Understanding Microstructure Evolution and Control During Hot Deformation: Application to Solid State Joining of High Strength Alloys

本项目的目的是更好地了解固态连接过程中控制微观结构演变的控制机制，特别是线性摩擦焊接。后者是一种很有前途的制造技术，它允许生产近净形状部件和连接不同的材料。这两个主题对制造业都非常重要，因为它们的广泛应用将导致更少的报废材料，更短的“上市时间”和更低的产品生命周期成本。然而，关于工艺参数（包括过程中的剧烈变形阶段）与微观组织演变之间的关系及其对接头疲劳寿命的综合影响的主要问题仍有待解决。与此同时，从实验室研究结果成功过渡到工业规模的组件需要更逼真的模拟工具，这些工具还可以将微观结构演变作为工艺参数的函数考虑在内。在这种背景下，该项目旨在开发一种包含微观结构演变的材料模型。一种用于飞机起落架的超高强度钢和一种用于飞机盘和叶片的新型高温合金将在本研究中使用。显微结构的演变将用光学和扫描电子显微镜进行研究。焊接后的热处理将被应用，并对其对接头的机械性能，包括其疲劳寿命的影响进行研究。这项工作的好处将从航空航天工业扩展到加拿大的其他行业，如汽车、铁路、石油和天然气，这些行业使用这些合金，并在许多部件上应用固态连接。此外，项目期间还将培养2名博士和2名硕士研究生。

The aim of the present project is to gain a better understanding of the governing mechanisms controlling microstructure evolution during solid state joining, specifically, linear friction welding. The latter is a promising manufacturing technology, which allows the production of near net shape components and joining of dissimilar materials. Both topics are of high importance to manufacturing industry as their widespread applications will result in lower scrapped material, shorter 'time-to-market' and lower life cycle cost of products.However, major questions regarding the relationships between process parameters (including the severe deformation phase during the process) and microstructure evolution and their combined influence on fatigue life of the joint, remain to be addressed. In parallel, successful transition from laboratory findings to industrial size components requires more realistic simulation tools, that can also take into account microstructure evolution as a function of process parameters. The project inscribes in this context and is aimed to develop a material model that will include microstructure evolution. An Ultra High Strength Steel, used for aircraft landing gear applications, and a new superalloy, developed for aircraft disk and blade applications will be used in the present investigation. The evolution of the microstructure will be studied using optical and scanning electron microscopies. Post weld heat treatments will be applied and their influences on mechanical properties of the joint, including its fatigue life, will be examined. The benefits of the work will extend beyond the aerospace industry to other Canadian industries, such as automotive, rail and oil and gas where these alloys are used and solid state joining is applied for many components. Moreover, two PhD and two Masters students will be trained during the course of the project.