Weld Strength Research Articles

Grey-Taguchi Approach for Optimizing FSW Parameters in Joining AA6262 and AA5083 Alloys

T his study concentrates on the friction stir welding (FSW) joining of dissimilar AA6262 and AA5083 plates. Four input parameters, namely tool rotational speed (TRS), welding speed (WSP), tool tilt angle (TTA), and pin depth (PDP) are chosen to analyze the output responses of tensile strength (UTS), hardness (HBN), and wear rate (WTR) in welding. The primary objective is to optimize the variables of the FSW process for AA6262 and AA5083 alloys using a combination of Taguchi and Grey Relational Analysis (GRA) methods, while also comprehending the correlations among process variables through the application of these two methods. Utilizing the Taguchi approach, L27 orthogonal array is constructed for conducting FSW experiments. After this, the multi-objective optimization challenge is streamlined into a single-objective optimization task by leveraging the grey relational degree. The significance and impact of the distinct variables are elucidated through the application of Analysis of Variance (ANOVA). Confirmation tests and predictive analysis are performed to validate the optimal variables, which are then compared against the acquired outcomes. The results highlight the welding speed as the paramount parameter, exerting substantial influence over the output responses of the welds in contrast to the other variables under examination. The application of the Grey-Taguchi methodology yields enhancements in Tensile Strength (245.23 MPa) and Hardness (99.2 Hv), while concurrently decreasing the Wear Rate (0.00456 m3/Nm). Furthermore, the Grey Relational Grade exhibits an advancement of 0.1312. These findings collectively signify an increased operational efficiency in the welding process, particularly for dissimilar alloys.

Taguchi Parametric Optimization of Mild Steel Weld-Strength in Arc Welding Process

Abstract—In the welding process, the major factors whose selection contributes to the welded product as they all affect the strength and quality of the weld strength to a larger extent are hardness, electrode diameter and weld design (edge preparation). The purpose of this thesis is to efficiently determine the optimum welding operation parameters for achieving the highest breaking strength in the range of parameters. In order to meet the purpose in terms of both efficiency and effectiveness, this study will utilize the Taguchi parameter design methodology. The study includes selection of parameters, utilizing an orthogonal array, conducting experimental runs, data analysis, determining the optimum combination, verification experimentally finally the Modelling of input parameters (Hardness, Diameter of Electrode & Weld Design) and output parameter (Breaking Strength) is done using Taguchi optimization technique. Key words: Welding Parameters, Electric Arc Welding, Taguchi Method, welding design, hardness.

Mechanical properties and corrosion behaviour of dissimilar friction stir-welded Al 7075 and Mg AZ31 alloys with Cd and Zn interlayer

ABSTRACT The objective of present research work is to study joint strength and corrosion behaviour of dissimilar Friction Stir Welding (FSW) of Al 7075 and Mg AZ31 alloys with Cd and Zn interlayer. The FSW process performed at rotational speed 1300 rev min–1 and travel speed 20 mm min−1. The comparative study of mechanical properties and corrosion behaviour of FSW with Cd and Zn interlayers has been attempted for the first time. The result shows that the maximum tensile strength of 129 MPa has been achieved for FSW with Cd interlayer as compared to 85 MPa in the case of FSW with Zn interlayer. The corrosion rate was found in order of FSW with Cd > FSW with Zn > BM AZ31 > BM-7075. It has been concluded that FSW with Zn interlayer resulted in comparatively lower strength and better polarisation resistance than the FSW with Cd interlayer in 3.5 wt-% sodium chloride (NaCl) solution.

Enhancing weld strength in high-strength steels: the role of regional preheating in RSW

Abstract In this study, automotive in sector use STRENX 700 CR and DP 800 steels were joined by resistance spot welding using medium frequency direct current. Some parts were joined under atmospheric conditions, while others were joined by applying regional preheating to their heat-affected zones before welding. The design, manufacturing, and adaptation of the preheating system to the welding machine were carried out as part of this study, considering it as a new system. After the joining process, nondestructive and destructive tests were performed on resistance spot welding connections between STRENX 700 CR and DP 800 steels. Hardness tests revealed that the preheating applied to the heat-affected zones before welding reduced the hardness of the weld metal by approximately 8 %, while the microstructure analysis showed that the regional preheating increased both the weld metal and the heat-affected zones width. The tensile-shear strength increased by about 7 %, and the cross-tension test strength increased by about 5 % with the preheating applied to the heat-affected zones before welding. In both the tensile-shear and cross-tension tests, all failures occurred in the form of button shearing from the heat-affected zones. The regional preheating treated specimens showed the highest fatigue life, with an average of 947,632 cycles.

