A Preliminary Study of Laser Directional Solidification for Potential Use in the Repair of Damaged Aviation Turbine Blades

Abstract

To achieve directional solidification repair of damaged aviation turbine blades, the directional growth repair layer was prepared using a Nd:YAG laser on the surface of superalloy DZ-22. A scanning electron microscope (SEM) was used to observe the microstructure. The element distribution was analyzed and the microhardness of the sample was measured. The results showed that primary dendrite size was proportional to the current and the pulse-width, and inversely proportional to the scanning speed. No obvious macrosegregation of the repair zone was evident. The zone exhibited a finer microstructure than the substrate and had a smaller columnar crystal size, which was approximately two orders of magnitude smaller than the substrate. The micro-segregation between the centers and the edges of the dendrites and in between adjacent dendrites and a decrease in microhardness from the repair zone (455 HV) to the substrate also were observed.

Keywords

• laser directional solidification
• aviation turbine blade
• microstructure
• micro-segregation
• cracking