Alloy 33 (UNS-R20033), a new corrosion-resistant austenitic material based on chromium (mass fraction of the elements, %: 33 Cr; 32 Fe; 31 Ni; 1.6 Mo; 0.6 Cu; 0.4 N), appeared on the market in 1995. In this paper, we present new data on its mechanical properties, formability, weldability, activation characteristics, and behavior under corrosion conditions. We have established that the mechanical properties of welded articles, including impact toughness, are a good match for the same properties of plates, allowing plastic deformation without fracture. When held for up to 8 h at a temperature from 600~ to 1000*C, the alloy is not activated in boiling azeotropic nitric acid (the Huey test). In tests under service conditions, alloy 33 displays exceptional corrosion resistance in 96-98% H2SO 4 at 135-140"C and in 99.1% H2SO 4 at 150"C. Alloy 33 also has rather successfully undergone testing in 96% H2SO 4 with nitrosyl impurities at 240"C. In nitric acid, alloy 33 is resistant at a concentration up to 85% at 75"C and even higher temperatures. The alloy also has corrosion resistance in 1 M HCI at 40"C and in NaOH/NaOCI solutions. In artificial sea water, the pitting potential remains unchanged at temperatures up to 75"C and also is much higher than the oxidation-reduction potential of sea water at 95"C.Alloy 33 is easily formed; articles of any required shape can be made from it. The new data confurm the generalpurpose nature of the ~alloy, which allows it to meet the diverse requirements of chemical technology, oil and gas, and oil refining industries.Alloy 33 was developed in the 1990's with the goal of obtaining exceptional corrosion resistance under conditions of a strongly oxidizing medium and overcoming problems arising in fabrication and welding of articles with large cross sections made from superferritic corrosion-resistant steels [1]. Furthermore, manufacturers of components of steels sometimes required material with higher structural stability for replacing the corrosion-resistant fractions with high molybdenum content. As a result, the described alloy was developed: a solid solution based on chromium, alloyed with nickel and nitrogen impurities for stabilization of the austenitic microstructure.The corrosion resistance of steel is enhanced as a result of adding molybdenum and copper impurities. As established in [2], the nominal pitting resistance equivalent (PRE) of the new steel is 50, which is higher than the PRE of 6% molybdenum austenitic corrosion-resistant steel and alloy 626 based on nickel. We should also note that, despite the presence of chromium and nitrogen, alloy 33 displays a high degree of thermal stability, which may be explained by the austenitic microstructure and balanced chemical composition.Weldability and Activation Behavior. As shown by the tests carried out according to ISO requirements, the impact toughness of alloy 33 is 280 J/m 2. After arc welding of a plate of thickness 15 mm with a tungsten electrode in a shielding gas medium (GTAW, Gas Tungsten Arc Welding) with the same mater...

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