Cavitation Erosion Resistance Research Articles

Cracking mechanism of CA6NM hydro turbine steel in cavitation erosion

Cavitation erosion is a main reason for the damage of hydro turbines. It is important to understand the cracking mechanism of hydro turbine steel in cavitation erosion. In this study, the crack initiation in CA6NM steel after cavitation erosion was examined through electron backscatter diffraction analyses. The crack propagation was investigated adopting focused ion beam milling and transmission electron microscopy. The reversed austenite transformed to strain-induced martensite in cavitation erosion. The lattice parameter of the strain-induced martensite was greater than that of the thermal martensite, which led to stress concentration between the two martensites and caused crack formation and propagation in the region. Finally, approaches aiming to improve the cavitation erosion resistance of hydro turbine parts are suggested.

Effect of ZrO2 Particles on the Microstructure and Ultrasonic Cavitation Properties of CoCrFeMnNi High-Entropy Alloy Composite Coatings

CoCrFeMnNi-XZrO2 (X is a mass percentage, X = 1, 3, 5, and 10) high-entropy alloy composite coatings were successfully prepared on 0Cr13Ni5Mo martensitic stainless steel substrates using laser cladding technology. The phase composition, microstructure, mechanical properties, and cavitation erosion behavior of the composite coatings under different contents of ZrO2 were studied. The mechanism of ZrO2 particle-reinforced cavitation corrosion resistance was studied using ABAQUS2023 finite element software. The results show that the phase structure of the composite coating organization is composed of FCC phase reinforced by ZrO2 phase. The addition of ZrO2 causes lattice distortion. The coatings have typical branch crystals and an equiaxed crystal microstructure. With the increase in ZrO2 content, the microhardness of the composite coatings gradually increases. When X = 10%, the coating’s microhardness reached 348 HV, which was 95.53% higher than the high-entropy alloys without ZrO2 added. Adding ZrO2 can prolong the incubation period of high-entropy alloys; the high-entropy alloy composite coating with 5 wt.% ZrO2 exhibited the best cavitation resistance, with a cumulative volume loss rate of only 15.74% of the substrate after 10 h of ultrasonic cavitation erosion. The simulation results indicate that ZrO2 can withstand higher stress and deformation in cavitation erosion, reduce the degree of substrate damage, and generate higher compressive stress on the coating surface to cope with cavitation erosion.

Investigation into the cavitation erosion of rolled Ti6Al4V titanium alloy strengthened by the ultrasonic-assisted laser shock peening process

The novel process known as ultrasonic-assisted laser shock peening (ULSP) is conducted on hot rolled Ti6Al4V titanium alloy with polished surface to improve its cavitation erosion (CE) resistance. The microstructure and phase structure were investigated by transmission electron microscope and X-Ray diffractometer. The microhardness and residual stress were measured by microhardness tester and X-Ray residual stress analyzer. After that, the CE mass loss and morphology were analyzed through high-precision analytical balance and scanning electron microscope to reveal the CE resistance mechanism of ULSP. The results show that ULSP treatment causes plastic deformation at the surface layer, resulting in refined grains and complex dislocation structures. The aforementioned process produces a hardened layer and compressive residual stress (CRS) layer with notable amplitude and deep influence. The surface microhardness of the ULSP-9J specimen is 410 ± 4 HV, which is a 14.8 % increase compared to the LSP-9J specimen. The CRS of the ULSP-9J specimen is −329 ± 6 MPa. As a result, it is vital in preventing the formation and propagation of CE cracks, strengthening the material's resistance to CE damage, reducing mass loss, and enhancing the overall morphology of CE.

