Study On Cold Bending Process And Quality Performances For High-grade Pipeline Steels

Cold bending production is one of the important links of long-distance oil and gas pipeline construction, pipeline diameter and with grade increasing, difficulty in making cold bend significantly increased the stability of cold bending pipe quality, performance, safety and service is more important. The topic for the major pipeline engineering demand, analysis systemically studied the cold bending deformation influence on cold bending pipe tensile properties, impact of size on cold bending appearance and mechanical properties of cold bending process parameters, and the limit of high grade steel, heavy caliber cold bending bearing capacity, the study determined the cold bending process parameters and key quality performance index.This topic through the small sample simulation test, analysis of the cold bending deformation effects on the tensile properties of cold-formed tube. The results show that the yield strength, tensile, of high grade pipeline steel yield ratio, uniform elongation, strain stress curve have important influence of cold pre deformation, and the extension of smaller influence on the tensile strength, broken rate. In the cold bending production, should strictly control the bending deformation, avoid yield ratio increased significantly, shaping a serious decline and other issues.This topic through the cold bending test of real process, analyze and research the effect size for different steel grade and diameter of cold bending appearance and mechanical properties of cold bending process parameters, including the ellipticity, waviness, wall thickness, the key quality performance index and the tensile properties, low temperature toughness and Vivtorinox hardness etc.. Results show that the mold through the improvement and optimization process can be high grade, large caliber cold bending springback amount, ovality, waviness and wall thickness control in good level. Singer by the package effect, cold bending bending section of longitudinal tensile property distribution is not uniform, but the low temperature impact toughness and hardness changes smaller Vivtorinox.Through the cold bending hydraulic blasting test and the tube bending test, analysis of limit of high grade steel and cold bending bearing capacity of large diameter. The results show that the bearing capacity of cold bending, can meet the requirements of the project, but in the positive under bending load, buckling ultimate strain of cold bending low, if in the special section cold bending strain based design of pipe laying, should first design check according to the specific conditions of strain.Based on the above results, optimized the high steel grade and large diameter cold bending process parameters and the key quality performance indicators, and provides technical support for the production and application of major pipeline engineering cold bend.