The machined performance and recast layer properties of AISI H13 steel processed by powder mixed EDM process: an investigation and comparison in fine-finishing and semi-finishing processes

Powder mixed electrical discharge machining (PMEDM) with different powders was studied by many researchers. However, the tungsten carbide powder in the electrical discharge machining (EDM) was investigated in limitation works. In this study, machined performance-i.e., MRR-material removal rate, and TWR-tool wear rate, and recast layer properties-i.e., RLT-recast layer thickness, percentage and composition of chemical elements on the surface of AISI H13 steel, and PSCDA-percentage of the surface micro-crack density acreage of AISI H13 steel in EDM process with tungsten carbide powder added in insulating oil solvent-were investigated in two processes: fine-finishing and semi-finishing processes. The results indicated that I-p-peak current, and T-on-pulse on time in fine-finishing and semi-finishing processes, and C-p-powder concentration, have a consequence on the machined performance and the recast layer properties. The MRR and TWR have altered in an upward tendency when I-p, T-on, and C-p were increased. At I-p = 4A; T-on = 50 mu s; C-p = 60 g/l, the largest variation in MRR and TWR was an increase of 93.949% and 103.333%, respectively, versus that of the EDM process. The percentage and composition of chemical elements on the recast layer were also changed as compared to that in the substrate of AISI H13 steel and that on the recast layer of the EDM process. PSCDA and RLT by the PMEDM process were remarkably reduced, the reduction being 39.325% and 62.928%, respectively, versus that of the EDM process. In addition, the study also compared the variation trend of machined performance and recast layer properties in the fine-finishing and semi-finishing processes.