Bead Width Research Articles

Process parameters optimization for cold metal transfer-deposited IN625 single-layer bead features by entropy weightage-assisted grey-based Taguchi analysis

The selection of the right set of parameters for the desired bead geometry leads to minimize the discontinuous weld bead, weld cracks, porosity, and waviness. The present work focuses on the multi-response optimization for the cold metal transfer-deposited IN625 weld bead characteristics that include bead height, bead width, and penetration depth along with a mechanical property of micro-hardness. Effects of input parameters such as input current, travel speed, and standoff distance are being selected for the investigation by implementing grey relational analysis where entropy weightage method is applied for the calculation of overall grey relation grade. The multi-responses of minimum bead width and maximum bead height, penetration, and microhardness by grey relational analysis are optimized at 140 A current, 4 mm/s travel speed, and 4 mm standoff distance. Confirmatory experiments were also carried out giving the satisfactory validation. The evaluation of bead features optimization can be used for the development of wire arc additive manufacturing process in later stages.

Experimental investigations and optimization of weld bead characteristics during submerged arc welding using recycled steel slag as a flux

A novel methodology has been established which allows to recycle steel slag as a suitable flux for submerged arc welding. The flux produced using waste slag as a raw material has been applied to deposit beads on plates. The bead geometry is dependent on welding parameters; hence optimization of parameters is essential. In this cut throat competition, researchers are striving to minimize the cost of experimentation using various experimental and optimization techniques to reduce number of experiments for save time, money, and resources. In this article various techniques have been explored for better optimized results. The welding parameters have been optimized to obtain desired bead geometry using various optimization techniques such as genetic and teaching–learning-based optimization algorithm, and desirability. It was observed that the genetic algorithm technique provides better results having a minimum error of penetration, bead width, and reinforcement (i.e. 1.12%, 1.83%, and 2.46%, respectively), as compared with other techniques applied. It is further observed that flux manufactured from waste slag is capable to produce desired bead profile which is similar with that of the fresh flux. Recycled slag is capable to produce optimum bead geometry having maximum penetration of 11.52 mm, bead width 20.73 mm, and reinforcement 3.24 mm.

Investigating the effect of residual stresses and distortion of laser welded joints for automobile chassis and optimizing weld parameters using random forest based grey wolf optimizer

The present investigation analyses the selection of the right welding method and joint and advanced testing methods (NDT) for highly durable automotive frames. Moreover, the present investigation analysis suggests the best machine learning (ML) algorithm for selecting the best weld method and optimal solution. The experiment was performed based on the response surface methodology (RSM) based design of the experimental approach. As a result, laser beam welding (LBM) and cross joint are the significant weld methods for automotive frames. The proposed ML algorithm successfully optimized the LBM input parameters as laser power = 1277 W, welding speed (WS) = 32.2 mm/s, focal point: 1 mm and working angle = 0.14 Rad with an average error of approximately 0.033. Based on the results, the optimum output weld parameters are bead width = 4322.7 µm, penetration depth (PD) = 3157.9 µm, total strain = 0.0098 mm/mm and residual stress = 645.2340 MPa, respectively.

On the connection of the heat input to the forming quality in wire-and-arc additive manufacturing of stainless steels

WAAM (wire-and-arc additive manufacturing) is recently gaining much interest for the fabrication of parts with wide size. A crucial issue associated to this technology is how to control the process variables to achieve expected qualities of parts. The aim of this investigation is to explore the relationship of the heat input (Q) with the forming quality of 308L stainless steel. The outcomes demonstrate that the heat input has significant effects on the shape, microstructures, and mechanical properties of the walls. Both the height and width of single weld beads increase with an increment in Q. The walls fabricated with the low heat inputs feature better mechanical properties and lower surface roughness. The tensile strengths (YS0.2% and UTS) and the surface roughness (Sa) of the walls built with the lower heat input (230 J/mm) are 292 ± 4.95 MPa, 523 ± 4.24 MPa, and 106 μm, respectively, whilst YS0.2% = 273 ± 4.34, UTS = 482 ± 5.66 MPa, and Sa = 179 μm for the wall fabricated with the higher heat input (576 J/mm). This investigation contributes to enriching the understanding on the WAAM process of steels and helping operators to select a proper heat input for specific applications.

Optimisation process parameters for Multipass GTAW dissimilar materials of SS316L to INCONEL625

This study aims to learn how welds' bead width and tensile strength have changed throughout time. The research welded the multipass dissimilar of nickel-based superalloy Inconel 625 and stainless steel 316L using CCGTAW and ERNiCrMo-3. This experimental cycle made use of the L9 orthogonal array. Analysis of Variance (ANOVA) is used to zero in on and identify the most critical variables. Weld quality is evaluated throughout production using a non-destructive method. Weld quality and tensile strength were tested in Universal testing Machine X-Ray Radiography. Welding current and root gap were shown to be significant factors.

