The application of ultrasonic vibration during the casting process has been proven to refine the microstructure and enhance the properties of the casting.By using the direct inserting method,wherein the ultrasonic hor...The application of ultrasonic vibration during the casting process has been proven to refine the microstructure and enhance the properties of the casting.By using the direct inserting method,wherein the ultrasonic horn is inserted directly into the melt,ultrasonic treatment can be utilized in the semi-continuous casting process to produce aluminum ingots with simple shapes.However,due to the attenuation of ultrasound,it is challenging to apply the direct inserting method in the die casting process to produce complex castings.Thus,in this study,the impact of ultrasonic vibration on the microstructure of a gravity die-cast AlSi9Cu3end cap was investigated by applying ultrasonic vibration on the core(indirect method).It is found that the effect of ultrasonic vibration relies greatly on the resonance mode of the core.Selection of ultrasonic vibration schemes mainly depends on the core structure,and only a strong vibration can significantly refine the microstructure of the casting.For castings with complex structures,an elaborated ultrasonic vibration design is necessary to refine the microstructure of the specified casting.In addition,strong vibration applied on the feeding channel can promote the feeding ability of casting by breaking the dendrites during solidification,and consequently reduce the shrinkage porosity.展开更多
In the process of semi-solid slurry preparation with direct ultrasonic vibration (UV) by dipping the horn into the melt, one of the questions is whether the gas content in the melt would be increased or not by the cav...In the process of semi-solid slurry preparation with direct ultrasonic vibration (UV) by dipping the horn into the melt, one of the questions is whether the gas content in the melt would be increased or not by the cavitation effect of ultrasonic vibration. By application of quantitative gas content measurement technique, this paper investigated the effect of the ultrasonic vibration on the gas content of both the melt and the semi-solid slurry of Al-Si alloys, and the variations of the gas contents in two kinds of aluminum alloys, i.e., A356 alloy and Al-20Si-2Cu-1Ni-0.6RE alloy (Al-20Si for short). The results show that ultrasonic vibration has an obvious degassing effect on the molten melt, especially on the semi-solid slurry of Al-Si alloy which is below the liquidus temperature by less than 20 ℃. The ultrasonic degassing efficiency of the A356 alloy decreases with the reduction of the initial gas content in the melt, and it is nearly unchanged for the Al-20Si alloy. The gas content of both alloys decreases when the ultrasonic vibration time is increased. The best vibration time for Al-20Si alloy at the liquid temperature of 710 ℃ and semi-solid temperature of 680 ℃ is 60 s and 90 s, respectively; and the degassing efficiency is 48% and 35%, respectively. The mechanism of ultrasonic degassing effect is discussed.展开更多
This paper aims to reviewthe state-of-the-art of ultrasonic vibration assisted friction stir welding(UVAFSW) process. Particular attention has been paid on the modes of ultrasonic exertion,experimental results and eff...This paper aims to reviewthe state-of-the-art of ultrasonic vibration assisted friction stir welding(UVAFSW) process. Particular attention has been paid on the modes of ultrasonic exertion,experimental results and effects of ultrasonic vibrations on process effectiveness and joint quality. The trends of various aspects with and without ultrasonic vibrations in FSW process are studied and presented. The influence of ultrasonic vibrations on welding loads, temperature history, weld morphology, material flow, weld microstructure and mechanical properties are revisited. Ultrasonic assisted FSW offers numerous advantages over the conventional FSW process. The superimposing of high-frequency vibrations improves various phenomena of the process and the physical,metallurgical,mechanical and tribological properties of the welded joint. The ultrasonic assisted FSW process has a potential to benefit the industry sector. A checklist listing the materials and process parameters used in the documented studies has been presented for quick reference.展开更多
The modification of eutectic silicon is of general interest since fine eutectic silicon along with fine primary aluminum grains improves mechanical properties and ductilities. In this study, high intensity ultrasonic ...The modification of eutectic silicon is of general interest since fine eutectic silicon along with fine primary aluminum grains improves mechanical properties and ductilities. In this study, high intensity ultrasonic vibration was used to modify the complex microstructure of aluminum hypoeutectic alloys. The ultrasonic vibrator was placed at the bottom of a copper mold with molten aluminum. Hypoeutectic Al-Si alloy specimens with a unique in-depth profile of microstructure distribution were obtained. Polyhedral silicon particles, which should form in a hypereutectic alloy, were obtained in a hypoeutectic Al-Si alloy near the ultrasonic radiator where the silicon concentration was higher than the eutectic composition. The formation of hypereutectic silicon near the radiator surface indicates that high-intensity ultrasonic vibration can be used to influence the phase transformation process of metals and alloys. The size and morphology of both the silicon phase and the aluminum phase varies with increasing distance from the ultrasonic probe/radiator. Silicon morphology develops into three zones. Polyhedral primary silicon particles present in zoneⅠ, within 15 mm from the ultrasonic probe/radiator. Transition from hypereutectic silicon to eutectic silicon occurs in zoneⅡ about 15 to 20 μm from the ultrasonic probe/radiator. The bulk of the ingot is in zoneⅢ and is hypoeutectic Al-Si alloy containing fine lamellar and fibrous eutectic silicon. The grain size is about 15 to 25 μm in zoneⅠ, 25 to 35 μm in zoneⅡ, and 25 to 55 μm in zoneⅢ. The morphology of the primary α-Al phase is also changed from dendritic (in untreated samples) to globular. Phase evolution during the solidification process of the alloy subjected to ultrasonic vibration is described.展开更多
