Wire Feed Speed Research Articles

Forming Process of Wire and Arc Additive Manufacture

The forming process of wire and arc additively manufacture (WAAM) was studied using the self-developed and designed WAAM system. The single-pass and single-layer weld bead samples were prepared with different process parameters, and the cross-sectional dimensions of the weld bead were measured. The influence rules of weld current, welding speed, wire feed speed and welding height on the weld bead size were obtained. In addition, the overlap experiment of the WAAM forming process was also carried out. The multiple and multilayer lap samples with different overlap rates were prepared, and the cross-sections of the lap samples were observed and analyzed. Finally, the overlap rate range of 35-45% with good forming effect was obtained.

Joint Properties of Aluminum Alloy and Galvanized Steel by AC Pulse MIG Braze Welding

In response to global environment and fuel efficiency regulations aiming to reduce CO2 emissions, multi-material structures that use lightweight materials are currently being developed to realize the weight reduction of vehicles in automotive manufacturing. The dissimilar welding of aluminum alloy to steel has great importance, but it is still challenging due to their widely varying thermo-physical properties and the formation of intermetallic compounds. This study aimed to investigate the effect of process parameters on the wettability, mechanical properties, and microstructure in AC Pulse MIG welded joints of AA6061-T6 and galvanized steel sheets. A parametric study on torch aiming position and welding current with EN ratio variation was performed to optimize the process parameters. The result showed that the amount of metal deposition increased with EN ratio. When the EN ratio was higher, the wire feeding speed increased and the heat input process lowered. Moreover, the wetting length increased, ranging from 6.6 to 8.4 mm, and the wetting angle increased from 31.2 to 67.6°, respectively. As a result of the tensile shear test, the maximum tensile shear load of dissimilar welded joints produced at 70 A with a 20% EN ratio was approximately 8.8 kN. From the result of scanning electron microscopy with energy-dispersive spectrometry, FeAl3 IMC was observed at the joint interface, and the IMC layer thickness decreased with EN ratio at 70 A.

Multi-properties optimization of welding parameters of wire arc additive manufacture in dissimilar joint of iron-based alloy and nickel-based superalloy using grey-based Taguchi method

In order to adapt to the high temperature and heavy load process environment of large forgings, a novel die with “fist-like” structure was designed. The iron-based welding material (RMD248) as the “bone” layer and the nickel-based superalloy welding material (ERNiCr-3) as the “skin” layer were welded on the matrix by wire arc additive manufacture (WAAM). In this work, the grey based Taguchi methodology was used to optimize welding parameters (welding voltage, welding speed and wire feed speed) considering excellent multi-properties (hardness and ultimate tensile strength of high-temperature tensile test) of the dissimilar joint of RMD248 and ERNiCr-3. Further, analysis of variance was done to ascertain the influence of welding parameters on response parameters. Experimental results showed that welding speed was the most effective input parameter followed by wire feed speed and welding voltage. Finally, optimal result was verified through confirmation experiments. Meanwhile, the effect of welding speed on the microstructure and mechanical properties of joint was studied. The microstructures were characterized by optical microscopy (OM), energy dispersive spectrometer (EDS). The results indicated that the microstructure of RMD248 was consisted of more retained austenite at lower welding speed. For ERNiCr-3, the finer columnar crystal structure at higher welding speed was observed. At lower welding speed, the microhardness of RMD248 was just slightly lower, but that of ERNiCr-3 was significantly higher, and the ultimate tensile strength was higher. Therefore, the specimen at lower welding speed had better comprehensive mechanical properties.

