Under the working environment of high temperature and strong load impact,hot forging die is prone to failure which reduces the service life of die.Using arc additive manufacturing in the die cavity,a gradient material...Under the working environment of high temperature and strong load impact,hot forging die is prone to failure which reduces the service life of die.Using arc additive manufacturing in the die cavity,a gradient material hot forging die with high precision,superior per-formance,and conformal cooling channels is developed.This improves the toughness of the die cavity and reduces the working temperature,thereby forming an isothermal field,which is an effective method to enhance the lifespan of the hot forging die.Three kinds of gradient flux-cored wires are designed for the surface of 5CrNiMo steel,and the microstructure and mechanical properties between gradient interfaces were studied.Based on the spatial curved structure of shaped waterways in the hot forging die cavity,a study was conducted on the strategy of partitioned forming for the manufacturing of the die with shaped waterways.In order to avoid interference with the arc gun,the hot for-ging die is divided into four regions,namely the transition region,upper,middle,and lower region,based on a combination of cavity depth and internal U-shaped and quadrilateral structures.The results show that the developed flux-cored wires have good moldability with straight sides of deposited metal under different process parameters and flat surface without cracks,pores and other defects.Under the same working conditions,the life of hot forging die formed by the gradient materials is more than multiple times that of the single material hot forging die,and the temperature gradient field of the shaped waterway die is 7℃/cm smaller than that of traditional straight waterway.展开更多
Based on wire arc additive manufacturing(WAAM)technology,AZ31 magnesium alloy in bulk was successfully fabricated,and its microstructure as well as mechanical properties in different planes were observed and analyzed....Based on wire arc additive manufacturing(WAAM)technology,AZ31 magnesium alloy in bulk was successfully fabricated,and its microstructure as well as mechanical properties in different planes were observed and analyzed.The AZ31 magnesium alloy has a similar microstructure in the building direction(Z)and travel direction(X),both of which are equiaxed grains.There are heat-affected zones(HAZs)with coarse grains below the fusion line.The second phase is primarily composed of the Mg17Al12 phase,which is evenly distributed in different directions.In addition,the residual stress varies in different directions.There is no significant difference in the hardness of the AZ31 alloy along the Z and X directions,with the average hardness being 68.4 HV and 67.9 HV,respectively.Even though the specimens’ultimate tensile strength along the travel direction is higher in comparison to that along the building direction,their differences in elongation and yield strength are smaller,indicating that the anisotropy of the mechanical properties of the material is small.展开更多
We focused on Ti/Al composite materials fabricated by wire and arc addictive manufacturing,and the microstructure and interface characteristics of them before and after hot compression deformation were compared.After ...We focused on Ti/Al composite materials fabricated by wire and arc addictive manufacturing,and the microstructure and interface characteristics of them before and after hot compression deformation were compared.After compression deformation,allαstructures of titanium were compacted with the emergence of Widmanstatten structures.Coarsened coloniesαof titanium were elongated and waved along the original growth direction,resulting in anisotropy of grains.Pores and Ti/Al intermetallic compounds of aluminum are significantly decreased after hot compression.Meanwhile,a good bonding interface between titanium and aluminum is obtained after hot compression,and the element diffusion is more intense.In addition,the mechanical properties and fracture behaviors of Ti/Al composite material with different clad ratio that is defined as the ratio of the thickness of titanium to that of the Ti/Al composite material are investigated by uniaxial tensile test.The experimental results show that the ultimate tensile strength of Ti/Al composite material is between that of single deposited titanium and aluminum,while the elongation of Ti/Al composite material with low clad ratio is lower than that of single aluminum due to the metallurgical reaction.As the clad ratio increases,the two component layers are harder to separate during deformation,which is resulted from the decrease of the inward contraction stress of three-dimensional stress caused by necking of aluminum.This work may promote the engineering application of Ti/Al bimetallic structures.展开更多
With a high energy efficiency,low geometric limitation,and low cracking susceptivity to cracks,wire arc additive manufacturing(WAAM)has become an ideal substitute for casting in the manufacturing of load-bearing high ...With a high energy efficiency,low geometric limitation,and low cracking susceptivity to cracks,wire arc additive manufacturing(WAAM)has become an ideal substitute for casting in the manufacturing of load-bearing high strength aluminum components in aerospace industry.Recently,in scientific researches,the room temperature mechanical performance of additive manufactured high strength aluminum alloys has been continuously broken through,and proves these alloys can achieve comparable or even higher properties than the forged counterpart.Since the aluminum components for aerospace usage experience high-low temperature cycling due to the absence of atmosphere protection,the high temperature performances of additive manufactured high strength aluminum alloys are also important.However,few research focuses on that.A special 2319Ag Sc with 0.4 wt.%Ag and 0.2 wt.%Sc addition designed for high temperature application is deposited successfully via cold metal transfer(CMT)based on WAAM.The microstructures and high temperature tensile properties are investigated.The results show that the as-deposited 2319Ag Sc alloy presents an alternate distribution of columnar grains and equiaxed grains with no significant textures.Main second phases are Al_(2)Cu and Al3Sc,while co-growth of Al_(2)Cu and bulk Al_(3)Sc is found on the grain boundary.During manufacturing,nanoscale Al_(2)Cu can precipitate out from the matrix.Ag and Mg form nano-scaleΩphase on the Al_(2)Cu precipitates.At 260℃,average yield strengths in the horizontal direction and vertical direction are 87 MPa±2 MPa,87 MPa±4 MPa,while average ultimate tensile strengths are 140 MPa±7 MPa,141 MPa±11 MPa,and average elongations are 11.0%±2.5%,13.5%±3.0%.Anisotropy in different directions is weak.展开更多
