STUDIES ON FORMATION OF THE DISTINCTIVE LAYER OF WHITE-HEART MALLEABLE CAST IRON (I)

Abstract

The charateristic structure of white-heart malleable castings in their distinctive outer layer was described. It was compared with the microstructure of the peeled one on which was studied by J.C.W. Humfrey and others in England. By microscopic examinsation, sulphur print and chemical analysis, it was recognized that such a sulphide penetration as in the case of the peeled layer did not exist in this layer but on the contrary desulphurization occurred.
Under various conditions, white castings were decarburized with mill-scales and tested by a microscope, and it was manifest that the time or the temperature of decarburizing process did not give any influence on the depth of the distinctive layer, but the pearlite band which existed in this layer/metal interface changed considerably. In consideration of the furnace atmosphere the mechanism of formation of this layer was described.