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

本项目的目的是为了更好地了解固态连接，特别是线性摩擦焊接过程中组织演变的控制机制。后者是一种很有前途的制造技术，它允许生产近净形状的部件并连接不同的材料。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低的废品率、更短的产品上市时间和更低的生命周期成本。 然而，关于工艺参数(包括工艺过程中的严重变形阶段)与组织演变之间的关系以及它们对接头疲劳寿命的联合影响等主要问题仍有待解决。同时，从实验室发现到工业尺寸组件的成功转换需要更现实的模拟工具，该工具还可以考虑微结构随工艺参数的变化。 该项目就是在这种背景下提出的，目的是开发一种包括微观结构演化的材料模型。一种用于飞机起落架应用的超高强度钢，以及一种用于飞机盘片和叶片应用的新型高温合金将在本次调查中使用。用光学显微镜和扫描电子显微镜研究微观结构的演变。将采用焊后热处理，并检查其对接头机械性能的影响，包括其疲劳寿命。 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、铁路和石油和天然气，这些行业使用这些合金，许多部件都采用固态连接。此外，两名博士生和两名硕士研究生将在项目过程中接受培训。

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.