THE DISTRIBUTION OF BORON IN LOW ALLOY CAST STEELS

The segregation and distribution of boron varied with heat-treatment in Mn-Mo-B-RE low alloy cast steels has been investigated. The influence of boron con-tent, rare earth additions and other alloying elements such as Mo upon the distri-bution of boron has been studied. It was shown that the boron segregation inthese steels is aggravated with the increase of its content. After norma1 homogeni-zation, the homogeneity of boron may be strongly affected by the segregation ofMo. In certain condition, the boron-bearing phases may precipitate either alongcertain austenite planes or at the grain boundaries to form coarse continuous networks, thus cause brittle fracture. The results also showed that rare earth elementsmay act as a fairly good protective additions for boron.