Arc Heat Source Research Articles

Characterization of nickel-titanium alloy graded materials using double wire alternating current cross arc additive manufacturing

Using an arc heat source, the filling ratio of Ti6Al4V and Inconel 625 wires was controlled to manufacture a TiNi gradient material using wire arc additive manufacturing (WAAM). The effects of wire filling ratio on the microstructure of the deposition layer were studied through X-ray diffraction (XRD), scanning electron microscope (SEM), and differential scanning colorimetry (DSC). The mechanical performance was evaluated using compression, Vickers hardness, and surface wear testing. The results show that increasing the ratio of Inconel 625 filling wire can form Ti 2 Ni and TiNi strengthening phases in the deposition layer. The Ti 2 Ni and TiNi phases are evenly distributed over the region owing to the stirring of the molten pool by the arc, which improves the compression and surface wear performance of the WAAM parts. When the Inconel 625 wire filling ratio is 35%, the Vickers hardness reaches 600 HV and the compression strength increases to 2.15 GPa. However, excessive Ti 2 Ni phase will reduce toughness. As an Inconel 625 wire filling ratio lower than 35% can achieve a well-performing structure, five kinds of wire filling ratios were chosen to fabricate different gradient materials, and the microstructure, elemental distribution, phase composition, and mechanical properties were analyzed thoroughly. • We propose a new AC-WAAM method to manufacture Ni-Ti alloy Graded Materials. • By adding lnconel625 filling wire and titanium alloy filling wire at the same time. • Changing alloy compound by adjusted the speed rate of lnconel625 and TC4 filling wire. • The effects of wire feeding rate on the microstructure and mechanic were analyzed.

Investigation of welding parameters effects on temperature field and structure field during laser-arc hybrid welding

Thermo-structural weak coupling model was adopted in numerical simulation of laser-arc hybrid T-joint welding. Gauss surface heat source and Rotary-Gauss body heat source were used to form a combined heat source in the temperature field analysis and simulate the arc and laser heat source. The laser-arc hybrid overlaying welding test of 304 stainless steel was carried out, and the weld molten pool morphology was obtained by metallographic corrosion test. The test results of a molten pool morphology show that the combination heat source can better simulate the laser-arc hybrid welding process. The effects of laser power, arc power and welding speed on residual stress and deformation of T-joint in laser-arc hybrid welding were studied by orthogonal experiments. Experimental results show that the arc power has great influence on the depth-width ratio, the laser power has great influence on the welding residual stress, and the welding speed has great influence on the thermal deformation. Through quantitative analysis and comparison, the optimal parameters were found during laser-arc hybrid welding.

The effects of ultrasonic frequency pulsed arc on wire + arc additively manufactured high strength aluminum alloys

Ultrasonic frequency pulsed variable polarity TIG and conventional variable polarity TIG arc heat source were employed to fabricate WAAM 2024 aluminum alloy thin-wall structures. Heat treatment procedure was conducted to process the components. The microstructure, porosity and mechanical properties were comparatively investigated to reveal the effects of ultrasonic frequency pulsed arc on the properties of WAAM aluminum alloys. With ultrasonic frequency pulsed arc, the grain was refined, and the porosity was significantly reduced. The micro hardness and its uniformity increased. Ultrasonic frequency pulsed arc can particularly increase the vertical tensile properties of heat-treated components and improve property isotropy. The refined grains and lower porosity in WAAM aluminum alloy structure with ultrasonic frequency pulsed arc were the reasons for property and isotropy improvement.

Effects of thermal undercooling and thermal cycles on the grain and microstructure evolution of TC17 titanium alloy repaired by wire arc additive manufacturing

Wire arc additive manufacturing (WAAM) can be used to repair blades or blisk made of titanium alloy with the advantage of high efficiency and low-cost. In this work, the finite element model of repairing the blade based on the arc heat source was established to investigate it. Results showed that the maximum effect of thermal undercooling appeared when the peak current transformed to the base current (1 Hz or 5 Hz), which will promote the grains refinement with the combination of sufficient constitutional supercooling. Compared to the single-layer deposition, the microstructure in the near-heat affected zone (near-HAZ) of multi-layer deposition changes from the metastable β phases to the extremely fine α phases, which was caused by the repeated thermal cycles.

