Experimental research of the influence of irrigation and duration of exploitation on crack resistance and corrosion destruction resistance of pipe steel

Abstract

For the first time in the work, systematic and comprehensive experimental studies of the influence of the service life of pipelines on the absorption of hydrogen by pipe steels, which is known to cause embrittlement of the metal, were carried out. In this regard, the microhardness of the structure increases sharply, and the crack resistance parameters of pipe steels also deteriorate. As an additional criterion for hydrogen exposure, the stress intensity factor K1C can be used, which characterizes the potential ability of a metal to resist brittle fracture. The curves of the temperature dependence of the K1C coefficient illustrate the change in the viscosity of steel caused by structural transformations during heat treatment and the subsequent effect of dissolved hydrogen on the metal structure during long-term operation of pipelines in corrosive and aggressive environments, in particular those used in water supply and drainage systems. It is known that the K1C coefficient is very sensitive to changes in the structure, that is, it is a local parameter of crack resistance that must be taken into account when designing and calculating pipeline structures. Additional studies established the dependence of the destruction of pipe steels of the 06G2BA brand, taking into account the preliminary stresses from 0.3σТ to 0.9σТ. Unstressed pipe steels are characterized by the highest resistance to destruction, that is, previous stresses of steel samples weaken the crack resistance of the metal. Additional studies of sulphide corrosion destruction according to the NACE methodology provided an opportunity to determine the susceptibility of pipe steels to corrosion destruction. Steels 06 G2BA and 08HMChА are characterized by the highest corrosion resistance.