Ultrasonic Impact Research Articles

Exfoliation behavior of EN AW 7020 with T6, step aging and ultrasonic impact peening processes

Abstract In this study the effect of T6 heat treatment, two-step aging treatment and ultrasonic impact peening on the exfoliation corrosion behavior of welded EN AW 7020 was investigated. Exfoliation tests were performed according to the ASTM G34-01 standard. As expected, as a result of the tests, the base material region of all three samples were showed better corrosion resistance than the heat-affected region. Ultrasonic impact peening and two-step aging treatment was observed that improved EXCO sensitivity in the weld area. When sorting was made by considering the resistance to corrosion of the heat affected zone of the samples, it was observed that the best resistance was shown by the sample with two-step aging treatment, and the worst resistance was shown by the sample with T6 heat treatment.

Ultrasonic Impact Treatment (UIT) combined with powder bed fusion (PBF) process for precipitation hardened martensitic steels

High-strength martensitic stainless steels such as 17–4 PH (SS 17–4 PH) generally exhibit poor ductility and strain-hardening rates. In this study, an Ultrasonic Impact Treatment (UIT) is combined with a powder bed fusion (PBF) manufacturing process with the objective of enhancing the mechanical properties of SS 17–4 PH. UIT is introduced as a surface peening step at regular intervals during the PBF process after depositing a set of predetermined number of layers. The coupon specimens extracted from the build are then subjected to a post-build heat treatment. Then the microstructural and the mechanical properties of these specimens are characterized. The characterizations reveal that the heavy plastic deformation induced by UIT drives microstructural relaxation and recrystallization under heat treatment, reducing defects extensively. The heavy plastic deformation also drives diffusional reversion of the austenite phase during deposition and an inhibition of the martensitic phase transformation during the post-build heat treatment. As a result, the UIT specimens subjected to post-build heat treatment exhibit remarkable enhancement in ductility along with high strength and strain-hardening rate compared to the non-UIT PBF specimens under as-built condition.

Effect of high-frequency dynamic characteristics in the ultrasonic surface rolling process on the surface properties

Ultrasonic surface rolling process (USRP) is a combination of ultrasonic impact and deep rolling techniques. However, the addition of ultrasonic vibrations complicates the working mechanism of USRP tools. Existing studies rarely consider the evolution of dynamic characteristics in USRP tools resulting from changes in ultrasonic amplitudes, which undoubtedly exert a significant influence on surface properties. Moreover, they typically limit the ultrasonic amplitude to a small range. This study aims to identify the boundary process parameters to differentiate between stable and unstable dynamic characteristics during USRP and to compare their effects on the surface integrity and the plastic deformation. Therefore, an equivalent USRP tool model was proposed to analyse the working mechanism at a large-scale ultrasonic amplitude. The boundary USRP parameters responsible for different dynamic characteristics were experimentally explored. Finally, comparative USRP experiments on the Ti-6Al-4 V alloy were conducted, and it was observed that USRP parameters under stable dynamic characteristics were beneficial to the excellent surface roughness. Conversely, altering the ultrasonic amplitude to attain unstable dynamic characteristics leads to a notable degradation in the surface quality; however, the extent of plastic deformation is significantly increased. This study provides insights into the effects of dynamic characteristics in USRP, thereby contributing to a deeper understanding of the process and facilitating effective design of process parameters.

Tailoring elastic, mechanical and texture properties of Cu-37Zn brass by ultrasonic impact treatment applied at ambient and cryogenic temperatures