Planification of amorphous carbon coatings via periodically transitional sp2/sp3 bonds to enhance cavitation erosion resistance

In the marine sector, hydraulic machinery suffers severe damage from cavitation erosion. Although amorphous carbon (a-C) coatings are an effective measure to enhance the cavitation erosion resistance (CER), their widespread application is hindered by their metastable nature characterized by internal stress. In this study, a planification strategy was employed via different sp2/sp3 distributions (including uniform ones with different sp2/sp3 levels and periodically transitional ones with different periods), aiming to construct a pure a-C coating that enhances CER on 316L stainless steel by modulating the bias during magnetron sputtering. The effects of the sp2/sp3 distributions on the microstructure, chemical bonding, adhesion strength, fracture toughness, corrosion resistance and CER was investigated and compared with the coatings featuring uniform sp2/sp3 distributions. The results show that the periodic-mode coatings exhibit much higher CER due to their lower internal stress, excellent adhesion strength, enhanced fracture toughness and high corrosion resistance. After the cavitation erosion test for 4 h, the periodic-mode coatings only show striped structures without any coating delamination, along with less graphitization tendency during cavitation erosion. Hence, the design approach of periodic sp2/sp3 carbon bonds provides a promising new direction for marine equipment with improved CER and potential applications in various other environments.

FEA-Guided development of Inconel 625 clad on mild steel using WAAM and their cavitation erosion resistance

FEA-Guided development of Inconel 625 clad on mild steel using WAAM and their cavitation erosion resistance

Ultrasonic Cavitation Erosion Behavior of GX40CrNiSi25-20 Cast Stainless Steel through Yb-YAG Surface Remelting.

Laser beam remelting is a relatively simple and highly effective technique for the physical modification of surfaces to improve resistance to cavitation erosion. In this study, we investigated the effect of laser remelting on the surface of cast stainless steel with 0.40% C, 25% Cr, 20% Ni, and 1.5% Si on cavitation erosion behavior in tap water. The investigation was conducted using a piezoceramic crystal vibrator apparatus. Base laser beam parameters were carefully selected to result in a defect-free surface (no porosity, material burn, cracks) with hardness capable of generating better resistance to cavitation erosion. The experimental results were compared with those of the reference material. Surface morphology and microstructure evolution after cavitation tests were analyzed using an optical metallographic microscope (OM), scanning electron microscope (SEM), and hardness tests to explore the mechanism of improving surface degradation resistance. The conducted research demonstrated that surfaces modified by laser remelting exhibit a 4.8-5.1 times greater increase in cavitation erosion resistance due to the homogenization of chemical composition and refinement of the microstructure, while maintaining the properties of the base material.

Study on Cavitation Corrosion Resistance of Supersonic Flame Spraying WC-10Co4Cr Coating on Aero-Engine Fuel Pump

Study on Cavitation Corrosion Resistance of Supersonic Flame Spraying WC-10Co4Cr Coating on Aero-Engine Fuel Pump

Effect of surface microstructure spacing on the cavitation erosion process of stainless steel

Fabricating microstructures on the surface is an innovative method to mitigate cavitation erosion (CE), but there are few studies focus on the effects and mechanisms of microstructure spacing on CE performance. This study has prepared a regular dot array-shaped microstructure with different spacings on the surface of samples. The CE experiments were carried out on both the microstructured samples and smooth samples through a magnetostrictive-vibration cavitation facility. Mass loss measurement and microscopic morphology were utilized to reveal CE characteristics. Numerical simulation was used to study the parameters of the flow field. The results clearly show that the microstructure spacing of 0.25 mm, 0.50 mm, and 1.00 mm samples can improve CE resistance. On these microstructured surfaces, the volume fraction of vapor is reduced and the bubbles move away from it. However, when the microstructure spacing enlarges to 1.50 mm, the damage inside the microstructure groove increases, which will reduce the CE resistance of the materials. As the spacing increases, the volume fraction of vapor on the sample surfaces will increase, and the bubbles in the microstructure groove will congregate, resulting in increasing damage. The research provides the dimensional basis for designing cavitation-resistant surface microstructures.

