Vibratory Cavitation Erosion Tests Research Articles

On the effect of salt bath nitrocarburizing on the cavitation erosion behavior of AISI 304L stainless steel

In this study, salt bath nitrocarburizing was applied on austenitic stainless steel AISI 304L to stabilize austenite at the surface exposed to cavitation attack. Samples were treated at 470 °C and 500 °C for 6 h, giving an average thickness of the nitrocarburized layer of 6 µm and 26 µm, respectively. The thickness of the nitrocarburized layer is found to influence the formation of deformation-induced martensite (DIM) in the material and, thereby, the cavitation erosion resistance. The mass loss vs. time plot shows that the nitrocarburized specimens performed significantly better than the base material under ultrasonic vibratory cavitation erosion test (ASTM G32). Cross-sectional micrographs show that the phenomenon responsible for the failure in the base material is the formation of DIM. The specimen, nitrocarburized at 470 °C, showed a reduction of about 90 % in mass loss when compared to the base material (AISI 304L SS), owing to a higher yield strength (/resilience) after the formation of more stable austenite.

Investigation into Morphology of Cavitation Erosion-Corrosion Pits on the Surface of Carbon Steel

Nano-sized films associated with the ring areasformed around micropits in cavitation erosion experimentswere investigated. The corrosion behavior and vibratory cavitation erosion tests of mild carbon steel in 3% NaCldistilled water were carried out. The results showed that thenano-sized films associated with the ring areas formedaround micropits in cavitation and free cavitation tests havea similar shape. The study proved that the nano-structure and the ring areas formed around micropits are the result ofcorrosion effects and not as a result of thermal effectsrelated to the collapse of the bubbles.

Cavitation-Erosion behavior of laser cladded Low-Carbon Cobalt-Based alloys on 17-4PH stainless steel

Stellite 728 (C14) with low-carbon and high-molybdenum was used for cavitation resistance application in this research. The specimens were fabricated on the surface of a martensitic precipitation hardening stainless steel called 17-4PH by laser cladding technique. The cavitation erosion behavior in 3.5 wt% NaCl solution is investigated using a 20 kHz vibratory cavitation erosion test machine. The electrochemical corrosion test was also explored to reveal the mechanism of the synergistic effect of cavitation and electrochemical corrosion. The experimental results of the Stellite 728 were compared with those of well-known cavitation-resistant Stellite 6 and wrought Stellite 6B. The surface morphology and microstructure evolution after cavitation were analyzed by means of metallographic microscope (OM), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and 3D optical surface morphometry to explore the cavitation erosion mechanism of the specimens. The experimental results show that the Co-based alloys have better cavitation erosion resistance than 17-4PH, and laser cladded Stellite 728 has better cavitation resistance in 3.5 wt% NaCl solution than laser cladded Stellite 6 and wrought Stellite 6B, owing to the formation of large amounts of Mo-rich intermetallic compound in the alloy.

Quantitative analysis of wear particles generated by cavitation erosion in glycerol-water mixtures

PurposeThis paper aimed to analyze removed particles from stationary specimen-aluminum (Al-99.92) produced by vibratory cavitation erosion tests in distilled water and glycerol-water mixtures.Design/methodology/approachThe particle morphology which include particle surface topography, size distribution, particle size parameters and particle shape parameters were examined for distilled water and glycerol-water mixtures having different viscosities.FindingsThe results showed that the variation of size parameters with viscosity was very similar to the variation of weight loss with viscosity. Both the size parameters and weight losses show a monotonic decrease in going from distilled water to glycerol-water mixtures having viscosity about 10.1 cSt, beyond which the change is very small. On the other hand, the shape parameters were much less sensitive to distinguish between the particles produced in water and glycerol-water mixtures. The mechanism of cavitation erosion is investigated in detail through observations of the removed particles. The particle surfaces topography demonstrated that the mechanism in water and glycerol-water mixtures was fatigue failure.Originality/valueCavitation often occurs in almost all machines that handle liquids, especially at high speeds, leading to irreparable damage of the components of these machines. Elucidation of such complex phenomenon demands full characterization of the erosion mechanism and controlling parameters inherent to it, so that cavitation erosion can be prevented or at least be reduced through adequate information and collection of relevant data under different operating conditions. Very few studies have been made to approach the viscosity effect upon cavitation erosion from the particle analysis standpoint. The aim of the present work is to identify the effect of liquid viscosity on the size, shape characteristics of the erosion particles and their morphological features. The prevailed mechanisms of wear and particle generation have been proposed based on the acquired information from particle analysis.

