Advanced materials development for safer energy pipelines

在需要金属暴露于化学环境的工业应用中，腐蚀导致材料结构完整性受损是一个常见的问题。根据金属在工业中的使用情况，存在不同形式的腐蚀，并且根据暴露环境，有些腐蚀可能比其他腐蚀更有害；例如，与完全暴露的合金表面的均匀腐蚀相比，局部腐蚀位于封闭区域（即垫片下方）。由于其隐蔽性，局部腐蚀可能难以识别，并且由于活性腐蚀区域的电化学性质难以测量，通常只能估计腐蚀速率。在石油和天然气行业中，最具破坏性的局部腐蚀形式是应力腐蚀开裂（SCC），这是在管道暴露于腐蚀性化学环境中受到施加应力时遇到的。SCC对管道退化的影响将通过在加拿大服役的管道上复制应力和化学环境的实验组合来研究。NOVA Chemicals （Calgary AB和Sarnia ON）和Western University （London ON）的实验资源将用于实现这一目标。先前在用管道的实验样品的加工将由NOVA进行。西部大学的研究人员将使用西部表面科学和地球科学系提供的先进表面分析技术来表征钢的成分和微观结构。然后，NOVA将使用机械测试系统施加应力载荷，同时监测预分析表面和模拟地下水中的电化学条件。在化学/机械暴露后，西方的研究人员将重新检查预分析的腐蚀表面，以确定哪些微观结构特性最容易受到应力诱导裂纹的产生和发展的影响。量化不同商业钢微结构的SCC降解率将有助于开发加拿大更安全的能源管道基础设施所需的新合金设计。

Compromise of a material's structural integrity caused by corrosion is a common problem in industrial applications that require metals to be exposed to chemical environments. Depending on the metal's industrial in-service use, different forms of corrosion exist and, depending on the exposure environment, some may be more deleterious than others; for example, corrosion localized within an occluded region (i.e., under gaskets) compared to uniform corrosion on an entirely exposed alloy surface. Because of its insidious nature, localized corrosion may be difficult to identify and corrosion rates are usually only estimates since the electrochemical properties of the actively corroding region are difficult to measure. Within the oil and gas industry the most damaging form of localized corrosion is Stress-Corrosion Cracking (SCC), which is encountered in pipelines that are subjected to an applied stress while exposed to a corrosive chemical environment. SCC's impact on pipeline degradation will be investigated by replicating experimentally the combination of stress and chemical environments anticipated on in-service pipelines in Canada. Experimental resources from NOVA Chemicals (Calgary AB and Sarnia ON) and Western University (London ON) will be utilized to pursue this goal. The machining of experimental samples from previously in-service pipelines will be performed by NOVA. Researchers at Western University will characterize steel compositions and microstructures using the advanced surface analytical techniques available at Surface Science Western and in the Department of Earth Sciences. NOVA will then apply a stress load using a mechanical testing system while simultaneously monitoring the electrochemical conditions, on the pre-analyzed surface, in simulated groundwater. After chemical/mechanical exposure, researchers at Western will re-examine the pre-analyzed corroded surface to determine which microstructural properties are most susceptible to the initiation and growth of stress-induced cracks. Quantification of SCC degradation rates for different commercial steel microstructures will facilitate the development of the new alloy designs required for a safer energy pipeline infrastructure in Canada.