Combination Of Welding Parameters Research Articles

Microstructure and mechanical properties evaluation of friction stir welded boron steel

The microstructure and mechanical properties of friction stir welded boron steel in butt joint configuration are experimentally studied. Two different friction stir welding (FSW) parameter combinations are used to successfully fabricate butt joints. Microstructural analysis exhibites that the stir zone (SZ) primarily consists of fine lath martensite, while the thermo-mechanically affected zone (TMAZ) comprises bainitic ferrite and granular bainite with a small amount of martensite. The presence of granular bainite in TMAZ suggests that alloying composition affects the phase transformation. The formation of recrystallized structures with lath martensites and high dislocation density in the SZ significantly enhance the hardness of the joints compared to that of the base metal. The results of the present study suggest that FSW can be used as a method for local hardening of structural components made of boron steels, without complicated heating and rapid cooling of a conventional hot stamping process.

Parametric study of the load carrying capacity of polyethylene FSSW single strap joints

Recently, some efforts have been made to study and develop the polymeric friction stir spot welded (FSSW) joints. The application of this type of welding process in the single strap joints of low density polyethylene (LDPE) plates is the main subject of this paper in which, the failure loads of different polyethylene FSSW single strap joints fabricated with different welding parameters are studied experimentally and numerically. To do so, a full factorial design of experiments is used, and the effects of welding parameters such as tool rotational speed, plunge rate, dwell time and tilt angle are investigated. A large deformation assumption is used to develop a finite element model of the FSSW single strap joint. It is observed that a good consistency exists between experimental and numerical results with errors of less than 8%. Also, it has been shown that the tool plunge rate and tilt angle have remarkable effects on the strength of the FSSW single strap joint. By selecting an appropriate combination of welding parameters, joint strength is improved by a factor of 11 with respect to the case study with the weakest strength.

Influence of Friction Pressure on Microstructure and Joining Phenomena of Dissimilar Joints

The present study investigates the feasibility of using friction welding for the dissimilar materials of stainless steel to high carbon steel. The major process conditions were identified to govern the welding strength and joining phenomena. The welding parameters combination influences the axial shortening in the welds. The friction pressure shows a major role in axial shortening and intermixing zone compared to other parameters. The axial shortening as a weld flash near the joint interface increases with the increase in friction pressure. The width of an intermixing zone among stainless steel and carbon steel grows toward stainless steel from carbon steel with increasing friction pressure. The joining mechanism of dissimilar steels is determined according to the friction stage and upset stage on the thermal behavior and physical properties of the joints.

Experimental Investigation and Optimization of Process Parameters in Laser welding of NiTinol Shape Memory Alloys

Abstract In this work, an attempt was made to conduct bead on plate welding of NiTinol Shape memory alloy utilizing Yb: YAG laser welding process and identify the optimized parameters using Deng’s Similarity based approach integrated with Entropy Weight Method. Bead on Plate welding was carried out based on L9 Taguchi array with laser power, focal position, shielding gas blown distance and welding speed as input parameters. Bead width (BW), depth of penetration (DOP), microhardness (MH), and corrosion current density were measured as output parameters. Entropy weight method was first utilized to determine the weights that had to be given to output parameter, and Deng’s similarity based approach was used to find the optimized welding parameter combinations. The metallurgical characterization of the optimized weld was discussed with the aid of microstructure. Entropy weight Method results suggested to give more importance to microhardness. Deng’s Similarity approach identified that the 7th experimental (welding speed = 2400 mm/min, shielding gas blown distance = 8mm, focal position= 0.5 mm, power = 900 W) run as the optimized parameter combination for getting the weld with full penetration, lesser bead width, higher microhardness and corrosion resistance

New Technological Solution for Friction Stir Welding of Composites

There has been a significant increase in the use of lightweight materials in many areas of industry and engineering, which were previously dominated by metallic components. Among these materials, polymers and fiber reinforced thermoplastics enable additional advantages including great design flexibility, low manufacturing cost, dimensional stability and most dominantly recyclability. Consequently, new technological solution for joining thermoplastic composites are crucial and attractive engineering subjects. Friction Stir Welding (FSW) proved to be a reliable method for welding metallic and polymeric materials, and further studies regarding thermoplastic based composites are required, especially concerning tool design and process optimization.A short fiber reinforced thermoplastic composite was used as the base material, to study the effect of the welding parameters on the joint strength. As the welding tool plays a fundamental role in this process, three different tool concepts for welding in a butt-joint configuration were tested and analyzed. After selecting the best welding tool, an L4 Taguchi Design of Experiment (DOE) was employed to optimize the welding parameters. For each welding parameters combination, welding temperature and active forces during welding were recorded to study their effect on the frictional heat generated. It was concluded that the traverse and rotational speeds have the main influence on the weld quality, as they are directly responsible for the heat generation. FSW showed promising results regarding joining thermoplastic based composites and a maximum joint efficiency of 58.8% was achieved. However, further investigation and improvement regarding the welding tool is still required.