Improving the cavitation corrosion resistance of 6061 aluminum alloy by anodizing

Anodic oxidation is a common surface strengthening method to improve the comprehensive properties of aluminium alloys (AAs), such as wear and corrosion resistance, but its application on cavitation erosion is rarely touched. In this paper, the effect of sealing treatment on the properties of anodized AA6061 was investigated by using scanning electron microscopy (SEM), friction and wear experiment, cavitation experiment, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The experiment results showed that the oxide film under hydrothermal sealing had a superior cavitation and corrosion resistance, due to the high hardness and less defects in the film. Compared to distilled water conditions, corrosion mitigated the cavitation erosion of anodized AA6061 in simulated seawater, and the weight loss under simulated seawater after sealing was reduced up to a maximum of 30%.

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.

Effect of Si and prolonged time on interfacial morphologies and cavitation erosion behavior of directionally solidified Fe-B alloy in flowing liquid zinc

The effect of Si and prolonged time on interfaces and cavitation erosion behavior of directionally solidified (DS) Fe-B alloy in flowing liquid zinc was investigated. The results show Si enriches in α-Fe intragranular and α/Fe2B boundaries to refine textured grains. DS Fe-B alloy with 2.5 wt%Si exhibits the best cavitation erosion resistance to flowing zinc, which is attributed to formation of alternating distributed Γ-Fe3Zn10 and FeSi and subsequently columnar ζ-FeZn13. Cavitation erosion resistance mechanism of DS Fe-B alloy with 2.5 wt%Si is manifested that Si-induced Γ-Fe3Zn10 and FeSi and the rooting-whisker ζ-FeZn13 layer can inhibit spallation and cracks of Fe2B and products.

CAVITATION EROSION BEHAVIOR OF WC–Co COATINGS ON TURBINE STEEL DEPOSITED BY COLD SPRAY

A renowned hard coating material (WC–Co) has the potential to overcome cavitation erosion (CE) in hydromachinery components. Hydro turbines that employ silt-filled water for electricity generation create a lot of metal waste due to erosion and cavitation caused by the particles. There is an urgent need for repair of hydropower components that have undergone damage due to cavitation. In this investigation, tungsten carbide composite coatings were produced on 13Cr4Ni (CA6NM) stainless steel substrates using the cold spray method. In order to create high-quality coatings, nitrogen was used as the propellant gas. The coating microstructures were characterized by EDS, SEM XRD, and microhardness tests. Cold-sprayed WC–Co-based coatings were exposed to enhance the cavitation erosion resistance of CA6NM steel. Cold spray coating prepared with WC-12/17Co powder has shown excellent wear-resistant properties due to higher hardness and lower porosity.

Effect of Marine Bacillus Subtilis on Cavitation Erosion Resistance of HVOF-Sprayed WC-10Co-4Cr Coating in Artificial Seawater

Effect of Marine Bacillus Subtilis on Cavitation Erosion Resistance of HVOF-Sprayed WC-10Co-4Cr Coating in Artificial Seawater

Microstructure, wettability, cavitation and corrosion performance of aluminum (Al6061) coated with RF-sputtered AlN thin film

This study addresses the challenge of enhancing aluminum substrates with AlN coatings for improved durability. Novel RF-sputtered AlN coatings were developed, demonstrating deposition with equiaxed crystals and a predominant presence of aluminum and nitrogen. The coatings exhibited hydrophobic properties as shown by contact angle measurements. Cavitation erosion resistance was systematically analyzed, revealing optimal parameters for minimizing mass loss, including jet velocity, impingement angle, and stand-off distance, thereby showcasing the protective role of the RF-sputtered AlN coating. Response Surface Methodology (RSM) provided insights into the correlation between operational parameters and mass loss, leading to process optimization with specific mass loss values and high desirability percentages. XPS analysis of corroded AlN on Al-6061 revealed aluminum compounds, sodium, NaCl, and oxidation products, aligning with SEM/EDS results and confirming the coating's effectiveness in mitigating corrosion. Carbon and oxygen were the most abundant elements by weight and peak area. Overall, this study offers valuable insights into the multifaceted performance and protective capabilities of RF-sputtered AlN coatings.

