Crack susceptibility of electro-discharge machined surfaces

Abstract

Cracking of workpieces after electro-discharge machining remains a fundamental concern. This paper examines the microstructure and cracks arising in pure iron, 0.15C and 0.5C steels when subjected to the same machining conditions. Pure iron is found to have predominantly two-sub-layer recasts whereas 0.15C and 0.5C steels would typically have a third intermediate sub-layer of eutectic-like structure: the latter is expected to lead to a greater propensity to cracking. Two other factors that have been found to have an important influence on crack susceptibility are the thermal conductivity of the work material and the hardness of the recast layer. © 1992.