Simulation and control of metal droplet transfer in bypass coupling wire arc additive manufacturing

The influences of bypass current and wire feed speed are utilized to change the metal droplet transfer mode for bypass coupling wire-arcing additive manufacturing (BC-WAAW). To fully understand the influence of experimental factors on the wire melting process, this study establishes a mathematical model for the wire melting process, and several simulation experiments are carried out to prove the effectiveness of this mathematical model. The influence of changing the filler wire process on the stability of the wire melting process is simulated. A negative feedback control method with a single input and single output is proposed, which can control the stability of the wire melting process. The results show that the established mathematical model can well reflect the wire melting process in bypass coupling arcing additive manufacturing. The wire feed speed has a strong influence on the wire extension. The negative feedback control method can realize real-time control of filler wire process stability. The deposition process is more stable in the arcing additive manufacturing process, and the forming accuracy of a single multilayer deposition wall is further improved.

Process control of pulsed laser enhanced metal transfer behavior in CO2 gas shielded welding

Spot pressure, as an arc repelling force, hinders the metal transfer process and has a negative effect on welding process stability in CO2 gas shielded welding. In addition, the direction of the spot pressure changes uncontrollably with the deflection of the droplet. Therefore, it is particularly critical to provide an additional force to improve droplet transfer characteristics without disturbing the arc stability. To this end, a new approach of the pulsed laser enhanced metal transfer (PLE-MT) process in CO2 gas shielded welding was proposed to control metal transfer behavior. The results demonstrate that: different from the uncontrollable deflection of droplets caused by laser incident on the solid–liquid interface (S-L-I) of the droplet, the irradiation of solid-state welding wire (S-W) can fundamentally solve the droplet deflection problem. The cut droplet can enter into the molten pool smoothly along the axis, and the change of the incident height does not significantly change the droplet's detachment velocity. The droplet’s detachment time at three different laser incident heights (0.5, 1, and 1.5 mm) remained almost unchanged, all of which were about 6–8 ms. When the wire feeding speed is 4 m/min and the voltage is 25 V, after laser irradiation is added, the metal transfer frequency increases from 5 to 25 Hz. The droplet transfer mode changes from SC transfer to spray transfer, and it avoids the short-circuit spatter. However, the metal evaporation mass produced by laser heating liquid droplet or welding wires is about 3.5% of the droplet mass. Under the condition of direct current electrode negative (DCEN), although the melting efficiency of the wire can be effectively improved, the droplet will be repelled until the arc is extinguished, and the stability of the arc will also deteriorate due to the rise of the arc. The irradiation of the pulsed laser can impede the climb of the droplet (cut off the droplet when its size is small before the arc climbs up), promote metal transfer, and improve the stability of the welding process in DCEN. While expanding the process interval of CO2 welding, an efficient spatter-free, low-pollution metal transfer process was obtained under a relatively small current through the PLE-CO2 welding process.

Process-related influences and correlations in wire arc additive manufacturing of high-strength steels

High-strength fine-grained structural steels have great potential for weight-optimized, efficient structures in many modern steel applications. Further advances in efficiency can be achieved through additive manufacturing and bionic design. Commercial high-strength filler materials for wire arc additive manufacturing (WAAM) are already provided by the consumable producers. Today, application would be strictly limited due to absence of quantitative findings or any guidelines for the industry regarding welding-related stresses and component safety during manufacturing and service. Hence, process- and material-related influences and design-related restraint conditions associated with formation of residual stresses and cold cracking risk are investigated. The aim is the accessibility of special WAAM self-restraining cold cracking tests and easy applicable processing recommendations, enabling an economical, fit-for-purpose and crack-safe WAAM of high-strength steels. This first study focuses on determination of interactions between WAAM process parameters, resulting layer geometry, microstructure and residual stresses, analyzed via X-ray diffraction. Defined reference specimens are automated welded using a special WAAM solid wire (yield strength >820 MPa). Geometric properties can be specifically adjusted by wire feed and welding speed, but cannot be varied arbitrarily, since a high heat input causes local overheating, inadmissible changes of microstructure and mechanical properties, defects and comparable high tensile residual stresses.