A high-building multi-directional pipe joint(HBMDPJ)was fabricated by wire and arc additive manufacturing using high-strength low-alloy(HSLA)steel.The microstructure characteristics and transformation were observed an...A high-building multi-directional pipe joint(HBMDPJ)was fabricated by wire and arc additive manufacturing using high-strength low-alloy(HSLA)steel.The microstructure characteristics and transformation were observed and analyzed.The results show that the forming part includes four regions.The solidification zone solidifies as typical columnar crystals from a molten pool.The complete austenitizing zone forms from the solidification zone heated to a temperature greater than 1100℃,and the typical columnar crystals in this zone are difficult to observe.The partial austenitizing zone forms from the completely austenite zone heated between Ac1(austenite transition temperature)and1100℃,which is mainly equiaxed grains.After several thermal cycles,the partial austenitizing zone transforms to the tempering zone,which consistes of fully equiaxed grains.From the solidification zone to the tempering zone,the average grain size decreases from 75 to20μm.The mechanical properties of HBMDPJ satisfies the requirement for the intended application.展开更多
To maximize the benefits of wire arc additive manufacturing(WAAM)processes,the effect of post-deposition heat treatment on the microstructure and mechanical properties of WAAM AZ80M magnesium(Mg)alloy was investigated...To maximize the benefits of wire arc additive manufacturing(WAAM)processes,the effect of post-deposition heat treatment on the microstructure and mechanical properties of WAAM AZ80M magnesium(Mg)alloy was investigated.Three different heat treatment procedures(T4,T5 and T6)were performed.According to the results,after T4 heat treatment,the microsegregation of alloying elements was improved with the eutectic structure dissolved.Samples after T5 heat treatment inherited the net-like distribution of secondary phases similar to the as-deposited sample,where the eutectic structure covering the interdendritic regions and theβ-phase precipitated around the eutectic structure.After T6 heat treatment,the tinyβ-phases re-precipitated from the matrix and distributed in inner and outer of the grains.The hardness distribution of the samples went through T4 and T6 heat treatment was more uniform in comparison to that of T5 heat treated samples.The tensile test showed that the T6 heat treatment improved the strength and ductility,and the anisotropy between horizontal and vertical can be eliminated.Moreover,T4 treated samples exhibited highest ductility.展开更多
A graded structural material(GSM)with a material transition from TA15 to TC11 was fabricated by wire arc additive manufacturing(WAAM)method.The grain morphology,chemical composition,microstructure and mechanical prope...A graded structural material(GSM)with a material transition from TA15 to TC11 was fabricated by wire arc additive manufacturing(WAAM)method.The grain morphology,chemical composition,microstructure and mechanical properties of the as-deposited GSM were all characterized to investigate their variations along the deposition direction.The results indicate that from TA15 to TC11,the grain size decreases and a transition from columnar grains to equiaxed grains occurs.The content of alloy element alters greatly within a short distance,and the width of the mutation zone is 800μm.Both TA15 and TC11 regions exhibit basketweave microstructure withα-phase andβ-phase.However,during the transition from TA15 to TC11,theα-lath becomes fine,which leads to an increase in microhardness.The tensile test shows that the bonding strength at the interface is higher than the longitudinal strength of TA15,and the lateral elongation at the interface is higher than that of TA15 and TC11.展开更多
Wire arc additive manufacturing(WAAM)is a novel manufacturing technique by which high strength metal components can be fabricated layer by layer using an electric arc as the heat source and metal wire as feedstock,and...Wire arc additive manufacturing(WAAM)is a novel manufacturing technique by which high strength metal components can be fabricated layer by layer using an electric arc as the heat source and metal wire as feedstock,and offers the potential to produce large dimensional structures at much higher build rate and minimum waste of raw material.In the present work,a cold metal transfer(CMT)based additive manufacturing was carried out and the effect of deposition rate on the microstructure and mechanical properties of WAAM Ti-6Al-4V components was investigated.The microstructure of WAAM components showed similar microstructural morphology in all deposition conditions.When the deposition rate increased from 1.63 to 2.23 kg/h,the ultimate tensile strength(UTS)decreased from 984.6 MPa to 899.2 MPa and the micro-hardness showed a scattered but clear decline trend.展开更多
In the paper, the finite element model(FEM) of wire arc additive manufacturing(WAAM) by TIG method was established by the ABAQUS soft, and the phase transformation latent heat was considered in the model. The evolutio...In the paper, the finite element model(FEM) of wire arc additive manufacturing(WAAM) by TIG method was established by the ABAQUS soft, and the phase transformation latent heat was considered in the model. The evolution rules of temperature field at the interlayer with the cooling time of 10 s, 30 s and 50 s were obtained by the model. The WAAM experiment were performed by 5356 aluminum alloy welding wire with φ1.2 mm, and the simulated temperature field were varified by the thermocouple. The result shows that the highest temperature at the molten pool center increases with the increased interlayers at the same interlayer cooling time;the highest temperature drops gradually and the decline is smaller with the increased interlayer cooling time at the same layer. No remelting occurs at the top layer, and at least two remelting times occur in the other layers, resulting in complex temperature field evolution.展开更多
Cold metal transfer plus pulse(C+P)arc was applied in the additive manufacturing of 4043 Al alloy parts.Parameters in the manufacturing of the parts were investigated.The properties and microstructure of the parts wer...Cold metal transfer plus pulse(C+P)arc was applied in the additive manufacturing of 4043 Al alloy parts.Parameters in the manufacturing of the parts were investigated.The properties and microstructure of the parts were also characterized.Experimental results showed that welding at a speed of 8 mm/s and a wire feeding speed of 4.0 m/min was suitable to manufacture thin-walled parts,and the reciprocating scanning method could be adopted to manufacture thick-walled parts.The thin-walled parts of the C+P mode had fewer pores than those of the cold metal transfer(CMT)mode.The thin-and thick-walled parts of the C+P mode showed maximum tensile strengths of 172 and 178 MPa,respectively.Hardness decreased at the interface and in the coarse dendrite and increased in the refined grain area.展开更多
Wire and arc additive manufacturing(WAAM) shows a great promise for fabricating fully dense metal parts by means of melting materials in layers using a welding heat source. However, due to a large layer height produce...Wire and arc additive manufacturing(WAAM) shows a great promise for fabricating fully dense metal parts by means of melting materials in layers using a welding heat source. However, due to a large layer height produced in WAAM, an unsatisfactory surface roughness of parts processed by this technology has been a key issue. A methodology based on laser vision sensing is proposed to quantitatively calculate the surface roughness of parts deposited by WAAM.Calibrations for a camera and a laser plane of the optical system are presented. The reconstruction precision of the laser vision system is verified by a standard workpiece. Additionally, this determination approach is utilized to calculate the surface roughness of a multi-layer single-pass thin-walled part. The results indicate that the optical measurement approach based on the laser vision sensing is a simple and effective way to characterize the surface roughness of parts deposited by WAAM. The maximum absolute error is less than 0.15 mm. The proposed research provides the foundation for surface roughness optimization with different process parameters.展开更多
