Domestic manufacturers of LSAW (Longitudinal Submerged Arc Welded) pipes often enhance the material's properties by adding alloys. After the cold drawing process, stress annealing is essential to eliminate residual stresses in the material, which helps prevent fractures in the LSAW pipes.
In China, LSAW pipe manufacturers typically increase the metal's strength through cold drawing deformation. However, this process comes at the cost of compromising the shape and toughness of the metal.
Cold-drawn straight seam welded pipes are valued in the market for their high dimensional accuracy and strength performance. To achieve optimal material performance and reduce negative effects, it is crucial to ensure that the deformation stays within a specific range. If deformation is too minimal, the pipe may not meet the required flatness and dimensional accuracy, while also failing to meet the strength requirements. On the other hand, excessive deformation can severely reduce the plasticity and toughness of the pipe. It can also lead to elongated grains that prevent the formation of a fiber structure, resulting in significant metal anisotropy.
The axial direction of cold-drawn straight seam welded pipes aligns with the elongation direction of the grains, which increases the pipe's strength along this axis. However, the strength is reduced perpendicular to the grain elongation direction. Furthermore, the maximum stress experienced by the hydraulic cylinder lies in the radial direction of the pipe. When deformation is too large, it prevents the pipe from fully utilizing the benefits of cold drawing, potentially compromising its overall performance.
To prevent breakage, it is essential to carefully control the cold drawing process, ensuring that deformation remains within optimal limits. This will balance the pipe's strength, toughness, and dimensional accuracy, thus enhancing its overall durability and performance.