The application of ultrasonic vibration to the casting process can be realized through mould(die)vibration.However,the resonant vibration of the mould is always accompanied by a non-uniform vibration distribution at d...The application of ultrasonic vibration to the casting process can be realized through mould(die)vibration.However,the resonant vibration of the mould is always accompanied by a non-uniform vibration distribution at different parts,which may induce a complex liquid flow and affect the casting fluidity during the mould filling process.The influence of non-uniform ultrasonic vibration on the fluidity of liquid AlSi9Cu3 alloy was studied by mould vibration with different vibration gradients.It is found that ultrasonic mould vibration can generate two opposite effects on the casting fluidity:the first,ultrasonic cavitation in melt induced by mould vibration promotes the casting fluidity;the second,the non-uniform mould vibration can induce a melt flow toward the weak vibration areas and turbulence there,consequently decreasing the casting fluidity.When the melt flow and turbulence are violent enough to offset the promoting effect of cavitation on fluidity,the ultrasonic vibration will finally induce a resultant decrease of casting fluidity.The decreasing effect is proportional to the vibration gradient.展开更多
In the paper, the experimental researches were carr ie d out to discuss the roundness forming rule and the influence of cutting paramet ers on roundness by ultrasonic vibration cutting of the camera’s guiding drawtu ...In the paper, the experimental researches were carr ie d out to discuss the roundness forming rule and the influence of cutting paramet ers on roundness by ultrasonic vibration cutting of the camera’s guiding drawtu be with 47.75 mm diameter and 0.6～1.5 mm wall thickness. The research results s h ow that the roundness error of ultra-thin wall parts in ultrasonic vibration cu tting is only one third of that in common cutting. The relations between the rou ndness error and the cutting parameters behave as: (1) The roundness error in co mmon cutting decreases gradually with the rise of cutting speed, while in ultras onic cutting, the roundness changes not obviously till the cutting speed is up t o a value, which is nearly equal to one third of the critical velocity. Then the roundness of workpiece will begin to increase slowly. (2) The roundness error i ncreases along with the feed rate both in common cutting and ultrasonic cutting. (3) Within the range of cutting depth in experiment, the influence of cutting d epth on the roundness error is more obvious in common cutting than that in ultra sonic vibration cutting. The conclusions are useful in machining such precise ul tra-thin wall parts. According to the tests, the following conclusions can be o btained: 1) Compared with common cutting, ultrasonic cutting can decrease effect ively roundness error of the workpiece. Under the same condition, the roundness error of the ultra-thin wall part in ultrasonic turning is about one third of t hat in common cutting. 2) In common cutting, cutting depth and feed rate have mu ch influence on the roundness and the influence of cutting velocity is little. W hile in ultrasonic cutting, the roundness was influenced heavily only when feed rate is more than 0.1 mm/r and cutting speed is more than 1/3 of the critical ro tation speed, cutting depth has little influence on the roundness in the experim ent. 3) Kerosene-oil is an optimum cutting fluid in machining ultra-thin wall workpiece. 4) To machine the ultra-thin wall precision part, ultrasonic cutting is the perfect method which can decrease the roundness error effectively an d ensure high quality of the surface.展开更多
Ultrasonic vibration technology has great potential to weaken hard rocks.Understanding the effect of ultrasonic vibration loading parameters is essential to accelerate the application of this technology in practical r...Ultrasonic vibration technology has great potential to weaken hard rocks.Understanding the effect of ultrasonic vibration loading parameters is essential to accelerate the application of this technology in practical rock engineering.In the present work,three-factor mixed-level orthogonal ultrasonic vibration rock breaking tests were conducted to investigate the influence of the main loading parameters,including confining pressure,vibration frequency,and static force,on the damage of granite specimens.The individual and combined influences were analyzed according to the porosity increase and P-wave decrease of granite specimens using the variance analysis method.The results show that the combined effect of the static force and vibration frequency mainly promotes fatigue damage of specimens,that the confining pressure determines the damage behaviour and failure mode of specimens under ultrasonic vibration,and that the confining pressure and vibration frequency are the main factors that cause the fracture concentration in the upper part of specimens,an effect mechanistically driven by the obvious load energy attenuation.The research results provide theoretical guidance for the application of ultrasonic vibration technology.展开更多
Ultrasonic vibration assisted tungsten inert gas welding was applied to joining stainless steel 316 L and low alloy high strength steel L415.The effect of ultrasonic vibration on the microstructure and mechanical prop...Ultrasonic vibration assisted tungsten inert gas welding was applied to joining stainless steel 316 L and low alloy high strength steel L415.The effect of ultrasonic vibration on the microstructure and mechanical properties of a dissimilar metal welded joint of 316 L and L415 was systematically investigated.The microstructures of both heat affected zones of L415 and weld metal were substantially refined,and the clusters ofδferrite in traditional tungsten inert gas(TIG)weld were changed to a dispersive distribution via the ultrasonic vibration.The ultrasonic vibration promoted the uniform distribution of elements and decreased the micro-segregation tendency in the weld.With the application of ultrasonic vibration,the average tensile strength and elongation of the joint was improved from 613 to 650 MPa and from 16.15%to31.54%,respectively.The content ofΣ3 grain boundaries around the fusion line zone is higher and the distribution is more uniform in the ultrasonic vibration assisted welded joint compared with the traditional one,indicating an excellent weld metal crack resistance.展开更多