Mixing behavior of Ti–Al interface during the ultrasonic welding process and its welding strength: Molecular dynamics study

In this study, we conducted molecular dynamics simulations to investigate the mechanical mixing and deformation behavior of hcp Ti/fcc Al bimetal formed by ultrasonic welding (UW). To analyze the effect of the interface shape, we considered sixteen sinusoidal interfaces of various heights and spatial periods along with the flat interface. Mechanical mixing between Ti and Al occurs mainly in the vibrational loading direction, while it is suppressed in the interface-normal direction, as the loading direction lies within the slip planes of both the hcp and fcc structures. The degree of mechanical mixing depended on the shape of the interface. According to the simulation results, mechanical mixing becomes active as the sinusoidal height increases, and the spatial period decreases because of the enlarged interface areas. During the bonding process, phase transformation is observed at the sinusoidal interface; hcp Ti is converted to fcc Ti as misfit dislocations formed at the interface glide as Shockley partials on the slip plane owing to the applied vibrational loading. A simple shear test was performed to analyze the welding strength. Although sinusoidal Ti/Al interfaces can have a welding strength that is higher than that of a flat interface, we found that the welding strength was not closely related to the degree of mechanical mixing. Rather, the welding strength was affected by the interaction between a wall of misfit dislocations, stacking fault tetrahedra, and lattice dislocations generated near the interface during the UW process.

Analyzing microstructural, residual stress, and mechanical characteristics in dissimilar welds of Inconel 59 and AISI 904L through double-pulsed gas metal arc welding

In this research, dissimilar welding of the nickel-based superalloy Inconel 59 and austenitic stainless steel AISI 904L steel was successfully done with double-pulsed gas metal arc welding (DP-GMAW) using the filler ERNiCrMo-13. Macroscopic analysis showed a defect-free weld with an aspect ratio of 2.4, attributed to the efficient heat delivery (0.642 kJ/mm) in DP-GMAW. The microstructure of the weld joint was examined through both optical microscopy and scanning electron microscopy. Examination of the microstructure of the weld interface exposed grain coarsening near the heat-affected zone on the AISI 904L side. In contrast, the weld fusion zone contained fine equiaxed dendrites. Microsegregation and alloying element migration across the entire weld area were assessed through energy dispersive X-ray spectroscopy point analysis and line mapping, revealing controlled microsegregation across the region. X-ray diffraction (XRD) analysis was used to ascertain the average grain size (38.41 nm) and secondary phase composition. The XRD-cosα method was used to assess the residual stress of the weld joint, revealing tensile residual stress in the weld zone and compressive residual stress in other regions. Tensile, Charpy impact, and Vickers hardness tests were conducted in the study to evaluate the strength, toughness, and hardness of a dissimilar weld. The impact of two cryogenic treatments, namely shallow and deep, on tensile and toughness characteristics was investigated in this study. The cryogenic treatments significantly enhanced the mechanical properties of weld samples compared to their as-welded condition, leading to an 11.5% increase in tensile strength and a 10% improvement in toughness.

Creep behaviour of dissimilar weld joint between buttered Grade 91 steel and Alloy 800

Creep rupture behaviour of dissimilar weld joint (DWJ) between buttered Grade 91 steel (G91) and Alloy-800 fabricated by Shielded Metal Arc Welding (SMAW) process is investigated at 873 K over a stress range of 90–160 MPa. DWJ exhibited lower creep rupture strength than the G91 steel and the failure location of the DWJ shifted with applied stress. At high stresses (≥140 MPa) fracture occurred in the over-tempered region of base metal, whereas it shifted to HAZ at lower stresses. In contrast to interface failures being considered the life-limiting factor in DWJs, the ruptured specimens in the present study revealed a clear interface (between the buttering layer and G91) free from deleterious coarse carbides and insignificant cavitation even after creep exposure of ≈ 5800 h. It’s important to highlight that the buttered G91 DWJ exhibited higher rupture life and weld strength reduction factor compared to joints fabricated without buttering by the SMAW process.

