Formation of carbides by electro-discharge machining of alpha iron

The surface of purr iron sheets have been submitted to spark-planing erosio n using kerosene as dielectric under a wide range of machining conditions: discharge duration times between 2 and 3072 mu s, and spark currents betwee n 3.3 and 25 A. The carbides formed by the electro-discharge machining proc ess have been identified by X-ray diffraction and Mossbauer spectroscopy. T wo different regimes of carbide formation were established: for sparks of e nergy below approximate to 0.5 J only epsilon-carbide, austenite and marten site were observed; for sparks of higher energy mainly cementite, austenite and traces of martensite, Fe7C3, or Fe5C2 were detected. (C) 2000 Elsevier Science S.A. All rights reserved.