The study examines the changes in elastic parameters and mechanical properties and the evolution of texture of thin plate specimens of Cu-37Zn alloy strain-induced at room and cryogenic temperatures using ultrasonic impact treatment (UIT) with wave-reflecting anvil. The precise measurements of the mass densities (ρ) and bulk-wave ultrasonic velocities (vij) by means of the pulse-echo method using a home-made automated apparatus provides quantitative data regarding the Debye temperature TD, elastic (E), shear (G) and bulk (B) moduli, Poisson coefficient (η), hardness HV, and Milman’s plasticity parameter δH, of the UIT-processed specimens. In addition, XRD, EBSD, TEM, and SAED analyses are used to characterize crystallographic texture and microstructure evolutions. As shown, the surface severe plastic deformation induced by multiple impacts during the UIT processing accompanied by ultrasonic vibrations results in an increase in TD, E, G, and HV and a decrease in η, B, and δH, which are more pronounced for air-UIT. Unusual dislocation activity is promoted by ultrasonic vibrations. Observed twinning and shear bands in cryo-UIT-ed specimen provide to the formation of the brass-type texture while the stress relaxation, unusual dislocation activity stimulated by ultrasonic vibrations and dislocation cell formation in the air-UIT-ed specimen leads to the copper-type texture. The longer UIT provides the nanostructuring regardless of the involved microscopic mechanisms and used temperature conditions.

Evaluation and optimization of volume fraction and aspect ratio of Polyethylene Terephthalate (PET) fibers in self-compacting lightweight concrete

ABSTRACT Use of Polyethylene Terephthalate (PET) fibers to reinforce the performance of self-compacting lightweight concrete (SCLC) is reported. Evaluation and optimization of the fiber addition is based on different properties. SCLC mixes were designed using three volume fractions Vf (0.5%, 0.75% and 1%) and three aspect ratios (l/d = 15, 30 and 45) of fibers. Slump flow, T500, L-box, segregation, density, absorption, porosity, compressive, splitting tensile and flexural strengths, modulus of elasticity, ultrasonic pulse velocity, thermal conductivity, flexural toughness, and impact resistance tests were performed and evaluated statistically. The results indicated that PET fibers in fresh SCLC negatively affected the flowability and passing ability, while they improved the segregation resistance. Compressive strength and modulus of elasticity slightly increased, whereas the tensile strength was significantly improved. Substantial improvements in flexural toughness, thermal and impact resistances were recorded, indicating beneficial enhancement in toughness and ductility. Less desirably, SCLC with PET showed slight increases in absorption and porosity. The statistical analysis showed that the fiber Vf controlled majority of the tested properties rather than the aspect ratio. Based on desirability function and multi-objective optimization, the optimum Vf and l/d were 0.65% and 35.6, respectively. Theoretical obtained values were verified experimentally for all properties with 0 to ±5% variance.

Effect of ultrasonic surface impact on the microstructural characterization and mechanical properties of 316L austenitic stainless steel.

In the present study, effect of ultrasonic impact treatment (UIT) on the microstructural characterization and mechanical properties of 316L stainless steel (hereinafter referred to as 316L) was investigated experimentally. The fatigue fracture mechanism of 316L before and after UIT was revealed. The experimental results indicated that the martensitic grain size induced at the impact edge was about 2.00 Å. The surface modified 316L formed a gradient nanostructure and induced a martensitic phase transformation. The hardness of the surface layer of the modified 316L was twice the hardness of its matrix. The tensile strengths of 316L before and after UIT were 576 MPa and 703 MPa, respectively. The stretching stripes of 316L were more disordered after UIT. The fatigue strengths of 316L before and after UIT were 267 MPa and 327 MPa, respectively. The fatigue cracking of 316L started from the austenite grain boundaries. The fatigue fracture surface was relatively rough. The fatigue crack sources of the modified 316L came from internal inclusions. The inclusions were oxides dominated by SiO2. As the stress range increased, the crack initiation site migrated to the interior and the fatigue fracture surface became flatter.

Surface gradient structures in single-crystal nickel alloy induced by ultrasonic-assisted high-speed grinding

The gradient structures in surface layer of single-crystal nickel alloy (SX alloy) were produced (i.e., nanograin, submicron grain and coarse single crystal of bulk material) by means of ultrasonic-assisted high-speed grinding (UAHSG). The surface layer with a grain size gradient (from 29.7 to 111.8 nm) along depth from the treated surface featured impressive nano-indentation hardness (up to 12.1 GPa) beyond the initial SX alloy. The coupled effects of high rotation speed of abrasive grain (100 m/s) and the severe ultrasonic vibration impact (up to 4.3 times per contact cycle) induced large strain (up to 6.67) and ultrahigh strain rate (∼109 s−1), resulting in the superiority of such a structure gradient. This study suggests a new approach of UAHSG that can not only achieve high machining efficiency, but also make nickel alloy stronger by tailoring the surface layer gradient structures.