Underwater wire-feed laser deposition of thin - Walled tubular structure of aluminum alloy

Thin-walled aluminum alloy tube of underwater laser in-situ deposition technique was carried out for the first time, and the influences of laser powers, wire feeding speeds and shielding gas flow rates on the deposition appearance, geometry characteristics, microstructure and microhardness of single track deposited layer were investigated. As the laser power increased, the height of deposited region (DR) and deposition angle decreased, but the height of fusion region (FR) and the width increased. Besides, the deposition appearance became better firstly and then worse. With the wire feeding speed increased, the height of DR, width and deposition angle increased, but the height of FR decreased. In addition, the deposition appearance was greatly improved. As the shielding gas flow rate increased, the height of DR and deposition angle decreased, but the height of FR and width increased. Besides, the deposition appearance deteriorated. The microstructure of FR and DR were columnar dendrites and equiaxial dendrites, respectively. With wire feeding speed increased, the microstructure had a tendency to refine and average microhardness value gradually increased. However, as the laser power and shielding gas flow rate increased, the microstructure became coarse gradually and average microhardness value gradually decreased.

Finite element analysis on processing stress of polysilicon cut by diamond multi-wire saw

At present, diamond multi-wire sawing technology has been applied to the slicing of polysilicon wafers. The residual microcracks on the surface and subsurface of the silicon wafer due to material brittle removal are prone to expand and interfere under the sawing stress, which reduces the fracture strength of the silicon wafer and leads to breakage. However, the dynamic change and distribution of sawing stress is still difficult to measure by experiment. In this paper, the two ways of ductile and brittle material removal of abrasives at different azimuth angles on the saw wire surface were considered, the sawing force model of diamond wire sawing was established. Then based on the sawing force model, a finite element model of multi-wire sawing polysilicon was established. The distribution and coupling characteristics of sawing stress and the influence of process parameters and silicon wafer size characteristics on the stress value and distribution were studied. The research results show that the mechanical stress value during the sawing process is relatively small and accounts for a small proportion of the coupling stress, but it will affect the distribution of the coupling stress, and the thermal stress is dominant. The coupling stress increases with the increase of saw wire speed and feed speed. When the ratio of saw wire speed to feed speed is constant, the larger the value of saw wire speed and feed speed is, the larger the coupling stress is. The increase in the size and thickness of the silicon wafer will increase the coupling stress, while the change in the thickness of the silicon wafer has little effect on the value of the coupling stress. The research results of the paper provide a theoretical reference for understanding the changes and distribution of sawing stress, optimizing process parameters and improving the quality of sawing.

Robotic skeleton arc additive manufacturing of aluminium alloy

To meet lightweight demands, complex support or near-net shaped structures are increasingly applied in modern industry sectors. Wire arc additive manufacturing (WAAM) of these structures requires a profound knowledge of the interactions between material properties, welding process and mechatronic engineering. This study shows a new WAAM strategy, termed skeleton arc additive manufacturing (SAAM), adapted especially for building freeform wire-structured aluminium component, and further contributes a bead modelling study to establish welding parameters, geometric features and material properties relationship. The results show that good geometrical features and sound metallurgical properties can be achieved for wire-structure aluminium parts using the proposed approach. The strut diameter gradually increased with the amplified welding arc-on time and wire feed speed; however, they present significant changes in the microstructural evolution and mechanical strength. A sample demonstration further displays an effective path to create typically wire-structure part with good quality and offers the main processing challenge and coping strategy during SAAM.