Vibratory Cavitation Erosion With Vibrating and Stationary Specimens

AbstractIn the framework of the International Cavitation Erosion Test (ICET), 119 vibratory cavitation erosion tests were performed. Seventy of these tests were with vibrating specimens (VRV), and forty-nine with stationary specimens (VRS). From these tests, twenty tests of each type were chosen for this study. VRV tests are covered by ASTM G32-10, whereas for VRS, no standard has yet been published. This anomaly stems from the difficulties encountered in both testing and evaluating of VRS tests. All forty cavitation erosion–time curves were analyzed by the Transient Response for Erosion (TRE) method. For each curve, all three parameters were determined, namely: time lag (TL), time constant (τ), and the asymptotic value of the mean depth of erosion, mean depth of erosion (MDE) MDEMAX. These parameters were further applied to calculate the scatter of test results as obtained from various specimens tested under identical conditions. This method enables the determination of the absolute and relative scatter values at any time value along the test. Finally, several guidelines are specified for preparation of a future VRS standard.

The Study of Cavitation Erosion Protection Performance of Heavy-Duty Engine Coolants

Ultrasonic vibratory cavitation erosion tests were carried out on studying the cavitation erosion protection performance of different type of heavy-duty engine coolants for cast iron material of wet sleeve cylinder liners. The influence of coolant type, freezing point, corrosion inhibitor content and test duration on anti-cavitation performance were analysed. The experimental results showed that the anti-cavitation erosion performance of organic acid type heavy-duty engine coolants were better than the inorganic salt type heavy-duty engine coolants. For the same formulation coolant, increasing the content of ethylene glycol or corrosion inhibitor can improve the anti-cavitation erosion performance. With the extension of ultrasonic vibration test time, the anti-cavitation erosion protection performance for cast iron was reduced.

Cavitation Erosion Behavior of the Antifriction Alloy YSn83

This paper presents the cavitation erosion research of the antifriction alloy YSn83 regarding on its behavior in laboratory. The antifriction alloy YSn83 is not subject to cavitation erosion in its practical applications, as is happening in reality at the materials used in hydraulic turbines, valves, piping; but the experimental tests for this material, highlight the laboratory research on its behavior by means of images and graphs in this paper. The laboratory tests were performed in accordance with the standards G32-92 (Standard Method of Vibratory Cavitation Erosion Test) and G32-10 (Standard Test Method for Cavitation Erosion Using Vibratory Apparatus).

EXAMINATION OF CAVITATION EROSION PARTICLES MORPHOLOGY IN CORROSIVE WATERS

Wear particles produced by vibratory cavitation erosion tests on 1045 carbon steels in three different corrosive media: distilled water, tap water and 3 % NaCl water were analyzed. Scanning electron microscope (SEM) of wear particles were acquired, forming database for further analysis. This study shows that there is no remarkable difference in the particle size with test solution. However, the frequency distribution of particle sizes differed with the test solution. It is the highest at small sizes for tap and distilled water. While for salt water, it is the highest for the larger sizes (larger than 50 µm). All the particles, irrespective of solution, manifested similar morphological features such as lamellar shape, crack propagation on the particle surface and secondary cracks. This indicates that the particles are produced by a single mechanism, namely, fatigue. With regard to the role of corrosion in the development of cavitation erosion, it was most pronounced in the case of salt water. It was found that dissolution of ferrite acts as areas of stress concentration which give rise to crack initiations. This gives a strong impetus to the crack initiations.

Investigation of the Ring Area Formed Around Cavitation Erosion Pits on the Surface of Carbon Steel

The ring areas formed around micropits in cavitation erosion experiments were investigated. The corrosion behavior and vibratory cavitation erosion tests of mild carbon steel in tap and distilled water were carried out. Thus, the ring areas were densely formed in tap water and scarcely formed in distilled water in cavitation tests. The ring areas formed around micropits in cavitation and free cavitation tests have a similar shape. Moreover, SEM examinations showed that the corrosion products spread within the ring areas. Thus, the ring areas formed around micropits are the result of corrosion effect and are not the result of thermal effects due to bubble collapse.

EFFECT OF LIQUID VISCOSITY ON CAVITATION DAMAGE BASED ON ANALYSIS OF EROSION PARTICLES

The effect of viscosity on the wear particles produced by vibratorycavitation erosion tests on Al-99.92 in distilled water and glycerol-watersolutions was analyzed. Scanning electron microscope images of wearparticles during incubation period were obtained. The surfacetopography examination revealed that the erosion particles were formedby fatigue. The particles removed from glycerol-water solutions differfrom that formed in distilled water, where fatigue striations formed onthe particle surface for glycerol-water solutions and not formed fordistilled water. Therefore, the stress produced by cavitation bubblesdecreases with increase of viscosity.