Optimization of Weld Parameters in Wire and Arc-Based Directed Energy Deposition of High Strength Low Alloy Steels

This paper aims to investigate the fabrication of high strength low alloy (HSLA) steels by wire and arc-based directed energy deposition (WADED). Firstly, the relationship between the process variables (including the travel speed-V, the current-C, and the voltage-U) and the geometrical characteristics of weld beads (including the bead height (BH), bead width (BW), and melting pool length (MPL)) was investigated. Secondly, the optimal process variables were identified using the desirability approach. The results indicate that voltage-U has the highest impact on BW and MPL, meanwhile the travel speed-V is the most impacting factor on BH. The optimal variables for the WADED process of HSAL steels are V = 0.3 m/min, C = 160 A, and U = 19 V. The component fabricated with the optimal variables is fully dense without spatters and defects, confirming the efficiency of the WADED process for HSLA steels.

Method for the Calculation of Local Bead Volume in Multi-Axis Additive Manufacturing

In recent history, Multi-Axis Additive Manufacturing enjoys increasing attention for both industrial and research application. In comparison to traditional processes, the additional rotation axes enable parts to be printed with greater design flexibility, while reducing the need for support structures. The multi-axis motion additionally allows for optimization of structural properties of the parts. However, curved-layer printing requires significantly higher effort for planning and computation, as the layers exhibit curvature in their shape and feature local variations of the layer height and bead width. Consideration of these properties is often neglected in the development of path planning methods, although they pose a significant influence to the optical and structural quality of the printed parts. Local over- or under-extrusion can result in material accumulation or voids within the part and need to be avoided. Additionally, some Multi-Axis Additive Manufacturing processes like Directed Energy Deposition are especially prone to errors in practice, as the melt-pool behavior is hard to model and predict accurately. This paper introduces a method for the precise calculation and adjustment of local bead volume, as a possible solution to these problems. The method processes existing Cartesian paths and uses a model of the bead geometry to simulate the extrusion by rasterization. The method considers printing head orientation, as well as neighborhood information of adjacent beads and builds a volumetric map of the paths. Local extrusion volume is then determined for each waypoint of the path from this volume map and provided to the printer along with the G-Code, enabling adjusted volume deposition both in advance and during the process by iterative path-adaptation. The provided implementation is able to achieve favorable results for both use-cases but proves especially beneficial for the latter.

Optimization of TIG Welding Parameters for Ti-6Al-4V Titanium Alloy using the Taguchi Design of Experiment

This paper presents the effect of tungsten inert gas welding parameters (i.e. welding current, welding speed and filler wire speed) on weld bead geometry, notch tensile strength (NTS) and weld bead hardness of 2.0 mm thick annealed Ti6Al4V titanium alloy sheet welded in a square butt joint configuration using Taguchi L9 (33) three level - three factor matrix. Taguchi’s signal to noise ratios was calculated to obtain optimum welding parameters for Vickers hardness at weld area, Notch tensile strength (NTS), Front bead width (FBW) and Front reinforcement height (FRH). Analysis of Variance (ANOVA) was conducted to find statistically significant and insignificant factors with respect to each response. It was noted that welding speed has significant effect on weld hardness, notch tensile strength, front bead width and height. Optimum parameters for hardness were found to be 120A current, 400 mm / min welding speed and 250mm/min filler wire speed. Confirmation test using the optimal levels of welding parameters was also conducted in order to compare predicted results with values obtained through experimentation.

T-joint Fillet Laser Welding of High-Strength Stainless Steel for Curtain Wall Frames

The aim of this study is to develop a frame for exterior facades of architectural curtain walls using numerical and experimental analyses of stainless steel T-joint fillet laser welds. The main characteristics required for this frame are that it should have an aesthetic surface from the narrow bead width and exhibit improved tensile strength at the joints. In this study, a method for optimizing the welding conditions was developed to simulateneously improve two mutually exclusive properties. It is essential to achieve more than 80% penetration of the weld zone to guarantee tensile properties. Laser welding parameters such as power, welding speed and focus height are the main variables. In addition, when high-strength stainless steel is applied as a curtain wall frame, its structural performance improves compared to conventional stainless steel.