Magnetic liquid can produce alternative internal pressure under the alternative high-frequency gradient magnetic field.Because it has higher bulk modulus,the internal pressure results in its volume change.Using piezoe...Magnetic liquid can produce alternative internal pressure under the alternative high-frequency gradient magnetic field.Because it has higher bulk modulus,the internal pressure results in its volume change.Using piezoelectric transducers,the ultrasonic wave generated by the vibration of magnetic liquids can be detected,which shows that the magnetic liquids have the magnetostrictive effect and can generate the ultrasonic vibration under the alternative magnetic gradient field.Some nonmagnetic abrasives and rust-proofing agents can be mixed into the magnetic liquids,under the alternative magnetic field,the abrasives held by magnetic liquids grind the surface of the workpieces,and thus,the finishing for the surface with complex shape,mold cavity and inner wall of tiny tubes can be realized.展开更多
To solve the problem of the poor plasticity and to meet the requirements of high temperature for forming titanium alloy,mechanical properties of TC2 titanium alloy under the compound energy-field(CEF)with temperature ...To solve the problem of the poor plasticity and to meet the requirements of high temperature for forming titanium alloy,mechanical properties of TC2 titanium alloy under the compound energy-field(CEF)with temperature and ultrasonic vibration were studied.The effects of CEF on tensile force,elongation,microstructure and fractography of the TC2 titanium alloy were compared and analyzed.The results show that,under the same thermal conditions,the deformation resistance of TC2 titanium alloy decreases with the increase of ultrasonic vibration energy.The formability is also improved correspondingly due to the input of ultrasonic vibration energy and its influence on the microstructure of the material.However,when the ultrasonic vibration energy is larger,the fatigue fracture will also appear,which reduces its formability.展开更多
In this paper, a new type of ultrasonic vibration de-gluing device has been designed to remove the cured epoxy resin adhesive </span><span style="white-space:normal;font-family:"">that&...In this paper, a new type of ultrasonic vibration de-gluing device has been designed to remove the cured epoxy resin adhesive </span><span style="white-space:normal;font-family:"">that </span><span style="white-space:normal;font-family:"">overflowed from the aluminum alloy structural parts in the high-speed train carriages. At present, manual removal is used to remove the cured epoxy resin adhesive that overflows at the bonding site. This method has low removal efficiency and leads to poor surface quality of the parts. The new type of ultrasonic vibration de-gluing device can solve these problems. Modal analysis and harmonic response analysis are carried out on the ultrasonic vibration oscillator system in the ultrasonic vibration de-gluing device, and the reasonable structure parameters and resonance frequency of the ultrasonic vibration oscillator system are determined. Finally, the impedance test and de-gluing effect test are carried out on the prototype of the ultrasonic vibration de-gluing device to verify the feasibility and practicability of the new type of ultrasonic vibration de-gluing device. The results show that the ultrasonic vibration de-gluing device’s stable resonant operating frequency is 28</span><span style="white-space:normal;font-family:"">,</span><span style="white-space:normal;font-family:"">270</span><span style="white-space:normal;font-family:""> </span><span style="white-space:normal;font-family:"">Hz, and the average error between the simulation and experimental results of the resonant operating frequency is less than 3%, which validates the simulation model.展开更多
The microstructure and properties of Al-20Si-2Cu-1Ni-0.4Mg alloy fabricated with semi-solid rheo-diecasting process were studied.A newly developed direct ultrasonic vibration process(DUV process) was used in the prepa...The microstructure and properties of Al-20Si-2Cu-1Ni-0.4Mg alloy fabricated with semi-solid rheo-diecasting process were studied.A newly developed direct ultrasonic vibration process(DUV process) was used in the preparation of the semi-solid slurry of this alloy.The results show that the primary Si particles in this alloy is about 20 μm in size under DUV for 90 s in the semi-solid temperature range,compared to about 30 μm in the alloy without DUV.It is discovered that the primary Si particles distribute more homogeneously and have regular shape,but have lower volume fraction after DUV.The tensile strength at room temperature is about 310 MPa,and the tensile strength and elongation of the semi-solid die castings are increased by 34% and 45%,respectively,compared with the traditional liquid die castings.The high-temperature tensile strength at 300 ℃ of this high Si aluminum alloy reaches 167 MPa,and the coefficient of thermal expansion is 17.37×10-6/℃ between 25 and 300 ℃.This indicates that this high Si content Al-Si alloy produced with the DUV process is suitable to be used in the manufacture of pistons or other heat-resistant parts.展开更多
Effect of ultrasonic vibration on deformation in micro-blanking was investigated with copper foils of different grain sizes using a developed device. It is found that maximum shearing strength is decreased by ultrason...Effect of ultrasonic vibration on deformation in micro-blanking was investigated with copper foils of different grain sizes using a developed device. It is found that maximum shearing strength is decreased by ultrasonic vibration, and this effect becomes bigger for coarse grain than that for fine grain, which can be attributed to acoustic softening effect considering the absorbed acoustic energy. Surface roughness R_a of smooth zone decreases for the polishing effect of vibration at the lateral contact surface. When ultrasonic vibration is applied, the sheared deformation area becomes relatively narrow, and it leads to the reduction of radius of rollover. The analysis of cross section in sheared deformation area shows that the crack initiation is inhabited for the existence of acoustic softening, and the proportion of smooth zone is increased. Also, angle of crack propagation becomes smaller because of periodic strain, and the angle of facture surface is decreased. As a result, the quality of micro-sheet parts is improved by applying ultrasonic vibration.展开更多
