Abstract
The effect of austenite grain boundary segregation of S atoms on internal cracking in 9% Ni cast steels has been studied mainly by means of Ion Microprobe Mass Analyzer (IMMA).
Internal cracks originate at the austenite grain boundaries which are also primary dendrite interfaces. Internal cracking, however, is not due to the formation of the grain boundary layers of low melting point substance, but arises from the decrease in grain boundary cohesion by S segregation. The segregation of S atoms is largely reduced by Mo addition and such an effect of Mo addition has also been discussed.
