Sintering Stainless Steels with Boron Addition in Nitrogen Base Atmosphere

Stainless steel has become increasingly used in the nuclear industry recently. Thus, this study is aimed at investigating stainless steel 316L with boron addition and the possibility of sinter these materials in nitrogen rich atmospheres. By analyzing the final product, the properties of the stainless steel 316L (good mechanical properties and high corrosion resistance) with the boron neutron absorption properties were found to unify. The P/M technologies enable higher boron quantities to be added to the steel. This was not possible with the solidification conventional technologies, as segregation is produced in the latter. Mixtures with 0.75 and 1.5% boron were prepared. Uniaxial compaction (at 700 MPa) was carried out to study the green density of compacted materials. The sintering atmosphere used was N2-10%H2-0.1%CH4, and was used to form boron nitrides instead of chromium nitrides. Although some boron nitride was formed, not all chromium nitride formation was avoided. The sintered samples were characterized through their physical properties (density and dimensional change), chemical analysis (carbon and nitrogen contents), mechanical behavior (bending strength and hardness) and wear behavior. To finish the materials characterization, a microstructural study is proposed. Lastly, the wear tracks were observed by SEM. Boron nitride has precipitated in grain boundaries, making more difficult the sintering of the material and reducing the properties of the stainless steel.