【作者】 刘明亮；

【导师】 张玉凤；

【作者基本信息】 天津大学 ， 材料加工工程， 2006， 硕士

【摘要】 海底管道作为一种焊接结构,担负着输送石油、天然气等介质的重要任务。但是由于焊接缺陷、残余应力、力学性能不均匀性等原因使焊接接头成为整个结构的薄弱环节。本文通过裂纹张开位移(CTOD)试验研究了X65管线钢焊接接头各部位的抗开裂性能。其中CTOD值是根据ISO标准BS7448在0℃下采用标准三点弯试样试验得到的。从试验结果可以看出,本研究所采用的X65管线钢焊接接头焊缝的冲击韧度和断裂韧度明显低于母材。从裂纹张开位移试验结果可以看出,供试的X65钢母材的抗开裂性能明显优于焊缝。本文采用欧共体提出的SINTAP(Structural Integrity Assessment Procedure)“结构完整性评定方法”为标准,运用自主开发的评定软件,对X65管线钢焊接接头中焊趾处的表面裂纹的进行了安全评定。根据母材和全焊缝拉伸试验结果,建立了X65管线钢焊接接头的0级、一级和三级评定曲线,评定结果表明,不论是采用0级、一级或是三级评定,各评定点均在评定曲线定义的范围内,表明该焊接接头是安全的。本研究将SINTAP方法应用于管道结构的安全评定过程中,具有实际的工程意义和经济价值,为SINTAP在国内管道结构安全评定中的应用奠定了基础。更多还原

【Abstract】 In the welded structure of offshore pipeline used to deliver oil and gas, the welded joints are the weakness location. This is mainly because there are inevitable welding defects, residual stresses and inhomogeneous microstructures and poor mechanical properties in the welded joint zone.In this study, the Crack Tip Opening Displacement (CTOD) tests were carried out to investigate the crack resistance behavior of weld metal, HAZ and base metal of X65 pipeline steel. CTOD tests were conducted at 0 degree and performed according to the requirements of the standard of BS7448, Part1: Method for determination of KIc, critical CTOD and critical J values of metallic materials and Part2: Method for determination of KIc, critical CTOD and critical J values of welds in metallic materials, in which a standard TPB (three point bending) shape was accepted. The test results show that the impact and fracture toughness of weld metal are much lower than that of base metal. The results of crack tip opening displacement tests show that the crack resistance of X65 base steel is much better than that of the weld.In this investigation, Structure Integrity Assessment Procedure (SINTAP) was applied as the standard to assessment and we used the procedure which designed by ourselves to assessment for welded joints of the API 5L X65 pipeline steel with surface flaw at the weld toe. The failure lines of level 0, 1 and 3 of the weld were derived from the tensile test results. The results of the assessment showed that all assessment points (Lr, Kr) are located within the failure lines of analysis level 0, 1 and 3. The results show that the welded joint of the pipeline is safe. The study is of great significance in terms of engineering and economic effectiveness. This study applied the designed procedure which based on SINTAP method to assessment the safety of pipelines structure has laid the foundation of application of SINTAP to pipeline structure assessment.更多还原