Simultaneous fabrication of Ti-MoS2 self-lubricating coatings and gradient structures to improve the wear resistance of AZ91D alloys

Magnesium alloys are essential for lightweight manufacturing. Nevertheless, defects such as low hardness and poor wear resistance severely restrict their further applications. Ultrasonic impact treatment (UIT) was used to simultaneously fabricate surface Ti-MoS2 self-lubricating coatings and interior gradient structures on AZ91D magnesium alloy for the first time. The surface morphology and microstructure were investigated, the tribological properties were evaluated at various normal loads, and the formation principles and anti-wear mechanisms of coatings and gradient structures were revealed. The findings indicate that the coatings present a particle-stacking microstructure. The gradient structures were characterized by grain, dislocation, and hardness distribution from greater to lesser along the depth direction. At all loads, the UIT samples exhibited superior anti-wear properties. Compared to untreated samples, the UIT sample's wear volume at 5 N, 15 N, and 25 N loads was reduced by 89.78 %, 84.23 %, and 43.88 %, respectively. The wear surface analysis indicates that the Ti-MoS2 coatings effectively enhance the lubricity of friction surfaces. Additionally, gradient structure works when the coatings fail and reduces the shear deformation, further reducing wear. This work presents a new method for fabricating simultaneously surface coatings and interior gradient structures using UIT, contributing to improving the anti-wear properties of magnesium alloys and enhancing their utilization in lightweight manufacturing fields.

Deformation Mechanisms and surface/interface Characteristics of Titanium-based Thermoplastic FMLs under Ultrasonic Impact Loading

Some typical defects like delamination, fiber fracture, non-uniform resin distribution and springback are inevitable as titanium-based thermoplastic FMLs are formed by general stamping process at elevated temperature due to the significant differences of various constituent materials in mechanical and thermal properties as well as deformation mechanism. Thus, a novel ultrasonic impact sizing/shaping process method was proposed in the present work, in which a stepped horn and impact tools with a cylindrical tip end was designed by means of vibration modal and harmonic response analysis, and the corresponding experiment setup was established to verify the process mentioned above. Moreover, ultrasonic impact tests were carried out for titanium-based FMLs stacked by titanium sheet, thermoplastic resin film and carbon fiber reinforced fabric to reveal their sizing/shaping mechanism and the effect of key process parameters such as ultrasonic amplitude, scanning speed of impact tool and its tip end diameter on the surface and interface characteristics of titanium-based FMLs. The research results show that the ultrasonic impact scheme with the ultrasonic amplitude of 12 μm, the scanning speed of impact tool within 2 mm/s ∼ 3 mm/s, the tip end diameter of impact tool within Ø4mm∼Ø6mm are proper for the ultrasonic impact sizing/shaping process of titanium-based FMLs.

Research on the corrosion resistance and the passive film growth of Ni-based superalloy surface treated by ultrasonic impact

PurposeThe purpose of this study is to investigate the corrosion resistance of superalloys subjected to ultrasonic impact treatment (UIT). The passive film growth on the superalloys’ surface is analyzed to illustrate the corrosion mechanism.Design/methodology/approachElectrochemical tests were used to investigated the corrosion resistance of GH4738 superalloys with different UIT densities. The microstructure was compared before and after the corrosion tests. The passive film characterization was described by electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS) tests.FindingsThe compressive residual stress and corrosion resistance of the specimens significantly increased after UIT. The order of corrosion resistance is related to the UIT densities, i.e. 1.96 s/mm2 > 1.71 s/mm2 > 0.98 s/mm2 > as-cast. The predominant constituents of the passive films are TiO2, Cr2O3, MoO3 and NiO. The passive film on the specimen with 1.96 s/mm2 UIT density has the highest volume fraction of Cr2O3 and MoO3, which is the main reason for its superior corrosion resistance.Originality/valueThis study provides quantitative corrosion data for GH4738 superalloys treated by ultrasonic impact. The corrosion mechanism is explained by the passive film’s characterization.

