Domestic high-precision seamless steel pipes
generally improve the properties of materials by adding alloys to metals. After cold drawing, seamless steel pipes need to be subjected to stress relief annealing to eliminate residual stress of materials, improve material structure and improve materials. Plasticity, so as to prevent the occurrence of fracture failure of seamless steel pipe.
At present, the material of China's stainless steel seamless steel pipe is ordinary 45# or 20# steel 27SiMn steel, which improves the strength of the metal by cold drawing deformation; however, it is at the expense of plasticity and toughness of the sacrificial metal. High-precision cold-drawn seamless steel pipe is based on its high dimensional accuracy and high strength performance. It must ensure that the deformation amount is within a certain range to maximize the performance of the material and reduce the material. Negative Effects.
The deformation of the seamless steel pipe is too small to meet the requirements of surface finish and dimensional accuracy, and the strength index of the component cannot be achieved; the deformation is too large, the plasticity and toughness of the seamless steel pipe are reduced too much, and the crystal grains are excessively elongated. The fibrous structure is formed and the metal will have significant anisotropy. The axial direction of the cold drawn seamless steel pipe is parallel to the elongation direction of the grain, and the strength is increased; the radial direction of the cold drawn seamless steel pipe is perpendicular to the elongation direction of the grain, and the strength is instead decreased, and the maximum stress of the hydraulic cylinder It is present in the radial direction of the seamless steel pipe, so the deformation is too large to be detrimental to the performance of the cold drawn pipe.