Improving low-temperature weld seam toughness of electric resistance welded X70 line pipe

为了满足公众对安全、安保和环保的期望，管道行业正在通过开发和实施新技术来实现零材料缺陷的管道。70 KSI屈服强度（X70）范围内的电阻焊（ERW）管线管在满足基于应变的设计和极低温度下的高韧性的技术要求方面具有很大的潜力。它符合当前的监管要求，即应使用经过验证的安全可靠的技术（而不是更高的强度等级），以最大限度地减少任何环境风险。ERW管线管的质量取决于其纵向粘合层的性能，在当前的X70管线管中，纵向粘合层在-5 ℃下可以表现出优异的韧性，但在较低温度下可以表现出不一致的低韧性。韧性是钢抵抗断裂能力的量度，因此，韧性是保证管道安全的关键力学性能。该CRD项目的研究目标是：（1）确定焊接方式对ERW X70管线钢管结合层的关键显微组织特征和低温韧性的影响;（2）通过对X70 ERW过程中的温度和变形进行数学建模，从根本上了解焊接过程。该项目对Evraz的预期价值包括产品和应用的更高质量和更低成本带来的经济效益，以及提高竞争力。此外，该项目将为加拿大劳动力队伍提供高素质的人才。

In response to the increased public expectations on safety, security, and environmental protection, the pipeline industry is targeting pipelines with zero material defects through develop and implement new technologies. Electric resistance welded (ERW) linepipe in the 70KSI yield strength (X70) range holds great promise to meet the technical requirements for strain based design and high toughness at extremely low temperatures. It meets current regulatory demand that proven, safe, and reliable technology (instead of a higher strength grade, for instance) should be used in order to minimize any environmental risks. The quality of ERW linepipe depends on the performance of its longitudinal bondline, which in current X70 linepipe can exhibit excellent toughness at -5 degree C, but can exhibit an inconsistently low toughness at lower temperatures. Toughness is a measurement of steel's capability to resist fracture, therefore, it is a key mechanical property to ensure the safety of a pipeline. The research objectives of this CRD project are, (1) to determine the key microstructure features and low-temperature toughness of the bondline of ERW X70 linepipe as influenced by how the welding is done, and (2) to fundamentally understand the welding process by mathematical modeling the temperature and deformation during ERW of X70. The anticipated value for Evraz from the project involves economic benefits from higher quality and lower costs in products and applications, and improved competitiveness. In addition, this project will contribute highly qualified personnel to the Canadian workforce.