The real-time monitoring of the weld pool during deposition is important for automatic control in plasma arc additive manufacturing.To obtain a high deposition accuracy,it is essential to maintain a stable weld pool s...The real-time monitoring of the weld pool during deposition is important for automatic control in plasma arc additive manufacturing.To obtain a high deposition accuracy,it is essential to maintain a stable weld pool size.In this study,a novel passive visual method is proposed to measure the weld pool length.Using the proposed method,the image quality was improved by designing a special visual system that employed an endoscope and a camera.It also includes pixel brightness-based and gradient-based algorithms that can adaptively detect feature points at the boundary when the weld pool geometry changes.This algorithm can also be applied to materials with different solidification characteristics.Calibration was performed to measure the real weld pool length in world coordinates,and outlier rejection was performed to increase the accuracy of the algorithm.Additionally,tests were carried out on the intersection component,and the results showed that the proposed method performed well in tracking the changing weld pool length and was applicable to the real-time monitoring of different types of materials.展开更多
Customized heat treatment is essential for enhancing the mechanical properties of additively manufactured metallic materials,especially for alloys with complex phase constituents and heterogenous microstructure.Howeve...Customized heat treatment is essential for enhancing the mechanical properties of additively manufactured metallic materials,especially for alloys with complex phase constituents and heterogenous microstructure.However,the interrelated evolutions of different microstructure features make it difficult to establish optimal heat treatment processes.Herein,we proposed a method for customized heat treatment process exploration and establishment to overcome this challenge for such kind of alloys,and a wire arc additively manufactured(WAAM)Mg-Gd-Y-Zn-Zr alloy with layered heterostructure was used for feasibility verification.Through this method,the optimal microstructures(fine grain,controllable amount of long period stacking ordered(LPSO)structure and nano-scaleβ'precipitates)and the corresponding customized heat treatment processes(520°C/30 min+200°C/48 h)were obtained to achieve a good combination of a high strength of 364 MPa and a considerable elongation of 6.2%,which surpassed those of other state-of-the-art WAAM-processed Mg alloys.Furthermore,we evidenced that the favorable effect of the undeformed LPSO structures on the mechanical properties was emphasized only when the nano-scaleβ'precipitates were present.It is believed that the findings promote the application of magnesium alloy workpieces and help to establish customized heat treatment processes for additively manufactured materials.展开更多
Magnesium(Mg)alloys,as the lightest metal structural material with good damping capacities,have im-portant application prospects in realizing structural lightweight and vibration reduction.However,their engineering ap...Magnesium(Mg)alloys,as the lightest metal structural material with good damping capacities,have im-portant application prospects in realizing structural lightweight and vibration reduction.However,their engineering application is greatly limited by poor plastic formability.Wire and arc additive manufactur-ing(WAAM)provides a potential approach for fabricating large-scale Mg alloy components with high manufacturing flexibility.In this study,the evolution of the solidification microstructure of a WAAM-processed Mg-Al-based alloy was quantitatively analyzed based on the analytical models;then,the cor-relations between the solidification microstructure and mechanical properties/damping capacities were investigated.The results revealed that the WAAM-processed Mg-Al-based alloy with an equiaxed-grain-dominated microstructure displayed a simultaneous enhancement in mechanical properties and damping capacities compared to those of the cast Mg-Al-based alloy.The good combination of mechanical prop-erties and damping capacities are mainly attributed to the weakened basal texture with a relatively high Schmid factor for basalslip,the twinning-induced plasticity(TWIP)effect associated with the profuse{10-12}tensile twinning,and the relatively high dislocation density caused by the thermal stress during the WAAM process.展开更多
To explore the feasibility of using wire arc additive manufacturing(WAAM)for forming and repairing marine components during ship navigation,this study conducted deposition experiments of ER50-6 steel and investigated ...To explore the feasibility of using wire arc additive manufacturing(WAAM)for forming and repairing marine components during ship navigation,this study conducted deposition experiments of ER50-6 steel and investigated the interference of ship-based vibrations on the WAAM equipment and influence of the characteristics of the arc droplets and sample morphology.The results revealed that the WAAM equipment vibrated with the external vibrations from the surrounding environment,and the welding gun and base plate produced dissimilar vibrations,which yielded unstable arc shapes resembling a bell,trumpet,fan,broom,and other irregular shapes.The mode of the droplet transfer ranged from the stable spray transfer mode to extensive amounts of large droplet transfer and short-circuit transfer.Although the morphology of the obtained sample deteriorated,the fully dense and defect-free interior demonstrated the applicability of ship-based WAAM.展开更多
Additive manufacturing(AM)of Mg alloys has become a promising strategy for producing complex structures,but the corrosion performance of AM Mg components remains unexploited.In this study,wire and arc additive manufac...Additive manufacturing(AM)of Mg alloys has become a promising strategy for producing complex structures,but the corrosion performance of AM Mg components remains unexploited.In this study,wire and arc additive manufacturing(WAAM)was employed to produce single AZ31 layer.The results revealed that the WAAM AZ31 was characterized by significant grain refinement with non-textured crystallographic orientation,similar phase composition and stabilized corrosion performance comparing to the cast AZ31.These varied corrosion behaviors were principally ascribed to the size of grain,where cast AZ31 and WAAM AZ31 were featured by micro galvanic corrosion and intergranular corrosion,respectively.展开更多
