Wire Feed Rate Research Articles

Parametric investigation of wire-EDM parameters for micro channel as a foundation of high-quality micro needle array fabrication

Micro channels are widely used in microfluidics, and medical science for the extraction of DNA, electrophoresis, and blood protein analysis. In the current work, the wire electrical discharge machining (WEDM) process was used to fabricate micro channels on the stainless steel 316 (SS316) substrate. To check the feasibility of fabricating high-quality micro channels and thereafter micro-scale structures with the WEDM process the effect of different process parameters such as pulse-off time, pulse-on time, servo gap reference voltage and wire feed rate were investigated. The quality attributes taken were namely surface roughness of the channel base, overcut, micro channel depth, and material removal rate (MRR). The pulse-on time significantly affects surface roughness and MRR. The servo gap reference voltage is the key process parameter affecting the overcut and micro channel depth. It was observed from the parametric study that 15 µs pulse-on time, 35 µs pulse-off time, 17 v servo gap reference voltage, and 8 m/min wire feed rate are the optimum levels for getting high MRR, low surface roughness, less overcut and high micro channel depth. Additionally, the topographical, morphological, surface, and sub-surface characterization were also carried out to assess the surface integrity and extent of thermal damage caused by the WEDM process. With the optimum combination of process parameters a 6 × 6 micro needle array was successfully fabricated on the same substrate using micro channels as a basis of the fabrication process for the first time using the WEDM process.

Properties Enhancement of Metal Additive Manufactured Part via Cold Deformation Process

Wire-arc additive manufacturing is a method of 3D printing metal using welding techniques. However, due to heat, the mechanical properties of the deposited material may be affected. Various methods have been proposed to mechanically improve the properties. In this study, cold deformation was introduced to enhance the properties. The effects of a few parameters, including welding speed, wire feed rate, heat input, thickness ratio, and types of material, were studied. Based on the result, the hardness, tensile, and wear properties of the manufactured part improved, while other properties, like impact toughness, had a lower value. Based on the preliminary result, cold deformation shows potential alternatives for part repair or reconstruction of worn or broken parts.

Application of Convolutional Neural Networks for Classifying Penetration Conditions in GMAW Processes Using STFT of Welding Data

For manufacturing components with thick plates, such as in the heavy equipment and shipbuilding industries, the gas metal arc welding (GMAW) process is applied. Among the components that apply the thick plate GMAW process, there are groove butt joints, which are fabricated through multi-pass welding. Various welding qualities are managed in multi-pass welding, and the root-pass weld is controlled to ensure complete joint penetration (CJP). Currently, the state of complete joint penetration during root-pass welding is managed visually, making it difficult to confirm the penetration condition in real time. Therefore, there is a need to predict the penetration condition in real time. In this study, we propose a convolutional neural network (CNN)-based prediction model that can classify penetration conditions using welding current and voltage data from the root pass of V-groove butt joints. The root gap of the joints was varied between 1.0 and 2.0 mm, and the wire feed rate was adjusted. During welding, the current and voltage were measured. The welding current and voltage are transformed into a short-time Fourier transform (STFT) representation depicting the arc and wire extension lengths. The transformed dynamic resistance STFT information serves as the input variable for the CNN model. Preprocessing steps, including thresholding, are applied to optimize the input variables. The CNN architecture comprises three convolutional layers and two pooling layers. The model classifies penetration conditions as partial joint penetration (PJP), CJP, and burn-through, achieving a high accuracy of 97.8%. The proposed method facilitates the non-destructive evaluation of the root-pass welding quality without expensive monitoring equipment, such as vision cameras. It is expected to be immediately applied to the thick plate welding process using readily available welding data.

