CALCULATION OF VESSEL LIFE TO MACROCRACK FORMATION UNDER PULSATING INTERNAL PRESSURE

Abstract

The reliability and durability of metal components in engineering systems and special structures operating under internal pressure depend significantly on changes in material’s mechanical properties under the combined effects of cyclic loads, elevated temperatures, and a corrosive environment. This study’s aim: to develop a methodology for calculating the durability of a vessel subjected to variable pressure, accounting for the influence of a corrosive environment on the material’s mechanical properties. 10GN2MFA steel’s mechanical properties were determined through static tensile testing at 10^-3-10^-6 s⁻¹ strain rates in air and distilled water at 280°C, using equipment with a high-pressure chamber. It was found that the steel’s ductility in high-temperature distilled water decreases significantly at 10⁻⁴-10⁻⁶ s⁻¹ strain rates, reaching a minimum at . Based on strain-based criteria for low-cycle failure, the number of loading cycles to macroscopic crack initiation was calculated. Given a certain deformation time proportion within the critical strain rate range, the calculated durability in the corrosive environment is 19-20% lower than in air. The work’s scientific novelty: the development of a methodology for calculating durability up to macroscopic crack initiation using steel ductility characteristics determined in a high-temperature corrosive environment. Unlike standard approaches based primarily on mechanical properties determined in air, the methodology accounts for changes in ductility caused by the operating environment. The practical significance: the potential to apply the approach to calculate the durability of metal components operating under internal pressure subject to the combined effects of cyclic loads, elevated temperatures, and a corrosive environment.