Metallurgical alterations in the surface of steel cavities machined by EDM

Abstract

The electrical discharge machining (EDM) is a process characterized by high thermal demands, which tend to cause metallurgical changes in the surface of the workpiece [1][2]. This work aims to conduct a discussion of metallurgical changes in the surface of cavities obtained by the process of EDM in the machining of steel. Several variables were employed, such as cavity depth, electrode geometry and technological parameters of the process. Thus, the goal was to identify the different metallurgical changes that can occur in the machined surfaces. The evaluation of these changes was made from metallographic analysis, measurements of microhardness and of the depth of the layer affected by process. The results of this work identified several metallurgical changes such as formation of white layer, hardness variation and change of microstructure. The occurrence of microcracks also was observed, especially in severe conditions. The greatest variations in results were caused by the change of technological parameters. However, the variation in cavity depth and the change of the electrode geometry also showed influence on the results.

Study of the Structure and Mechanical Properties after Electrical Discharge Machining with Composite Electrode Tools

“…The morphology and roughness of the surfaces after EDM [1][2][3][4][5]7,8,[12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] The melting of the treated surface is accompanied by a change in its structure, the grain is refined, and zones of plastic deformation appear. Surface roughness after EDM is characterized by a set of mutually intersecting single holes.…”

“…The white layer formed on the surfaces after EDM. [5,6,8,9,13,15,19,[21][22][23]25,[31][32][33] The white layer has a fine-grained structure with high chemical resistance. The white layer after EDM has a rough surface and contains many voids, pores, and microcracks.…”

Influence of Process Parameters on the Microstructural Characteristics and Mechanical Properties of Recast Layer Thickness Coating on Die Steel Machined Surface after Electrical Discharge Machining

“…Therefore, the quality of the machined surface in EDM is also different from it in traditional machining. The white layer on the machined surface should be removed by grinding or polishing [2]. Therefore, the research results to clarify the quality of the surface layer after EDM, and it will make an important contribution to reduce the cost of machining of the surfaces and helping to lower the manufacturing costs of the product.…”

Study of Electrical Discharge Machining Parameters on Stainless Steel Using Copper Tool Electrode and Its Effect on the Structure and Electrochemical Properties

“…Electrical discharge machining (EDM) is one of the most effective processes that can produce high-quality materials precisely with a wide range of strength, hardness, and shape. 1,2 In the EDM process by applying an electrical potential between the workpiece and the tool electrode immersed in a dielectric solution a discharge current is created. Then the discharge current overcomes the dielectric solution resistance and is discharged in the form of sparks on the workpiece surfaces.…”