Microstructural Development and Performance of Welds in Energy-Related Alloys

全球对廉价能源的需求促使我们的工业不断提高效率，降低自然资源开发的成本。能源开采设备，如钻井井、管道和压力容器，越来越多地设计用于更高温度、更高压力和更恶劣的化学环境，这就需要使用更高等级的合金，如新的铬钼钢和镍基高温合金。焊接是设备制造或维修中不可缺少的环节，焊接接头往往会产生不利的组织变化和热应力，成为结构中最薄弱的环节。本应用程序的短期目标是：(1)对选择焊接和焊后热处理条件的显微组织演变进行充分的研究，并将显微组织与铬钼钢焊缝的室温和高温强度联系起来；(2)开发一种创新的镍基高温合金激光熔覆工艺，以使定向钻井轴产生最小的稀释和变形。并证明快速的加热循环可以促进微细组织的形成和抑制有害相的形成。该课程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数值模拟方面的高素质人才。我们的长期目标是开发先进合金的新型焊接冶金技术，以制造高性能结构，并保持加拿大在能源和自然资源焊接和金属制造方面的竞争力。拟议的项目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中数百台Cr-Mo钢结构单元的效率和安全性。合金轴材料成本的直接节省估计仅在阿尔伯塔省就有数百万美元。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提供微观组织-工艺-性能关系的新知识。在铬钼钢的检测方法方面将有技术创新，在精密和昂贵的718合金激光焊接方面将有新发明。最后但并非最不重要的是，该研究项目将有助于保持申请人在HQP培训方面的记录，并作为培养关键合金非平衡物理冶金高质量研究生的独特平台。

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.