薄肉構造体へのファイバーレーザ補修技術の適用とその最適化

抄録

In a gas turbine combustor operated at high temperature, cracks are generated from cooling holes in the combustor due to thermal stress and combustion oscillation. Since the combustor consists of thin-walled and cylindrical structure, it is difficult to repair the combustor by conventional overlay welding. Therefore, a new method for repairing the combustor with cracks is needed. We proposed a laser repairing technology for thin-walled component with crack. This technology is based on melting and bonding of crack by a pulsed laser. However, influence of laser conditions and thermal properties of material on the molten geometry has not been well understood yet. In this study, in order to clarify the relationship between laser condition and molten geometry, four kinds of metallic materials (SUS304, SUS430, SS400 and A5052) were irradiated by a fiber laser. The influence of laser power, scan speed and thermal properties of the materials on width and depth as the molten geometry was investigated. As a result, it was confirmed that the width and depth strongly depend on laser power, scan speed, and material. Based on those results, a new parameter called “laser operating parameter (LOP)” was proposed for estimating the molten geometry.