We present experimental estimates of the resistance of 30KhGSNA steel after heat treatment in various modes to corrosive-erosive wear in inhibited water. We established the existence of threshold amplitudes under cavitation, below which wear of the steel is not observed. They vary more significantly in the case of inhibiting the medium than owing to a change in the steel structure from perlite to martensite. We compared the results obtained with the literature data concerning the structural sensitivity of the steel under study to corrosion fatigue in the range of high-and low-amplitude loading. We conclude that corrosive-erosive fracture is controlled by the process of initiation and growth of short corrosion cracks.Corrosive-erosive fracture during cavitation is considered, as a rule, from the position of cyclic deformation of local regions in the surface layer of a material [1][2][3]. For this reason, investigators often try to find correlation relationships between the characteristics of fatigue fracture and corrosive-erosive fracture. One can use them, on the one hand, for predicting the resistance of a material to corrosive-erosive fracture according to data of cyclic tests and, on the other hand, for its structural optimization aimed to achieve a strong counteraction to both loadings often corresponding to actual conditions of operation. Such relationships are usually based on the" characteristics of the resistance to cyclic fracture in air, neglecting the role of the corrosion factor. However, the process of corrosiveerosive fracture is purely mechanical [4,5], and the role of the corrosion factor can be substantial and even predominant [5]. This fact, in turn, indicates the expediency to use just the characteristics of corrosive-fatigue fracture upon the construction of correlation relationships with the parameters of the resistance to corrosive-erosive fracture.The goal of this work is to study the structural sensitivity of economically alloyed 30KhGSNA steel to corrosive-erosive fracture, to compare it with the sensitivity to corrosive-fatigue fracture, and, on this basis, to analyze the role of the corrosion factor in the processes of corrosive-erosive fracture.
Experimental ProceduresWe tested steel after hardening in olive oil from a temperature of 940~ with subsequent two-hourly tempering at temperatures of 150~ 350~ and 550~ and also after annealing at 960~As a result, microstructures of martensite, troostite, sorbite, and fine-grained perlite with ultimate strengths of the material of 1930, 1590, 1010, and 950 MPa, respectively, were formed.We tested cylindrical specimens 12 mm in diameter and 8 mm in length in tap water on a UZDN-1 magnetostrictor with a frequency of 22 kHz and amplitudes of magnetostrictor oscillations A in a range 4-55 pro. In certain cases, we added the corrosion inhibitor piperidine with a concentration of 10 g/liter to water. We periodically recorded a loss in weight of the specimen W (with an accuracy of _+ 0.00005 g), which made it possible to construct the time dependence...