In many fields of high-tech industry the ultra-t hi n wall parts are employed. In this paper the experiments were carried out to dis cuss the surface microstructure of the camera’s guided drawtube by applying ult ras...In many fields of high-tech industry the ultra-t hi n wall parts are employed. In this paper the experiments were carried out to dis cuss the surface microstructure of the camera’s guided drawtube by applying ult rasonic vibration cutting device to the traditional lathe. The influence rule of the cutting condition on the surface roughness was put forward, which was drawn by comparing the ultrasonic cutting with the common cutting by use of the cemen ted carbide tool and the polycrystalline diamond (PCD) tool. The test results sh owed that the ultrasonic cutting performs better than the common cutting in the same condition. According to the test results analyzing, the surface characteriz ation is influenced clearly by the rigidity of the acoustic system and the machi ne tool, as well the setting height of the tool tip. Otherwise, the dense regula r low frequency vibration ripples will be scraped on the machined surface. When the tool tip is set higher than the rotating center of the work piece by three t imes of the amplitude of ultrasonic vibration, the vibration ripples behave alig ht; they turn light and shade alternatively when the tool tip is lower than the rotating center of the work piece by three times of the amplitude of ultrasonic vibration. According to the test result analyzing, the following conclusions are put forward: 1) The surface roughness in ultrasonic cutting is better than that in common cutting. Under a one third critical cutting velocity, the value of th e surface roughness in ultrasonic cutting rise slightly along with the cutting v elocity, while in common cutting it decreases contrast to the cutting velocity; the curves of the surface roughness in ultrasonic cutting and common cutting see m to be alike, both increase along with the feed rate and the cutting depth, but the value in ultrasonic cutting is smaller in the same condition.2) The influen ce of the coolant on the surface roughness cannot be ignored. The kerosene can b e employed to improve the surface roughness in ultrasonic machining.3) In ultras onic cutting process of aluminum alloy ultra-thin wall work piece, the PCD tool performs better than the cemented carbide tools.4) The vibration ripples result from the not enough rigidity of the acoustic system and the improper setting he ight of the tool tip. The departure of the tool tip from the rotating center of the work piece to some extent causes the vibration ripples on the machined surfa ce.展开更多
To decrease the diamond tool wear and improve the surface quality of the workpieces, ultrasonic vibration was applied to diamond turning of titanium alloy. The effect of vibration parameters on the surface roughness a...To decrease the diamond tool wear and improve the surface quality of the workpieces, ultrasonic vibration was applied to diamond turning of titanium alloy. The effect of vibration parameters on the surface roughness and the tool wear was analyzed. The results show that vibration parameters have great effects on the surface roughness and tools life. Under given conditions, the smaller the vibrating amplitude is, the larger the surface roughness(R_a) is , and the more rapidly the tools is worn. Accordingly, the higher the vibrating frequency is, the smaller the surface roughness is and the longer the tools life is. The surface roughness value (R_a) is less than 0.15μm when vibrating amplitude is 14μm and vibrating frequency is 40kHz in the experiments.展开更多
The effect of synergistic action of ultrasonic vibration and solidification pressure on tensile properties of vacuum counter-pressure casting ZL114 A alloys was studied systemically through testing and analyzing the t...The effect of synergistic action of ultrasonic vibration and solidification pressure on tensile properties of vacuum counter-pressure casting ZL114 A alloys was studied systemically through testing and analyzing the tensile strength and elongation subjected to different ultrasonic powers and solidification pressures. The results indicate that the synergistic action of ultrasonic vibration and solidification pressure can result in the refinement of grains and improvement of tensile properties. Both the highest tensile strength and elongation of aluminum alloy were obtained under synergistic action of 600 W ultrasonic power and 350 kPa solidification pressure. Moreover, the tensile fracture morphology shows obvious ductile fracture characteristics. When the solidification pressure is lower than 300 kPa, the effect of ultrasonic power on tensile strength and elongation is more obvious, but when the solidification pressure is higher than 300 kPa, the effect of solidification pressure on tensile strength and elongation is greater. Meanwhile, the size and morphology of the eutectic silicon were improved significantly by the ultrasonic vibration and pressurized solidification. The strip and massive eutectic silicon phase are completely converted into small short rod-like and evenly distributed Si phases at the grain boundary of primary α-Al.展开更多
High-intensity ultrasonic vibration was focused on the tip of conical steel specimens to induce severe plastic deformation at room temperature. We found, for the first time, that grain size smaller than 200 nm was obt...High-intensity ultrasonic vibration was focused on the tip of conical steel specimens to induce severe plastic deformation at room temperature. We found, for the first time, that grain size smaller than 200 nm was obtained. Furthermore, the sharp tip of the conical specimen became umbrella-shaped or disk-shaped. The tip size changed from 0.5 mm diameter to a disk about 5 mm diameter, representing a large amount of plastic deformation in the metal at the tip of the conical specimen.展开更多
The effects of ultrasonic vibration on the grain size and morphology of Mg2Si in Mg-4 wt% Al-1 wt%Si(AS41) alloys designed were evaluated. The results show that the major constituents of the alloy include β-Mg17Al12 ...The effects of ultrasonic vibration on the grain size and morphology of Mg2Si in Mg-4 wt% Al-1 wt%Si(AS41) alloys designed were evaluated. The results show that the major constituents of the alloy include β-Mg17Al12 and Mg2Si phase, and no difference in the type of constituents between without ultrasonic vibration and with ultrasonic vibration. Without any ultrasonic vibration, the grain size and Mg2Si phase in AS41 alloy are coare structure. However, the microstructure with fine uniform grains and Mg2Si particles are achieved with ultrasonic vibration. The crystal grains and Mg2Si particles refine with increase in the ultrasonic vibration intensity. When the ultrasonic vibration intensity was too low or too high, coarse structures could be obtained. The analysis of refinement mechanism indicates that the acoustic cavitation and flows induced by ultrasonic vibration lead to the fine uniform microstructure.展开更多