Multi-response optimization of friction stir welding process parameters for dissimilar joining of Al6101 to pure copper using standard deviation based TOPSIS method

Friction stir welding is a new and effective solid-state welding process for joining dissimilar materials such as aluminum (Al) and copper (Cu). Joint quality of the friction stir welded materials gets influenced by the welding strategy and different friction stir welding process parameters, i.e. rotational speed, welding speed, tool design, tool pin offset, and tilt angle. In this paper, the effect of combination of different friction stir welding process parameters during joining of Al-6101 and pure copper is studied using Taguchi L18 orthogonal array. Four friction stir welding process parameters, i.e. shoulder diameter (A), pin offset (B), welding speed (C), and rotational speed (D) each at three levels except shoulder diameter, which is at two levels are selected. The effect of different combinations of these parameters on ultimate tensile strength and micro-hardness of the joints is investigated. Subsequently, single response optimization for ultimate tensile strength and micro-hardness and multi-response optimization of ultimate tensile strength and micro-hardness taken together is carried out to obtain the optimal combination of the friction stir welding process parameters. Taguchi method is used for single response optimization, whereas Taguchi-based TOPSIS method is employed for multi-response optimization. For single optimization, the optimum combination of the friction stir welding parameters yielding maximum strength and micro-hardness are A1B1C2D2 and A2B1C2D3, respectively. The optimum combination of the process parameters for multi-response optimization is A2B1C2D2. From the results of the study for single- and multi-response optimization, it is revealed that the rotational speed is the most significant process parameter affecting the tensile strength and micro-hardness of the joints followed by the welding speed. Further, the macro/microstructure and micro-hardness profile of the joint obtained at the optimal combination of the multi-response optimization are given and discussed for better understanding of material mixing and joining.

A Virtual Design of Experiments Method to Evaluate the Effect of Design and Welding Parameters on Weld Quality in Aerospace Applications

During multidisciplinary design of welded aircraft components, designs are principally optimized upon component performance, employing well-established modelling and simulation techniques. On the contrary, because of the complexity of modelling welding process phenomena, much of the welding experimentation relies on physical testing, which means welding producibility aspects are considered after the design has already been established. In addition, welding optimization research mainly focuses on welding process parameters, overlooking the potential impact of product design. As a consequence, redesign loops and welding rework increases product cost. To solve these problems, in this article, a novel method that combines the benefits of design of experiments (DOE) techniques with welding simulation is presented. The aim of the virtual design of experiments method is to model and optimize the effect of design and welding parameters interactions early in the design process. The method is explained through a case study, in which weld bead penetration and distortion are quality responses to optimize. First, a small number of physical welds are conducted to develop and tune the welding simulation. From this activity, a new combined heat source model is presented. Thereafter, the DOE technique optimal design is employed to design an experimental matrix that enables the conjointly incorporation of design and welding parameters. Welding simulations are then run and a response function is obtained. With virtual experiments, a large number of design and welding parameter combinations can be tested in a short time. In conclusion, the creation of a meta-model allows for performing welding producibility optimization and robustness analyses during early design phases of aircraft components.

Experimental investigation of TIG welding on AA 6082 and AA 8011

Abstract Aluminium alloys gathers wide range of acceptance and potential application in automobile, aerospace, ship building industries, off shore structures & construction of bridges owing to its low weight, superior strength to weight ratio and other anti-corrosive properties. In the realm of welding processes of aluminum and its alloys, the TIG welding continues its peak spot because of its flexibility and versatility in adaptability. Present investigation reports the deformation behavior of AL6082 & AL8011 butt welded joint during tensile tests. TIG welding was performed in the rolling direction of two aforementioned dissimilar aluminum alloys. The Rockwell hardness testing technique was employed. These tests were carried out on the weldments to ascertain the joint integrity prior to characterization to have an idea of the weld quality. Many considerations come into the picture and one has to balance to reach to an optimized combination of various welding parameters. Therefore, present study focused on evaluating and exploring the influence of various welding parameters on ultimate tensile strength and hardness of the welded specimens by conducting tensile experiments.