Influence of Wire Arc Additive Manufacturing Beads’ Geometry and Building Strategy: Mechanical and Structural Behavior of ER70S-6 Prismatic Blocks

Wire arc additive manufacturing (WAAM) with high deposition rates has attracted industry interest for the demonstrated economic production of medium-to-large-scale metallic components. The structural integrity and mechanical properties of the built parts depend on the selection of the optimum deposition parameters and the tool path strategy. In this study, an alternate orthogonal deposition strategy was employed. The influence of the beads’ geometry and the associated heat input on the mechanical and structural behavior of mild steel (ER70S-6) were investigated. The influence of the bead width (BW) and the overlapping percentage (OP) between the adjacent beads on the average and layer-by-layer hardness of the blocks along the building direction were evaluated. Tensile strength was also characterized. The alternate orthogonal building strategy enhanced the geometrical uniformity of the built blocks and the microstructural isotropy along the building direction. Increasing the BW increased the total heat input per bead per layer, which significantly reduced the hardness and tensile strength of the built blocks by 19% and 17% compared to 8% and 7% when increasing the OP, respectively. Total heat input, number of heating cycles, and cooling rates triggered the phases formed, and their morphologies along the building direction were also characterized.

Effect on Various Parameter of Stainless Steel 316L Weld Bead Geometry using Cold Metal Transfer (CMT) Process

This study influences the effect of various process parameters on Cold Metal Transfer (CMT) of stainless steel 316L using mild steel as substrate. CMT has a benefit of a minimal heat input, a high deposition rate, and increased efficiency. Typically, single pass weld beads are utilized for repair and remanufacturing. The geometry of the beads determines the cladding performance of additively produced components. Therefore, optimal range of bead characteristics is necessary to ensure superior mechanical qualities. The parameters includes as: welding current, travel speed and feed speed, were tuned to produce joints with complete penetration depth and zero defects. The weld bead with lower wire travel speed of (2.9 m/min) and higher wire feed speed of (4.9 m/min) at current value of (141A) shows the optimum value of (bead width: 3.56 mm, bead height: 1.72mm, weld penetration: 3.83mm and dilution: 1.5%). This was attributed to the decreases of wire travel speed and increases of wire feed speed ensuring better penetration and larger molten metal. While a higher current value causes the convexity area of the bead to rise, it displays a stronger penetration and minimal dilution.

Fatigue Strength Assessment of Single-Sided Girth Welds in Offshore Pipelines Subjected to Start-Up and Shut-Down Cycles

During the service life of offshore pipelines, many start-up and shut-down cycles take place, possibly leading to significant cyclic loads. Fatigue failure may occur, resulting in serious environmental pollution and loss of property. The study aims to assess the fatigue strength of single-sided girth welds in offshore pipelines under these specific fatigue loads. The longitudinal stress range caused by the variation of the pipeline’s internal pressure and temperature is calculated. The effective notch strain approach is used to assess the fatigue strength of welds. The plastic behaviour of the weld root is investigated for a study case to justify the use of low-cycle fatigue assessment approaches. The effect of weld root geometry on the notch stress factor is studied to identify the dominant geometrical parameters. The fatigue strength of the study case is assessed, and some limitations of the assessment are discussed. The results show that the plastic behaviour of the weld root is only significant for severe local stress concentrations, which is mainly governed by the axial misalignment, weld root angle and the weld root bead width. If the fatigue damage at failure is 0.1, a limited number of start-up and shut-down cycles are allowed during the service life of the pipeline for the study case, indicating the necessity of fatigue strength assessment.

Improvement in the microstructural properties of super duplex and austenitic stainless steel dissimilar joints by incorporating Ni-based austenitic interlayer

Tungsten inert gas welding (TIG) has remained a worldwide utilized welding technology in the industry to till date. Activated tungsten inert gas welding (ATIG) is also an advanced variant of TIG to enhance the penetration depth and reduce the width of the weld bead in single-pass compared to traditional TIG welding. The current study focuses on utilizing the Inconel interlayer approach to link dissimilar cold-rolled super duplex and austenitic stainless steels, which are mostly used in the offshore and marine industries. A systematic strategy is used to emphasize the studies conducted after using the ATIG interlayer procedure over the traditional TIG interlayer welding process. The research also studies and compares the microstructure, elemental mapping of the weld interface, phase identification and mechanical properties of dissimilar welded super duplex and austenitic steel samples. • ATIG welding approach for achieving single pass penetration of 6 mm thick plate with reduced weld heat input. • Without any weld defects such as weld porosity, undercut, overlap defect, and hot cracking a dissimilar welding of austenitic 202 and super duplex 32760 plates were successfully completed. • Microstructure evolution such as reduction in the width of heat affected zone, and reduction in the width of the unmixed zone was seen after using the ATIG interlayer weld technique. • Mechanisms such as reverse Marangoni and arc constriction in ATIG welding techniques could easily reduce parent metal loss in weld zones.