Strength-ductility trade-off is a common issue in Mg alloys. This work proposed that a synergistic enhancement of strength and ductility could be achieved through tuning interlayer dwell time(IDT) in the wire and arc ...Strength-ductility trade-off is a common issue in Mg alloys. This work proposed that a synergistic enhancement of strength and ductility could be achieved through tuning interlayer dwell time(IDT) in the wire and arc additive manufacturing(WAAM) process of Mg alloy.The thermal couples were used to monitor the thermal history during the WAAM process. Additionally, the effect of different IDTs on the microstructure characteristics and resultant mechanical properties of WAAM-processed Mg alloy thin-wall were investigated. The results showed that the stable temperature of the thin-wall component could reach 290 ℃ at IDT=0s, indicating that the thermal accumulation effect was remarkable. Consequently, unimodal coarse grains with an average size of 39.6 μm were generated, and the resultant room-temperature tensile property was poor. With the IDT extended to 60s, the thermal input and thermal dissipation reached a balance, and the stable temperature was only 170 ℃, closing to the initial temperature of the substrate. A refined grain structure with bimodal size distribution was obtained. The remelting zone had fine grains with the size of 15.2 μm, while the arc zone owned coarse grains with the size of 24.5 μm.The alternatively distributed coarse and fine grains lead to the elimination of strength-ductility trade-off. The ultimate tensile strength and elongation of the samples at IDT=60s are increased by 20.6 and 75.0% of those samples at IDT=0s, respectively. The findings will facilitate the development of additive manufacturing processes for advanced Mg alloys.展开更多
Additive manufacturing is a very promising manufacturing method widely used in various industries.In this study,for the first time,a new type of combined cable wire(CCW)with multi-element composition has been designed...Additive manufacturing is a very promising manufacturing method widely used in various industries.In this study,for the first time,a new type of combined cable wire(CCW)with multi-element composition has been designed and developed for arc additive manufacturing(AAM)of non-equiatomic Al-Co-Cr-FeNi high-entropy alloy.CCW composed of 7 filaments and 5 elements has the advantages of high deposition efficiency,self-rotation of welding arc and energy saving capability.Thin HEA walls were fabricated under pure argon gas using cold metal transfer technology.Microstructural observations of the developed HEA reveal(i)BCC and FCC phases,(ii)Good bonding between layers and(iii)defect-free microstructure.The developed alloy exhibits high compression strength(~2.8 GPa)coupled with high plastic strain(~42%)values(possess both strength and ductility).It has been identified that by varying the heat input via torch travel speed,the microstructure and mechanical properties of the HEA can be controlled.From this feasibility study,it has been proved that the innovative CCW method can be used to manufacture HEAs with CCW-AAM.Further,the study highlights the advantage of the rapid cooling involved in the CCW-AAM process which gives rise to superior mechanical properties.展开更多
Realizing improved strength in composite metallic materials remains a challenge using conventional welding and joining systems due to the generation and development of brittle intermetallic compounds caused by complex...Realizing improved strength in composite metallic materials remains a challenge using conventional welding and joining systems due to the generation and development of brittle intermetallic compounds caused by complex thermal profiles during solidification.Here,wire arc additive manufacturing(WAAM)process was used to fabricate a steel-nickel structural component,whose average tensile strength of 634 MPa significantly exceeded that of feedstock materials(steel,537 MPa and nickel,455 MPa),which has not been reported previously.The as-fabricated sample exhibited hierarchically structural heterogeneity due to the interweaving deposition strategy.The improved mechanical response during tensile testing was due to the inter-locking microstructure forming a strong bond at the interface and solid solutions strengthening from the intermixing of the Fe and Ni increased the interface strength,beyond the sum of parts.The research offers a new route for producing high-quality steel-nickel dissimilar structures and widens the design opportunities of monolithic components,with site-specific properties,for specific structural or functional applications.展开更多
Aluminum alloy is the most widely used light alloy at present.By combining different types of aluminum alloys,their functional properties can be expanded.In the present research,two components composed of 2319(Al-6.5C...Aluminum alloy is the most widely used light alloy at present.By combining different types of aluminum alloys,their functional properties can be expanded.In the present research,two components composed of 2319(Al-6.5Cu)and 5B06(Al-6.4Mg)dissimilar alloys were fabricated by wire and arc additive manufacturing(WAAM).The deposited component with the bottom half of 2319 and the top half of 5B06 exhibits better mechanical properties than its counterpart deposited vice versa.Its ultimate tensile strength,yield strength,and elongation are 258.5 MPa,139.3 MPa,and 5.6%,respectively,which are only slightly inferior to the mechanical properties of 2319 base metal.The results show that for both components,fracture occurred at a layer thickness above the interface layer during the tensile test,regardless of the deposition order.It appears that the thermal stress due to the long dwell time and the remelting of the S-AlCu Mg phase are the main factors promoting crack initiation.Depending on the deposition order,cracks propagate either along the aggregated pores or stripθ-AlCu phase distributed along the grain boundary.By analyzing the heat input and selecting the appropriate depositing order,the strength of WAAM dissimilar aluminum alloys can be effectively improved through the proper control of microstructure and internal defects.展开更多
基金supported by the National Key R&D Program of China(No.2017YFB1103200).
文摘Under the working environment of high temperature and strong load impact,hot forging die is prone to failure which reduces the service life of die.Using arc additive manufacturing in the die cavity,a gradient material hot forging die with high precision,superior per-formance,and conformal cooling channels is developed.This improves the toughness of the die cavity and reduces the working temperature,thereby forming an isothermal field,which is an effective method to enhance the lifespan of the hot forging die.Three kinds of gradient flux-cored wires are designed for the surface of 5CrNiMo steel,and the microstructure and mechanical properties between gradient interfaces were studied.Based on the spatial curved structure of shaped waterways in the hot forging die cavity,a study was conducted on the strategy of partitioned forming for the manufacturing of the die with shaped waterways.In order to avoid interference with the arc gun,the hot for-ging die is divided into four regions,namely the transition region,upper,middle,and lower region,based on a combination of cavity depth and internal U-shaped and quadrilateral structures.The results show that the developed flux-cored wires have good moldability with straight sides of deposited metal under different process parameters and flat surface without cracks,pores and other defects.Under the same working conditions,the life of hot forging die formed by the gradient materials is more than multiple times that of the single material hot forging die,and the temperature gradient field of the shaped waterway die is 7℃/cm smaller than that of traditional straight waterway.