Experimental investigations on coated copper wire and annealed copper wire electrodes in wire EDM machining through a comparative assessment employing the TOPSIS technique

Metals that are electrically conductive but are difficult to work with are typically machined using WEDM (Wire Electric Discharge Machining). The production of tiny components, which are challenging to mill using earlier non-traditional machining techniques, has undergone a substantial transformation thanks to these machines. Two wire electrodes coated copper wire and annealed copper wire electrodes are used for the testing in this investigation, and the analysis is completed utilizing the tool material. The workpiece material, D2 Steel, was cut into cubes that were 10 mm thick for the experiment, and a wire electrode with a diameter of 0.25 mm was used. Using an L27 orthogonal array, six input variables were employed at three different levels in the testing. The TOPSIS technique is utilized to optimize the output variables, leading to the determination of various output parameters, including Material removal rate (MRR), Kerf width (KW), tool wear rate (TWR), and surface roughness (SR). The chosen input variables include wire tension (WT), a gap voltage (GV), input current (IP), wire feed rate (WF), pulse off time (Toff), and pulse on time (Ton). The 10 mm-wide D2 steel was milled using two wire electrodes, and an ANOVA table was made to identify the factors that had the greatest impact on the WEDM parameters. The rank and ideal Wire EDM parameter values must be calculated using main effect plots and tables of replies. From this investigation, we can also draw the conclusion that for machining D2 steel, annealed wire electrodes provide greater MRR than coated wire.

Mechanical and microstructural characterization of AISI SAE 4130 steel welded joints made by robotic gas metal arc welding process: influence of electrode work angle in 'T' welded joints

Microstructural variations within welded metals, specifically in terms of phases and their corresponding volume fractions, play a crucial role in influencing weld strength and other mechanical properties. Welded joints in a ‘T’ configuration pose a unique challenge due to the dynamic heat distribution caused by changes in the electrode work angle (EWA) between perpendicularly aligned plates. This study focuses on characterizing the microstructure and micro-hardness of ‘T’ welded joints in a 6 mm thick plate of AISI SAE 4130, welded using the robotic gas metal arc welding process. The examination covers three distinct zones: the base material (BM), the fusion zone (FZ), and the heat-affected zone (HAZ). The extent of the HAZ is meticulously measured on both the vertical and horizontal plates within the weld zones. The x-ray diffraction (XRD) analysis results indicated that the average crystallite size of the base metal and fusion zone is 25.75 nm and 24.51 nm respectively. As per the scanning electron microscope (SEM) image observations, the higher wire feed rate yields to brittle fracture surface. The torch angles notably influence the dimensions of the HAZ on the vertical and horizontal plates of a ‘T’-Joint. Welding at higher EWA and contact-tip-work-distance, results in a larger HAZ on the vertical plate. Conversely, employing a flattened EWA and an increased contact-tip-work-distance leads to a greater extent of the HAZ on the horizontal plate. Furthermore, the micro-hardness of the fusion zone and heat-affected zone demonstrates an increase at higher settings of wire feed rate and travel speed. This phenomenon is attributed to the elevated heat inputs, which contribute to the formation of a finer microstructure within the weldment.

Mechanical model of diamond wire sawing for curved surfaces

Diamond wire sawing is effective in machining complex parts. During the wire-cutting process, the cutting force affects the wire causing different shape changes, thereby affecting the machining quality. This paper introduces a wire sawing mechanical model for curved surfaces that considers the interdependence between the spatial motion of the wire, cutting force, and material removal. A wire bow angle measurement system was built using spring displacement sensors, and the accuracy of the mechanical model was verified through curved surface cutting experiments. The mechanical model was used to analyze the influences of the machining parameters and twist surface cutting process on the wire bow angle. The results showed that the sawing twisted surface increased the float amplitude of the wire bow angle. The wire feed rate at both ends varied with time owing to the wire twisting motion. The change in the wire feed rate at both ends was the primary factor affecting the change in the wire bow angle during the twist surface-sawing process. When sawing twisted, curved surfaces, the wire bow angle gradually decreases with increasing preloading force and wire velocity and a decreasing workpiece feed rate. Increasing the wire velocity and decreasing the workpiece feed rate can reduce the float amplitude of the wire bow angle, thereby enhancing the stability of the cutting process. This study lays the theoretical groundwork for understanding wire deformation during curved surface sawing.

