Welding Solutions Advancement of High-Strength Pipeline Steels

在过去的二十年中，不断提高的能源输送率以及石油和天然气勘探向寒冷和恶劣地区的扩展，要求改进指定的材料和采用更高强度的管线钢，如X100和X120级。然而，这些高强度钢的传统电弧焊存在重大挑战，例如热影响区（HAZ）软化，冷裂纹（氢助开裂（HAC））以及缺乏关于其在恶劣北极环境中腐蚀行为的信息。拟议的Discovery赠款申请将侧重于开发先进高强度钢的焊接解决方案，并了解其在恶劣环境中的腐蚀行为，特别强调API X100和X120钢，以支持在海上和石油天然气项目中大规模实施这些材料。将采用先进的气体保护金属极电弧焊（GMAW）过渡模式，如根部焊道的表面张力过渡（STT），然后采用脉冲（P）-GMAW，以提高接头强度，并实现更高水平的可靠性和完整性。STT转移模式的独特之处在于，它通过熔区渗透的逐滴控制来提供组合的降低的能量和改进的能量控制，这可以有利于最小化HAZ软化和HAC的程度。本文的主要工作是：（i）研究STT/P-GMAW工艺对X100和X120管线钢接头组织和力学性能的影响，（ii）建立一个完整的热-组织模型，利用商用有限元分析软件模拟熔合区和热影响区的瞬态传热和组织演变;（iii）通过研究接头在含H2S/CO2环境中的氢致开裂（HIC）和硫化物应力开裂（SSC）敏感性来研究接头在恶劣环境中的腐蚀行为。这些交付成果将作为在海洋和石油天然气行业大规模使用高强度X100和X120钢的长期愿景的平台，特别是在北极环境中，从而显著节省投资成本。 该项目的成功实施不仅将对高强度钢的焊接和腐蚀行为的科学和技术产生关键的基本见解，而且将提高管道焊接操作的可预测性，完整性和一致性。拟议的工作将显著影响核心研究向行业的传播，并培养五名高素质的人才（10名合作社学生），这将为加拿大近海和石油天然气行业提供竞争优势。

During last two decades, continuously increasing energy delivery rates and the expansion of oil and gas exploration to cold and harsh regions have demanded advancements of the assigned materials and employment of higher strength pipeline steels, such as grade X100 and X120. However, there are significant challenges with conventional arc welding of these high-strength steels, such as heat affected zone (HAZ) softening, cold cracking (Hydrogen-assisted cracking (HAC)), and lack of information on their corrosion behavior in harsh arctic environments.*** The proposed Discovery grant application will focus on developing welding solutions for advanced high-strength steels and understanding their corrosion behavior in harsh environment with a specific emphasis on API X100 and X120 steels to support the large-scale implementation of the materials in offshore and oil and gas projects. The use of advanced Gas Metal Arc Welding (GMAW) transfer modes, such as Surface Tension Transfer (STT) for the root pass followed by Pulsed (P)-GMAW, will be employed to improve the joint strength and achieve a higher level of reliability and integrity. The unique feature of STT transfer mode is that it offers a combined reduced energy and improved energy control through droplet by droplet control of the fusion zone penetration, which can be beneficial to minimize the extent of HAZ softening and HAC. The key objectives of the proposed work are: (i) evaluate the role of STT/P-GMAW process on microstructure and mechanical properties of X100 and X120 pipeline steels joint; (ii) develop an integrated thermal and microstructural model to simulate the transient heat transfer and microstructure evolution in the fusion zone (FZ) as well as HAZ using a commercial finite element analysis package; (iii) investigate the corrosion behavior of the joints in harsh environment by studying the hydrogen induced cracking (HIC) and sulfide stress cracking (SSC) susceptibility of the joints in H2S/CO2 containing environment. These deliverables will act as a platform for the long-term vision of large-scale utilization of high-strength X100 and X120 steel in offshore and oil and gas industry, particularly in arctic environments leading to a significant investment cost saving. The successful fulfillment of this project will not only develop critical fundamental insight into science and technology of welding and corrosion behavior of high-strength steels, but will improve predictability, integrity, and consistency of the pipeline welding operation. The proposed work will significantly impact dissemination of core research to industry and train five highly qualified personnel (10 counting Co-op students), which will provide a competitive advantage to Canadian offshore and oil and gas industries.