An important factor in solving the problem of stainless steel corrosion resistance is carbon concentration reduction. However, a decrease in carbon content of austenitic steels leads to a drop in level of their strength properties. Theoretically, nitrogen alloying can lead to a strength increase in all types of austenitic corrosion-resistant steels. Practically, nitrogen alloying is effectively only with low-carbon compositions. This work shows the effect of nitrogen on the mechanical properties of middle-alloying nitrogen, containing stainless steel, and a study of AISI 304L and pilot steel with different nitrogen content (from 0.16 to 0.30 wt. %). Nitrogen increases strength of steel, which is approximately 30-60% higher than for steel without nitrogen, but reduces technological plasticity. Pilot steels show high corrosion resistance and fine austenite grains.

The influence of concentration of nitrogen dissolved in the steel and the small additions of nitride-forming elements on the hardenability of boron-treated manganese-vanadium steel 40GF-VI was studied. It is shown that an increase of nitrogen concentration from 0.004 % to 0.015 % increases the hardenability of steel. It has been found that a small amount of titanium (about 0.02 %) in steel with a low content of nitrogen (0.004 %) is enough to bind the latter to nitrides, which allows to save most of the boron in the active state (in the solid solution). The residual amount of titanium and aluminum in the range of 0.015-0.020 % of each in steel with nitrogen content in the range of 0.010-0.015 %, which is typical for an electric arc melting steel, is insufficient to bind all nitrogen. As a result, a part of nitrogen is spent on the formation of boron nitrides, which reduces the effect of boron on hardenability of the manganese-vanadium steel micro-alloyed with boron. In conclusion, some methods of protecting boron in steel are briefly described.

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