An investigation on machined performance and recast layer properties of AISI H13 steel by Powder Mixed-EDM in fine-finishing process

Abstract

Powder-mixed electric discharge machining (PMEDM) has been studied with many different powders. However, limited works have used the tungsten carbide powder in the PMEDM process and investigated its effects on machined performance (MP) and recast layer properties (RLP) of samples. Thus, to fill the missing gaps on the PMEDM. In this paper, an investigation of the effect of main process parameters, including peak current (Ip) and pulse on time (Ton) in fine-finishing process, and powder concentration (Cp) on the MP and RLP of AISI H13 steel was performed. Firstly, the MP – i.e., material removal rate (MRR), and tool wear rate (TWR) was investigated. The results showed that the MRR and TWR have varied in an upward tendency when Ip, Ton, and Cp was increased. At Ip = 2A; Ton = 32 μs; Cp = 60 g/l, the largest change in MRR and TWR is the increase of 132.022% and 132.353% respectively versus the EDM process. And nextly, the RLP – i.e., percentage and composition of chemical elements, recast layer thickness (RLT), and percentage of the surface micro-crack density acreage (PSCDA) was explored, namely that the percentage and composition of chemical elements of machining surfaces were also transformed versus that in the substrate layer of AISI H13 steel, and that on the recast layer of the EDM process. The determined method of the RLT and PSCDA has been proposed. The results of PSCDA and RLT formed by the PMEDM process were notably decreased, down to 52.547% and 65.606% respectively versus that of the EDM process. In addition, this study also investigated, and compared the variation trend of the MRR, the TWR, the percentage and composition of chemical elements, the PSCDA, and the RLT in the fine-finishing process when the powder concentration was added.