基金support from the International Science and Technology Cooperation Program of Shaanxi Province(No.2023-GHZD-50)Projects of Major Innovation Platforms for Scientific and Technological and Local Transformation of Scientific and Technological Achievements of Xi'an(No.20GXSF0003)+1 种基金Projects of Major Scientific and Technological Achievements Local Transformation of Xi'an(No.2022JH-ZDZH-0039)the Higher Education Institution Discipline Innovation and Intelligence Base of Shaanxi Province(No.S2021-ZCGXYZ-0011).
文摘Based on wire arc additive manufacturing(WAAM)technology,AZ31 magnesium alloy in bulk was successfully fabricated,and its microstructure as well as mechanical properties in different planes were observed and analyzed.The AZ31 magnesium alloy has a similar microstructure in the building direction(Z)and travel direction(X),both of which are equiaxed grains.There are heat-affected zones(HAZs)with coarse grains below the fusion line.The second phase is primarily composed of the Mg17Al12 phase,which is evenly distributed in different directions.In addition,the residual stress varies in different directions.There is no significant difference in the hardness of the AZ31 alloy along the Z and X directions,with the average hardness being 68.4 HV and 67.9 HV,respectively.Even though the specimens’ultimate tensile strength along the travel direction is higher in comparison to that along the building direction,their differences in elongation and yield strength are smaller,indicating that the anisotropy of the mechanical properties of the material is small.
基金Funded by the National Natural Science Foundation of China(No.51775068)。
文摘We focused on Ti/Al composite materials fabricated by wire and arc addictive manufacturing,and the microstructure and interface characteristics of them before and after hot compression deformation were compared.After compression deformation,allαstructures of titanium were compacted with the emergence of Widmanstatten structures.Coarsened coloniesαof titanium were elongated and waved along the original growth direction,resulting in anisotropy of grains.Pores and Ti/Al intermetallic compounds of aluminum are significantly decreased after hot compression.Meanwhile,a good bonding interface between titanium and aluminum is obtained after hot compression,and the element diffusion is more intense.In addition,the mechanical properties and fracture behaviors of Ti/Al composite material with different clad ratio that is defined as the ratio of the thickness of titanium to that of the Ti/Al composite material are investigated by uniaxial tensile test.The experimental results show that the ultimate tensile strength of Ti/Al composite material is between that of single deposited titanium and aluminum,while the elongation of Ti/Al composite material with low clad ratio is lower than that of single aluminum due to the metallurgical reaction.As the clad ratio increases,the two component layers are harder to separate during deformation,which is resulted from the decrease of the inward contraction stress of three-dimensional stress caused by necking of aluminum.This work may promote the engineering application of Ti/Al bimetallic structures.
基金the National Natural Science Foundation of China(Grant No.U21B2080,52305351,52275324)the China Postdoctoral Science Foundation(Grant No.2023M730838)+1 种基金the Heilongjiang Provincial Postdoctoral Science Foundation(Grant No.LBH-Z22128)the Natural Science Foundation of Heilongjiang Province(Grant No.LH2023E039).
文摘With a high energy efficiency,low geometric limitation,and low cracking susceptivity to cracks,wire arc additive manufacturing(WAAM)has become an ideal substitute for casting in the manufacturing of load-bearing high strength aluminum components in aerospace industry.Recently,in scientific researches,the room temperature mechanical performance of additive manufactured high strength aluminum alloys has been continuously broken through,and proves these alloys can achieve comparable or even higher properties than the forged counterpart.Since the aluminum components for aerospace usage experience high-low temperature cycling due to the absence of atmosphere protection,the high temperature performances of additive manufactured high strength aluminum alloys are also important.However,few research focuses on that.A special 2319Ag Sc with 0.4 wt.%Ag and 0.2 wt.%Sc addition designed for high temperature application is deposited successfully via cold metal transfer(CMT)based on WAAM.The microstructures and high temperature tensile properties are investigated.The results show that the as-deposited 2319Ag Sc alloy presents an alternate distribution of columnar grains and equiaxed grains with no significant textures.Main second phases are Al_(2)Cu and Al3Sc,while co-growth of Al_(2)Cu and bulk Al_(3)Sc is found on the grain boundary.During manufacturing,nanoscale Al_(2)Cu can precipitate out from the matrix.Ag and Mg form nano-scaleΩphase on the Al_(2)Cu precipitates.At 260℃,average yield strengths in the horizontal direction and vertical direction are 87 MPa±2 MPa,87 MPa±4 MPa,while average ultimate tensile strengths are 140 MPa±7 MPa,141 MPa±11 MPa,and average elongations are 11.0%±2.5%,13.5%±3.0%.Anisotropy in different directions is weak.
基金financially supported by the National Key R&D Program of China(No.2017YFB1103200)the Independent Innovation Research Fund Project of Huazhong University of Science and Technology(No.2018KFYXMPT002)。
文摘A high-building multi-directional pipe joint(HBMDPJ)was fabricated by wire and arc additive manufacturing using high-strength low-alloy(HSLA)steel.The microstructure characteristics and transformation were observed and analyzed.The results show that the forming part includes four regions.The solidification zone solidifies as typical columnar crystals from a molten pool.The complete austenitizing zone forms from the solidification zone heated to a temperature greater than 1100℃,and the typical columnar crystals in this zone are difficult to observe.The partial austenitizing zone forms from the completely austenite zone heated between Ac1(austenite transition temperature)and1100℃,which is mainly equiaxed grains.After several thermal cycles,the partial austenitizing zone transforms to the tempering zone,which consistes of fully equiaxed grains.From the solidification zone to the tempering zone,the average grain size decreases from 75 to20μm.The mechanical properties of HBMDPJ satisfies the requirement for the intended application.