Acceleration mechanism of abrasive particle in ultrasonic polishing under synergistic physical vibration and cavitation: Numerical study

Ultrasonic technology is widely applied in the engineering ceramic polishing processes without the limitation of material properties and ideally integrated into computer numerical control system. Ultrasonic-induced cavitation and mechanical vibration effect could accelerate the motion of solid abrasives. The individual behaviors of microjet/shockwave of ultrasonic cavitation in gases and liquids, and micro-abrasives with simple harmonic vibrations in solids and liquids has been extensively studied. To conduct a systematic and integrated study of abrasives behavior in the polishing contact region involving abrasive, surround-workpiece wall, ultrasonic physical vibration, and ultrasonic cavitation impact, a novel model integrating the free abrasive motion velocity and fixed abrasive indentation depth under multi-scale contact was proposed according to Hertzian contact theory, Greenwood-Williamson model, indentation deformation theory, the basic equations of cavitation bubble dynamics, cavitation impact control equations, and Newton's law of motion equation. The effects of ultrasonic amplitude, ultrasonic frequency, preloading force and particle size on the proposed model were investigated by theoretical analysis and numerical simulations. Ultrasonic physical vibration mainly influences the dynamic gap and further influence the number of different abrasives. Furthermore, the indentation depth of fixed abrasive depends mainly on the abrasive geometry. As the contact gap and abrasive size decrease, the indentation depth gradually decreases. Under the synergistic effect of cavitation-induced shock wave and microjet, the velocity of free abrasive in this paper is generally 0–150 m/s, and the kinetic energy of free abrasive increases roughly linearly with increasing frequency and approximately as a quadratic function with increasing particle size. Increasing the preloading force leads to a reduction in the abrasive kinetic energy. Besides, the kinetic energy induced by the shock wave has a cliff-like increment at an amplitude of 0.7–0.8 μm. It is revealed that the abrasive kinetic energy is suppressed by the cavitation bubble expansion and collapse at smaller ultrasonic pressure amplitude and surround-wall distance. This research provides a theoretical reference for the modeling of potential defects and material removal on the workpiece surface caused by abrasive motion during polishing, and reduces the trial cost for parameter optimization in actual polishing processing.

Enhanced Wear Behavior of a Stainless Steel Coating Deposited on a Medium-Carbon Low-Alloy Steel Using Ultrasonic Impact Treatment

This study aims to explore the effects of ultrasonic impact parameters on the surface modification of a stainless steel coating deposited on a medium-carbon low-alloy steel using argon arc surfacing welding. Ultrasonic impact treatment (UIT), at three different vibration strike numbers (40,000 times/(mm2), 57,600 times/(mm2), and 75,000 times/(mm2)) marked UIT–1, UIT–2, and UIT–3, respectively, was carried out to modify the surface structure and properties of the stainless steel coating. The surface morphological and structural features, phase compositions, grain size, topography, micro-mechanical properties, as well as the wear resistance of the coating before and after UIT with different impact parameters were experimentally investigated. The results of optical microscopy (OM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and X-ray diffraction (XRD) analyses revealed that the grain refinement accompanied by the formation of the strain-induced α′–martensite occurred on the UIT-treated coating surface. With the increase in the vibration strike number, the surface grain size and roughness decreased, while the α′–martensite content increased. Micro-hardness after UIT was increased by about 19% (UIT–1), 39% (UIT–2), and 57% (UIT–3), and the corresponding wear rate obtained was decreased by 39%, 72%, and 85%, respectively. Significant improvements in wear resistance were achieved using UIT. However, an excessive vibration strike number on the per unit area (/mm2) might result in unwanted micro-cracks and delamination on the treated surface, deteriorating the performance of the coating. These findings validate that UIT parameters (such as the vibration strike number on per unit area) are of great importance to bringing about improvements in wear performance, and UIT is found to have a high potential in modifying the surface characteristics and optimizing the mechanical performances of the deposited coating for a wide range of potential applications.

