Influence of EDM pulse energy on the surface integrity of martensitic steels

Electro-discharge machining (EDM) is essentially a thermal process with a complex metal-removal mechanism, involving the formation of a plasma channel between the tool and workpiece electrodes, resulting in metallurgical transformations, residual tensile stresses and cracking. These properties determine the operational behaviour of the material and can be included in one term: surface integrity. Results of different experimental analysis to characterise the surface integrity of steels used in the production of moulds after EDM are presented. The roughness of the surface, the metallurgical structure, the residual stress state and the surface crack network of the near-surface layers, in the electro-discharge steels studied, as well as their dependence on the main processing parameters, are examined and discussed quantitatively and qualitatively. (C) 1998 Elsevier Science S.A. All rights reserved.