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. © 1998 Elsevier Science S.A. All rights
reserved.