基金supported by the Natural Science Foundation of Shandong province(Grant No.ZR2021ME023)the Innovation Team Project of Jinan,China(Grant No.2019GXRC035)SQ project[2021370113124591]。
文摘The application of ultrasonic vibration during the casting process has been proven to refine the microstructure and enhance the properties of the casting.By using the direct inserting method,wherein the ultrasonic horn is inserted directly into the melt,ultrasonic treatment can be utilized in the semi-continuous casting process to produce aluminum ingots with simple shapes.However,due to the attenuation of ultrasound,it is challenging to apply the direct inserting method in the die casting process to produce complex castings.Thus,in this study,the impact of ultrasonic vibration on the microstructure of a gravity die-cast AlSi9Cu3end cap was investigated by applying ultrasonic vibration on the core(indirect method).It is found that the effect of ultrasonic vibration relies greatly on the resonance mode of the core.Selection of ultrasonic vibration schemes mainly depends on the core structure,and only a strong vibration can significantly refine the microstructure of the casting.For castings with complex structures,an elaborated ultrasonic vibration design is necessary to refine the microstructure of the specified casting.In addition,strong vibration applied on the feeding channel can promote the feeding ability of casting by breaking the dendrites during solidification,and consequently reduce the shrinkage porosity.
基金supported by the National Natural Science Foundation of China (No. 50775086)the National Basic Research Program of China (973 Program, No. 2012CB619600)
文摘In the process of semi-solid slurry preparation with direct ultrasonic vibration (UV) by dipping the horn into the melt, one of the questions is whether the gas content in the melt would be increased or not by the cavitation effect of ultrasonic vibration. By application of quantitative gas content measurement technique, this paper investigated the effect of the ultrasonic vibration on the gas content of both the melt and the semi-solid slurry of Al-Si alloys, and the variations of the gas contents in two kinds of aluminum alloys, i.e., A356 alloy and Al-20Si-2Cu-1Ni-0.6RE alloy (Al-20Si for short). The results show that ultrasonic vibration has an obvious degassing effect on the molten melt, especially on the semi-solid slurry of Al-Si alloy which is below the liquidus temperature by less than 20 ℃. The ultrasonic degassing efficiency of the A356 alloy decreases with the reduction of the initial gas content in the melt, and it is nearly unchanged for the Al-20Si alloy. The gas content of both alloys decreases when the ultrasonic vibration time is increased. The best vibration time for Al-20Si alloy at the liquid temperature of 710 ℃ and semi-solid temperature of 680 ℃ is 60 s and 90 s, respectively; and the degassing efficiency is 48% and 35%, respectively. The mechanism of ultrasonic degassing effect is discussed.
基金Sponsored by the National Natural Science Foundation of China(Grant Nos.51475272 and 51550110501)the GKP Acknow ledges the Research Fellow ship of Shandong University
文摘This paper aims to reviewthe state-of-the-art of ultrasonic vibration assisted friction stir welding(UVAFSW) process. Particular attention has been paid on the modes of ultrasonic exertion,experimental results and effects of ultrasonic vibrations on process effectiveness and joint quality. The trends of various aspects with and without ultrasonic vibrations in FSW process are studied and presented. The influence of ultrasonic vibrations on welding loads, temperature history, weld morphology, material flow, weld microstructure and mechanical properties are revisited. Ultrasonic assisted FSW offers numerous advantages over the conventional FSW process. The superimposing of high-frequency vibrations improves various phenomena of the process and the physical,metallurgical,mechanical and tribological properties of the welded joint. The ultrasonic assisted FSW process has a potential to benefit the industry sector. A checklist listing the materials and process parameters used in the documented studies has been presented for quick reference.
基金supported by the US Department of Energy,Office of Energy Efficiency and Renewable Energy,Industrial Technologies Program,Industrial Materials for the Future(IMF),under Contractor No.DE-PS07-02ID14270 with UT-Battelle,LLC
文摘The modification of eutectic silicon is of general interest since fine eutectic silicon along with fine primary aluminum grains improves mechanical properties and ductilities. In this study, high intensity ultrasonic vibration was used to modify the complex microstructure of aluminum hypoeutectic alloys. The ultrasonic vibrator was placed at the bottom of a copper mold with molten aluminum. Hypoeutectic Al-Si alloy specimens with a unique in-depth profile of microstructure distribution were obtained. Polyhedral silicon particles, which should form in a hypereutectic alloy, were obtained in a hypoeutectic Al-Si alloy near the ultrasonic radiator where the silicon concentration was higher than the eutectic composition. The formation of hypereutectic silicon near the radiator surface indicates that high-intensity ultrasonic vibration can be used to influence the phase transformation process of metals and alloys. The size and morphology of both the silicon phase and the aluminum phase varies with increasing distance from the ultrasonic probe/radiator. Silicon morphology develops into three zones. Polyhedral primary silicon particles present in zoneⅠ, within 15 mm from the ultrasonic probe/radiator. Transition from hypereutectic silicon to eutectic silicon occurs in zoneⅡ about 15 to 20 μm from the ultrasonic probe/radiator. The bulk of the ingot is in zoneⅢ and is hypoeutectic Al-Si alloy containing fine lamellar and fibrous eutectic silicon. The grain size is about 15 to 25 μm in zoneⅠ, 25 to 35 μm in zoneⅡ, and 25 to 55 μm in zoneⅢ. The morphology of the primary α-Al phase is also changed from dendritic (in untreated samples) to globular. Phase evolution during the solidification process of the alloy subjected to ultrasonic vibration is described.