Investigation of Temperature Effects on Cavitation Erosion Behavior Based on Analysis of Erosion Particles

The effect of temperature on the wear particles produced by vibratory cavitation erosion tests on Al-99.92 in distilled water was analyzed. Scanning electron microscope images of wear particles were obtained, forming a database for further analysis. This study showed that the variation of average particle size with temperature was very much similar to the variation of weight loss with temperature. The average particle size was maximum at 40°C. It was also observed that the average particle size was time dependent. The particle’s morphology features revealed that the predominant erosion mechanism was fatigue failure, irrespective of the temperature.

Quantitative Analysis of Cavitation Erosion Particle Morphology in Dilute Emulsions

Wear particles produced by vibratory cavitation erosion tests on 1017 carbon steels in water and oil-in-water (o∕w) emulsions were analyzed. Scanning electron microscope (SEM) images of wear particles were acquired, forming a database for further analysis. The particle morphology features were first clarified. Next, the size parameters (size, area, and perimeter) and shape factors (elongation and roundness) were determined for each test liquid, using image analysis software. The size parameters of the removed particles were higher in water than in o∕w emulsions. While the shape factors could not significantly discriminate between the particles produced in water and o∕w emulsions. The size distribution was in a wide range for water than that for o∕w emulsions. The cavitation erosion mechanism is fatigue failure for water and o∕w emulsions.

The Effect of Molybdenum on Cavitation Erosion and Corrosion Resistance of Fe-Cr-C-Si Hardfacing Alloys

The cavitation erosion behavior of Fe-Cr-C-Si-xMo (x = 0, 3 and 6 wt.%) hardfacing alloys were investigated for up to 50 hours by using 20 kHz vibratory cavitation erosion test equipment. With increasing Mo contents, M23C6 and M6C carbides were formed instead of Cr-rich M7C3 and M23C6 type carbides observed in the interdendritic region of the Mo-free Fe-Cr-C-Si hardfacing alloy. This microstructural change was responsible for the improvement of mechanical properties such as hardness and cavitation erosion resistance of the Mo-added Fe-Cr-C-Si hardfacing alloy.

Effect of boron addition on the cavitation erosion resistance of Fe-based hardfacing alloy

The cavitation erosion behavior of Fe–Cr–C–Si– xB ( x = 0, 0.3 and 0.6 wt.%) alloys were investigated up to 50 h by using 20 kHz vibratory cavitation erosion test equipment. The boron-added alloys showed the improved cavitation erosion resistance compared to the boron-free alloy. This improvement was attributed to that the boron addition enhanced the grain boundary strength and refined the grain size of the matrix. However, the cavitation erosion rate of the 0.6 wt.% boron specimen was higher than that of the 0.3 wt.% boron specimen. The higher erosion rate of the 0.6 wt.% boron was due to the larger carbide volume in the matrix.

Effect of manganese on the cavitation erosion resistance of iron–chromium–carbon–silicon alloys for replacing cobalt-base Stellite

The cavitation erosion behavior of Fe–Cr–C–Si–xMn (x=5, 10 and 15wt%) alloys were investigated for 50h using 20kHz vibratory cavitation erosion test equipment. Low-Mn alloys (<5wt% Mn) and high alloys (>10wt% Mn) exhibited the γ→α′ and γ→ε strain-induced martensitic transformation, respectively. Mn-addition above 10wt% was observed to increase the cavitation erosion resistance of the Fe-based alloy. It was concluded that the γ→ε strain-induced martensitic transformation would be more beneficial than the γ→α′ strain-induced martensitic transformation due to the blocking of the dislocation motion, thus increasing the hardness of the matrix by effective work-hardening. The phase transformation was examined by X-ray diffraction before and after the cavitation erosion tests and the surface damage of the tested specimens was also investigated by scanning electron and optical microscopy.