Characteristic Analysis of Double Arcing on the Top Surface of STS304 in Plasma Arc Piercing

Plasma arc cutting is a thermal cutting method that melts and removes the material by projecting an arc heat source onto the cutting part of material. In the case of cutting thick plate, plasma arc piercing is performed before plasma arc cutting for cutting quality and cutting efficiency. The quality of plasma arc piercing varies greatly depending on several variables. In particular, the factors such as stand-off distance, current and thickness of material play an important role in inducing double arcing. Therefore, it is necessary to investigate the phenomenon that occurs during plasma arc piercing according to the factors. In this study, we synchronized the arc shape photographed with a high-speed camera using a band-pass filter and the voltage waveform measured with the DAQ equipment. And it was confirmed that the smaller the stand-off distance, the stronger the current and the thicker the thickness of material, the worse the top surface of the material by double arcing.

Analytical Solution of the Non-Stationary Heat Conduction Problem in Thin-Walled Products during the Additive Manufacturing Process.

The work is devoted to the development of a model for calculating transient quasiperiodic temperature fields arising in the direct deposition process of thin walls with various configurations. The model allows calculating the temperature field, thermal cycles, temperature gradients, and the cooling rate in the wall during the direct deposition process at any time. The temperature field in the deposited wall is determined based on the analytical solution of the non-stationary heat conduction equation for a moving heat source, taking into account heat transfer to the environment. Heat accumulation and temperature change are calculated based on the superposition principle of transient temperature fields resulting from the heat source action at each pass. The proposed method for calculating temperature fields describes the heat-transfer process and heat accumulation in the wall with satisfactory accuracy. This was confirmed by comparisons with experimental thermocouple data. It takes into account the size of the wall and the substrate, the change in power from layer to layer, the pause time between passes, and the heat-source trajectory. In addition, this calculation method is easy to adapt to various additive manufacturing processes that use both laser and arc heat sources.

Local energy adjustment mechanism in a novel laser-enhanced plasma arc heat source

This study aims to enhance the localized energy of the plasma arc to meet the requirement of thick metal plate welding. To achieve this, a novel hybrid heat source by coaxial arranging the laser and plasma arc was proposed, named laser-enhanced plasma arc (LPA). This special torch combines the two kind sources by a tubular tungsten electrode which the laser passes through, use laser to heat localized plasma arc to modify the energy distribution. The three-dimensional temperature field was measured to clarify the effect of laser on plasma arc energy distribution and the absorption characteristics of laser by plasma arc. The numerical simulation model was established to reveal the influence mechanism. Results show that there is a high laser absorption region in the plasma arc, and it exists obvious effects of plasma arc pressure and temperature on laser absorption rate. The location and size of the high laser absorption region change as the welding parameters because the temperature and pressure of plasma arc change. The results also substantiate that the hybrid source energy can be adjusted locally to increase the effective flame length of the plasma arc by changing the laser energy and plasma arc parameters, which is beneficial for thick metal plate welding.

Impact of driving forces on molten pool in gas metal arc welding

A numerical scrutiny was performed to analyze the effect of driving forces on molten pool in gas metal arc welding. In addition to the basic governing equations required for a general heat and mass transfer analysis by computational fluid dynamics, a volume-of-fluid equation for free surface tracking and additional conservation equations for calculating the distribution of alloy elements were used. Driving forces—buoyancy, drag force, arc pressure, electromagnetic force, Marangoni pressure, and droplet impingement—and the arc heat source were mathematically modeled and applied to the simulation. In order to examine the effect of driving forces, a two-dimensional axisymmetric simulation was performed, and the effect of each driving force was analyzed using the velocity components. In the radial velocity component, the effect of droplet impingement and the Marangoni force was large, and in the vertical velocity component, the droplet impingement effect was dominant. A three-dimensional simulation was also performed considering all the driving forces together, and the result was verified by comparison with experimental results. Relatively high alloying element contents were found at the bottom of the fusion zone, which was due to the droplet impingement generating a high vertical velocity.

