INFLUENCE OF CHEMICAL COMPOSITION AND HEAT TREATMENT ON PITTING CORROSION RESISTANCE OF NEUTRON-IRRADIATED AISI 316 LN STEEL

In this work, the influence of alloying elements (nitrogen, manganese, copper, and tungsten) and neutron irradiation in the VVR-K reactor up to a maximum fluence of 2·1020 n/cm2 on the resistance to pitting corrosion of austenitic steel AISI 316 LN, subjected to provoking heating at temperatures in the range of 500-800 °C. It has been established that alloying with nitrogen and manganese significantly improves the corrosion properties of AISI 316 LN steel, and the addition of copper and tungsten reduces the resistance to pitting corrosion. It has been shown that provoking heating at temperatures from 500 to 800 °C with an interval of 100 °C worsens the corrosion resistance of steels in a non-irradiated state due to the formation of chromium nitrides and carbides, and the addition of copper reduces the degree of sensitization. According to the results obtained, it was established that neutron irradiation to a maximum fluence of 2·1020 n/cm2 of the studied steels after cold rolling and not subjected to provoking heating led to a decrease in the corrosion rate. Provoking heating at temperatures of 700–800 °C of neutron-irradiated samples of steels 211 L-213 L led to an increase in the corrosion rate, especially in steels alloyed with copper. Neutron irradiation greatly enhances the sensitization effect.