Nano-SIMS investigation of boron distribution in steels

The introduction of boron in amounts of tens parts per million (ppm) increases the hardenability of steels. Nevertheless, this positive effect of boron can drastically be reduced during the industrial process if boron precipitation occurs. In order to identify the different steps of boron precipitation for the main parts of the process (deformation at high temperature, cooling and welding), the distribution of boron in high strength steels is studied through SIMS nano-analysis. It is shown that the B state and the nature of the B precipitates can be directly deduced from different ion maps (B-11, C-12, (BC)-B-11-C-12, (BN)-B-11-N-14, (BO)-B-11-O-16) acquired simultaneously. Depending on the progress of the process, borocarbides and boron nitrides precipitates are observed. Copyright (C) 2010 John Wiley & Sons, Ltd.