Welding Solutions Advancement of High-Strength Pipeline Steels

在过去的二十年里，不断提高的能源输送速率和将油气勘探扩展到寒冷和严酷的地区，要求指定材料的进步，并使用更高强度的管线钢，如X100和X120级。然而，这些高强度钢的常规弧焊面临着巨大的挑战，如热影响区(HAZ)软化、冷裂纹(HAC)以及缺乏关于它们在严酷北极环境中的腐蚀行为的信息。 拟议的发现拨款申请将专注于开发先进高强度钢的焊接解决方案，并了解它们在恶劣环境中的腐蚀行为，特别是API X100和X120钢，以支持这些材料在海上和石油和天然气项目中的大规模实施。将使用先进的气体保护焊(GMAW)过渡模式，例如根部的表面张力过渡(STT)，然后是脉冲(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，它通过液滴控制熔合区的穿透来降低能量和改善能量控制，这有利于将HAZ软化和HAC的程度降至最低。研究的主要目标是：(I)评价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)利用商用有限元分析程序，建立一个综合的热和微观组织模型，模拟熔合区(FZ)和热影响区(HAZ)的瞬时传热和组织演变；(Iii)通过研究接头在含H_2S/CO_2的环境中的氢致开裂(HIC)和硫化物应力开裂(SSC)敏感性，研究接头在恶劣环境中的腐蚀行为。这些交付成果将作为平台，实现在海上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，特别是在北极环境下，从而大幅节省投资成本。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有重要的基础性见解，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，并培训5名高素质人员(10名计算合作社学生)，这将为加拿大近海和石油和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.