Wire Bow In Situ Measurement for Monitoring the Evolution of Sawing Capability of Diamond Wire Saw during Slicing Sapphire.

Electroplated diamond wire sawing is widely used as a processing method to cut hard and brittle difficult-to-machine materials. Currently, obtaining the sawing capability of diamond wire saw through the wire bow is still difficult. In this paper, a method for calculating the sawing capability of diamond wire saw in real-time based on the wire bow is proposed. The influence of the renewed length per round trip, crystal orientation of sapphire, wire speed, and feed rate on the wire sawing capability has been revealed via slicing experiments. The results indicate that renewing the diamond wire saw, and reducing the wire speed and feed rate can delay the reduction in sawing capability. Furthermore, controlling the value of renewed length per round trip can make the diamond wire saw enter a stable cutting state, in which the capability of the wire saw no longer decreases. The sawing capability of diamond wire saw cutting in the A-plane of the sapphire is smaller than that of the C-plane, and a suitable feed rate or wire speed within the range of sawing parameters studied in this study can avoid a rapid decrease in the sawing capability of the wire saw during the cutting process. The knowledge obtained in this study provides a theoretical basis for monitoring the performance of the wire saw, and guidance for the wire cutting process in semiconductor manufacturing. In the future, it may even be possible to provide real-time performance parameters of diamond wire saw for the digital twin model of wire sawing.

Effect of heat input on bead geometry and mechanical properties in wire arc additive manufacturing of a nickel aluminum bronze alloy

Wire arc additive manufacturing (WAAM) stands as an efficient and cost-effective method for producing large-scale engineering components while minimizing waste. This study explores the influence of WAAM process parameters on nickel aluminum bronze (NAB) parts, focusing on the wire feed rate (WFR) as a key factor governing heat input and its effects on bead geometry, microstructure, and mechanical properties. The investigation involved depositing a single bead from NAB alloy while varying the WFS within the 2–7 m/min range, resulting in heat inputs ranging from 20.600 to 57.960 kJ/m. The results revealed that increasing heat input up to 34.944 kJ/m led to an augmentation in the bead dimensions and increased hardness due to κ-precipitates formation within the α-Cu matrix. However, with further increments in heat input to 49.088 kJ/m and 57.960 kJ/m, the bead dimensions and hardness exhibited a decline as the uniformity of intermetallic κ distribution lessened. Through optimization of WAAM process parameters, a defect-free single-wall NAB was successfully manufactured with enhanced properties. The tensile strength along the horizontal direction for the single-wall NAB alloy was found to be superior to that of the vertical direction, irrespective of the specimen's extraction regions. Additionally, the bottom specimen exhibited slightly higher tensile strength than the center and upper specimens due to being the initial layers of the wall deposited on the substrate plate, undergoing a faster cooling rate. These findings underscore the potential of WAAM as a robust method for the fabrication of larger NAB components with precision and efficiency.

Single-pass high-power laser-Arc hybrid welding of thick stainless steel clad plates: Microstructure and mechanical properties

In order to solve the existing problem of low efficiency of multi-layer and multi-pass welding methods for thick stainless steel clad plate (SSCP), this paper proposes high-power laser-arc hybrid welding (HP-LAHW) single-pass weld thick SSCP. The effects of wire feeding rate (WFR) on the weld's composition distribution, microstructure and mechanical properties were investigated. The weld morphology is nail-shaped, consisting of a wide arc zone (ArcZ) within the stainless steel layer and a long narrow laser zone (LaserZ), mainly in the carbon steel layer. With the increase of WFR, the dilution rate of the carbon steel layer to the ArcZ decreases first and then increases. The influence of WFR on the microstructure and mechanical properties of the weld is observed mainly in the ArcZ. When the WFR reaches 6 m/min, the composition of the microstructure within the ArcZ will change from martensite, ferrite, and a small amount of granular austenite to ferrite and a small amount of austenite, resulting in the microhardness of the ArcZ decreasing rapidly from 398 HV to 210 HV. The solidification type and microstructure transformation mechanisms within the weld were elucidated based on quantitative calculations of the chromium and nickel equivalent ratios. The microstructure of the LaserZ in all welds is predominantly martensitic due to the rapid cooling rate, which makes the tensile properties of the weld higher than the base metal (BM). The results of this study provide technical support for realizing high-efficiency and high-performance single-pass HP-LAHW of thick SSCP.