Structure safety and weld strength evaluation by metallic weld joints in FCAW with TAGUCHI design

Several industries, including shipbuilding and automobile manufacturing, extensively use welding as a joining method. Welding processes are always plagued by distortion. Many parameters influence distortion on weld joints, including the properties of materials and welding parameters. To obtain optimal distortion parameters, the Shielded Metal Arc Welding (SMAW) process on angular distortion is used. However, this technique contains slag inclusions and it gives low productivity. To overcome this issue the Flux-Cored Arc Welding (FCAW) technique is used to combine the metals and alloys in a variety of sectors. It offers several advantages over other methods, including simplicity and adaptability over Submerged-arc welding (SAW), higher productivity over SMAW, and superior surface appearance. In this work, during the welding operation, two dissimilar high-carbon steels (EN8 and EN19) are used and the welding quality is checked by utilizing destructive and microstructure tests. To analyze the effects of process parameters on welded joints, mechanical tests like yield strength, tensile strength, and hardness test are performed and optimized using TAGUCHI design (L9 array). The accurate input parameter of EN8 and EN19 steel with a thickness of 6mm is determined. The welding process parameters are optimized by utilizing the MINITAB-17 software. As a result, the FCAW has higher tensile and yield strength than the conventional method of SAW.

Numerical and experimental investigations on AA6063 extrudates: effect of number of portholes on extrusion load and weld strength

In aluminium extrusion process, metal flow is greatly controlled by the die geometry and a variety of intricate profiles can be achieved by designing dies of different configurations. In porthole die extrusion, number of portholes used for a profile is often determined by the subjective knowledge of designers. Nevertheless, extrusion load and weld strength of profile produced are not only dependent on extrusion ratio, temperature of deformation but also on the number of portholes along with other die geometry variables. In the present investigation, systematic studies were carried out on three different dies with four ports, three and two ports around die center to extrude profiles of outer diameter 29.4 mm and thickness 2 mm. Numerical simulations were carried out for estimation of pressure, temperature, strain, and strain rate parameters in the weld chamber for all the dies, followed by press trials and profiles produced were subjected to wedge expansion test. The results from numerical simulations indicated that pressure generated inside weld chamber increases with number of portholes. The surface plots indicated highest pressure of about 280 MPa for four port hole and about 276 MPa for three ports die and pressure of about 160 MPa was estimated for two port hole die at the entry of weld chamber , which is 65 mm from profile end. Similarly, temperature at profile exit was 551 °C for four portholes die and 546 °C for three portholes die and 537 °C for two portholes die. Furthermore, press trials indicated peak extrusion loads of 5241 kN, 4406 kN and 3961 kN respectively for four, three and two portholes die. Thus, the peak extrusion load decreased by about 16% for three port and about 25% for two ports die in comparison with four port die. Also, the extruded profiles in wedge expansion test indicated mean compression load of 22.70 ± 0.14 kN in four porthole die, mean compression load 22.29 ± 0.26 kN for three port die and mean compression load of 17.841 ± 0.27 kN.

Investigation of Friction Stir Welded Polycarbonate Plates

This study investigates how different input parameters (speed and feed rate) affect the force components during welding and weld strength. In addition, we used microscopic imaging to observe the welding defects that occurred and their effects on failure. The measurement results show that welding forces decrease with increasing tool speed. The highest weld strength (28.5 MPa) was obtained at 1000 rpm and a feed rate of 8 mm/min.

