On the nature of the so-called "ghost lines" in stand-cast steel

Abstract

One of the defects which show up in strand-cast steel and persist in the rolled shapes and forgings, irrespective of the degree of hot plastic deformation, is the so-called "ghost lines ". Because of their appearance on magnetic inspection of finite parts and macrographic etching, they are still termed "Innenrisse " (internal cracks) in Germany, and sometimes considered-objectionable. In this study it is shown that they consist of segregated metal, enriched with sulphur and alloy elements, with the exception of carbon and nickel. Their influence on the mechanical behaviour of the steel, at least as long as their amount does not substantially exceed that present in our material is of little, if any, importance.