Prediction of Weld Interface Depth and Width at Optimum Laser Welding Temperature for Polypropylene

In this preliminary research, Through Transmission Laser Welding (TTLW) of polypropylene is systematically studied through finite element method (FEM) and response surface methodology (RSM) combined approach. The thermal field simulated by solving a three-dimensional transient heat diffusion equation using COMSOL Multiphysics. Statistical software Minitab v17 has been used to develop an experimental design as per central composite design. The objective of the work is in twofold. The first objective of the study aims to develop mathematical models to predict the weld interface depth (MD), weld interface width (MW) and maximum temperature (Tmax), primarily in terms of the process line-energy. The developed mathematical models are examined by analysis-of-variance (ANOVA) technique to check their adequacy. The second objective of the study is to establish an optimised combination of laser welding parameters (laser power, scanning speed and spot diameter) to prevent polypropylene thermal degradation. The desirable MD and MW conditions have been predicted for the established optimised set of laser welding parameters. The results from this preliminary investigation using a FEM approach, can provide the basis for future design of experiments to help predict and obtain enhanced weld quality for polypropylene specifically and other polymer material system in general.

Experimentation and weld parameter optimisation using grey fuzzy analysis

The most popular steel grade material highly used in the fabrication of industrial pressure vessels and boilers is SA516 grade 70. Submerged Arc Welding is a metal joining technique widely used in heavy fabrication industries for its high quality, reliability, attaining deeper penetration and a smooth appearance of weld bead. In this paper, Taguchi's L27 orthogonal array is used to perform welding of SA 516 grade 70 steel plates. To improve the weld quality, the optimal combination of welding parameters is chosen using grey relational analysis. Grey fuzzy optimisation of welding parameters is based on four different output performance characteristics, namely, bead reinforcement, bead width, bead penetration and dilution. From analysis of variance it is evident that electrode stick out is the most influential factor in submerged arc welding process parameters. Mechanical and metallurgical studies are performed to confirm the effectiveness of the approach.

Welding Process Influence on Welding Deformation of Orthotropic Steel Bridge Slab

Orthotropic bridge deck is the main structural form of steel box girder bridge deck. Due to the dense U-rib weld and complex structure, it is easy to produce large deformation during welding. At present, the determination of the amount of deformation is mainly based on the empirical value and the trial and error method. It is of great significance for welding deformation control to study the influence of welding process on welding deformation of orthotropic bridge deck and clarify the influence of welding parameters and welding sequence. Based on Marc software, the finite element thermoelastic analysis method is used to simulate the post-weld residual deformation of orthotropic bridge deck. The influence of welding parameters and welding sequence on welding deformation is analyzed, and the sensitive parameters affecting welding deformation are determined. The optimal combination of welding parameters was developed, and the reasonable sequence of U-rib welding was established, which laid a foundation for welding deformation control of orthotropic bridge deck.

Effect of residual Alclad on friction stir spot welds of AA2219 alloys

Abstract This paper aims to determine the role of in-nugget/residual Alclad in the friction stir spot welds of 1.6 mm thick Alclad AA2219 aluminum alloy via an assessment of microstructure, mechanical properties and fracture modes of welds. Alclad redistribution/dispersion within the stir zone of the alloy is varied by using different tool profiles (pinless and conical pin tools) and welding parameter combinations. The results reveal that a pinless tool facilitates the retention of Alclad within the weld's effective joint line/width while no substantial residual Alclad is observed in the effective bonded width of a conical pin weld. The increase in tool depth improves the weld strength of a pinless weld. The fracture morphology of a pinless weld is influenced by the in-nugget Alclad content. Interfacial fracture with midpoint defect, interfacial fracture and nugget pull-out are the fracture modes of pinless welds while a conical pin weld fails by circumferential nugget shear failure. A direct correlation exists between nugget rotation and lap shear failure load. Maximum lap shear failure loads of 4.0 kN and 2.1 kN are obtained in pinless and conical pin welds at the optimum welding parameter combinations of 1500 rpm – 0.8 mm – 8 s and 1400 rpm – 0.43 mm – 4 s, respectively.