Investigations of heat source models in transient thermal simulation of pulsed MIG welding of AA6061-T6 thin sheet

The automobile and aviation industries are exhaustively working on weight reduction by replacing steel with aluminium alloy. However, joining the aluminium alloy body panel is remain a big challenge because of the inherent properties of aluminium. The dynamic behaviour of arc plasma in the pulsed MIG welding process is a multifaceted heat mass transfer phenomenon involving chemical, electro-magnetic, and fluid dynamics. Numerical simulation using FEA techniques are greatly helpful in understanding responses of weld bead and material behaviour. Simultaneously it reduces time and cost consuming experimental trial and error approach. The approximation of the welding arc heat source is paramount for precise prediction in the welding process simulation model. The article focuses on the comparison, suitability and effects of various moving heat source models by developing the transient thermal simulation of pulsed MIG welding of 1mm thick AA6061-T6 sheet in ANSYS workbench. Moving heat source models were developed as ANSYS APDL command subroutine. It is observed that for 1mm thin sheets Gaussian surface heat source model is also valid. The difference in temperature field is not prominent in comparison with Goldak’s double ellipsoidal heat source model.

Plasma-Assisted Hybrid Dissimilar Friction Stir Welding for Joining of DH36 Steel and AISI 1008 Steel: Thermal Modelling and Experimental Analysis

Dissimilar materials joining by hybrid FSW involve preheating the harder material ahead of the FSW tool, which reduces the vertical force and improves the weld quality by enhancing the material flow. In this work, both experimental and numerical analyses were conducted for the friction stir welding (FSW) and plasma-assisted friction stir welding (PAFSW) of dissimilar steels such as DH36 shipbuilding steel and AISI 1008 steel. The comparative study was performed on the thermal history, vertical force, mechanical and microstructural characterizations under different welding conditions. The 3D transient thermal phenomenological models were established using Abaqus/CAE 2017 finite element (FE) software package. The moving heat source models for FSW and PAFSW were successfully established, which were embedded in a Fortran code and fed to Abaqus/CAE through DFLUX subroutine. The additional heat source, i.e. plasma arc heat source, was modelled using the Gaussian distribution of heat flux. The stir zone isotherms of the developed numerical models and the transient thermal profiles in the FSW and PAFSW were matched fairly well with experimental results. For the reliable comparative study, the consequence of FSW parameters (i.e. traverse speed and rotational speed) and preheating parameters (i.e. plasma offset and preheating current) on thermal history was investigated. It was observed that the assistance of the plasma preheating ahead of FSW tool was significantly reduced the grain size and vertical force. In contrast, the hardness and the impact toughness values were increased compared to that of FSW.

Thermal analysis of Wire Arc Additive Manufacturing process

Wire arc additive manufacturing process (WAAM) is an innovative technology that offers freedom in terms of designing functional parts, due to its ability to manufacture large and complex workpieces with a high rate of deposition. This technology is a metal AM process using an electric arc heat source. The parts manufactured are affected by thermal residual stresses due to high-energy input between wire and workpiece despite numerous advantages with this technology. It could cause severe deformation and change the global mechanical response. A 3D transient thermal model was created to evaluate the thermal gradients and fields during metal deposition. The material used in this study is a steel alloy (S355JR-AR). This numerical model takes into account the heat dissipation through the external environment and the heat loss through the cooling system under the base plate. Birth-element activation strategy was used to generate warm solid part following the movement of the heat source. The metal deposition is defined with constant welding speed. Goldak model was used to simulate the heat source in order to have a realistic heat flow distribution. Results were in concordance for thermal cycles at different points comparing with experimental results issued from bibliography in terms of: (1) Temperature maximum, (2) Thermal cycles and (3) Cooling gradient phase. This study enabled to check the numerical model and used as a predictive tool