Increasing the efficiency of drying cellulose by ultrasonic influence

Relevance. Significant part of renewable and fossil energy resources is spent to generate heat and electricity needed to implement drying. At the same time, cellulose drying, due to the large-tonnage production, is one of the significant consumers of energy resources. One of the ways to reduce energy costs of drying is ultrasonic vibrations impact. There are practically no studies on ultrasonic exposure during cellulose drying. Therefore, it is necessary to consider possible options for non-contact ultrasonic treatment during convective drying of wood cellulose. Main aim. To identify the most rational options for placing the material to be dried, taking into account the direction of exposure to ultrasonic vibrations and the flow of warm air relative to the layers of the material to be dried at different temperatures. Objects. Non-contact ultrasonic action on wood cellulose. Methods. Mathematical modeling based on the finite element method was used to determine the distribution of oscillation amplitudes of a disk radiator. In the experimental part of the research, a material moisture content was determined by the weight method using verified technical means. Results. When ultrasonic vibrations have parallel direction relative to cellulose thin layers, a 2.5-fold reduction in drying time was shown at a sound pressure level of 162 ±3 dB and a drying agent temperature of 60 °C. The authors have found that temperature decrease of a drying agent makes it possible to increase the relative efficiency of ultrasonic treatment. An assessment of energy efficiency showed that the use of ultrasonic exposure leads to a 2.3-fold decrease in the energy spent on drying compared to only convective drying, all other things being equal. The conducted studies confirmed the effectiveness of the ultrasonic drying method for industrial use and made it possible to recommend options for the most rational placement of the material to be dried when designing the structures of drying chambers.

Effect of ultrasonic impact treatment on the microstructure and properties of laser cladded CoCrFeNiMox high entropy alloy coatings

Ultrasonic impact technology was applied to improve the property of laser cladded CoCrFeNiMox (x = 0, 0.25, 0.5, 0.75) high entropy alloy coatings on the surface of low-carbon steel. The phase structures and the microstructural characteristics were studied in detail through X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The microhardness distributions, wear resistance, and corrosion resistance of the samples are illustrated using a microhardness tester, a micro-friction and wear tester, and an electrochemical test system. Single FCC phase solid solution was identified to be the main phase structure, with the interdendritic σ phase precipitating with the increasing Mo content. Although ultrasonic impact treatment did not change the phase composition of the high-entropy alloy (HEA) cladding coatings, evident plastic deformation and broken σ phase appeared near the surface of the impacted layers. Through the combined effects of dislocation, fine-grain, and dispersion strengthening, the microhardness of the CoCrFeNiMox coatings was improved after ultrasonic impact treatment. In addition, ultrasonic impact treatment decreased the surface roughness and increased the wear resistance, and the main wear mechanism of the impacted layers changed from fatigue spalling to abrasive wear. The wear mass of the ultrasonically impacted layers was approximately 92 % of the laser cladded CoCrFeNiMox coatings. Furthermore, ultrasonic impact treatment improved the corrosion resistance of the HEA coatings.

Microstructure, mechanical and corrosion properties of FeCrNiCoMnSi0.1 high-entropy alloy coating via TIG arc melting technology and high-frequency ultrasonic impact with welding

With the increase in studies on high-entropy alloys and their impressive structural properties, the preparation processes and applications of high-entropy alloys have become a popular research topic in metallic materials. In this paper, the preparation of FeCrNiCoMnSi0.1 high-entropy alloy coatings was carried out by the follow-welding high-frequency power ultrasonic impact composite TIG arc melting process, the effects of different power ultrasonic impacts on the microstructure and properties of the coatings are investigated. The results showed that the average grain size is reduced by 74 % (from 278 μm to 72 μm), the average microhardness is increased by 41 % from 568 HV1 to 807 HV1, the abrasion resistance is improved by 68 % under the effect of ultrasonic impact. The ultrasonic impact treatment process can effectively refine the microstructure of the coatings and improve the strength of grain boundaries. The corrosion resistance of the coating in 3.5 wt% NaCl solution is enhanced by 65 %, the corrosion type was changed from intergranular corrosion to uniform corrosion. This is mainly caused by the ultrasonic impact treatment which suppresses the elemental segregation of Cr and Mn and improves the grain boundary strength.