Evaluating Welding Electrode Angle and Root Gap Effects on Joint Quality

Welding is a type of manufacturing method that offers greater advantages than riveting for combining metals or sheets. By adjusting the welding process parameters to predict welding strength, a higher quality of joint can be achieved. In this study, the weld processing parameters welding current (WC), electrode angle (EA), and root gap (RG) were taken into account. We performed destructive testing, such as tensile and hardness tests, to evaluate the metal piece's weld strength after it had been joined. Stainless steels and carbon steels, two unrelated materials, were used in this project. The Taguchi method was used to carry out joint processes in arc welding (AW), and nine samples were produced by altering the input parameters. Steel alloy 308L has been used as the electrode for forming connections.

Effect of Filler Wires on Welding Strength and Microstructural Changes of Inconel 718 and AISI 316L Dissimilar Weldments

In this research, the effect of fillers wires on weldability, welding strength and structural changes of dissimilar welds of Inconel 718 and AISI 316L are studied. Pulse arc mode in TIG welding with multiple passes were used to join V-groove configuration with 1.6 mm filler diameter. Constant welding parameters were used for both the weldments to study the effect of alloying elements of filler wires. Tensile properties were evaluated by conducting tensile test on universal testing machine as per ASTM E/8 standards. To reveal the structural changes at various zones of weldment, optical microscope was utilized. The dissimilar metals were joined successfully using two-filler wires without any internal defects. The highest tensile strength of 553 MPa was observed in Hastelloy filler weldment when compared with ERNiCrMo-4 filler weldment (530 MPa). Also, the better yield strength properties were observed in Hastelloy filler weldment. Well defined with clear grain boundaries were observed in both the filler weldments. Due to the pulsed arc mode, segregation of alloying elements was reduced.

Comprehensive Evaluation method of Bond Strength in Ultrasonic Welding for CFRTP

In this study, we propose a comprehensive method to evaluate the bond strength of ultrasonic-welded carbon-fiber-reinforced-thermosetting-plastic (CFRTP) considering combined stress state. Ultrasonic welding is one of the promising welding methods for CFRTP that are expected to apply to bonding large parts such as aircraft components, but this welding has not been generally applied because the quantitative evaluation method for bonding strength has not been established yet. In the present study, two types of fracture tests are proposed for ultrasonic-welded CFRTP with the goal of evaluating the strength of the adhesive interface considering the combined shear and tensile stresses. One is a ‘compression shear test’, which evaluates the strength when compressive stress is applied in the shear direction to the adhesive interface. The other is a ‘flatwise test’, which evaluates the strength when tensile stress is applied perpendicular to the interface. Finite element analysis (FEM) is used to simulate both tests to obtain accurate shear and tensile stresses, taking into account the combined stress state and stress distribution. Based on the above results, a quantitative and comprehensive evaluation of adhesive strength at the welding interface is attempt.

Optimizing and Redesigning the Vertical Milling Fixture for Friction Stir Welding of Aluminium Alloy (Al 6061)

Friction stir welding is a kind of solid-state fusion process for welding like or unlike metals. Established and patented by “The Institute of Welding” in the UK in December 1991, it involves using a compressive force applied by a conventional milling machine to make contact with work-pieces. The work-pieces are one or the other revolving or moving proportional to a pin tool, generating the heat necessary for atomic diffusion and thereby uniting the material at the edges. FSW can be functional in a variety of materials, together with stainless steel, aluminium, and various alloys. The process typically takes place on vertical milling machines, requiring a vertical milling fixture to firmly hold the plates being welded. In this paper, vertical milling holding setup and fixture for FSW procedures on vertical milling machines are established. Materials such as aluminium and aluminium alloy (Al 6061) are analyzed for their suitability in FSW operations, to identify the best material for the process. Additionally, there is potential for extending the FSW process to plastics and similar materials. Friction stir welding offers significant advantages in terms of weld quality, strength, and versatility across a range of industries, making it a versatile option for solid-state joining processes.

Optimization of laser welded ASTM A36 mild steel with different laser beam oscillation patterns utilizing experimental and simulation data

Recently, there has been an increase in the use of laser beam welding of mild steel in various industries, including petroleum refineries, power plants, pharmaceuticals, and even residential areas. This research paper focuses on studying the effects of laser welding process parameters, such as laser power and welding speed, on the tensile strength of welds. To do this, three types of laser beam oscillations (sinusoidal path, triangular path, and square path) were performed to weld 125mm x 60 and 1.8 thick sheets of ASTM A36 mild steel alloy. The researchers used statistical tools such as ANOVA to generate mathematical models and experimental designs using the Taguchi method. The results indicate that the optimal welded joint has good mechanical properties after laser welding. For ASTM A36 mild steel, the optimal parameters for laser welding are a laser power of 1800 W, a welding speed of 50 mm/s, and triangular welding mode.