Droplet transfer behavior and weld formation of gas metal arc welding for high nitrogen austenitic stainless steel

Abstract High nitrogen austenitic stainless steel (HNASS) wire with 0.78 wt.% nitrogen content was used for gas metal arc welding (GMAW) test. The characteristics of droplet transfer and weld formation in different welding parameters were investigated. There were three typical metal transfer modes in GMAW of HNASS, namely in terms of stable short circuit transfer, unstable short circuit transfer and spray transfer. With wire feed speed (WFS) of 3 m/min∼8 m/min and moderate arc voltage, the droplet transfer was stable short-circuiting transition mode. The transfer period and waveform of electrical parameters were regular and the weld formation was satisfactory with few spatters. With the increasing of arc voltage or WFS, the droplet grew up to abnormal large size due to the expansion of supersaturated nitrogen. The electric parameters were more disordered and the metal transfer became unstable with spatter. When wire feed speed was over 10 m/min with high arc voltage, the droplet transfer became spray transfer accompanied by numerous welding fumes. The weld formation of HNASS for unstable short circuit and spray transfer mode was inferior with serious spatters.

Effect of different variants of filler metal S Ni 6625 on properties and microstructure by additive layer manufactured using CMT process

The influence of arc energy and different filler metal composition on the mechanical properties and macro- and microstructure of additively welded thin-walled structures of Ni-based alloy were investigated using four different variants commercially available solid wire electrodes of type S Ni 6625. As the welding process, the Cold Metal Transfer (CMT) process was used. The heat input and cooling rate were varied by adjusting wire feed and travel speed. The results show that an increase in arc energy leads to longer t10/6 cooling times. This leads to an increase in the dendrite arm spacing and thus to a reduction in the strength values and hardness of the thin-walled structures. The higher Fe-containing variant of S Ni 6625 produces the highest strength and hardness values, while the W-alloyed solid wire electrode produces the lowest values. The porosity in the walled structures was very low, and unacceptable weld defects, hot cracks and lack of fusion did not occur. Segregations occur in all weld metal specimens. While niobium, molybdenum and titanium are the preferred segregations in the Nb-alloyed Ni 6625 type weld metal, only Mo is present in the W-alloyed Ni 6660 type weld metal.

Globular-to-Spray Transition in Cold Wire Gas Metal Arc Welding

The electrical current required for a transition from globular to spray droplet transfer during gas metal arc welding (GMAW) is determined by the specified wire feed speed in the case of constant-voltage power supplies. Generally, in narrow groove welding, spray transfer is avoided, be-cause this transfer mode can severely erode the groove sidewalls. This work compared the globular-to-spray transition mechanism in cold wire gas metal arc welding (CW-GMAW) vs. standard GMAW. Synchronized high-speed imaging with current and voltage samplings were used to characterize the arc dynamics for different cold wire mass feed rates. Subsequently, the droplet frequency and diameter were estimated, and the parameters for a globular-to-spray transition were assessed. The results suggest that the transition to spray occurs in CW-GMAW at a lower current than in the standard GMAW process. The reason for this difference appears to be linked to an enhanced magnetic pinch force, which is mainly responsible for metal transfer in higher welding current conditions.

Optimization of MIG welding parameters

Welding is a technique used for joining metal parts usually during the application of heat. There are many types of welding, including an electric arc welding this means that welding is a process in which the electric arc forms a metal work piece and an electrode, which leads to this work to heat the metals and cause them to melt, and connect them with an inert metallic gas (MIG). This study clarifies the conclusion of welding parameters such as travel speed, current and wire feeding speed to medium carbon steel through Welding. Get the greatest parameters as it gives nature to alteration of the strength and the quality of product and its impact on tensile strength, and hardness at studies the conduct of AISI 1040 steel by using the Taguchi method in this experimental procedure and analysis of variance in Minitab software and Optimization method (OptiY program / Evolutionary Algorithms). It was found that the increase in current leads to an increase in the amount of tensile strength(TS) and hardness of the material. Also, decreasing the welding speed during the welding process leads to an increase in the tensile strength and hardness of the welding area. While, the effect of the input welding wire feed values ​​on the welding region, specifications are largely dependent on the welding current and welding speed values ​​chosen

Development of mathematical model and optimization of GMA welding parameters of IS 2062 grade A steel weldments