Laser welding of FeCoCrNiMnAl x (x = 0, 0.75) high-entropy alloys fabricated by additive manufacturing

In the present study, the laser melting deposition (LMD) technology was adopted to fabricate FeCoCrNiMn and FeCoCrNiMnAl0.75 high entropy alloys (HEAs). Then, laser welding method was used to join the HEAs in forms of similar (FeCoCrNiMnAl/FeCoCrNiMnAl and FeCoCrNiMnAl0.75/FeCoCrNiMnAl0.75) and dissimilar (FeCoCrNiMnAl0/FeCoCrNiMnAl0.75) combinations, respectively. Ultra-depth field microscope and electron backscatter diffraction detection were used to observe the macro-morphology and microstructure, respectively. It was found that the width of the weld bead and heat-affected zone with higher aluminium content was larger. In both base metals and welded joints, aluminium promoted the face-centered cubic (FCC) phase transfer into body-centered cubic (BCC), significantly refined the grain and the dislocation density of HEA is also increased, which increased strength and hardness, and decreased ductility. Highlights The FeCoCrNiMn/FeCoCrNiMn, FeCoCrNiMn/FeCoCrNiMnAl0.75, FeCoCrNiMnAl0.75/FeCoCrNiMnAl0.75 joints were produced by laser welding. The widths of the weld bead and heat-affected zone increased with higher Al content. The weld bead with higher content of Al exhibited higher strength and hardness, but lower ductility.

Bulk Fabrication of SS410 Material Using Cold Metal Transfer-Based Wire Arc Additive Manufacturing Process at Optimized Parameters: Microstructural and Property Evaluation

To make metallic parts for manufacturing industries, additive manufacturing (AM) has acquired considerable significance. However, most efforts have concentrated on powder-based techniques, and there remains a dearth of the experimental evidence on the mechanical characteristics and structural behavior of metallic elements produced using wire-and-arc additive manufacturing (WAAM). This article examined the optimal parameters to enable bulk fabrication of thick walls made with a SS410 wire. The objective was to assess the optimized variables utilizing response surface methodology (RSM), followed by the microstructural analysis and mechanical property evaluation. During optimization, the influence of wire feed speed, travel speed, and gas flow rate on bead width and height was determined. Further, the optimized variables resulted in the successful formation of thick walls. Secondly, the microstructural analysis mainly featured the martensite and delta ferrite, with the latter’s percentage increasing with build height. The maximum micro-hardness of 452 HV was obtained at the base of the wall. In addition, the remarkable increases in the standard deviation of micro-hardness represent the great extent of anisotropy in the thick wall. Moreover, the maximum UTS (803 ± 8 MPa) and YS (659 ± 10 MPa) are achieved for the OB sample, which is similar to conventional components. However, the current investigation’s percentage elongation of 5% (max) demands more study before the actual use of the WAAM manufactured SS410 material. Therefore, due to the significant degree of anisotropy and poor percentage elongation, the findings conclude that post-processing is required after bulk SS410 manufacturing.

Metallurgical and mechanical properties evolution in cusp-magnetic field-assisted GTAW of low carbon steel

In this work, magnetic field-assisted autogenous gas tungsten arc welding (GTAW) of low carbon steel has been studied. The external magnetic field was generated by custom made rectangular shaped samarium cobalt permanent magnets which were arranged in a manner to generate a cusp-type magnetic field (CMF). The impact of CMF on the morphology and microstructural evaluation of the weld joints were examined prudently using optical microscope, Field-emission scanning electron microscope and X-Ray Diffraction technique. The experimental results exhibited that the CMF assisted GTAW produce joints with better mechanical and metallurgical properties compared to conventional GTAW. In CMF assisted welds, width of weld beads was reduced by an average of 4% and depth of penetration was increased by 13%. Temperature measurement on the work piece showed a significant amount of temperature decrease for the same amount of heat input under the influence of the CMF. An improvement in grain refinement was observed in the heat-affected zone (HAZ) adjacent to fusion boundary by 12% and HAZ adjacent to base metal by 15% compared to conventional GTAW, which in turn promoted a considerable increase in hardness. The tensile properties in CMF assisted welds were enhanced by 3% and 8%, respectively, for an increase of heat inputs from 0.34 to 0.45 kJ mm−1.

