High-techs in materials science: through-the-thickness austenitic nitriding of heat-resistant steel

The topicality of the research is occasioned by exaggeration working conditions products used at high temperatures and made heat-resistant sheet alloys, including in particular austenitic chromium-nickel steels. When steel parts under load are operated an oxidizing atmosphere aggressive environments, besides resistance to electrochemical gas corrosion, they require increased strength, hardness, heat resistance. increase characteristics these proper-ties achieved three-dimensional surface hardening techniques, which include nitration process. applica-tion traditional technologies furnace nitriding for steels complicated due problems low rate nitrogen saturation, significantly increases process time, formation chromium nitrides, negatively affects corrosion development new high-alloyed chromium-containing carried out direction saturation intensification regulation phase composition nitrided layer minimize nitrides. article aimed defin-ing rational technological options modes austenic steel, making it possible strength RT higher without sacrificing its Thermodynamic modeling based on CALPHAD technique shows that primary ways minimizing release nitrides concentration titanium reduce activity saturat-ing atmosphere, inert dilution nitrogen. Experimental studies were samples 1.5 mm thick type X18N10T with a standard (0.5%Ti) (1%Ti) titane content. experiments laboratory installation high-temperature (900.1200 °); pure mixtures argon as saturating media. Two-stage processes consisting followed afterburning also investigated. Metallographic analysis showed same nitrid-ing temperature, amount decreases experimental content, reduces temperature nitride release. According study kinetic, time through-the-thickness sample different was deter-mined, well duration de-nitriding annealing, calculated basis known thickness zone. It found dispersion zones internal leads both compared base 08X18N10T after typical treatment, while greatest effect 1%Ti. Recommended steel: tn=1050 ℃, N2, 16 h; tn= 1100 50%N2 + 50%Ar, 22 tn=1100 5 h tann=1200 Ar, 9 h. temporary passive hardness 45...50%, when tested 800 ℃ - 40... 65%, de-pending mode. Through-the-thickness makes raise 100.150 ° long-term strength. 900 remains level non-carbonated two-stage ensure maximum removal from annealing stage.