Development of a Thermomechanical Treatment Mode for Stainless-Steel Rings

Abstract

This article describes a technology for the thermomechanical treatment of stainless-steel piston rings. This technology makes it possible to obtain rings with an optimal combination of plastic and strength properties that is essential for piston rings. The following thermomechanical treatment is suggested for piston rings manufacturing: quenching at 1050 °C, holding for 30 min and cooling in water, then straining by the HPT method for eight cycles at cryogenic temperature and annealing at a temperature up to 600 °C. The resulting microstructure consisted of fine austenite grains sized 0.3 μm and evenly distributed carbide particles. Annealing above this temperature led to the formation of ferrite in the structure; however, preserving the maximum fraction of austenitic component is very important, since the reduction of austenite in the structure will cause a deterioration of corrosion resistance. The strength properties of steel after such treatment increased by almost two times compared with the initial ones: microhardness increased from 980 MPa to 2425 MPa, relative elongation increased by 20%. The proposed technology will improve the strength and performance characteristics of piston rings, as well as increase their service life, which will lead to significant savings in the cost of repair, replacement and downtime.

Experimental Analysis of the Stress State of a Prestressed Cylindrical Shell with Various Structural Parameters

“…As a result, the structure is facilitated, metal is saved, the technology is simplified and the cost of structures is reduced. The results of the research confirm the possibility of using prestress taking into account the parameters for different cases in a cylindrical shell [ 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 ].…”

“…In any case, the pitch, according to the recommendations of [ 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 ], should be less than the half-wave length— , and it should be selected according to the conditions of the tasks solved by prestressing and a technical and economic comparison of options.…”

“…The analysis of experimental studies of a prestressed cylindrical shell is presented below for Stage-I and Sub-stage I-A, according to Tables 1 and 2. In any case, the pitch, according to the recommendations of [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40], should be less than the half-wave length-2. 5 √ rδ, and it should be selected according to the conditions of the tasks solved by prestressing and a technical and economic comparison of options.…”

“…The works [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ] present the results of studies, including the modeling of shell structures under various static and dynamic loads, where studies were also carried out taking into account the deformations of the shell body (pipelines, reservoirs, cisterns, etc.). In the studies [ 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 ], work was carried out to study the effect of damage and defects in steel wrappings on the stiffness and natural frequencies of prestressed pipes as well as the characteristics of metals. Nonlinear analysis of prestressed round cylindrical shells’ free vibrations was studied, and the simultaneous influence of the prestressed state and the elastic foundation on the eigenfrequencies of shells under various boundary conditions was considered in detail.…”

“…The results of the above works [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 ] show the general issues of construction and design of steel structures with and without prestressing shells.…”