The role of steel chemistry on the microstructure/properties in the heat affected zone for high strength linepipe

输送能源（天然气和液体）的管道是北美能源格局的一个组成部分。仅加拿大就有超过75,000公里的天然气管道和25,000公里的液体（如精炼石油和沥青）管道。此外，还有建设新管道的建议，如TransCanada Pipeline的Energy East项目，该项目将石油产品从阿尔伯塔省输送到加拿大东海岸的炼油厂（每天4500公里110万桶石油）。安全、经济地建设和运营这一广泛的管道网络对加拿大具有重要的战略意义。采用更大直径的管道和/或增加管道的操作压力以提高系统的吞吐量是一种趋势。这导致使用更高强度的管线钢牌号，以避免使用厚壁管线钢。目前的技术水平使用X70或X80钢等级（屈服应力分别为490和560mpa）。使用更高强度的钢材意味着所需的材料更少，从而降低了材料和运输成本。这些材料的工程挑战之一是强大的制造和现场连接工艺的发展，即环焊缝。该项目涉及与所用钢的机械性能有关的方面，特别是焊接对一系列不同钢化学性质的这些性能的影响。目前，钢的评估遵循基于性能的规范，如屈服应力，即没有明确考虑钢的成分。该行业面临着两个根本性的挑战。对于像Evraz这样的钢铁生产商来说，挑战在于化学优化（特别是适当添加Cr、Mo和Nb的合金）。另一方面，管道建设者/操作员（如TCPL）必须了解不同的钢材在管道施工期间如何响应焊接产生的热量输入。这个项目的结果将是i)增加了高级热影响区的微观结构/机械性能的知识库，ii)将这些知识转移给我们的行业合作伙伴，iii)培养了5名高素质人才（3名博士，2份pdf文件）。

Pipelines to transport energy (natural gas and liquids) are an integral part of the North American energy landscape. Canada alone has more than 75,000 km of natural gas and 25,000 km of liquids (e.g. refined oil and bitumen) pipelines. Further, there are proposals to construct new pipelines such as TransCanada Pipeline's Energy East project to deliver oil products from Alberta to refineries on Canada's east coast (4,500 km 1.1 million barrels of oil per day). The safe and economic construction and operation of this extensive pipeline network is of strategic importance to Canada. There is a trend towards using pipelines of larger diameter and/or increasing the operation pressure of the pipeline to improve the throughput of the system. This leads to using higher strength linepipe steel grades to avoid using thicker wall linepipe steel. The current state of the art uses X70 or X80 steel grades (yield stress of 490 and 560 MPa, respectively). Using higher strength steels translates into less material being required thereby lowering material and transportation cost. One of the engineering challenges for these materials is the development of robust manufacturing and in field joining processes, i.e. girth welds. This project addresses aspects related to the mechanical behavior of the steels used and, in particular, the effects of welding on these properties for a range of different steel chemistries. Currently, the evaluation of steels follows performance based specifications such as the yield stress, i.e. the composition of the steel is not explicitly considered. There are two fundamental challenges that face the industry. For steel producers such as Evraz, the challenge relates to chemistry optimization (in particular, the appropriate alloy additions of Cr, Mo and Nb). On the other hand, pipeline constructors/operators such as TCPL have to understand how the different steels will respond to the heat input from welding during the construction of the pipeline. The results from this project will be i) an increased knowledge base for the microstructure/mechanical properties in the heat affected zone for advanced, ii) transfer of this knowledge to our industry partners and iii) the education of 5 high qualified personal (3 Ph.D., 2 PDFs)