DIRECT OBSERVATION OF NON-METALLIC INCLUSIONS IN STEEL WITH AN ELECTRON MICROSCOPE

Abstract

It is significant to study on the inclusion in steel. The anthors tried the direct observation of inclusions in steel with an electron microscope by extraction replica technique using evaporated carbon film. The evaporated carbon film has many advantageous characteristics needed to act as extraction replica such as being amorphous, chemically inert and stable for electron bombardment or having large mechanical strength, etc.
Some new techniques were used in operating extraction replica: (1) Cleaning the etched specimen surface. (2) Evaporation technique for carbon. (3) Separating the carbon film from the specimen surface.
The authors observed some inclusions, that is, TiN, FeS, SiO₂ and MnS etc, in steels by this technique. Moreover, for the purpose of obtaining the sharp electron diffraction pattern, they have observed the extractive (manganese sulfide in sulfuretted free-cutting steel) with a high-voltage electron microscope. As the result of increasing beam potential, some new effective facts were obtained.