Finite element analysis of wire EDM process parameters on performance characteristics of Al–SiC hybrid composite with micro and nano reinforcements

Aluminum Hybrid Composites (AHC) microchannels find extensive applications in aerospace, refrigeration and air conditioning (RAC), microelectronics, automotive, biomedical, and marine industries due to their improved mechanical properties. The combination of lower density, high hardness, elevated thermal and electrical conductivity, superior elasticity, and heightened oxidizing ability at low temperatures makes machining aluminum hybrid composites challenging through orthogonal methods in an open environment. Therefore, it is imperative to investigate the impact of various machining conditions to determine optimal parameter values for microchannel fabrication in aluminum hybrid composite materials. This study aims to identify the ideal machining parameters for Al–SiC micro-SiC nano hybrid composites using wire electrical discharge machining. Four distinct process parameters (pulse on time, gap voltage, wire tension, and wire feed rate) and two response parameters (material removal rate (MRR) and surface roughness (SR)) were considered for process optimization. Additionally, finite element modeling was conducted for the aforementioned process, and the results were compared with experimental outcomes. Single-variable optimization yielded maximum MRR at 125 tons (μs), 25 SV (volt), 12 WT (kgf), and 2 WFR (m/min), and minimum SR at 125 tons (μs), 10 SV (volt), 12 WT (kgf), and 4 WFR (m/min). Single-variable optimization for simulations resulted in maximum MRR at 125 tons (μs), 40 SV (volt), 4 WT (kgf), and 6 WFR (m/min), and minimum SR at 110 tons (μs), 10 SV (volt), 12 WT (kgf), and 2 WFR (m/min). Precise modeling aids in minimizing unnecessary machining, enabling exploration of a broader range of experimental results, thereby promoting environmentally friendly and sustainable machining practices.

Parametric influence and effect of cooling channel on bead geometry profiles of ER70S-6 manufactured using wire arc additive manufacturing

This study investigated the complex relationship between key process parameters and their effects on weld bead geometrical profile in wire arc additive manufacturing (WAAM) of ER70S-6 low-carbon steel for part production. Specifically, the influence of wire feed rate (WFR), traverse speed (TS), and voltage (U) on weld bead height (WBH), weld bead width (WBW), and weld bead penetration (WBP) was meticulously analyzed. Research methodology integrated the Taguchi technique, analysis of variance (ANOVA), regression modeling, and gray relational analysis (GRA) to investigate and optimize process parameters. Results revealed distinct patterns, with increasing WFR leading to proportional increases in WBH, while elevated TS or U results in reduced WBH due to their impact on arc behavior and heat input. Conversely, WFR and U exhibit notable effects on WBW and WBP, underscoring the importance of optimizing process parameters for desired weld bead geometries. To tackle multi-objective optimization, GRA efficiently determines optimal process parameters for WBH, WBW, and WBP: WFR at 6 m/min, TS at 4 mm/sec, and U at 24 V. Furthermore, the inclusion of a cooling channel beneath the substrate plate significantly influences weld bead geometry, enhancing WBH and WBW while impacting WBP. The cooling channel’s ability to dissipate heat promotes faster solidification, ultimately improving weld bead quality and integrity. These findings offer valuable comprehensions for improving WAAM processes and enhancing the efficiency and quality of part fabrication.

