Abstract
The effect of laser trepanning speed and, as a result, recast layer thickness on the high temperature corrosion fatigue behaviour of CMSX-4 superalloy acute angled holes was investigated. The experimental test results show that an increasing laser drilling speed caused a reduction in corrosion fatigue life by 35–50% at 850°C, under low cycle fatigue regime. This reduction was found to correlate directly with the recast layer thickness and surface anomalies within the recast layer produced during the laser drilling process. Corrosion had a smaller effect on the overall life of the laser drilled specimens under the conditions tested. The results presented show that laser trepanning speed is influential in limiting the life performance of laser drilled components in service.
Highlights
One of the main applications of the laser drilling process in the aerospace industry includes the manufacture of cooling holes in hot section turbine blades, nozzle guide vanes and combustor liners
The results show that the high temperature low cycle corrosion fatigue (HT LCCF) behaviour of specimens with laser drilled holes at different conditions are dependent on the trepanned recast layer thickness
The poorest HT LCCF performance was obtained in laser drilling conditions A and C specimens which had the thickest estimated recast layer
Summary
One of the main applications of the laser drilling process in the aerospace industry includes the manufacture of cooling holes in hot section turbine blades, nozzle guide vanes and combustor liners. These components are usually made of nickel-base alloys that are resistant to high temperature and associated corrosion environment. Previous studies have shown that for the Nd:YAG laser drilling process, parameters such as pulse energy, pulse duration, pulse frequency, and drilling speed are the most influential; increasing the recast layer thickness and leading to micro crack formation both in percussion [3] and trepanning mode [4]
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