Transactions of Materials and Heat Treatment

Title：Study on strain distribution of cold bending pipe for high deformability steel X70

Authors： Yan Lijun Shi Jia Liu Yu Li Yuzhuo Zhu Peng Luo Hongsong Qin Xiuli

Unit： China Petroleum Pipeline Machinery Manufacture Co. Ltd. China National Petroleum Corporation Occupational Health Center China Petroleum Pipeline Research Institute China Petroleum Pipeline Bureau NO.1 Construction Company China Petroleum Pipeline Bureau NO.5 Construction Company

KeyWords： cold bending pipe high deformability steel X70 strain plastic deformation grid method

ClassificationCode：TG142.14

year,vol(issue):pagenumber：2015,40(11):132-136

Abstract：

The grid side lengths of outer surface of high deformability line pipe X70 before and after cold bending processing were measured by the square grid method. The relative plastic deformation in different regions was calculated by length variations, and was regarded as the plastic strain of cold bending pipe. The strain distribution and its reasons were analyzed and the plastic deformation properties of pipe were discussed. The results indicate that the longitudinal strain of cold bending pipe is in agreement with theoretical calculation value, which increases with the increase of forming angle within unit step. It is more reasonable to design the forming angle within unit step by selecting the longitudinal strain. But the change of the transverse strain is smaller from -0.9% to 0.5%, and the maximum compressive strain -3.12% only occurs in the transverse regions 120°-150°,5-7 m, which is 1.23% higher than the theoretical calculation strain(1.89%). The pipe is of excellent plastic deformation property and uniform distribution of strain under the technology of 0.5 °/300 mm. The analysis shows that the forming angle within unit step is the main factor influencing the strain distribution. The quality of cold bending pipe can meet standard code and specification when cold bending process is designed reasonably.

Funds：

中国石油天然气集团公司科学研究与技术开发项目（2011B-3303）

晏利君（1985-），男，硕士，助理工程师

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