The Cavitation Behavior of Fe-Cr-C-Si-Ni Alloys

The cavitation erosion behavior of Fe-Cr-C-Si-xNi (x = 1, 2 and 3 wt.%) alloys were investigated for 50 hours using a 20 kHz vibratory cavitation erosion test equipment. 1 wt.% Ni added Fe-based hardfacing alloy showed excellent cavitation erosion resistance, comparable to the stellite 6. Above 1 wt.% Ni, however, the erosion resistance deteriorated quickly. It is conjectured that Ni addition above 1 wt.%, which has been shown to increase the stacking fault energy (SFE), resulted in reduction of the work hardening rate during the erosion test. Therefore, the enhanced cavitation erosion resistance of the 1 wt.% Ni alloy over the 2 and 3 wt.% Ni alloys could be explained in terms of the SFE, Ms temperature and work hardening.

Thermal Control of the Test Liquid in Vibratory Cavitation Erosion Tests

Abstract Implosion of vaporous cavities is exothermal, thereby heating the cavitating liquid. In vibratory cavitation erosion (VCE) tests the erosion rate increases with test liquid temperature. In order to obtain the erosive properties of a given material at a given temperature, it is necessary to control the test liquid temperature. The prevailing ASTM standard specifies cooling of the test liquid, and allows a maximal temperature rise of 4°C during the VCE test. However, cooling alone does not ensure the required uniformity of test liquid temperature near the specimen. In order to obtain a uniform test liquid temperature near the specimen during VCE tests, a thermal control system is recommended. This system consists of three subsystems for cooling, heating, and mixing the test liquid. Correct location of the temperature sensor and operation of the thermal control system improve the thermal control appreciably. This control method was used during 24 VCE tests with water as a test liquid. The average temperature rise in these tests was 1.5°C during the transient stage and 0.2°C during steady state operation.

Investigation of Al2O3‐ and SSiC‐ceramic under lubricated, reciprocating sliding contact and cavitation erosion

AbstractTribological performance of alumina and silicon carbide ceramics as well as of the hardened steel 100Cr6 for reference was studied during reciprocating sliding and cavitation erosion in isooctane as substitute of gasoline and in distilled water. It was the aim to characterize effects of surface finish of the specimens and the liquid media on friction, resistance to sliding wear and cavitation erosion. Sliding wear tests were run on the self‐mated ceramics and ceramic/steel pairs under conditions of boundary lubrication using a laboratory tribometer with cylinder‐on‐plate geometry. Vibratory cavitation erosion tests were conducted according to ASTM G 32‐92.High initial surface roughness of coarse ground specimens led to a distinct running‐in period during sliding contact with a transition from high to low values of friction coefficient and wear intensity. Incubation time was reduced with increasing surface roughness in the cavitation tests. Depending on the materials investigated, the type of liquid media showed strong effects both during reciprocating sliding and cavitation erosion.

Modeling of Cumulative Mass Loss—Time Curves for Six Erosion and Abrasion Test Methods

Abstract Cumulative mass loss-time curves of six erosion and abrasion test methods are studied. These methods include: vibratory cavitation erosion, film cavitation erosion, flow cavitation erosion, cavitating liquid jet erosion, liquid impact erosion, and slurry abrasion. It has been previously well established that the cumulative erosion-time curves of vibratory cavitation erosion tests can be modeled by the Weibull cumulative distribution function. Validity of this model is further extended for the five additional erosion test methods. The typical Weibull plot for these test methods is bimodal, consisting of two intersecting straight lines. Mode 1 of the plot represents the boundary layer, and Mode 2 represents the base material of the specimen. This type of plot is the result of a two-layered test specimen. Data obtainable from the cumulative erosion-time curve are rather limited, since the analysis is empirical. Analysis of the Weibull cumulative distribution function plots yields much more information, and facilitates the evaluation of the test specimen's structure, test procedure, and test results.

耐食・耐摩耗性を備えた肉盛材料の開発

For fluid machinery used in seawater, the overlaying technique is an effective means for the resistance to corrosion, erosion and abrasive wear in terms of cost, performance and repair. Therefore, we had attempted to combine the manufacturing technique of anti-wear resistant Co based KV powder and Crevelloy alloy with excellent crevice corrosion resistance. As the results, the overlayer containing 15%massVC, 35%massCr, and 15%massMo shows high hardness and excellent anti-corrosion property. High hardness of overlayer is mainly caused by matrix phase with lamellar structure consisting Ni-Cr-Mo-Fe alloy phase and carbide phase. Corrosion property was evaluated by cyclic potentiodynamic anodic polarization curve measurement in 3.0%NaCl aq. at 25°C, pitting potential measurement in 3.5%NaCl aq. at 80°C and 6-months immersion test in seawater. Erosion property was evaluated by slurry jet test and vibratory cavitation erosion test. From the evaluation results, developed material VCRMO is recommended as overlaied alloy for seawater applications.