| During the manufacturing of the pipe for oil and gas pipeline, the Yield Strength of pipe was decreased, which was called the Bauschinger Effect. The Bauschinger Effect of Longitudinal-seem Submerged-Arc Welded (LSAW) Line Pipe made by JCOE Forming Process was studied in this paper. By the Tensile Test of the plate and its corresponding pipe in different size of X65 grade and X70 grade, the Yield Strength ( σs0.5), Ultimate Tensile Strength ( σb), Rate of Elongation and the rate of Yield Strength to Ultimate Tensile Strength ( σs0.5/ σb) of the plate and its corresponding pipe were tested, by analyzing the test results the conclusions were drew as follows:1. As for the X70 grade Φ1016×21mm pipe and its corresponding plate, the higher tested Yield Strength of plate, the lower Bauschinger Effect for its pipe; while the higher the tested Yield Strength of pipe, the smaller Bauschinger Effect it showed; the higher tested rate of Yield Strength to Ultimate Tensile Strength, also the greater Bauschinger Effect; and the higher tested Ultimate Tensile Strength of plate induced to the higher tested Ultimate Tensile Strength;2. As for the X65 grade Φ511.2 × 15.9mm Longitudinal-seem Submerged-Arc Welded(LSAW) Line Pipe, the average tested Yield Strength was 50MPa more than its corresponding plate; and so did the X65 grade Φ508× 14.3mm pipe, 30MPa more than the average tested Yield Strength of its corresponding plate. That was to say, the Bauschinger Effect was not visible for pipe of this size because it was less than the Deformation Strengthen Effect result from the small outside diameter of pipe and much deformation during forming process;3. As to the average tested Yield Strength of the X70 grade Φ1016×...
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