基金supported by the Natural Science Foundation of Shandong province (ZR2021ME023)the Innovation Team Project of Jinan,China (2019GXRC035)
文摘The application of ultrasonic vibration to the casting process can be realized through mould(die)vibration.However,the resonant vibration of the mould is always accompanied by a non-uniform vibration distribution at different parts,which may induce a complex liquid flow and affect the casting fluidity during the mould filling process.The influence of non-uniform ultrasonic vibration on the fluidity of liquid AlSi9Cu3 alloy was studied by mould vibration with different vibration gradients.It is found that ultrasonic mould vibration can generate two opposite effects on the casting fluidity:the first,ultrasonic cavitation in melt induced by mould vibration promotes the casting fluidity;the second,the non-uniform mould vibration can induce a melt flow toward the weak vibration areas and turbulence there,consequently decreasing the casting fluidity.When the melt flow and turbulence are violent enough to offset the promoting effect of cavitation on fluidity,the ultrasonic vibration will finally induce a resultant decrease of casting fluidity.The decreasing effect is proportional to the vibration gradient.
文摘In the paper, the experimental researches were carr ie d out to discuss the roundness forming rule and the influence of cutting paramet ers on roundness by ultrasonic vibration cutting of the camera’s guiding drawtu be with 47.75 mm diameter and 0.6～1.5 mm wall thickness. The research results s h ow that the roundness error of ultra-thin wall parts in ultrasonic vibration cu tting is only one third of that in common cutting. The relations between the rou ndness error and the cutting parameters behave as: (1) The roundness error in co mmon cutting decreases gradually with the rise of cutting speed, while in ultras onic cutting, the roundness changes not obviously till the cutting speed is up t o a value, which is nearly equal to one third of the critical velocity. Then the roundness of workpiece will begin to increase slowly. (2) The roundness error i ncreases along with the feed rate both in common cutting and ultrasonic cutting. (3) Within the range of cutting depth in experiment, the influence of cutting d epth on the roundness error is more obvious in common cutting than that in ultra sonic vibration cutting. The conclusions are useful in machining such precise ul tra-thin wall parts. According to the tests, the following conclusions can be o btained: 1) Compared with common cutting, ultrasonic cutting can decrease effect ively roundness error of the workpiece. Under the same condition, the roundness error of the ultra-thin wall part in ultrasonic turning is about one third of t hat in common cutting. 2) In common cutting, cutting depth and feed rate have mu ch influence on the roundness and the influence of cutting velocity is little. W hile in ultrasonic cutting, the roundness was influenced heavily only when feed rate is more than 0.1 mm/r and cutting speed is more than 1/3 of the critical ro tation speed, cutting depth has little influence on the roundness in the experim ent. 3) Kerosene-oil is an optimum cutting fluid in machining ultra-thin wall workpiece. 4) To machine the ultra-thin wall precision part, ultrasonic cutting is the perfect method which can decrease the roundness error effectively an d ensure high quality of the surface.
基金This study was funded by the National Natural Science Foundation of China(Project Name:Research on mechanism of ultrasonic vibration breaking rock,Project No.41572356).
文摘Ultrasonic vibration technology has great potential to weaken hard rocks.Understanding the effect of ultrasonic vibration loading parameters is essential to accelerate the application of this technology in practical rock engineering.In the present work,three-factor mixed-level orthogonal ultrasonic vibration rock breaking tests were conducted to investigate the influence of the main loading parameters,including confining pressure,vibration frequency,and static force,on the damage of granite specimens.The individual and combined influences were analyzed according to the porosity increase and P-wave decrease of granite specimens using the variance analysis method.The results show that the combined effect of the static force and vibration frequency mainly promotes fatigue damage of specimens,that the confining pressure determines the damage behaviour and failure mode of specimens under ultrasonic vibration,and that the confining pressure and vibration frequency are the main factors that cause the fracture concentration in the upper part of specimens,an effect mechanistically driven by the obvious load energy attenuation.The research results provide theoretical guidance for the application of ultrasonic vibration technology.
基金financially supported by the Technology Project of Nanchong and Southwest Petroleum University(SWPU)Cooperation(No.18SXHZ0032)。
文摘Ultrasonic vibration assisted tungsten inert gas welding was applied to joining stainless steel 316 L and low alloy high strength steel L415.The effect of ultrasonic vibration on the microstructure and mechanical properties of a dissimilar metal welded joint of 316 L and L415 was systematically investigated.The microstructures of both heat affected zones of L415 and weld metal were substantially refined,and the clusters ofδferrite in traditional tungsten inert gas(TIG)weld were changed to a dispersive distribution via the ultrasonic vibration.The ultrasonic vibration promoted the uniform distribution of elements and decreased the micro-segregation tendency in the weld.With the application of ultrasonic vibration,the average tensile strength and elongation of the joint was improved from 613 to 650 MPa and from 16.15%to31.54%,respectively.The content ofΣ3 grain boundaries around the fusion line zone is higher and the distribution is more uniform in the ultrasonic vibration assisted welded joint compared with the traditional one,indicating an excellent weld metal crack resistance.
