Effect of Thermocycling and Mechanical Loads on Corrosion Resistance of High-Strength Nitrogen Austenitic Steels

Abstract

The effect of long-term thermocycling and mechanical loads on the corrosion resistance of novel nitrogen austenitic Cr – Ni – Mn steels melted under laboratory conditions is studied in various aggressive environments. The steels are subjected to 400 thermal cycles in the temperature range from –100 to 100°C and to cyclic mechanical loading during 1 × 106 cycles. The structure and the mechanical properties of the steels after the cyclic loading are studied. Tests for resistance to general and pitting corrosion in sea water (3% NaCl) and in an acid environment (0.5M H2SO4 including blasting with hydrogen sulfide), to pitting corrosion in an aqueous solution of iron chloride, to intercrystalline corrosion in a test solution, to corrosion cracking under load, and for cavitation damage in a 3% solution of NaCl are conducted. It is shown that the developed high-strength nitrogen austenitic steels 10Kh19G10N6AM2 and 09Kh19G10N6AM2D2 both in the initial condition and after the thermocycling and cyclic mechanical loading have high resistance to the types of corrosion studied, which exceeds the resistance of steels 04Kh18N9 and 04Kh18AN9. Requirements on the composition and the structure of the steels are developed.