A comparison of single and twin tungsten electrode – wire electrode IAW

ABSTRACT Twin tungsten electrode – wire electrode indirect arc welding (TTW IAW) was a novel welding method. In this paper, the wettability and spreading of weld bead of TTW IAW were investigated by comparing with single tungsten electrode – wire electrode indirect arc welding (STW IAW). Results showed that compared to STW IAW, TTW IAW possessed larger arc width and greater arc heat distribution range with smaller variation gradient, due to the lower velocity of charged particles toward the arc center, caused by the smaller electromagnetic force acting on the arc plasma. So did the temperature distribution of weld pool of TTW IAW. Moreover, the process stability of TTW IAW was better. Besides, at the molten pool front, the transverse convection of the melted metal of TTW IAW was adequate, because of the superior wettability and long flow duration of the melted metal; at the molten pool rear, the inward convection of the melted metal of TTW IAW was weak mainly owing to the low Marangoni force. Therefore, the weld bead width of TTW IAW increased by about 25.0% and the wetting angle of the weld bead decreased by about 25.7% compared to STW IAW, which indicated that the weld bead spreading of TTW IAW was better.

Experimental studies and optimization of process parameters in laser welding of stainless steel 304 H

The prime objective of this work is to find the best combination of parameters in laser welding of stainless-steel 304 H plates. CO2 laser welding was used to join 5 mm thick stainless-steel 304 H plates. Laser power, welding speed, and focal position were used as input parameters, and experiments were conducted on the basis of the Taguchi L27 matrix. The quality of the weld was analysed by measuring depth of penetration, bead width and hardness. The best parameter combination was found using artificial neural network and genetic algorithm. The Levenberg–Marquardt algorithm predicted output responses more accurately. A confirmatory test was carried out for the optimized parameters identified by the genetic algorithm. The percentage error between the experimental and predicted genetic algorithm values was below 6%. In comparison to the base metal, the optimized weld hardness was increased by 8%. The electron backscatter diffraction analysis of the optimized weld revealed the presence of a higher percentage of high-angle grain boundary than low-angle grain boundary.

Effect of welding parameters on bead characteristics and mechanical properties of wire and arc additive manufactured inconel 718

In this study, a bi-directional, low-cost, gas metal arc welding (GMAW) based wire arc additive manufacturing (WAAM) setup is used to deposit aerospace-grade super-alloy IN718. The orthogonally designed experiments are carried out to optimize process parameters for bead geometry characteristics. Study result shows that with an increase in heat input, the bead parameters like bead width, reinforcement, dilution, penetration, and weld form factor are increasing, while it has a detrimental effect on weld shape factor and wetting angle. Microstructural examination reveals that at high heat input, coarser grain structure having average grain size of 72.29 µm is obtained while at low heat input, a finer grain structure with average grain size of 32.12 µm along with smaller amount of Laves phases are present. The XRD reveals NbC and TiC phases present in case of low heat input sample which enhances the mechanical properties of deposited material. The multilayer wall structures fabricated at high heat input showed more uniformity in shape with lesser waviness than that fabricated with low heat input. The tensile result of low heat input sample (775.82 MPa) shows higher strength than high heat input sample (741.07 MPa) which is because of smaller grain structure and higher hardness (278.11 HV) as obtained in low heat input sample as compared to high heat input sample (257.26 HV). The EBSD analysis also confirms highly textured surface, more grain boundary lengths and larger grain boundary orientation in low heat input sample imparted better mechanical properties.

Toward defect-free components in laser metal deposition with coaxial wire feeding through closed-loop control of the melt pool temperature

Laser metal deposition (LMD) is an additive manufacturing process in which a metal powder or wire is added to a laser-induced molten pool. This localized deposition of material is used for the manufacturing, modification, and repair of a wide range of metal components. The use of wire as feedstock offers various advantages over the use of powder in terms of the contamination of the process environment, the material utilization rate, the ease of handling, and the material price. However, to achieve a stable process as well as defined geometrical and microstructural properties over many layers, precise knowledge on the effects of the input variables of the process on the resulting deposition characteristics is required. In this work, the melt pool temperature was used as an input parameter in LMD with coaxial wire feeding of stainless steel, which was made possible through the use of a dedicated closed-loop control system based on pyrometry. Initially, a temperature range was determined for different process conditions in which a stable deposition was obtained. Within this range, the cause-effect relationships between the melt pool temperature and the resulting geometry as well as the material properties were investigated for individual weld beads. It was found that the melt pool temperature is positively correlated with the width of the weld bead as well as the dilution. In addition, a dependence of the microhardness distribution over the cross section of a weld bead on the melt pool temperature was demonstrated, with an increased temperature negatively affecting the hardness.