Impact of Nitrocarburizing on Hardening of Reciprocating Compressor’s Valves

Abstract

One of the urgent problems in reciprocating machinery is ensuring the functional properties of direct-flow valves. Coatings of these parts should increase energy efficiency, reduce compressed gas temperature, and increase compressor performance. In this article, the effect of nitrocarburizing in pastes on increasing the performance and resource of such valves was studied. The primary research methods were metallographic and electron-metallographic research of the surface layer structure of steel 60Si2Cr. Comparison with similar characteristics obtained for stainless steel 09Cr15Ni8Al was also performed. As a result, it was determined that nitrocarburizing of carbon spring steel 60Si2Cr leads to a greater depth of the diffusion layer than nitrocarburizing of alloyed chromium-nickel steel 09Cr15Ni8Al. Simultaneously, the diffusion layers of both types of steel are almost the same. Simultaneously, the increase in the endurance limit of 60Si2Cr steel during nitrocarburizing is about 1.3 times compared to untreated material. Finally, the predictive maintenance showed that the evaluated lifetime of nitrocarburized valves increases by 5.7 times compared with untreated valves.

Investigation of Changes in the Structural-Phase State and the Efficiency of Hardening of 30CrMnSiA Steel by the Method of Electrolytic Plasma Thermocyclic Surface Treatment

“…Figure 3 3a-d, the phase structure of 30CrMnSiA steel mainly implies of α'-Fe and Fe 3 C grains, which are α'-martensite and Fe 3 C-cementite (iron carbide), as well as the broadening of interference lines from the crystallographic plane (110). The broadening of the interference lines of the plane (110) and the increase in their relative intensity are presumably associated with an increase in the density of dislocations during the formation of martensite and is determined mainly by the tetragonality of martensite, which is consistent with the results reported by other authors [42][43][44]. However, it is known that with the help of X-ray diffraction analysis, it is possible to detect the presence of any phase with its content in the amount of at least 2%, and to identify phases in smaller quantities, it is necessary to use other methods of analysis.…”