DISTRIBUTION OF BORON AT AUSTENITE GRAIN BOUNDARIES AND BAINITIC TRANSFORMATION IN LOW CARBON STEELS.

Abstract

The segregation and precipitation of boron in austenite was studied by autoradiography, with particular reference to bainitic transformation of low carbon 3% Mn and 5% Ni-0. 02Mo steels. the main findings are that boron atoms migrate to austenite grain boundaries during cooling from the austenitizing temperature and the effect of bainitic transformation depends predominantly on the distribution of boron at these boundaries. Decrease of the hardenability effect of boron in the presence of nitrogen is caused by decrease in effective boron during quenching.