Effect of keyhole mode on weld shape and mechanical properties of thin sheets of Al-Si coated 22MnB5 steel

The great change of plasma or plumes and weld pool flows existed between “blind” keyhole and open keyhole, especially for thin sheets. The keyhole mode could be changed by increasing the power density for deeper keyhole penetration. In this study, weld shape, aluminum content, δ ferrite fraction, and tensile strength were investigated in laser welding Al-Si coated steel. “Blind” keyhole led to “Y” weld shape, lower aluminum content, less δ ferrite, and higher strength at the optimized parameter. On the contrary, open keyhole led to “X” weld shape, higher aluminum content, more δ ferrites, and lower strength. The microstructure was more homogeneous in low speed “Y” weld. From the high speed images, the open keyhole was accompanied with fierce molten flow on the bottom side. The bottom coating was also important in the aluminum increase. In the suitable combination of welding parameters for “blind” keyhole, their strength could reach the level of decoated sample with no need for decoating preparation.

Experimental investigation and optimization of weld bead characteristics during submerged arc welding of AISI 1023 steel

Abstract Submerged arc welding (SAW), owing to its high deposition rate and high welding quality, is widely used in the fabrication of pressure vessel, marine vessel, pipelines and offshore structures. However, selection of an optimum combination of welding parameters is critical in achieving high weld quality and productivity. In this work, initially, the SAW experiments were performed using fractional factorial design to analyze the effect of direct and indirect input parameters, namely, welding voltage, wire feed rate, welding speed, nozzle to plate distance, flux condition, and plate thickness on weld bead geometrical responses viz. bead width, reinforcement, and penetration. The bead on plate technique was used to deposit weld metal on AISI 1023 steel plates. The effect of SAW input parameters on response variables were analyzed using main and interaction effects. The linear regression was used to develop the mathematical models for the response variable. Then, the multi-objective optimization of input parameters was carried out using desirability approach, genetic algorithm and Jaya algorithm. The Jaya algorithm offered better optimization results as compared to desirability approach, genetic algorithm.

Comprehensive Analysis of TIG Welded Inconel–718 Alloy for Different Heat Input Conditions

In this research, the effects of heat input on tensile properties and microstructure were investigated for super alloy Inconel-718 sheets weld by Tungsten Inert Gas (TIG) welding process. The tensile properties and microstructure of weld joints were evaluated. The experiment was conducted with six different combinations of welding parameters like welding current, voltage and welding speed, which were give in six different welding heat input combinations of welding parameters. The experimental results shows that the welding joints weld with low welding heat input was yield higher tensile properties. From the experimentation it was understand that the tensile properties increases when the welding heat input decrease. Drastic grain coarsening was evidenced when the heat input was increases. For the weld joints experimented in this research it was also observed that amount of laves phase was increased with increase in the welding heat input which is the major fact for noticeable variation in the ultimate tensile strength of the weld joints welded by TIG welding process with different welding heat input.

Microstructure and mechanical properties of micro-resistance spot welding between stainless steel 316L and Ti-6Al-4V

In this study, austenitic stainless steel 316L and titanium alloy (ASTM grade 5) were welded together by micro-resistance spot welding at different combinations of welding parameters and by using specifically designed electrode geometry. The welded joints were subjected to tensile shear strength test in order to determine the strength of the welded zones. In addition, micro-hardness and microstructural examinations of the fracture mode (failure analysis) were carried out in order to examine the influence of welding parameters on the welded joints. The results showed that using a combination of 2.0 kN welding current, 100 ms welding time, and 241 N welding force yield the highest load value, 378.25 N by using full factorial design of experiment (DOE). Welding current is the most significant parameter which is obtained through analysis of variance (ANOVA). However, the increase in welding current should be controlled to avoid weld metal expulsion. The microstructure of these resistance-welded metals are detailed and investigated by using SEM and EDS mapping analysis. Based on the SEM observations, columnar dendritic structures can be seen at the fusion zone (FZ) of the welded nugget.