基金the China Scholarship Council[grant numbers:201907000039],the National Key Research and Development Plan of China[grant number 2017YFB0305905]The authors acknowledge the financial support from the 2020 open projects[grant numbers:KLATM202003]of Key laboratory of Advanced Technologies of Materials,Ministry of Education China,Southwest Jiaotong University。
文摘To maximize the benefits of wire arc additive manufacturing(WAAM)processes,the effect of post-deposition heat treatment on the microstructure and mechanical properties of WAAM AZ80M magnesium(Mg)alloy was investigated.Three different heat treatment procedures(T4,T5 and T6)were performed.According to the results,after T4 heat treatment,the microsegregation of alloying elements was improved with the eutectic structure dissolved.Samples after T5 heat treatment inherited the net-like distribution of secondary phases similar to the as-deposited sample,where the eutectic structure covering the interdendritic regions and theβ-phase precipitated around the eutectic structure.After T6 heat treatment,the tinyβ-phases re-precipitated from the matrix and distributed in inner and outer of the grains.The hardness distribution of the samples went through T4 and T6 heat treatment was more uniform in comparison to that of T5 heat treated samples.The tensile test showed that the T6 heat treatment improved the strength and ductility,and the anisotropy between horizontal and vertical can be eliminated.Moreover,T4 treated samples exhibited highest ductility.
基金financial supports from the National Natural Science Foundation of China(Nos.51875041,51875042)。
文摘A graded structural material(GSM)with a material transition from TA15 to TC11 was fabricated by wire arc additive manufacturing(WAAM)method.The grain morphology,chemical composition,microstructure and mechanical properties of the as-deposited GSM were all characterized to investigate their variations along the deposition direction.The results indicate that from TA15 to TC11,the grain size decreases and a transition from columnar grains to equiaxed grains occurs.The content of alloy element alters greatly within a short distance,and the width of the mutation zone is 800μm.Both TA15 and TC11 regions exhibit basketweave microstructure withα-phase andβ-phase.However,during the transition from TA15 to TC11,theα-lath becomes fine,which leads to an increase in microhardness.The tensile test shows that the bonding strength at the interface is higher than the longitudinal strength of TA15,and the lateral elongation at the interface is higher than that of TA15 and TC11.
基金Projects(52075317,51905333)supported by the National Natural Science Foundation of ChinaProject(IEC\NSFC\181278)supported by the Royal Society through International Exchanges 2018 Cost Share(China)Scheme+2 种基金Project(19YF1418100)supported by Shanghai Sailing Program,ChinaProjects(19511106400,19511106402)supported by Shanghai Science and Technology Committee Innovation,ChinaProject(19030501300)supported by Shanghai Local Colleges and Universities Capacity Building Special Plan,China。
文摘Wire arc additive manufacturing(WAAM)is a novel manufacturing technique by which high strength metal components can be fabricated layer by layer using an electric arc as the heat source and metal wire as feedstock,and offers the potential to produce large dimensional structures at much higher build rate and minimum waste of raw material.In the present work,a cold metal transfer(CMT)based additive manufacturing was carried out and the effect of deposition rate on the microstructure and mechanical properties of WAAM Ti-6Al-4V components was investigated.The microstructure of WAAM components showed similar microstructural morphology in all deposition conditions.When the deposition rate increased from 1.63 to 2.23 kg/h,the ultimate tensile strength(UTS)decreased from 984.6 MPa to 899.2 MPa and the micro-hardness showed a scattered but clear decline trend.
基金This work was supported by the National Natural Science Foundation of China(Grant No.51905423)Natural.Science Basic Research Plan in Shaanxi Province of China(Grant No.2021JM338)+1 种基金China Scholarship Council(Grant No.201908610042)Application Technology R&D Project of Beilin District(GX2102).
文摘In the paper, the finite element model(FEM) of wire arc additive manufacturing(WAAM) by TIG method was established by the ABAQUS soft, and the phase transformation latent heat was considered in the model. The evolution rules of temperature field at the interlayer with the cooling time of 10 s, 30 s and 50 s were obtained by the model. The WAAM experiment were performed by 5356 aluminum alloy welding wire with φ1.2 mm, and the simulated temperature field were varified by the thermocouple. The result shows that the highest temperature at the molten pool center increases with the increased interlayers at the same interlayer cooling time;the highest temperature drops gradually and the decline is smaller with the increased interlayer cooling time at the same layer. No remelting occurs at the top layer, and at least two remelting times occur in the other layers, resulting in complex temperature field evolution.
基金the National Natural Science Foundation of China(Nos.51605276 and51905333)Shanghai Sailing Program(No.19YF1418100)+2 种基金Shanghai Science and Technology Committee Innovation Grant(Nos.17JC1400600 and 17JC1400601)Karamay Science and Technology Major Project(No.2018ZD002B)Aid for Xinjiang Science and Technology Project(No2019E0235)。
文摘Cold metal transfer plus pulse(C+P)arc was applied in the additive manufacturing of 4043 Al alloy parts.Parameters in the manufacturing of the parts were investigated.The properties and microstructure of the parts were also characterized.Experimental results showed that welding at a speed of 8 mm/s and a wire feeding speed of 4.0 m/min was suitable to manufacture thin-walled parts,and the reciprocating scanning method could be adopted to manufacture thick-walled parts.The thin-walled parts of the C+P mode had fewer pores than those of the cold metal transfer(CMT)mode.The thin-and thick-walled parts of the C+P mode showed maximum tensile strengths of 172 and 178 MPa,respectively.Hardness decreased at the interface and in the coarse dendrite and increased in the refined grain area.
基金Supported by National Natural Science Foundation of China(Grant Nos.51505394,61573293)Key Technologies R&D Program of Sichuan Province of China(Grant No.2015GZ0305)
文摘Wire and arc additive manufacturing(WAAM) shows a great promise for fabricating fully dense metal parts by means of melting materials in layers using a welding heat source. However, due to a large layer height produced in WAAM, an unsatisfactory surface roughness of parts processed by this technology has been a key issue. A methodology based on laser vision sensing is proposed to quantitatively calculate the surface roughness of parts deposited by WAAM.Calibrations for a camera and a laser plane of the optical system are presented. The reconstruction precision of the laser vision system is verified by a standard workpiece. Additionally, this determination approach is utilized to calculate the surface roughness of a multi-layer single-pass thin-walled part. The results indicate that the optical measurement approach based on the laser vision sensing is a simple and effective way to characterize the surface roughness of parts deposited by WAAM. The maximum absolute error is less than 0.15 mm. The proposed research provides the foundation for surface roughness optimization with different process parameters.