In this experimental works, the effect of GMA welding process parameters, such as arc voltage, wire feed speed, and gas flow rate on the mechanical quality of IS 2062 structural steel of grade A has been studied. Process parameters play an important role in determining the weld quality. In this research work response surface methodology (RSM) technique via design expert (DOE) 12 version software was applied to determining the weld quality and also to develop a mathematical model that can predict the main effect of the above said parameters on weld quality i.e. toughness and hardness. A set of experiments has been conducted to collect the data using a central composite design and ANOVA was used to predict the impact of welding parameters on toughness and hardness and Comparison also made between the actual result and predicted value and from the result that is clear that toughness and hardness of weldment is significantly affected by arc voltage, wire feed speed, and follow by gas flow rate.

System study of the formability, nitrogen behaviour and microstructure features of the CMT wire and arc additively manufactured high nitrogen Cr-Mn stainless steel

Large-scale high nitrogen steel (HNS) components with complex facade promote the application of Wire and Arc Additive Manufacturing (WAAM) technology in this area. However, the lack of fundamental research restricts its development. In this study, a self-made HNS wire with 0.99 wt.% nitrogen content (N%) was systematically studied in the aspects of the additive seam formability, nitrogen behaviour, along with microstructure characterizations. A designed Tanguich experiment with three factors (cold metal transfer (CMT) models, wire feeding speed and oxygen content in shielding gas) and four levels were used to reveal the suitable parameters for AM and the rule of nitrogen behaviour in the molten pool. For the semi-quantitative calculation of the N%, a modified kinetic model was proposed with the prediction accurate less than 12 %. Besides, the nitrogen pore and microstructure characterizations under different CMT models were studied. Results showed that for fewer pores in a smaller size, the molten pool volume should be in the range of 200 ∼ 300mm3. The austenite cell substructures in the microstructure were mainly found in the low heat input additive seams with a diameter around 9 μm. The microhardness test showed that for the AM of HNS, the first few layers can also be used with no need to remove. When the N% is lower than 0.8 %, positive relativity between N% and microhardness can be expected. Besides, the fluctuation of microhardness was found to be connected with the irregular columnar grains, Mn Oxides and Cr nitrides in the additive seams.

Metal Transfer Mapping for Flux-Cored Arc Welding Process by Using Near-Infrared Filming

In the flux-cored arc welding (FCAW) process, the transfer of filler metal to the base material to accomplish the weld bead, determines the weld quality. It must be pointed out that the radiation emitted from the weld arc, fumes and particles (spattering) in this process represent a barrier for these studies based on the process visualization. The objective of this study is to assess metal transfer during the FCAW process of ASTM 1020 steel by filming the phenomena with assistant of near-infrared visualization, contributing to a better understanding of this process and to evaluate characteristics of metal transfer. It can clearly be seen that how the droplet is created and transferred in this process and also identify the different modes of metal transfer by changing the parameters of voltage and wire feed speed in metal transfer maps. Finally, having achieved the metal transfer maps, the suitable condition and approach for developing arc control strategies for the FCAW process were introduced.

Experimental Investigation of Additive Manufacturing Using a Hot-Wire Plasma Welding Process on Titanium Parts.

In this paper, we propose hot-wire plasma welding, a combination of the plasma welding (PAW) process and the hot-wire process in the additive manufacturing (AM) process. Generally, in plasma welding for AM processes, the deposit grain size increases, and the hardness decreases as the wall height increases. The coarse microstructure, along with the large grain size, corresponds to an increase in deposit temperature, which leads to poorer mechanical properties. At the same time, the hot-wire laser process seems to contain an overly high interstitial amount of oxygen and nitrogen. With an increasing emphasis on sustainability, the hot-wire plasma welding process offers significant advantages: deeper and narrow penetration than the cold-wire plasma welding, improved design flexibility, large deposition rates, and low dilution percentages. Thus, the hot-wire plasma welding process was investigated in this work. The wire used in the welding process was a titanium American Welding Society (AMS) 4951F (Grade 2) welding wire (diameter 1.6 mm), in which the welding was recorded in real time with a charge-coupled device camera (CCD camera). We studied three parameters of the hot-wire plasma welding process: (1) the welding speed, (2) wire current, and (3) wire feeding speed. The mechanical and physical properties (porosity, Vickers hardness, microstructure, and tensile strength) were examined. It was found that the number of layers, the length and width of the molten pool, and the width of the deposited bead increased, while the height of the layer increased, and the hot-wire current played an important role in the deposition. In addition, these results were benchmarked against specimens created by a hot-wire plasma welding/wire-based additive manufacturing process with an intention to develop the hot-wire PAW process as a potential alternative in the additive manufacturing industry.