Effect of Wire Preheat and Feed Rate in X80 Steel Laser Root Welds: Part 1 — Microstructure

Laser welding with cold versus hot wire feed was employed as a root pass to weld X80 pipeline steel. The influences of wire feed rate and preheat on the fusion zone microstructure were investigated. Increasing the wire feed rate helped generate acicular ferrite in the weld metal, and preheating the wire further suppressed the formation of bainite. The acicular ferrite in the upper region of the fusion zone was finer than that in the lower region, which was due to an increase in nucleation sites available. Five fill and cap passes were applied by gas metal arc welding to fill the remaining top part of the groove. Compared to arc welding with a higher heat input, laser welding led to finer prior austenite grains and smaller bainite packet size in the coarse-grained heat-affected zone and limited the formation of martensite-austenite constituents in the intercritically reheated coarse-grained heat-affected zone.

Experimental investigation of the impact of GMAW welding parameters on the mechanical properties of AISI 316L/ER 316L using quaternary shielding gas

In this study, the parameters of Metal Inert Gas (MIG) and Metal Active Gas (MAG) were investigated of AISI 316L/ER 316L. A quaternary shielding gas mixture consisting of Argon (Ar), Helium (He), Carbon Dioxide (CO2), and Nitrogen (N2) was chosen. The Taguchi orthogonal array (OA-L9) methodology was employed to explore optimal welding settings, including arc current (120A, 160A, 200A), wire feed rate (3, 3.5, 4 m min−1), and shielding gas combination (G1, G2, G3). The findings highlighted the importance of shielding gas in influencing the ultimate tensile strength (UTS), elongation percentage (EL%), and material toughness of welding joints. Notably, the highest UTS (515.77 MPa), EL% (20.85%), and material toughness (133J) were achieved by the specific group gas combination shown as G1. It is recommended to configure welding parameters to an arc current of 160A, a wire feed rate of 4 m min−1, and the G1 gas combination. Welded specimens using a G1 gas mixture showcased the best UTS and EL%. Additionally, it was found that the fusion zone (FZ) and heat-affected zone (HAZ) hardness are most profoundly influenced by the choice of gas combination (G2), resulting in the best hardness values of 253.79 HV and 239.68 HV, respectively. The optimal parameters for achieving the desired material hardness were precisely identified as (120A, 3 m min−1, G2). These insights offer a pathway to enhance welding performance and, in turn, elevate the quality and efficiency of industrial applications.

Analysis of wire-cut electric discharge machining behaviour of AA6061 / C / ZrO2 hybrid nano composites using Taguchi’s method

This study focuses on the optimization of wire-cut electric discharge machining (WEDM) process for hybrid metal matrix nanocomposites. AA6061 alloy reinforced with graphene (C) and zirconia (ZrO2) was fabricated through the stir casting method with ultrasonic assistance for three different weight proportions: 92% AA6061 / 3% C / 5% ZrO2, 87% AA6061 / 3% C / 10% ZrO2, and 82% AA6061 / 3% C / 15% ZrO2. Microstructural examination confirmed the uniform distribution of reinforcements in the matrix alloy. The fabricated composite was machined by WEDM using an L27 orthogonal array designed by Taguchi’s method. Four electrical control factors of pulse on-time, pulse off-time, wire feedrate and peak current were considered, along with one reinforcement factor and three output responses: kerf width, surface finish and material removal rate to analyse the machining behaviour. Analysis of Variance was performed to determine the significant parameters. The results revealed that the most significant factor is pulse on-time among the five different factors. Optimized parameters were identified and examined through confirmation experiments resulting in improved machining characteristics.

Experimental investigation to assess the surface integrity in WEDM of Al-based hybrid composite material

