Residual stresses and surface topography investigation of AISI D3 tool steel under of ultrasonic vibration assisted wire-EDM.

It is an important concern for the researcher to understand the morphology of the Wire Cut-EDM surface. Heat-affected zones, residual stresses, and surface roughness are the main contributing factors to the underprivileged surface morphology of the workpiece. In the present study, authors investigate the effect of ultrasonic workpiece vibration in Wire Cut-EDM on the surface morphology of AISI D3 tool steel workpiece. The five parameters peak current, pulse on time, pulse off time, wire feed rate, and amplitude of vibration were selected to evaluate effects on heat effect zone, residual stresses, material removal rate, and surface roughness. In order to evaluate residual stress of the machined surface, high-resolution Field emission scanning electron microscope micrographs were used. X-ray Residual Stress Analyzer COS (α) method was also employed for the analysis of heat affected zones and micro-cracks. Design expert software is used to formulate mathematical models and derive the individual desirability values for material removal rate and surface roughness. A quadratic model is obtained that might suitable for all proposed objective functions. At lower range of vibration of amplitude of 15 µm resulted in better surface characteristics; on the other hand, high vibration amplitude resulted in poor machining stability because of critical wire breakage. The residual stress results indicated that the higher values of peak current and pulse of time gave rise to undesirable machined surface quality characteristics. Detailed 3D Debye–Scherrer ring distortions and high peak strength, residual stress data were indicators of a damaged workpiece surface with large craters, micro-cracks, and high tensile residual stress. [ABSTRACT FROM AUTHOR]