基金Sponsored by Zhejiang Province Scientific and Technological Key Task Program (2007C21025)Ningbo Science and Technological Key Task Program (2007B10010)
文摘Magnetic liquid can produce alternative internal pressure under the alternative high-frequency gradient magnetic field.Because it has higher bulk modulus,the internal pressure results in its volume change.Using piezoelectric transducers,the ultrasonic wave generated by the vibration of magnetic liquids can be detected,which shows that the magnetic liquids have the magnetostrictive effect and can generate the ultrasonic vibration under the alternative magnetic gradient field.Some nonmagnetic abrasives and rust-proofing agents can be mixed into the magnetic liquids,under the alternative magnetic field,the abrasives held by magnetic liquids grind the surface of the workpieces,and thus,the finishing for the surface with complex shape,mold cavity and inner wall of tiny tubes can be realized.
基金Funded by the National Natural Science Foundation of China(Nos.52075347,51575364)
文摘To solve the problem of the poor plasticity and to meet the requirements of high temperature for forming titanium alloy,mechanical properties of TC2 titanium alloy under the compound energy-field(CEF)with temperature and ultrasonic vibration were studied.The effects of CEF on tensile force,elongation,microstructure and fractography of the TC2 titanium alloy were compared and analyzed.The results show that,under the same thermal conditions,the deformation resistance of TC2 titanium alloy decreases with the increase of ultrasonic vibration energy.The formability is also improved correspondingly due to the input of ultrasonic vibration energy and its influence on the microstructure of the material.However,when the ultrasonic vibration energy is larger,the fatigue fracture will also appear,which reduces its formability.
文摘In this paper, a new type of ultrasonic vibration de-gluing device has been designed to remove the cured epoxy resin adhesive </span><span style="white-space:normal;font-family:"">that </span><span style="white-space:normal;font-family:"">overflowed from the aluminum alloy structural parts in the high-speed train carriages. At present, manual removal is used to remove the cured epoxy resin adhesive that overflows at the bonding site. This method has low removal efficiency and leads to poor surface quality of the parts. The new type of ultrasonic vibration de-gluing device can solve these problems. Modal analysis and harmonic response analysis are carried out on the ultrasonic vibration oscillator system in the ultrasonic vibration de-gluing device, and the reasonable structure parameters and resonance frequency of the ultrasonic vibration oscillator system are determined. Finally, the impedance test and de-gluing effect test are carried out on the prototype of the ultrasonic vibration de-gluing device to verify the feasibility and practicability of the new type of ultrasonic vibration de-gluing device. The results show that the ultrasonic vibration de-gluing device’s stable resonant operating frequency is 28</span><span style="white-space:normal;font-family:"">,</span><span style="white-space:normal;font-family:"">270</span><span style="white-space:normal;font-family:""> </span><span style="white-space:normal;font-family:"">Hz, and the average error between the simulation and experimental results of the resonant operating frequency is less than 3%, which validates the simulation model.
基金Project (2007AA03Z557) supported by the National High-Tech Research and Development Program of ChinaProject (50775086) supported by the National Natural Science Foundation of China
文摘The microstructure and properties of Al-20Si-2Cu-1Ni-0.4Mg alloy fabricated with semi-solid rheo-diecasting process were studied.A newly developed direct ultrasonic vibration process(DUV process) was used in the preparation of the semi-solid slurry of this alloy.The results show that the primary Si particles in this alloy is about 20 μm in size under DUV for 90 s in the semi-solid temperature range,compared to about 30 μm in the alloy without DUV.It is discovered that the primary Si particles distribute more homogeneously and have regular shape,but have lower volume fraction after DUV.The tensile strength at room temperature is about 310 MPa,and the tensile strength and elongation of the semi-solid die castings are increased by 34% and 45%,respectively,compared with the traditional liquid die castings.The high-temperature tensile strength at 300 ℃ of this high Si aluminum alloy reaches 167 MPa,and the coefficient of thermal expansion is 17.37×10-6/℃ between 25 and 300 ℃.This indicates that this high Si content Al-Si alloy produced with the DUV process is suitable to be used in the manufacture of pistons or other heat-resistant parts.
基金Funded by the National Natural Science Foundation of China(No.51635005,51875128,and 51375113)the Fundamental Research Funds for the Central Universities(No.HIT.BRETⅢ.201404)
文摘Effect of ultrasonic vibration on deformation in micro-blanking was investigated with copper foils of different grain sizes using a developed device. It is found that maximum shearing strength is decreased by ultrasonic vibration, and this effect becomes bigger for coarse grain than that for fine grain, which can be attributed to acoustic softening effect considering the absorbed acoustic energy. Surface roughness R_a of smooth zone decreases for the polishing effect of vibration at the lateral contact surface. When ultrasonic vibration is applied, the sheared deformation area becomes relatively narrow, and it leads to the reduction of radius of rollover. The analysis of cross section in sheared deformation area shows that the crack initiation is inhabited for the existence of acoustic softening, and the proportion of smooth zone is increased. Also, angle of crack propagation becomes smaller because of periodic strain, and the angle of facture surface is decreased. As a result, the quality of micro-sheet parts is improved by applying ultrasonic vibration.