Wire-Based Additive Manufacturing of Stainless Steel Components

Three different wire-fed additive manufacturing (AM) processes were employed to evaluate differences between laser, arc, and electron beam heat sources used for high-deposition-rate AM on the order of 1 kg/h. Optimum weld and build parameters were developed independently to match the characteristics of each heat source using 308L stainless steel welding wire as the feedstock. Laser-wire AM was made with the lowest energy per unit length of weld and had the best control of the melt pool and surface finish. Wire arc-based AM had an intermediate energy per unit length of weld of approximately 5× that of the laser process, while electron beam wire AM had the highest energy per unit length of weld at approximately 10× that of the laser process. Analysis of the parts that were built included evaluation of mechanical properties and microstructures, and these properties are discussed with respect to the difference in input energy and cooling rates. Results show that all three processes build parts with properties that exceed those of annealed 304L wrought stainless steel. How-ever, significant differences exist between the processes, and the results presented here can be used to help select the best wire-fed process for a given high-deposition-rate application.

Mathematical modelling of formation process for multi-layer 3D structure produced by additive method using arc heat sources

The results of modelling of temperature fields, kinetics of deposition of layers of dissimilar metals and nature of structural transformations in formation of multi-layer structure of 17G1S and 30KhGS steels are presented. Computer modelling was performed using COMSOL Multiphysics software package. The work takes into account effect of temperature on thermal and physical parameters of steels. To increase productivity of additive process the work has studied simultaneous effect of 3 arcs on process of deposit formation, kinetics of structural transformations and diffusion processes of alloying elements redistribution. The calculations show that preheating of the substrate by arc in the beginning of the process before application of deposited material is necessary in order to decrease a stress level between additive deposit and substrate to 50 MPa. It is shown that the time of passing between neighbor arc heat sources shall be kept in 5- 30 s range. It is determined that low power of arc (1 kW) mainly provokes formation of ferrite-bainite structure in the deposit, portion of bainite in which makes 71 %, ferrite 28% and martensite ~ 1%. Application of larger power arc (5 kW) forms in the deposit bainite-martensite structure, portion of bainite in which makes ~ 50%, portion of martensite rises up to 40% and that of ferrite to 10%. Increase of arc power results in rise of maximum temperature of liquid pool to 1750-1850 °C, growth of cooling rate to 15 – 25 °C/s , and, as a consequence, increase of martensite portion in the structure of deposited layers.

Detecting the influence of heat sources on material properties when producing aviation parts by a direct energy deposition method

Quality of the material obtained by the method of direct energy deposition using three heat sources (plasma arc, electric welding arc and welding arc with cold metal transfer) was studied. AlMg5 alloy wire was used as the filler material. The study was conducted to establish at what heat source the deposited material will have the highest physical and mechanical characteristics and performance. It was also necessary to assess quality, size and uniformity of distribution of the deposited layers since these indicators determine accuracy of the resulting product and make it possible to reduce machining allowance. Influence of heat sources on formation of surface of deposited plates was revealed: the specimens obtained by the method of plasma surfacing had protrusion height of the deposited layers on the side surface up to 2 mm, the specimens obtained by the method of electric arc and CMT surfacing had protrusion height of 0.5 mm. The obtained data will enable determination of the minimum allowable machining allowance. Analysis of chemical composition has shown that each heat source ensured chemical composition of the finished product corresponding to chemical composition of original material. Distribution of alloying elements was uniform among the deposited layers. However, the CMT process provided the most accurate distribution of alloying elements. Physical and mechanical properties of the plates obtained by the direct growth method were approximately at the same level with the materials obtained using conventional methods of casting and pressing. The specimens obtained by the method of plasma surfacing had the highest values of mechanical properties: σ t =28 MPa; σ 0.2 =15 MPa; δ=30.4 % which can be explained by a more dispersed structure and a high level of fusion of the deposited layers. The obtained data will make it possible to determine which heat source is more expedient to use in order to obtain properties necessary for a concrete technological process. They also make it possible to evaluate applicability of the method of direct growth using arc heat sources in mass production of parts

Determination of the heat source parameters for the case of simultaneous two-sided laser-arc welding of extended T-joints

Effective application of hybrid laser technologies can help to decide the problem of creating high-performance welding technologies that allow to optimize the process of producing critical structures, as well as to reduce labor intensiveness material consumption. Today the development of industrial technologies for the manufacture of extended body parts under minimum tolerance condition requires the numerical simulation of thermal deformation processes occurring in the material during welding and affecting the final operating characteristics of products. The article is devoted to the search for the optimal solution of the problem of determining the T-joint geometrics, taking into account the possibility varying the positional relationship of the laser and arc heat sources on both sides. The thermal field that is created by two simultaneously operating combined heat sources is one of the key parameters of the process.

