Experimental studies of the bearing capacity of pipe steels of sewage systems

Abstract

It was established that the value of the critical stress SK for all experimental steels increases with the increase in the service life, and the impact viscosity decreases, which indicates structural embrittlement of pipe steels associated with their sudden flooding. It is shown that the new 20FA steel has the highest visco-plastic properties and resistance to brittle fracture, which is economically modified with a carbide-forming element (vanadium) and has a fine-grained structure and a low content of harmful impurities (sulfur, phosphorus). The microstrain of the α-Fe crystal lattice, as well as the quantitative decay of cementite and the redistribution of carbon between ferrite and pearlite, were evaluated by X-ray diffraction methods. The new steel grade 10FA is recommended for use in the construction of underground sewage systems and, for example, bridge structures, which are constantly under cyclic loads with simultaneous contact with a corrosive and aggressive environment. For the first time, the influence of the service life of pipelines on the hydrogen content and microcracks in pipe steels was determined.