Study on Polished Surface of Sulphurized Cast Iron by Electron Diffraction and Electron Microscope

Abstract

It has been reported that the wear-resisting property of cast iron is improved by sulphurizing treatment. In the present study, the surface of cast iron (3.10%C, 1.62%Si) sulphurized in H₂S at 500°C for 2 hr was polished with emery paper 04# and its surface layer was studied by reflection electron diffraction, electron microscope and micro-vickers test. The results obtained were as follows; (1) Beneath the outermost scale which was easily peeled mechanically, there was a sulphurized layer of dark grey. (2) The maximum hardness was attained, when the thickness of the specimen was decreased by 0.1 mm by wearing, and the flowing of α-Fe as well as the slipping of graphite was observable by electron diffraction and electron microscope. (3) The promoted slipping of graphite might be one of the reasons why sulphurized cast iron shows a good wear-resisting property.