文摘In many fields of high-tech industry the ultra-t hi n wall parts are employed. In this paper the experiments were carried out to dis cuss the surface microstructure of the camera’s guided drawtube by applying ult rasonic vibration cutting device to the traditional lathe. The influence rule of the cutting condition on the surface roughness was put forward, which was drawn by comparing the ultrasonic cutting with the common cutting by use of the cemen ted carbide tool and the polycrystalline diamond (PCD) tool. The test results sh owed that the ultrasonic cutting performs better than the common cutting in the same condition. According to the test results analyzing, the surface characteriz ation is influenced clearly by the rigidity of the acoustic system and the machi ne tool, as well the setting height of the tool tip. Otherwise, the dense regula r low frequency vibration ripples will be scraped on the machined surface. When the tool tip is set higher than the rotating center of the work piece by three t imes of the amplitude of ultrasonic vibration, the vibration ripples behave alig ht; they turn light and shade alternatively when the tool tip is lower than the rotating center of the work piece by three times of the amplitude of ultrasonic vibration. According to the test result analyzing, the following conclusions are put forward: 1) The surface roughness in ultrasonic cutting is better than that in common cutting. Under a one third critical cutting velocity, the value of th e surface roughness in ultrasonic cutting rise slightly along with the cutting v elocity, while in common cutting it decreases contrast to the cutting velocity; the curves of the surface roughness in ultrasonic cutting and common cutting see m to be alike, both increase along with the feed rate and the cutting depth, but the value in ultrasonic cutting is smaller in the same condition.2) The influen ce of the coolant on the surface roughness cannot be ignored. The kerosene can b e employed to improve the surface roughness in ultrasonic machining.3) In ultras onic cutting process of aluminum alloy ultra-thin wall work piece, the PCD tool performs better than the cemented carbide tools.4) The vibration ripples result from the not enough rigidity of the acoustic system and the improper setting he ight of the tool tip. The departure of the tool tip from the rotating center of the work piece to some extent causes the vibration ripples on the machined surfa ce.
文摘To decrease the diamond tool wear and improve the surface quality of the workpieces, ultrasonic vibration was applied to diamond turning of titanium alloy. The effect of vibration parameters on the surface roughness and the tool wear was analyzed. The results show that vibration parameters have great effects on the surface roughness and tools life. Under given conditions, the smaller the vibrating amplitude is, the larger the surface roughness(R_a) is , and the more rapidly the tools is worn. Accordingly, the higher the vibrating frequency is, the smaller the surface roughness is and the longer the tools life is. The surface roughness value (R_a) is less than 0.15μm when vibrating amplitude is 14μm and vibrating frequency is 40kHz in the experiments.
基金financially supported by the National Natural Science Foundation of China(No.51261025)the Aerospace Science and Technology Innovation Foundation of Shanghai,China(No.SAST2016046)the Key Projects of Superior Science and Technology Innovation Team of Jiangxi,China(No.20181BCB19001)
文摘The effect of synergistic action of ultrasonic vibration and solidification pressure on tensile properties of vacuum counter-pressure casting ZL114 A alloys was studied systemically through testing and analyzing the tensile strength and elongation subjected to different ultrasonic powers and solidification pressures. The results indicate that the synergistic action of ultrasonic vibration and solidification pressure can result in the refinement of grains and improvement of tensile properties. Both the highest tensile strength and elongation of aluminum alloy were obtained under synergistic action of 600 W ultrasonic power and 350 kPa solidification pressure. Moreover, the tensile fracture morphology shows obvious ductile fracture characteristics. When the solidification pressure is lower than 300 kPa, the effect of ultrasonic power on tensile strength and elongation is more obvious, but when the solidification pressure is higher than 300 kPa, the effect of solidification pressure on tensile strength and elongation is greater. Meanwhile, the size and morphology of the eutectic silicon were improved significantly by the ultrasonic vibration and pressurized solidification. The strip and massive eutectic silicon phase are completely converted into small short rod-like and evenly distributed Si phases at the grain boundary of primary α-Al.
文摘High-intensity ultrasonic vibration was focused on the tip of conical steel specimens to induce severe plastic deformation at room temperature. We found, for the first time, that grain size smaller than 200 nm was obtained. Furthermore, the sharp tip of the conical specimen became umbrella-shaped or disk-shaped. The tip size changed from 0.5 mm diameter to a disk about 5 mm diameter, representing a large amount of plastic deformation in the metal at the tip of the conical specimen.
基金Funded by the National Basic Research Program of China (Nos.2007CB613701 and 2007CB613702)the National Natural Science Foundation of China (Nos. 50904018 and 51004032)+2 种基金the New Century Excellent Talents Program in University (No. NCET-08-0098)the Fundamental Research Funds for the Central Universities (Nos. N090409002 and N090209002)the China Postdoctoral Science Foundation Funded Project(No.20100471468)
文摘The effects of ultrasonic vibration on the grain size and morphology of Mg2Si in Mg-4 wt% Al-1 wt%Si(AS41) alloys designed were evaluated. The results show that the major constituents of the alloy include β-Mg17Al12 and Mg2Si phase, and no difference in the type of constituents between without ultrasonic vibration and with ultrasonic vibration. Without any ultrasonic vibration, the grain size and Mg2Si phase in AS41 alloy are coare structure. However, the microstructure with fine uniform grains and Mg2Si particles are achieved with ultrasonic vibration. The crystal grains and Mg2Si particles refine with increase in the ultrasonic vibration intensity. When the ultrasonic vibration intensity was too low or too high, coarse structures could be obtained. The analysis of refinement mechanism indicates that the acoustic cavitation and flows induced by ultrasonic vibration lead to the fine uniform microstructure.