Parametric Optimization of Gas metal arc welding process by PCA based Taguchi method on Austenitic Stainless Steel AISI 316L

In the present work AISI 316L stainless steel samples have been welded by MIG welding. Butt joints have been made. Plate thickness is kept constant (= 3mm). Some important parameters have been varied during welding. Thus several butt-welded joints have been made. Each sample of the joints has been prepared under certain combination of welding parameters. The parameters considered for variation, in the present work have been welding current, gas flow rate and nozzle to plate distance. The influence of the process parameters (mainly current, gas flow rate and nozzle to plate distance) has been examined visually and also through X-ray radiographic tests. Next, samples have been cut, machined to conform to some specified dimensions for tensile testing. The quality of the weld has been evaluated in terms of ultimate strength, yield strength and percentage of elongation of the welded specimens. The observed data have been interpreted, discussed and analyzed by using principal component analyses (PCA). Optimum parametric setting has been predicted and validated as well. Useful interpretations of the experimental results and subsequent analysis have been made to draw some meaningful conclusions.

Optimisation of laser welding parameters for incoloy 800HT joints using Grey-fuzzy Taguchi approach

The present study attempts to find the optimal level of parameters for multi performance characteristics in laser welding of incoloy 800HT using Grey-Fuzzy algorithm. Incoloy 800HT, which comes under the family of austenitic nickel-chromium-based super alloys exhibits good strength, excellent resistance to carburization and oxidation in high-temperature exposure. This alloy has been considered as a prominent material for fourth generation nuclear power plants. Laser welding has proved to be advantageous due to its characteristics such as narrow fusion zone, low heat input, concentrated heat intensity and the ability to align the beam to a specific position with respect to joint line. Taguchi L9 experiment was used to perform laser welding on incoloy 800HT. The input parameters chosen were the welding speed, focal position and laser power. The output performance characteristics were the hardness, toughness and ultimate tensile strength. To improve the quality of the weld, the optimal combination of laser welding parameters was chosen using grey relational analysis and grey fuzzy logic approach offers improved Grey-Fuzzy reasoning grade and has less uncertainties when compared with grey relational technique. Analysis of variance (ANOVA) was used to find percentage contribution of the laser welding parameters and found that welding speed was the most influential factor in welding of incoloy 800HT.

Review of GTAW Welding Parameters

Welding as a fabrication process is one of the vital production routes for most manufacturing industries. Several factors are involved in the choice of welding process for specific applications; notable among these are compositional range of the material to be welded, the thickness of the base materials and type of current. Most metals oxidize rapidly in their molten state, and therefore, the weld area needs to be protected from atmospheric contamination; this is achieved in gas tungsten arc welding GTAW by a shielding gas (argon, helium, nitrogen). GTAW technique is one of the major processes for joining austenitic stainless steels (ASS) and ferritic stainless steel (FSS) fabrication. However, the microstructural change that occurs during welding and at weld joint is still a major challenge today as it affects both the corrosion resistance and the mechanical properties. Therefore, this present paper reviews past research findings on GTA welding of ASS and FSS. Results of the findings have confirmed that, depending on the amount of heat input, which can be controlled by welding parameters (welding speed, voltage and current), welded joints particularly, heat affected zones (HAZs) of both grades of steels can undergo mechanical failure and can be susceptible to corrosion attack if the joints are produced with a less ideal combination of welding parameters.

Fiber Laser Welding of Dissimilar 2205/304 Stainless Steel Plates

In this study, an attempt on pulsed-fiber laser welding on an austenitic-duplex stainless steel butt joint configuration was investigated. The influence of various welding parameters, such as beam diameter, peak power, pulse repetition rate, and pulse width on the weld beads geometry was studied by checking the width and depth of the welds after each round of welding parameters combination. The weld bead dimensions and microstructural progression of the weld joints were observed microscopically. Finally, the full penetration specimens were subjected to tensile tests, which were coupled with the analysis of the fracture surfaces. From the results, combination of the selected weld parameters resulted in robust weldments with similar features to those of duplex and austenitic weld metals. The weld depth and width were found to increase proportionally to the laser power. Furthermore, the weld bead geometry was found to be positively affected by the pulse width. Microstructural studies revealed the presence of dendritic and fine grain structures within the weld zone at low peak power, while ferritic microstructures were found on the sides of the weld metal near the SS 304 and austenitic-ferritic microstructure beside the duplex 2205 boundary. Regarding the micro-hardness tests, there was an improvement when compared to the hardness of duplex and austenitic stainless steels base metals. Additionally, the tensile strength of the fiber laser welded joints was found to be higher when compared to the tensile strength of the base metals (duplex and austenitic) in all of the joints.