength is low. The maximum pressure of the seamless steel tube is radial, and the deformation is too large, so the negative performance of the cold-drawn steel tube can be fully exerted.