Numerical simulation of the spheroidization process with cored wire injection in liquid iron using finite volume method

We develop a finite volume method for the simulation of the liquid iron cored wire feeding spheroidization technology, which can realize the visualization of the spheroidization process and provide guidance for parameter optimization. In this work, we first define a two-dimensional unsteady heat-transfer mathematical model for single-core structure cored wire melting in liquid iron and then discretize the governing equation numerically. The present solver is validated by comparing it with the data obtained from experimental studies. Interestingly, in the numerical results we found that the absorption velocity of the magnesium element can be improved to the greatest extent to get the most ideal spheroidizing effect. To further show the melting and boiling characteristics of spheroidization, we also explore the relationship between melting and boiling depth, wire feeding speed, and temperature of liquid iron in the feeding process, and the wire feeding speed–depth function was also obtained.

The Effect of Wire Feeding Speed on Solidification Cracking of CMT Welding for Al-Si Alloys

In this work, a welding solidification crack sensitivity test platform was established to study the effect of wire feeding speed (WFS) on solidification crack sensitivity during cold metal transfer (CMT) welding for AA6061 aluminum alloy. The test results show that as the WFS increased from 4 m/min to 5.5 m/min, the sensitivity of the solidification cracks also increased. With a further increase in the value of the WFS, the crack sensitivity decreased and eventually ceased to exist. A new perspective of the microstructure and crack propagation mechanics model was applied to understand the effect of WFS on solidification cracks. With the use of scanning electron microscopy (SEM) and a high-speed camera, it was found that as the WFS increased from 4 m/min to 5.5 m/min, the microstructure of the grain size changed from bigger to smaller, and the stability of the crystal microstructure was reduced. The crack propagation mechanics model was changed, which promotes crack propagation, increasing by 233%. When the WFS continued to increase beyond 5.5 m/min, the size of the crystal structure changed from small to big, the stability of the crystal microstructure was increased, the crack generation was suppressed, and the cracking rate was significantly reduced.

Model of weld beads geometry produced on surface temperatures by Wire and Arc Additive Manufacturing (WAAM)

Wire and Arc Additive Manufacturing (WAAM) is an Additive Manufacturing (AM) technology that knows a strong interest in recent years. With this technology, the combination of an electrical arc welding and a metallic wire feedstock is used to manufacture parts layer by layer. As part geometry depends strongly on deposition conditions, this study is focused on the characterization of single bead walls and their geometrical evolutions according to welding parameters and surface temperatures. Our experiment has consisted of the production of walls manufactured with a 5083Al wire and built from 1 layer up to 10 layers with several surface temperatures (Tsur fixed at 100, 200, 300 and 400°C). Before the deposition of each new layer, we ensure that the substrate is at the correct temperature using a thermometer in order to guarantee constant welding conditions. Those welding parameters have been kept constant with a Wire Feed Speed (WFS) at 5 m/min and a Travel Speed (TS) at 0.6 m/min. Wall bead geometry and dimensions, width (w) and height (h), have been then measured using a 3D scanner. Results are used to feed a predictive model developed with a circular model curve fitting each top layer cross-section of walls. Data form this study, coupled with thermal simulation, will allow us to predict faithfully parts shapes and to control their dimensions.