Effect of sintered electrode on microhardness and microstructure in electro discharge deposition of magnesium alloy

In this study, an endeavour have been made to depositing the electrode materials over the surface of the magnesium alloy using electrical discharge machining (EDM) with WC-Cu powder compacted sintered electrode. Various process parameters such as compaction load, discharge current and pulse on time are selected to carry out the experiment in order to attain the maximum material migration rate (MMR) or deposition rate and microhardness (MH). It was concluded that the MMR and MH increased with increase in discharge current and pulse on time at low compacted electrode but it is decreased at lower discharge current and pulse on time. Highest MMR and MH were attained successfully at partial sintered low compaction load electrode. Microstructure evaluation has been carried out on deposited surface using scanning electron microscopy (SEM) and presence of electrode element in the deposited surface was confirmed by energy dispersive spectroscopy (EDS). Defects mechanism such as globules and craters are formed during EDC with high current and pulse on time respectively, which diminishes the surface roughness. It was observed that the compaction load is the influence parameter on the MMR and MH.

EDMed Inconel 718 using powder metallurgy (P/M) sintered electrode made with nano and micron sized powders

This work presents experimental data carried out for surface modification of Inconel 718 using WC/Cu composite powder metallurgy (P/M) electrodes made of nano and micron sized particles. Both machine and tool parameters were selected for study and experiments were planned as per Taguchi’s L18 mixed orthogonal array in order to find the influence of parameters on surface roughness (SR) and micro-hardness (MH). Peak current, particle size and pulse on time were found to be most significant on both SR and MH. High reactive surface area of nano particles made surface alloying greater than the other tool electrodes and has shown its influence positively on both SR and MH. The EDX analysis reveals the migration of WC and Cu elements and deposition of carbon and oxygen particles on the surface. The XRD spectrum confirms presence of carbides (WC, W2C, Fe5C2, Cr7C3, Fe7C3 and Fe3C), oxides (Fe3O4, WO3 and Cr3O) and other intermetallics at different machining conditions indicating the influence of Pulse on time (TON) and Peak current (IP) on discharge energies and in turn on the properties of machined surface. The carbides generated on the machined surface increased the hardness to 845HV without much sacrifice of the roughness of the machined surface. The range of roughness values obtained in the present investigation is 2.443 to 4.098µm.