基金support provided by the China Scholarship Council and Basic and Applied Basic Research Foundation of Guangdong Province(Grant No.2022A1515110733).
文摘The real-time monitoring of the weld pool during deposition is important for automatic control in plasma arc additive manufacturing.To obtain a high deposition accuracy,it is essential to maintain a stable weld pool size.In this study,a novel passive visual method is proposed to measure the weld pool length.Using the proposed method,the image quality was improved by designing a special visual system that employed an endoscope and a camera.It also includes pixel brightness-based and gradient-based algorithms that can adaptively detect feature points at the boundary when the weld pool geometry changes.This algorithm can also be applied to materials with different solidification characteristics.Calibration was performed to measure the real weld pool length in world coordinates,and outlier rejection was performed to increase the accuracy of the algorithm.Additionally,tests were carried out on the intersection component,and the results showed that the proposed method performed well in tracking the changing weld pool length and was applicable to the real-time monitoring of different types of materials.
基金supported by the Projects of Major Scientific and Technological Achievements Local Transformation of Xi’an(2022JH-ZDZH-0039)International Science and Technology Cooperation Program of Shaanxi Province (2023-GHZD-50)+9 种基金Project of Qin Chuangyuan ‘Scientist+Engineer’team constructionKey R&D plan of Shaanxi Province (S2023-YF-QCYK-0001-237)Projects of Major Scientific and Technological Achievements Local Transformation of Xi’an (2022JH-ZDZH-0039)National Natural Science Foundation of China (52101134)Natural Science Foundation of Guangdong Province (2022A1515010275)Scientific Research Program Funded by Shaanxi Provincial Education Department (22JK0479)Doctoral Dissertations Innovation Fund of Xi’an University of Technology (101-252072305)Research Start-up Project of Xi’an University of Technology(101-256082204)Natural Science Foundation of Shaanxi Province (2023-JC-QN-0573)Natural Science Basic Research Program of Shaanxi(2023-JC-YB-412)
文摘Customized heat treatment is essential for enhancing the mechanical properties of additively manufactured metallic materials,especially for alloys with complex phase constituents and heterogenous microstructure.However,the interrelated evolutions of different microstructure features make it difficult to establish optimal heat treatment processes.Herein,we proposed a method for customized heat treatment process exploration and establishment to overcome this challenge for such kind of alloys,and a wire arc additively manufactured(WAAM)Mg-Gd-Y-Zn-Zr alloy with layered heterostructure was used for feasibility verification.Through this method,the optimal microstructures(fine grain,controllable amount of long period stacking ordered(LPSO)structure and nano-scaleβ'precipitates)and the corresponding customized heat treatment processes(520°C/30 min+200°C/48 h)were obtained to achieve a good combination of a high strength of 364 MPa and a considerable elongation of 6.2%,which surpassed those of other state-of-the-art WAAM-processed Mg alloys.Furthermore,we evidenced that the favorable effect of the undeformed LPSO structures on the mechanical properties was emphasized only when the nano-scaleβ'precipitates were present.It is believed that the findings promote the application of magnesium alloy workpieces and help to establish customized heat treatment processes for additively manufactured materials.
基金supported by the National Key Research and Development Program of China (No.2021YFB3701100)the National Natural Science Foundation of China (Nos.U20A20234,51874062)+1 种基金the Postdoctoral Science Foundation of China (No.2022M710503)the Chongqing Foundation and Advanced Research Project (No.cstc2019jcyj-zdxmX0010).
文摘Magnesium(Mg)alloys,as the lightest metal structural material with good damping capacities,have im-portant application prospects in realizing structural lightweight and vibration reduction.However,their engineering application is greatly limited by poor plastic formability.Wire and arc additive manufactur-ing(WAAM)provides a potential approach for fabricating large-scale Mg alloy components with high manufacturing flexibility.In this study,the evolution of the solidification microstructure of a WAAM-processed Mg-Al-based alloy was quantitatively analyzed based on the analytical models;then,the cor-relations between the solidification microstructure and mechanical properties/damping capacities were investigated.The results revealed that the WAAM-processed Mg-Al-based alloy with an equiaxed-grain-dominated microstructure displayed a simultaneous enhancement in mechanical properties and damping capacities compared to those of the cast Mg-Al-based alloy.The good combination of mechanical prop-erties and damping capacities are mainly attributed to the weakened basal texture with a relatively high Schmid factor for basalslip,the twinning-induced plasticity(TWIP)effect associated with the profuse{10-12}tensile twinning,and the relatively high dislocation density caused by the thermal stress during the WAAM process.
基金supported by Zhejiang Provincial Fundamental Re-search Funds of China(Grant.No.2021J010).
文摘To explore the feasibility of using wire arc additive manufacturing(WAAM)for forming and repairing marine components during ship navigation,this study conducted deposition experiments of ER50-6 steel and investigated the interference of ship-based vibrations on the WAAM equipment and influence of the characteristics of the arc droplets and sample morphology.The results revealed that the WAAM equipment vibrated with the external vibrations from the surrounding environment,and the welding gun and base plate produced dissimilar vibrations,which yielded unstable arc shapes resembling a bell,trumpet,fan,broom,and other irregular shapes.The mode of the droplet transfer ranged from the stable spray transfer mode to extensive amounts of large droplet transfer and short-circuit transfer.Although the morphology of the obtained sample deteriorated,the fully dense and defect-free interior demonstrated the applicability of ship-based WAAM.