Microstructural transformation and corrosion–cavitation behavior of ultrasonic nanocrystal surface modified nickel aluminum bronze (NAB)

In this study, nickel–aluminum bronze (NAB) is optimized by ultrasonic nanocrystal surface modification (UNSM), and its surface microstructural evolution, surface hardness, electrochemical corrosion behavior, and cavitation erosion behavior are investigated. The potentiodynamic polarization curves and electrochemical impedance spectra before and after UNSM treatment of NAB are measured using a typical three-electrode system. The cavitation erosion process is simulated through the vibration of ultrasonic waves underwater, and the cavitation erosion resistance performance of various specimens is evaluated. UNSM significantly refines the coarse and heterogeneous multi-phase structure of the cast NAB, providing a relatively uniform and dispersed structure. Simultaneously, severe plastic deformation rapidly increases micro-strains on the NAB surface, which effectively improves its surface hardness from 211 to 360 Hv. After UNSM treatment, the corrosion potential increases slightly; and the passivation potential and current decrease considerably, dropping from 207 to 103 mV and from 5.23 to 2.41 mA/cm2, respectively. This is primarily because of the slowdown of selective-phase corrosion and the uniform formation of an oxide film. Additionally, UNSM parameters affect corrosion potential by regulating surface roughness. A smoother surface corresponds to a higher corrosion potential at the same load. UNSM treatment significantly improves the cavitation corrosion resistance of NAB, primarily because an increase in hardness and uniform distribution of structure effectively slows the speed of crack formation and propagation, which is a result of the synergistic improvement of mechanical and corrosion resistance properties.

Effects of W element on the microstructure, wear and cavitation erosion behavior of CoCrFeNiMnWx high entropy alloy coatings by laser cladding

CoCrFeNiMnWx (x = 0, 0.5, 1, 1.5, 2) high entropy alloy (HEA) coatings were prepared on the surface of 304 stainless steel (304 SS) by laser cladding technology. The effects of W addition on the microstructure, microhardness, friction and wear properties, and cavitation erosion (CE) resistance of the coatings were thoroughly studied. The results show that the phase structure of the CoCrFeNiMnWx HEA coatings exhibits FCC structure, and the microstructure is typical dendrite (DR) and inter-dendrite (ID) morphology. With the increase of W content, the average grain size of CoCrFeNiMnWx HEA coatings gradually decreases. The microhardness of CoCrFeNiMnWx HEA coatings increases first and then decreases due to the brittle cracking caused by the excessive addition of W element. The wear resistance of CoCrFeNiMnW1 HEA coating is the highest, and its wear rate is much lower than that of CoCrFeNiMn HEA coating without W addition. The wear mechanism of CoCrFeNiMnWx HEA coatings is mainly adhesive wear, abrasive wear and oxidation wear, and the fatigue wear mechanism appears on CoCrFeNiMnW2 HEA coating. In addition, CoCrFeNiMnW1 HEA coating displays the highest CE resistance, and its mass loss after CE in 3.5 wt%Nacl solution is lower than that of CoCrFeNiMn HEA coating. The appropriate addition of W element can effectively improve the resistance to wear and CE of CoCrFeNiMnWx HEA coatings, showing a great potential in improving the service lifespan of overflow parts in marine environment.

Cavitation erosion-corrosion properties of as-cast TC4 and LPBF TC4 in 0.6 mol/L NaCl solution: A comparison investigation

