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效率，降低自然资源开采的成本。能源开采设备，如钻井轴，管道和压力容器，越来越多地设计用于更高的温度，更高的压力和更苛刻的化学环境，这需要使用更高等级的合金，如新的铬钼钢和镍基高温合金。焊接作为设备制造或维修的一个必不可少的过程，通常会在接头处引起不利的组织变化和热应力，而接头往往成为结构中的薄弱环节。** 本申请的短期目标是（1）对微观结构演变进行合理的研究，以选择焊接和焊后热处理条件，并将微观结构与铬钼钢焊缝的室温和高温强度相关联，以及（2）开发一种创新的镍基合金激光熔覆工艺，为了使定向钻轴产生最小的稀释和变形，并证明激光熔覆过程中的快速加热循环将促进更精细的微观结构并抑制有害相的形成，采用了基于Al 2 O3的高温合金。该计划的教育目标是培养未来高素质的人才，从事钢和高温合金的非平衡相变，先进的机械测试方法以及非均质材料性能的数值模拟。我们的长期目标是为先进合金开发一种新的焊接冶金技术，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。** 预计拟议计划对加拿大工业的技术经济影响将非常大。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个Cr-Mo钢结构单元的效率和安全性。仅在阿尔伯塔省，合金轴材料成本的直接节省估计就达数百万美元。其次，技术成果将有助于材料工程和物理冶金提供新的知识的微观结构-工艺-性能的关系，为一类重要的工程合金。在铬钼钢的测试方法方面将有预期的技术创新，在精密和昂贵的718合金的激光焊接方面也将有新的发明。最后但并非最不重要的是，该研究计划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学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.