Influence Of Corrosive Media Research Articles

Determination of the Residual Service Life of a Torsion Bar Under the Influence of Corrosive Media

Determination of the Residual Service Life of a Torsion Bar Under the Influence of Corrosive Media

Tribo-mechanism of amorphous carbon films under corrosion solution and various mechanical loads

Diamond-like carbon films (DLC) as a prominent surface protection coating are used to enhance the tribological performance of engineering components due to their low coefficient of friction (COF), high wear resistance and excellent chemical stability. In recent years, researchers have separately studied the environment-dependent and load-dependent tribological behaviors of DLC films. However, there is few studies about the influence of corrosive media on the load-dependent tribological behaviors of DLC films. In this paper, we explained the tribo-mechanism of chromium doped DLC film (Cr-DLC) in hydrochloric acid (HCl) by combing the effect of load-dependent. For comparison, tribological behaviors of Cr-DLC films in ambient air and distilled water environment were also investigated. It is found that the coefficient of friction of Cr-DLC film complies with the Hertzian elastic contact model in HCl solution. In other words, the COF decreases with the increase of normal contact load except 2 N. The Cr-DLC film shows the highest wear resistance with wear rate of 1.79 × 10−7 mm3/Nm at 5 N. The main wear mechanism at 2 N and 5 N is governed by the formation of a graphite-like transfer film and tribochemical products on friction interfaces; Whereas the wear mechanism for 7 N and 10 N contact load is attributed to the superimposed effect of the high Hertzian contact stress and the corrosion function of chloride ion. The insights acquired from this study can be used to the design of high-performance of DLC coated tribo-systems in corrosive environment.

Corrosion Resistance of the Surface Layer of Steel 45 Components Subjected to Combined Strengthening Treatment

Corrosion breakdown of the surface layer of components made of steel 45 subjected to combined strengthening (electromechanical treatment (EMT) + surface plastic deformation (SPD)) and operating under the influence of corrosive media is investigated. It is established that hardness and corrosion resistance of a hardened surface layer is influenced by the amount of tool feeding during EMT, which determines the distribution of structural components (white layer, original material), as well as the degree of medium corrosivity and interaction time with this medium.

The use of pulsed beams for increasing radiation resistance of ceramics

Paper presents the results of a study of the applicability of pulsed C+/H+ (85/15) beams with a high current density for directional modification and hardening of the surface layer of AlN nitride ceramics. The purpose of the modification is to increase the radiation resistance to helium embrittlement and swelling as a result of the accumulation of helium in the surface layer. It has been established that an increase in the number of processing pulses leads to a sharp change in the morphology of surface layer, as well as a change in strength characteristics of ceramics. The sharp deterioration of strength characteristics is due to the presence in the structure of the surface layer of a high density of dislocations and defects, as well as the formation of microcracks as a result of pulsed processing with a large number of pulses. The effect of modification on the change in the structural characteristics of investigated samples has been established. It should be noted that these changes occur in a small surface layer with a thickness of not more than 0.5 μm, which is most susceptible to degradation under irradiation and influence of corrosive media during practical use.

Separation of surface, subsurface and volume fatigue damage effects in AISI 348 steel for power plant applications

Abstract A wide range of industries including energy, chemistry, pharmacy, textiles, food and drink, pulp and paper, etc. is using stainless steels. Metastable austenitic steels such as used in power plants and chemical industry are subjected to cyclic mechanical and thermal loading in air as well as under the influence of corrosive media. This paper provides an overview on different nondestructive and electrochemical measurement techniques, which allow differentiating fatigue damage effects in total strain controlled multiple and constant amplitude tests with respect to damage appearance on surface, in subsurface area as well as in volume of specimens or components microstructure. In addition to conventional mechanical stress-strain hysteresis curves, electrical resistance, magnetic and open circuit potential measurements have been applied to characterize the cyclic deformation behavior of the metastable austenitic steel AISI 348 (X10CrNiNb18-9) in laboratory air and in distilled water. Based on these results obtained, the paper provides an outlook on the possibility for an efficient (remaining) fatigue life evaluation approach, which is adapted to the needs of the application areas.