Aluminum-based hybrid composites are used in various engineering applications due to their unique properties, such as high strength, good wear resistance, excellent corrosion resistance, and low density. Aluminum metal matrix (AMMC) composites reinforced with ceramic particles can be more difficult to machine than traditional aluminum alloys because of their increased hardness and abrasiveness. Wire electric discharge machining is a non-traditional machining process that uses a thin metal wire, typically made of molybdenum, brass or tungsten to cut through a workpiece using electrical discharge sparks. This process is useful for precision machining of complex shapes and profiles in hard or difficult to machine materials. WEDM is a commonly used process for cutting Al-SiC-ZrO2 HAMMCs due to their hardness and difficulty in machining using conventional techniques. The present study examines the relationship between machining parameters like pulse on time (TON), pulse off time (TOFF), peak current (IP) and wire feed (WF) and material removal rate (MRR) and surface roughness ( Ra) for Al-SiC-ZrO2 in WEDM. The Box-Beckham Design was used to plan the experiments, and response surface method was employed to develop the models. The pulse duration, TOFF, IP, and quadratic terms of [Formula: see text] and [Formula: see text] are the most influential factors of the MRR. The TON, IP and interaction term (TON × IP), and [Formula: see text] were the most significant factors for Ra. Multi-response optimization of process parameters was obtained using the desirability function approach. Furthermore, the machined samples were analyzed for surface integrity using SEM techniques. The prediction from this model validated the confirmation results.

Effect of Wire Preheat and Feed Rate in X80 Steel Laser Root Welds: Part 2 — Mechanical Properties

In Part 1 of this study, the influences of feed rate and preheat of the wire on the fusion zone microstructure of X80 steel laser root welds were investigated. Part 2 of this study reveals the effect of cold versus hot wire feed on mechanical properties. Although strength overmatching with the X80 base metal was maintained, the wire alloying elements reduced the hardness of the upper region of the laser fusion zone but had limited effect on the bottom of the fusion zone due to the incomplete mixing of the filler material with the base metal in the bottom root region of the joint. The addition of ER70S-6 filler wire improved the impact toughness of the weld metal at 0°C, due to the formation of an acicular ferrite microstructure. As the temperature decreased to –20°C (–4°F) and –45°C (–49°F), ductile to brittle transition occurred, leading to lower weld metal toughness.

Experiment Comparative Analysis of Feed Rate with Velocity Control in Cutting Mono Crystalline Silicon Using a Diamond Wire Saw.

Fixed-diamond abrasive wire saw cutting is one of the most common methods for cutting hard and brittle materials. This process has unique advantages including a narrow kerf and the ability to use a relatively small cutting force. In the cutting process, controlling the main process parameters can improve the processing efficiency, obtaining a better processing surface roughness. This work designs the PI controller (Proportional-Integral controller) based on the reciprocating wire saw cutting process. The control objects are the workpiece feed rate and wire saw velocity, and the control objective is the normal cutting force. For the control trials, several reference values of various normal cutting forces were chosen. The effects of feed rate and saw velocity on the cutting surface finish and cutting time were investigated in this work using wire saw cutting analysis on a square monocrystalline silicon specimen. The results of this study showed that under a constant applied force of 2.5 N, the optimal feed rate of the diamond wire through the specimen could reduce cutting time by 42% while achieving a 60% improvement in the measured surface finish. Likewise, optimal control of the wire saw velocity could reduce cycle time by 18% with a 45% improvement in the surface finish. Consequently, the feed speed control is more effective than the wire saw velocity.

Исследование изменения геометрических параметров образцов, наплавленных методом GMAW при воздействии на электрическую дугу продольного магнитного поля

Introduction. The paper presents the results of research of additive manufacturing process by electric arc with axial feeding of steel filler wire in protective gas environment (GMAW technology) with additional influence of external longitudinal magnetic field on electric arc. Purpose of work: an experimental study of the effect of a longitudinal magnetic field during additive manufacturing by an electric arc with axial feed of filler wire made of structural steels in a protective gas environment on the change in the geometrical characteristics of the layers being surfaced. Research Methods. The manufacturing of specimens was carried out on a 5-axis additive machine based on a CNC machine. Surfacing was carried out in the following modes: voltage 17.5 V; current 55–65 A; wire diameter 1.2 mm; wire material Sv-08G2S; wire feed rate 2,267 mm/min; approximate roll diameter 3.0 mm; roll length 50 mm; number of wires per one roll 312.5 mm; number of layers when surfacing the wall 5; magnet operation mode: alternating current with frequency 50 Hz, voltage 30 V; measured magnetic induction 5.7 mTl; initial height of the magnet above the substrate 10 mm; electrode stickout 10 mm; shielding gas: welding mixture CO2-Ar; gas pressure (flow rate) 0.15 MPa. Results and discussion. The conducted experimental study showed that the effect of longitudinal magnetic field had a statistically significant effect on the change in the dimensions of the singular, namely an increase in the width of the layers being surfaced by 34.1 %, with a calculated significance index close to zero, and a decrease in height by 20.2 %, with a calculated significance index equal to 2.7105. The effect of longitudinal magnetic field had a statistically significant effect on the change of the overall dimensions of the specimens consisting of five layers, namely, the width of the specimens increased by 11.2 % with a calculated significance index of 4.3103, and the height of the specimens decreased by 10.3 % with a calculated significance index of 6.3105. The effect of longitudinal magnetic field had no statistically significant effect on the change of the vertical deviation from straightness for the side walls of the specimens, with a calculated significance index of 0.3277, and had no statistically significant effect on the change of the error of the width of the walls of the specimens, with a significance index of 0.098.