基金the financial support by National Key Research and Development Project(Grand No.2020YFC1107202)Guangdong Basic and Applied Basic Research Foundation(Grand No.2020A1515110754)+3 种基金MOE Key Lab of Disaster Forest and Control in Engineering,Jinan University(Grand No.20200904008)Educational Commission of Guangdong Province(Grand No.2020KTSCX012)the Fundamental Research Funds for Central Universities(Grand No.21620342)the support from National Natural Science Foundation of China,NSFC(Grand No.51775556)。
文摘Additive manufacturing(AM)of Mg alloys has become a promising strategy for producing complex structures,but the corrosion performance of AM Mg components remains unexploited.In this study,wire and arc additive manufacturing(WAAM)was employed to produce single AZ31 layer.The results revealed that the WAAM AZ31 was characterized by significant grain refinement with non-textured crystallographic orientation,similar phase composition and stabilized corrosion performance comparing to the cast AZ31.These varied corrosion behaviors were principally ascribed to the size of grain,where cast AZ31 and WAAM AZ31 were featured by micro galvanic corrosion and intergranular corrosion,respectively.
基金the support from Projects of Major Innovation Platforms for Scientific and Technological and Local Transformation of Scientific and Technological Achievements of Xi’an (No.20GXSF0003)the Higher Education Institution Discipline Innovation and Intelligence Base of Shaanxi Provincial (No.S2021-ZC-GXYZ0011)National Natural Science Foundation of China (Grants No.51801154)。
文摘Strength-ductility trade-off is a common issue in Mg alloys. This work proposed that a synergistic enhancement of strength and ductility could be achieved through tuning interlayer dwell time(IDT) in the wire and arc additive manufacturing(WAAM) process of Mg alloy.The thermal couples were used to monitor the thermal history during the WAAM process. Additionally, the effect of different IDTs on the microstructure characteristics and resultant mechanical properties of WAAM-processed Mg alloy thin-wall were investigated. The results showed that the stable temperature of the thin-wall component could reach 290 ℃ at IDT=0s, indicating that the thermal accumulation effect was remarkable. Consequently, unimodal coarse grains with an average size of 39.6 μm were generated, and the resultant room-temperature tensile property was poor. With the IDT extended to 60s, the thermal input and thermal dissipation reached a balance, and the stable temperature was only 170 ℃, closing to the initial temperature of the substrate. A refined grain structure with bimodal size distribution was obtained. The remelting zone had fine grains with the size of 15.2 μm, while the arc zone owned coarse grains with the size of 24.5 μm.The alternatively distributed coarse and fine grains lead to the elimination of strength-ductility trade-off. The ultimate tensile strength and elongation of the samples at IDT=60s are increased by 20.6 and 75.0% of those samples at IDT=0s, respectively. The findings will facilitate the development of additive manufacturing processes for advanced Mg alloys.
基金the National Natural Science Foundation of China(No.51975419)。
文摘Additive manufacturing is a very promising manufacturing method widely used in various industries.In this study,for the first time,a new type of combined cable wire(CCW)with multi-element composition has been designed and developed for arc additive manufacturing(AAM)of non-equiatomic Al-Co-Cr-FeNi high-entropy alloy.CCW composed of 7 filaments and 5 elements has the advantages of high deposition efficiency,self-rotation of welding arc and energy saving capability.Thin HEA walls were fabricated under pure argon gas using cold metal transfer technology.Microstructural observations of the developed HEA reveal(i)BCC and FCC phases,(ii)Good bonding between layers and(iii)defect-free microstructure.The developed alloy exhibits high compression strength(~2.8 GPa)coupled with high plastic strain(~42%)values(possess both strength and ductility).It has been identified that by varying the heat input via torch travel speed,the microstructure and mechanical properties of the HEA can be controlled.From this feasibility study,it has been proved that the innovative CCW method can be used to manufacture HEAs with CCW-AAM.Further,the study highlights the advantage of the rapid cooling involved in the CCW-AAM process which gives rise to superior mechanical properties.
基金carried out at the Welding Engineering Research Group,University of Wollongong,and it was supported by China Scholarship Council(No.201506680056)the National Natural Science Foundation of China(No.51805085)。
文摘Realizing improved strength in composite metallic materials remains a challenge using conventional welding and joining systems due to the generation and development of brittle intermetallic compounds caused by complex thermal profiles during solidification.Here,wire arc additive manufacturing(WAAM)process was used to fabricate a steel-nickel structural component,whose average tensile strength of 634 MPa significantly exceeded that of feedstock materials(steel,537 MPa and nickel,455 MPa),which has not been reported previously.The as-fabricated sample exhibited hierarchically structural heterogeneity due to the interweaving deposition strategy.The improved mechanical response during tensile testing was due to the inter-locking microstructure forming a strong bond at the interface and solid solutions strengthening from the intermixing of the Fe and Ni increased the interface strength,beyond the sum of parts.The research offers a new route for producing high-quality steel-nickel dissimilar structures and widens the design opportunities of monolithic components,with site-specific properties,for specific structural or functional applications.
基金the National Natural Science Foundation of China(No.51805415)the China Postdoctoral Science Foundation(No.2019M663682)the Open Fund of the State Key Laboratory for Mechanical Behavior of Materials(No.20212311)。
文摘Aluminum alloy is the most widely used light alloy at present.By combining different types of aluminum alloys,their functional properties can be expanded.In the present research,two components composed of 2319(Al-6.5Cu)and 5B06(Al-6.4Mg)dissimilar alloys were fabricated by wire and arc additive manufacturing(WAAM).The deposited component with the bottom half of 2319 and the top half of 5B06 exhibits better mechanical properties than its counterpart deposited vice versa.Its ultimate tensile strength,yield strength,and elongation are 258.5 MPa,139.3 MPa,and 5.6%,respectively,which are only slightly inferior to the mechanical properties of 2319 base metal.The results show that for both components,fracture occurred at a layer thickness above the interface layer during the tensile test,regardless of the deposition order.It appears that the thermal stress due to the long dwell time and the remelting of the S-AlCu Mg phase are the main factors promoting crack initiation.Depending on the deposition order,cracks propagate either along the aggregated pores or stripθ-AlCu phase distributed along the grain boundary.By analyzing the heat input and selecting the appropriate depositing order,the strength of WAAM dissimilar aluminum alloys can be effectively improved through the proper control of microstructure and internal defects.