Study of the Mechanical Behaviors of Fabric Made of Polyester Fibers in the Corrosive Ozone Gas Environment

Polyester textile is widely adopted in ordinary engineering applications where mechanical properties like high strength and relatively good plasticity are demanded at the same time. Though there has been some research on the change to its mechanical behavior in corrosive environments to study the effects of corrosion, for example, the ultraviolet (UV) light, the influence of corrosive media like ozone gas (O3) on its mechanical properties is rarely explored up to now. Here fabric made of polyester fibers is chosen to study the possible influence of ozone gas with extremely high concentration in the tensile strength as well as the failure behavior of this material. The aim of this research is at extending or expanding the application of polyester fabric to wider engineering areas through the study of the influence of extreme environment conditions in the mechanical properties of polyester fabric and the failure mechanism as well.

Application of the Theory of Dimensionalities to the Evaluation of the Influence of Corrosive Media on the Long-Term Strength of Materials

UDC 539.376 The methods used for the investigation of long-term strength are based on the relations of phenomenological theories generalizing significant amounts of empirical data. This is explained by the complexity of the physical fracture processes on the micro- and mesolevels of structures. It is thus an extremely difficult problem to get a physically grounded model with relatively small number of experimentally measured parameters, which seems to be quite important because the experimental investigation of long-term strength is connected with significant technical and economical difficulties. This is even more urgent for the investigation of the influence of corrosive media on the long-term strength of materials. In deducing phenomenological relations, the researcher chooses the most significant parameters of the problem (e.g., time, stresses and/or strains, etc.) and constructs the relationships for these quantities on the basis of the experimental data. In the present work, we demonstrate some advantages of the analysis of dimensionalities used to establish regularities in some limiting cases. The form of these regularities can be useful for subsequent generalization and formulation of correct and adequate phenomenological relations.

Influence of corrosive media on ceramic insulators

Influence of corrosive media on ceramic insulators

Influence of working media on the cyclic strength of an AD33-B composite (report 2)

With low volumes of accumulated damages (Μ⩽8%) to a test base of 2 · 105 cycle in not more than 150 h the influence of corrosive media on the residual strength of AD33-B composite is not significant. At levels of cyclic stresses of σa>0.6σb, the use of AD33-B composite in 3% NaCl solution and water is undesirable without anticorrosion measures.

Effect of aqueous operating media on the low-cycle fatigue of constructional steels

The action of aqueous corrosive media on the strength of steels under cyclic loading is determined to a significant degree by the influence of two active elements, oxygen and hydrogen, participating in the corrosion process. The authors have investigated the influence of these active elements on the strength of constructional steels under cyclic loading under conditions simulating the operating conditions of heat-transfer equipment. The metal of the samples was hydrogen impregnated with cathodic polarization. The deaerated media have an insignificant effect on the low-cycle life of 20, 15Kh2MFA, 15Kh2NMFA AND 08Kh 18N10T steels at a temperature of 120-270/sup 0/C and under the quite long influence of corrosive media at low levels of elastoplastic deformation. The action of hydrogen occluded by the plastically loaded steel with cathodic polarization led to a sharp decrease in low cycle life. The tested steels revealed different tendencies toward hydrogen cyclic fatigue. The influence of the test conditions may be determined in an analysis of the adequateness of the Lanjer-Manson model. The results of determination of the adequateness according to the Fisher criterion are shown. The norm of the logarithms of lives in the low-cycle area is practically independent of the level of deformation.

Stress-corrosion cracking of thermomechanically treated steels

The effect of high-temperature thermomechanical treatment (HTMT) on the susceptibility of high-strength chromium-silicon steels to stress-corrosion cracking was studied. The considerable improvement produced by this treatment was attributed to the resulting reduction in the sensitivity of steels of this kind to the presence of notches formed by corrosion under stress. Comparison of results obtained for specimens tested in tension and torsion made it possible to assess various theories of long-term strength for heat-treated steel (quench-hardened and subjected to low-temperature tempering) under the influence of corrosive media.

The effect of working media on the fatigue strength of steel under high-frequency loads

The effect of working media on the fatigue strength of metals in the load frequency range 10–20 kHz/sec has not been extensively studied. While, a few years ago, it was believed [1] that in view of the short test duration at such high frequencies the influence of corrosive media may be neglected, it is now known that this effect may be quite considerable.

Influence of corrosive media on the fatigue strength of duralumin in relation to the loading frequency

Electrode potentials of D16T duralumin specimens during fatigue tests in a 3% NaCl solution at loading frequencies of 200 and 3000 cpm were measured and the fatigue strength of this material tested in air and water at loading frequencies of 200 and 6000 cpm was determined. It was established that the effect of corrosive media on the fatigue limit and endurance of duralumin depends on the loading frequency.