Advancements in Friction Stir Welding: A Comprehensive Review of Process Variables and Emerging Developments

Friction stir welding (FSW) is a solid-state welding technique widely employed to join materials such as Aluminum (Al), Copper (Cu), Magnesium (Mg), and their respective alloys. These materials find extensive use in industries like transportation, where lightweight materials with superior mechanical properties are in demand due to their reduced mass. Conventional fusion welding methods can adversely affect the mechanical properties of these welds.Over the last two decades, FSW has emerged as a specific and significant advancement in welding technology. Various parameters, including shoulder diameter, shoulder profile, pin length, pin diameter, tool angle, rotating speed, feed rate, and weld speed, play crucial roles in determining weld strength, quality, heat generation, and material mixing.The current research focuses on investigating the process variables that influence the characteristics of welded products. Furthermore, it includes an in-depth exploration of FSW fundamentals, recent advancements, and comprehensive literature reviews.

Intelligent Prediction of FSW Physical Quantity and Joint Mechanical Properties

Friction stir welding (FSW) process parameters influence welding temperature field and axial force, which affect welding strength. At present, how the FSW process parameters of aluminum alloy 2219-T8 thick plates influence process physical quantity and how the process physical quantity changes the tensile strength about the welded joint are unknown. We focus on the intelligent prediction of FSW temperature, axial force, and mechanical properties, to provide a basis for FSW process control of aluminum alloy 2219-T8 thick plate. Firstly, we conducted the FSW experiment of aluminum alloy 2219-T8 thick plate. Then, we input the welding process parameters, set up a prediction model by particle swarm optimization-back propagation (PSO-BP) neural network to predict the peak temperature and axial force. Finally, we input the peak temperature and axial force, use genetic algorithm-back propagation (GA-BP) neural network to establish a weld tensile strength estimation model, and comply with the prediction of tensile strength.

Evaluation of different surface topography measurement methodologies for characterizing weld beads in shipbuilding

The weld bead is crucial in identifying defects during laser welding, aiding in the evaluation of weld strength and quality. However, accurately monitoring and identifying defects with cameras can be challenging in the preassembly phase. This paper compares surface topography of laser weld beads using in-process Optical Coherence Tomography (OCT) and post-process Focus Variation Microscopy (FVM). Both techniques were employed on welded A36 structural steel plates to detect the surface defects. The weld profile was evaluated according to EN ISO 13919-1, and the quality level B was given to the surface topography measurement from both techniques. The correspondence between these two methodologies is imperative for implementing profile data in advanced monitoring systems. Thus, by reducing the delay between defect formation and inspection, this paper supports a more intelligent welding process, particularly in the shipbuilding industry.

High injection molding welding strength and cross-sectional analysis of carbon fiber composite materials

In this study, carbon fibers, commonly used as reinforcement materials, were added to polyamide (nylon) PA6 to fabricate carbon fiber-reinforced thermoplastic composites (CFRTP), which were then subjected to injection molding welding. The aim of this research was to investigate the positive influence of carbon fibers on injection molding welding strength and explore the optimal injection conditions. Three different joining combinations and various injection parameters were examined. The tensile fracture surfaces after welding were observed using polarized microscopy and scanning electron microscopy. The reinforcing mechanism of carbon fibers was analyzed. Ultimately, the optimal conditions were determined as a mold temperature of 120°C, an injection temperature of 380°C, and an injection velocity of 150 mm/s. The addition of carbon fibers exhibited significant strengthening effects on the injection molded joints, and it also provided the potential for injection molding welding between resins with poor compatibility.

Impact of Friction Stir Spot Welding Process Parameters on Weld Strength for Similar Aluminum Alloys

Impact of Friction Stir Spot Welding Process Parameters on Weld Strength for Similar Aluminum Alloys