Formation of the Diffusion Coatings Structure on the Surface of the Fe–Cr–Al Alloy during Hot-Dip Aluminizing with Ultrasonic Impact

Formation of the Diffusion Coatings Structure on the Surface of the Fe–Cr–Al Alloy during Hot-Dip Aluminizing with Ultrasonic Impact

Microstructure and properties of Ti60 alloy by laser solid forming and ultrasonic impact hybrid manufacturing

The hybrid manufacturing of laser solid forming (LSF) and ultrasonic impact treatment (UIT) was used to improve the structure and properties of Ti60 alloy by strengthening the surface layer-by-layer. The microstructure, mechanical properties, and burn resistance of LSFed Ti60 samples before and after UIT by SEM, TEM, and XRD were analyzed and compared. The results showed that the grains of LSFed Ti60 alloy were refined and metallurgical defects were reduced after the UIT process. Meanwhile, the deposited layer was severely deformed after UIT and nanocrystals were formed on the surface. In addition, the microhardness of the deposition layer surface increased and the residual stress changed from tensile stress to compressive stress. The area of the ablation hole was reduced by 21% and the proportions of Mo, Nb, and Zr elements increased. In summary, hybrid manufacturing of LSF and UIT can improve the microstructure and properties of LSFed Ti60 samples.

A method to eliminate the cracking of Stellite 6 + WC laser cladding layers using ultrasonic impact treatment

Enhancing the wear resistance of coatings is a widely used technique that involves adding WC ceramic particles to Stellite alloy. Practical applications may be challenging due to the significant coating breaking that might result from the inclusion of WC ceramic particles. In this paper, the ultrasonic impact treatment (UIT) method was used to decrease the residual stress during the cladding process of WC reinforced Stellite 6 alloy coating, consequently reducing the coating's tendency to crack. The results showed that the cracking can be eliminated in the coating reinforced by 20 % WC ceramic particles utilizing UIT.

Nonporous water-proof coatings with resistance to harsh water environments and spontaneous dewetting

The superhydrophobic surfaces in harsh water environments (such as deep sea or extreme rainstorms) often suffer from irreversible air layer collapse or structural damage. However, the rough micro/nano-structures dominating superhydrophobicity are usually loose and fragile, which generate insufficient anti-wetting capillary pressure to deal with harsh water environments. Here, an electrostatic-field-assisted aerosolization deposition (EFAAD) method was proposed to fabricate a densified superhydrophobic surface featuring nonporous microlevel protrusion with nanoscale secondary modification. The mechanism of controllable deposition was investigated and spraying parameter configuration was optimized. The EFAAD coating showed exciting tolerance of high-speed jet impact (85.4 m/s, Weber number of 202588), ultrasonic micro jet impact (25 min), and hydrostatic pressure (5 MPa) for the coordinated structural robustness and air layer stability. Even though the superhydrophobicity of EFAAD coating was compromised under extreme conditions, the water film could dewet spontaneously induced by any bubble with radium than 130 μm. Moreover, the EFAAD coating has also proved comprehensive tolerance to tape peeling (more than 400 cycles), UV irradiation, and severe solution corrosion, exhibiting particularly promising for various high-water-pressure applications.

Effect of Ultrasonic Impact Treatment on Microstructure and Fatigue Life of 3D Printed Ti–6Al–4V Titanium Alloy

Effect of Ultrasonic Impact Treatment on Microstructure and Fatigue Life of 3D Printed Ti–6Al–4V Titanium Alloy