Numerical simulation of keyhole behaviors and droplet transfer in laser-MIG hybrid welding of Invar alloy

PurposeThis paper aims to describe a three-dimensional mathematical and numerical model based on finite volume method to simulate the fluid dynamics in weld pool, droplet transfer and keyhole behaviors in the laser-MIG hybrid welding process of Fe36Ni Invar alloy.Design/methodology/approachDouble-ellipsoidal heat source model and adaptive Gauss rotary body heat source model were used to describe electric arc and laser beam heat source, respectively. Besides, recoil pressure, electromagnetic force, Marangoni force, buoyancy as well as liquid material flow through a porous medium and the heat, mass, momentum transfer because of droplets were taken into consideration in the computational model.FindingsThe results of computer simulation, including temperature field in welded plate and velocity field in the fusion zone were presented in this article on the basis of the solution of mass, momentum and energy conservation equations. The correctness of elaborated models was validated by experimental results and this proposed model exhibited close correspondence with the experimental results with respect to weld geometry.Originality/valueIt lays foundation for understanding the physical phenomena accompanying hybrid welding and optimizing the process parameters for laser-MIG hybrid welding of Invar alloy.

A Study on the Dissimilar Metal Joining of Aluminum to Steel Using the Arc Heat Source (Ⅱ) - Mechanism of Dissimilar Metal Joining -

A Study on the Dissimilar Metal Joining of Aluminum to Steel Using the Arc Heat Source (Ⅱ) - Mechanism of Dissimilar Metal Joining -

A Study on the Dissimilar Metal Joining of Aluminum to Steel Using the Arc Heat Source (Ⅰ) - Research Trends and Comparison of the Processes -

A Study on the Dissimilar Metal Joining of Aluminum to Steel Using the Arc Heat Source (Ⅰ) - Research Trends and Comparison of the Processes -

A Study on the Dissimilar Metal Joining of Aluminum to Steel Using the Arc Heat Source (Ⅲ) - Static Strength and Fracture Behaviors -

A Study on the Dissimilar Metal Joining of Aluminum to Steel Using the Arc Heat Source (Ⅲ) - Static Strength and Fracture Behaviors -

Effects of Solution Treatment Temperatures on Microstructure and Mechanical Properties of TIG–MIG Hybrid Arc Additive Manufactured 5356 Aluminum Alloy

A novel additive manufacturing method with TIG–MIG hybrid heat source was applied for fabricating 5356 aluminum alloy component. In this paper the microstructure evolution, mechanical properties and fracture morphologies of both as-deposited and heat-treated component were investigated, and how these were affected by different heat-treated temperature. The as-deposited microstructure showed dominant equiaxed grains with second phase, and the size of them is coarse in the bottom region, medium in the middle region and fine in the top region owing to different thermal cycling conditions. Compared with as-deposited microstructure, the size of grain becomes large and second phases gradually dissolve in the matrix as heat-treated temperature increase. Different microstructures determine the mechanical properties of component. Results show that average ultimate tensile strength enhances from 226 to 270 MPa and average microhardness increases from 64.2 to 75.3 HV0.1 but ductility decreases from 33 to 6.5% with heat-treated temperature increasing. For all components, the tensile properties are almost the same in the vertical direction (Z) and horizontal direction (Y) due to equiaxed grains, which exhibits isotropy, and the mechanisms of these are analyzed in detailed. In general, the results demonstrate that hybrid arc heat source has the potential to fabricate aluminum alloy component.