Lanthanum, yttrium, titanium, zirconium and boron effect on high-tem erature properties of chromium-nicel alloys in different media

To further improve the properties of chromium-nickel steels with a high chromium content the effect of small additions of yttrium, lanthanum, titanium and zirconium (up to 1%) and boron (up to 0.01%) on oxidation kinetics, composition and structure of oxide films formed on 40Ni-60Cr alloy during oxidation in the air and during interaction with products of natural gas burning and products of mazut burning, containing approximately 3% S, has been studied. It is shown that alloying the 40Ni-60Cr alloy with low additions of boron, lanthanum, yttrium, titanium and zirconium decreases considerably the rate of its oxidation in the air, especially at high temperatures. Alloying with rare earths is the most efficient one. Heat resistance of chromium-nickel alloys in products of natural gas burning is higher than in the air. Corrosion resistance of chromium-nickel alloys with high chromium content in products of high-sulphur mazut burning is higher than that of industrial heat resisting alloys. Alloying the 40Ni-60Cr alloy with small additions of lanthanum or titanium increases its corrosion resistance 5-15%. Low additions of boron, lanthanum, yttrium, titanium and zirconium increase significantly plasticity of the 40Ni-60Cr alloy without considerable decrease of its heat resistance