Enhancing the surface hardness and roughness of engine blades using the shot peening process

Abstract

The effects of shot peening on the mechanical properties of steel 1070 were studied to enhance the material’s properties and surface characteristics. In this study, pressure and exposure time were the main parameters governing surface hardness and surface roughness. The optimal time duration and pressure were determined after several experimental trials. Changes in hardness and surface roughness were monitored as the pressure of the shot and the exposure time were varied. Furthermore, the microstructure was evaluated by scanning electron microscopy (SEM) and the images were enhanced by image processing techniques to evaluate the surface changes. Pareto charts were constructed to estimate the effects of pressure and time on both surface hardness and surface roughness. The novelty of this study is the concentration on engine blades which are frequently used in aircrafts to determine the optimal time-pressure combination for shot peening to achieve suitable mechanical and surface properties. The results show that shot peening pressure (up to 482.6 kPa for 7 min) has positive effect on enhancing the surface and mechanical properties for steel 1070 blades; however, an increase in either pressure or time above that level adversely affected both surface hardness and surface roughness.

Keywords

shot peening / roughness / hardness / engine blades / scanning electron microscopy

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