The Effect of Provoking Heating on the Electrochemical Corrosion Properties of VNS53 and VNS53-M Steels

Numerous directions of modern manufacturing are in need of a new generation of steels. In a number of properties, such steels should surpass those already existing, widely produced, and rather intensively used. One of the most effective ways to improve the functional properties of high-alloy stainless steels is the use of nitrogen as an alloying element. It has been shown in a number of works that nitrogen leads to a decrease in the energy of stacking faults, an expansion of the region of existence of austenite, and a narrowing of the region of existence of delta ferrite. In this regard, we can note such high-strength austenitic steels as 0.08Cr21Mn11NNi6 (VNS53) with anitrogen content of up to 0.5%, as well as 0.08Cr21Mn11NNi6NbV (VNS53-M), additionally containing niobium and vanadium. Taking into account the prospects for expanding the production and use of these steels, this paper presents the results of studying the electrochemical corrosion behavior of high-alloy steels VNS53 and VNS53-M, little studied in this aspect, in comparison with the similar behavior of the widely used steel 08Cr18Ni10Ti steels. The electrochemical corrosion behavior of these steels was carried out by the method of potentiodynamic polarization in an aqueous borate buffer solution at pH 7.4, as well as in the same solution with the addition of sodium sulfate at a concentration of 0.01 mol/L. The studied steels were subjected to sensitization heating at different temperatures. It is shown that, in the tested electrolytes after heat treatment, there is no significant change in the corrosion resistance of these steels. Some decrease in the rate of anodic dissolution is observed for the VNS53-M steel after heat treatment at 600°С. This result is especially important for the VNS53-M steel, which has complex alloying, which can lead to the formation of carbide and nitride phases both in the volume and on the surface of the steel.