Microstructural Development and Performance of Welds in Energy-Related Alloys

全球对廉价能源的需求推动我们的工业不断提高自然资源开采的效率和降低成本。能源开发设备，如钻井筒、管道和压力容器，越来越多地设计用于更高的温度、更高的压力和更恶劣的化学环境，这些环境要求使用更高等级的合金，如新型铬钼钢和镍基高温合金。焊接作为制造或维修设备不可缺少的一道工序，通常会在接头处引起不利的组织变化和热应力，成为结构中最薄弱的环节。 这项应用的短期目标是(1)进行合理的组织演变研究，以选择焊接和焊后热处理条件，并将显微组织与铬钼钢焊缝的室温和高温强度相关联，(2)开发一种创新的镍基高温合金激光熔覆工艺，以最大限度地减少对定向钻杆的稀释和变形，并证明激光熔覆过程中的快速加热循环将促进更细小的组织，并抑制有害相的形成。该专业的教育目标是培养未来在钢和高温合金的非平衡相变、先进的机械测试方法和非均质材料性能的数值模拟方面的高素质人才。我们的长期目标是开发一种新的先进合金焊接冶金技术，以制造高性能的结构，并保持加拿大在能源和自然资源的焊接和金属制造方面的竞争力。 拟议中的计划对加拿大工业的技术经济影响预计将非常大。首先，研究成果将直接提高化工、发电和自然资源行业数百个铬钼钢结构单元的效率和安全性。据估计，仅在艾伯塔省，合金轴的材料成本就直接节省了数百万美元。其次，这些技术发现将有助于材料工程和物理冶金，为一类重要的工程合金的微观结构-工艺-性能关系提供新的知识。预计将在铬钼钢的测试方法方面进行技术创新，并在精密而昂贵的718合金的激光焊接方面进行新的发明。最后但并非最不重要的一点是，该研究项目将有助于保持申请人在HQP培训方面的记录，并为培训关键合金的非平衡物理冶金方面的高质量研究生提供独特的平台。

The global demand for cheap energy pushes our industries to ever increase the efficiency and decrease the cost of natural resources exploitation. Energy exploitation equipment, such as drilling shafts, piping, and pressure vessels, are increasingly designed for higher temperature, higher pressure, and more severe chemical environments, which require the usage of higher-grade alloys, such as new chrome-moly steels and nickel-based superalloys. As an indispensible process for fabricating or repairing the equipment, welding generally induces unfavorable microstructure changes and thermal stresses in the joint, which often becomes the weakest link in a structure. The Short-term Objectives in this application are (1) to conduct a well-justified study of microstructural evolution for selecting welding and post-weld heat treatment conditions, and to correlate microstructure with room-temperature and high-temperature strength of chrome-moly steel welds, and (2) to develop an innovative laser cladding process for a nickel-based superalloy to produce minimal dilution and distortion to the directional drilling shafts, and to prove rapid heating cycles during laser cladding will promote finer microstrucure and suppress the formation of detrimental phases. The educational objective of this program is to train future highly qualified personnel in non-equilibrium phase transformations of steels and superalloys, advanced mechanical testing methods, and numerical modeling of heterogeneous material performance. Our Long-term Objective is to develop a new welding metallurgy for advanced alloys in order to manufacture high-performing structures and maintain Canada’s competitiveness in welding and metal fabrication for energy and natural resources. The techno-economic impact of the proposed program on Canadian industry is expected to be very large. Firstly, the research results will directly enhance the efficiency and safety of hundreds of Cr-Mo steel structural units in chemical, power generating, and natural resources industries. The direct savings in the material cost of alloy shafts are estimated to be millions of dollars in Alberta alone. Secondly, the technical findings will contribute to materials engineering and physical metallurgy by offering new knowledge on the microstructure-process-properties relationship for an important class of engineering alloys. There will be expected technical innovations in the testing methods for chrome-moly steels, and new inventions in laser welding of precision and expensive Alloy 718. Last but not least, this research program will help maintain the applicant’s track record in HQP training and serve as a unique platform for training high-quality graduate students in non-equilibrium physical metallurgy of critical alloys.