In this work study, a comparative analysis was undertaken to investigate investigation into the cavitation erosion (CE) and corrosion behavior of laser powder bed fusion (LPBF) TC4 and as-cast TC4 in 0.6 mol/L NaCl solution. Relevant results indicated that LPBF TC4 revealed a rectangular checkerboard-like pattern with a more refined grain size compared to as-cast TC4. Meanwhile, LPBF TC4 surpassed its as-cast counterpart in CE resistance, demonstrating approximately 2.25 times lower cumulative mass loss after 8 h CE. The corrosion potential under alternating CE and quiescence conditions demonstrated that both LPBF TC4 and as-cast TC4 underwent a rapid potential decrease at the initial stages of CE, while a consistent negative shift in corrosion potential was observed with the continuously increasing CE time, indicative of a gradual decline in repassivation ability. The initial surge in corrosion potential during the early CE stages was primarily attributed to accelerated oxygen transfer. As CE progressed, the significant reduction in corrosion potential for both LPBF TC4 and as-cast TC4 was attributed to the breakdown of the passive film. The refined and uniform microstructure in LPBF TC4 effectively suppresses both crack formation and propagation, underscoring the potential of LPBF technology in enhancing the CE resistance of titanium alloys. This work can provide important insights into developing high-quality, reliable, and sustainable CE-resistant materials via LPBF technology.

Influence of surface finishing by grinding on the cavitation erosion resistance of 316L and NiAl-bronze

Improving the mechanical properties of bulk and near-surface materials and alternating the dynamics of cavitating bubbles are two main methods to reduce cavitation erosion damage. Grinding and polishing, as two common surface finishing stages, can alter the cavitation erosion damage on metallic materials by affecting both the bubble dynamics and the mechanical properties of the surface. In this paper, the ultrasonic cavitation erosion resistance of 316L and NiAl-bronze alloys, each with two initial surface conditions of grinding and polishing is investigated, focussing on the material reaction. The mechanisms of material removal are discussed based on surface and subsurface observations to explain the effect of surface finishing on the cavitation erosion damage. After 8.5 h cavitation erosion testing time, a lower erosion mass loss was obtained for both alloys in the ground state as compared to the polished state suggesting that grinding can improve the cavitation erosion resistance of alloys. On the other hand, the polishing process improved the erosion resistance of NiAl-bronze at the early stages of cavitation. This is discussed in light of the two distinct surface characteristics of roughness and hardness, which, in turn, tend to increase and decrease cavitation erosion damage. Planar crystallographic boundaries and intermetallic-matrix interfaces were found to be the most susceptible sites to early erosion damage on the polished 316L and bronze, respectively.

Influence of TiO2dopingand spraying power on the microstructure, mechanical properties and cavitation erosion resistance of YSZ coatings

Yttria-stabilized zirconia (YSZ) and TiO2- doped YSZ (TiYSZ) coatings were prepared using Atmospheric Plasma Spraying (APS) at different power levels to protect of flow passage components from cavitation erosion. We analyzed, the effects of TiO2 doping and spraying power on the coatings' phase structure, microstructure and mechanical properties using XRD, Raman spectroscopy, SEM, Vickers hardness and nano-indentation. We tested the cavitation erosion behavior of TiYSZ coatings and YSZ coatings (as a reference) in a laboratory setting employing vibration-induced cavitation in accordance with ASTM standard G32-16. The results showed that the YSZ coating contained 50% c-phase and 50% t-phase, while the TiYSZ coating contained approximately 78 % c-phase. Spraying power hadlittle effect on the phase structure of either coating. However, higher spraying power increased the density of the coating, leading to greater microhardness. TiYSZ coatings were denser than YSZ at any power level and did not exhibit a distinct microcolumnar grain structure, unlike YSZ. Additionally, TiYSZ coatings displayed better mechanical properties, including higher hardness, elastic modulus, toughness, and fracture strength compared to YSZ. As a result, the cavitation resistance of TiYSZ coatings improved by about 50% compared to YSZ. Furhermore, we found that chemical degradation of YSZ-based ceramics under cavitation erosion conditions plays a role in cavitation erosion. We also observed that cavitation-induced amorphization is a key mechanism contributing to this degradation.

Trade-Off Among Cavitation Erosion Resistance, Corrosion Resistance, and Antifouling Properties of HVOF-Sprayed WC-CoCr Coating via Adding Stainless Steel and Copper

Trade-Off Among Cavitation Erosion Resistance, Corrosion Resistance, and Antifouling Properties of HVOF-Sprayed WC-CoCr Coating via Adding Stainless Steel and Copper