Repair of Single Crystal Turbine Blades by the Laser Engineered Net Shaping Process

本研究项目的主要目的是了解如何通过激光局部熔化和再凝固来消除单晶中的缺陷，并随后将此基本信息用于修复航空航天发动机和发电厂中使用的单晶涡轮机叶片中的缺陷。在单晶再凝固过程中导致缺陷消除的条件目前还不清楚，这妨碍了成功的修复。这项研究所采用的方法是跨学科的，涉及机械工程和材料工程系的学生和教师共同努力，首先确定如何在不同的凝固条件下保持单晶性质。这一基础性研究将有助于建立单晶凝固的物理和数值模型。然后，该基本信息将被应用于控制激光修复过程，使得熔化区域以去除缺陷并恢复涡轮机叶片的单晶性质的方式重新凝固。这项研究的结果将使人们更好地理解单晶凝固的机理，并有助于建立目前还没有的单晶凝固的物理和数值模型。available.此外，将这些结果应用于单晶涡轮机叶片的修复将导致与涡轮机叶片的制造和更换相关的大量成本节约。例如，一个涡轮机叶片目前的制造成本约为30，000美元，并且一个发动机包含许多叶片。在某些情况下，由于初始制造过程中形成的缺陷，刀片无法使用。一旦制造出无缺陷的刀片并投入使用，由于磨损，最终必须将其从服务中移除并更换为新刀片。目前，大多数表现出制造缺陷或使用损坏的叶片必须被丢弃，因为没有可靠的技术来修复这些缺陷。该计划的工业合作伙伴已经确定，每次检查和/或大修发动机时，成功的维修方法可以节省多达10万美元。

The primary objectives of this research project are to understand how defects in single crystals can be eliminated by localized melting and re-solidification using lasers, and subsequently use this basic information for repairing defects in single crystal turbine blades that are used in aerospace engines and power plants. The conditions, which lead to defect elimination during re-solidification in single crystals, are currently not clearly understood, and this has precluded successful repair. The approach to be taken in this research is interdisciplinary and involves students and faculty in Mechanical Engineering and Materials Engineering Departments working together to first establish how the single-crystal nature can be preserved under different solidification conditions. This fundamental research will lead to a physical and numerical model of single crystal solidification. This basic information will then be applied to control laser repair processes so that the melted area re-solidifies in a manner that removes the defect and restores the single crystal nature of the turbine blade.If successful, the results of this research will provide an improved understanding of the mechanism of single crystal solidification and lead to the creation of physical and numerical models of single crystal solidification that are currently not available. In addition, application of these results for repair of single crystal turbine blades will lead to a substantial cost savings associated with manufacturing and replacement of turbine blades. For example, one turbine blade currently costs approximately $30,000 to manufacture, and one engine contains many blades. In some cases the blades cannot be used because of defects that formed during initial manufacturing. Once a defect-free blade is manufactured and placed into service, it must eventually be removed from service because of wear and replaced with a new blade. At present, most blades exhibiting manufacturing defects or service damage must be discarded because there is no reliable technique to repair these defects. The industrial partner of this program has determined that a successful repair method could result in savings of as much as $100,000 each time an engine is inspected and/or overhauled.