Nickel-aluminide cladding on a steel substrate using dual wire arc additive manufacturing

In this study the nickel-aluminide intermetallic cladded on AISI 1010 steed using dual wire arc process. The nickel-aluminide is fabricated in situ through an arc provided by a gas tungsten arc welding process and changing aluminum wire feeding rate. The research findings reveal that at a constant Ni wire feeding rate of 450 mm/min, by decreasing the Al wire feeding rate lower than 800 mm/min, the instability of the melt pool prevents the formation of a uniform deposit on the substrate. Although deposition has been done at an Al wire feeding rate higher than 1600 mm/min, transverse cracks have formed in the clad layer. Increasing the aluminum wire feeding rate from 1000 to 1400 mm/min decreases the dendritic arm size from 9.2 ± 0.1 to 4.1 ± 0.3 μm. Although unreacted nickel is visible in the microstructure at the Al wire feeding rate of 1000 mm/min, at a high feeding rate (1400 mm/min), most of the microstructure contains AlNi and Ni3Al intermetallic compounds. With the rise in Al wire feeding rate from 1000 to 1400 mm/min, both yield strength and ultimate tensile strength increase from 521.45 ± 14.16 to 620.89 ± 16.08 MPa and from 762.11 ± 19.89 to 855.65 ± 21.54 MPa, respectively. Intriguingly, the clad layer's tensile toughness decreases from 26.51 ± 2.43 to 18.32 ± 2.56 MJ m−3. By increasing the wire feeding rate from 1000 to 1400 mm/min, the wear rate at room temperature, 500 °C, and 800 °C increases by 61.2, 45.7, and 44.3%, respectively.

A new method for refinement of Ti-6Al-4 V prior-β grain structure in the alternating magnetic field assisted narrow gap gas tungsten arc welding (AMF-GTAW) via filler wire oscillation

This study presents a new method for refining Ti-6Al-4 V prior-β grain in the alternating magnetic field assisted narrow gap gas tungsten arc welding (AMF-GTAW) process by stirring the molten pool, which is accomplished directly through the use of an oscillating filler wire. The wire feed rate can be increased from 1.8 m/min to 2.2 m/min by filler wire oscillation in the traditional AMF-GTAW process with minimal heat input. This method greatly increases welding efficiency by efficiently utilizing the energy of the arc and molten pool. Using a high-speed camera, the flow behavior of the molten pool was investigated under different filler wire oscillating amplitudes. The results showed that the oscillation of the filler wire can cause a violent stir in the molten pool. By increasing the oscillating amplitude of filler wire, one can refine the columnar prior-β grain structure and attain a morphology of the upper layer of the welded joint that is nearly equiaxed with crystallographic texture, all while maintaining a fixed heat input. This is because the wire's insertion into the molten pool also creates a negative thermal gradient and the filler wire's high-frequency and high-amplitude oscillation creates an intense convection that prevents randomly oriented nuclei and/or dendrite fragments from remelting and promotes nucleation activation. The oscillating amplitude of 6 mm and the oscillating frequency of 100 Hz are the ideal values for this effect.