Abstract
The water droplet erosion (WDE) performance of laser shock peened (LSP) Ti-6Al-4V was investigated. LSP condition using two or three peening impacts per unit area induced compressive residual stresses. However, LSP treatment showed a mild increase in microhardness and no observable changes in the microstructure. The effect of LSP and its associated attributes on the WDE performance was studied according to the American Society for Testing and Materials Standard (ASTM G73). Influence of the impact speed between 150 and 350 m/s on the WDE performance was explored. Two sample geometries, T-shaped flat and airfoil, were used for the WDE tests. For the flat samples, LSP showed little or no beneficial effect in enhancing the WDE performances at all tested speeds. The peened and unpeened flat samples showed similar erosion initiation and maximum erosion rate (ERmax). The LSP airfoil samples showed mild improvement in the WDE performance at 300 m/s during the advanced erosion stage compared to the as-machined (As-M) condition. However, at 350 m/s, no improved WDE performance was observed for the LSP airfoil condition at all stages of the erosion. It was concluded that compressive residual stresses alone are not enough to mitigate WDE. Hence, the notion that the fatigue mechanism is dominating in WDE damage is unlikely.
Highlights
Gas turbine efficiency in the power generation industry is affected by changes in temperature [1].This is mostly experienced during summer when ambient temperature increases
The current study explores similar sample geometries (T-shaped flat and airfoil), a different surface treatment (LSP) is employed
Section reports the effect of the laser shock peening (LSP) process on the observed XRD pattern, compressive residual stress, microstructure, and microhardness
Summary
Gas turbine efficiency in the power generation industry is affected by changes in temperature [1].This is mostly experienced during summer when ambient temperature increases. In order to increase the gas turbine efficiency, cost effective techniques are employed to keep the temperature at the inlet of the gas turbine compressor as low as possible. Among these techniques, the fog cooling technique has been used successfully. A major setback of this method is the erosion damage caused to the leading edge of the rotating blades during service. This is due to the combined effect of the rotating blades and the injected liquid droplets during fog cooling [3]. Despite the known causes of the erosion damage, the erosion process of materials is considered to be a complex
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