Effect of wire diameter on surface integrity of wire electrical discharge machined Inconel 706 for gas turbine application

- Inconel 706 has been recognized as an advanced superalloy to substitute the Inconel 718 for gas turbine application.
- Wire electrical discharge machining (WEDM) of Inconel 706 has been performed to explore the usages of WEDM process in the manufacturing of gas turbine components.
- The effect of wire electrode diameter on various performance characteristics (i.e., cutting speed, surface roughness, recast surface, microhardness, surface topography, microstructural and metallurgical changes) have been evaluated to attain the further improvement in WEDM process.

Inconel 706 superalloy has established itself in the field of gas turbine industry because of its easy fabricability combined with high mechanical strength. Due to its high stress rupture and tensile yield strength, conventional machining of this superalloy exhibits poor surface and low dimensional accuracy of the machined components. It is well known that most of the gas turbine components include complex shaped profile with high precision and hence, wire electrical discharge machining (WEDM) of Inconel 706 has been performed to achieve the feasibility in manufacturing of complex shaped components for gas turbine application. In the current investigation, the effect of wire diameter on WEDM performance characteristics such as cutting speed, surface roughness, surface topography, recast layer formation, microhardness, microstructural and metallurgical changes have been evaluated. It was investigated that smaller diameter wire is advantageous over the larger diameter wire since it improves productivity as well as surface quality of the machined components under the same settings of control parameters. In addition, smaller diameter wire has shown comparatively lower recast layer thickness, minimum hardness alteration and shorter manufacturing time. The XRD result has confirmed the presence of residual stress within WED machined component.

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