Welding Tool Research Articles

Microstructural and Mechanical Properties of Dissimilar Aluminium Alloys by Friction Stir Welding

In the present study, the dissimilar aluminium alloys AA 2014-T651 and AA 7075-T651 of 16 joints was successfully joined with (four welding speeds (50, 60, 70, 80 mm/min), four rotational speeds (900, 1000, 1100, 1200 rpm), four different weld tool profiles (T1=12/4, T2=15/5, T3=16/4, T4=20/5 in D/d ratio) by friction stir welding machine. In the optical microstructure and SEM very fine equiaxed grains are formed in the stir zone. The maximum hardness value is 150 HV obtained in the weld nugget area of the specimen 2 under the conditions of 900 rpm, 70 mm/min for T3 profile. Compare to other tool profiles T3 profile attained maximum hardness value. The minimum hardness value is attained for the specimen 13 for the tool profile T1 was 103 HV compared to all tool profiles. In post weld heat treatment conditions, hardness values were decreased compare with as weld conditions due to over heating followed by ageing. The maximum joint efficiency attained is around 90 to 95% with T2 and T3 profiles at rotational speed of 1000 rpm, 1200 rpm and welding speed of 60, 70 mm/min. The T1 profile attained least joint efficiency of 69.5 % at 900 rpm, 50 mm/min, since it has very less shoulder diameter or contact area and maintain a D/d ratio is 3.

Tailoring of Dissimilar Friction Stir Lap Welding of Aluminum and Titanium

An approach was proposed to optimize dissimilar friction stir lap welding of aluminum and titanium alloys. The basic concept of the new technique included (i) the plunging of the welding tool solely into the aluminum part (i.e., no direct contact with the titanium side) and (ii) the welding at a relatively high-heat input condition. It was shown that sound welds could be readily produced using an ordinary cost-effective tool, with no tool abrasion and no dispersion of harmful titanium fragments within the aluminum side. Moreover, the intermetallic layer was found to be as narrow as ~0.1 µm, thus giving rise to excellent bond strength between aluminum and titanium. On the other hand, several important shortcomings were also revealed. First of all, the high-heat input condition provided significant microstructural changes in the aluminum part, thereby resulting in essential material softening. Furthermore, the new approach was not feasible in the case of highly alloyed aluminum alloys due to the relatively low rate of self-diffusion in these materials. An essential issue was also a comparatively narrow processing window.

Thermal-fluid-structure coupling analysis of void defect in friction stir welding

Understanding the void defect formation mechanism and simultaneous predicting the tool service life in friction stir welding are critical for optimizing the welding parameters. However, the void defect formation mechanism in friction stir welding is not yet elucidated. In this study, a novel integrated thermal-fluid-structure coupling model of the friction stir welding process was proposed for simultaneous prediction of the weld formation and tool service life. A new non-uniform distribution model of the tool-workpiece contact pressure was proposed to describe the interaction between the tool and the workpiece. The void defect formation mechanism was quantitatively studied using the proposed integrated thermal-fluid-structure coupling model. The results show that the plastic material flows in the horizontal direction and can completely fill the cavity behind the tool for the welding condition of forming a sound weld. While the tool-workpiece contact interfacial frictional shear stress in the rear of the tool is decreased significantly which leads to a severe decrease in the plastic material flow velocity. Therefore, after bypassing the tool from the retreating side, the plastic material at the bottom of the weld stagnates, and void defect forms in the middle and lower part of the weld at the advancing side. The difference between the maximum and the minimum tool-workpiece contact pressure could serve as a numerical criterion to predict void defects. A sound joint is formed when the difference is lower than the critical value of 15 MPa, while a void defect is formed in the weld if it is higher than this critical value. The maximum equivalent stress acting on the tool is located at the pin root with severe stress concentration at a high welding speed. The front of the tool is subjected to tensile stress while its rear is subjected to compressive stress, therefore the tool is apt to fracture at its root under an inappropriate welding condition. The average normal stress of the tool varies periodically with its period consistent with the rotation period of the tool. The service life of the tool is decreased with the increase in welding speed and the decrease in rotation speed. The model is validated by experimental results.

The Effect of Tool Geometry on the Strength of FSW Aluminum Thin Sheets.

Welding tools of different designs have been used to join friction stir welding 2-mm-thick Al 7075 sheets, to investigate the effect of the tool geometry on the weld performance. Five cylindrical tools with different pin geometries were manufactured from heat-treatable low alloy steel WNr 1.6582/DIN 34CrNiMo6. Additionally, the effect of the welding speed was considered in the work, with six different speeds ranging from 80 mm/min to 300 mm/min. The weld tool rotational speed was kept constant at 1000 rpm and all other parameters were also kept constant in the experiments. The tensile strength was measured to investigate the mechanical properties of the weld. Results were processed with statistical analysis tools, which showed that the mechanical strength was affected by tool geometry as well as welding speed. The weld tool with the highest pin diameter achieved the highest tensile strength. The welding speed affected the tensile strength differently in the different weld tool geometries studied. The highest weld efficiency reported in the tests is 72.20%, achieved with a cylindrical pin weld tool at 250 mm/min.

Microstructural formation and mechanical performance of friction stir double-riveting welded Al-Cu joints

A novel friction stir double-riveting welding (FSDRW) technology was proposed in order to realize the high-quality joining of upper aluminum (Al) and lower copper (Cu) plates, and this technology employed a Cu column as a rivet and a specially designed welding tool with a large concave-angle shoulder. The formations, interfacial characteristics, mechanical properties and fracture features of Al/Cu FSDRW joints under different rotational velocities and dwell times were investigated. The results showed that the well-formed FSDRW joint was successfully obtained. The cylindrical Cu column was transformed into a double riveting heads structure with a Cu anchor at the top and an Al anchor at the bottom, thereby providing an excellent mechanical interlocking. The defect-free Cu/Cu interface was formed at the lap interface due to the sufficient metallurgical bonding between the Cu column and the Cu plate, thereby effectively inhibiting the propagation of crack from the intermetallic compound layer at the lap interface between the Al and Cu plates. The tensile shear load of joint was increased first and then decreased when the rotational velocity and dwell time of welding tool increased, and the maximum value was 5.52 kN. The FSDRW joint presented a mixed mode of ductile and brittle fractures.

Effectiveness of the indigenously developed static shoulder friction stir welding tool on textural characteristics of Al6061 alloy – A comparison to external cooling media friction stir welds

• A novel static shoulder friction stir welding tool has been developed. • Developed tool is both rotating and non-rotating shoulder tool without sub shoulder. • The tool's effectiveness in lowering HAZ width is compared to cooling media FSW. • Texture components reflect different recrystallization types for both processes. A novel in-house friction stir welding (FSW) tool that can act as both static shoulder and rotating shoulder was developed. In this article, two Al6061 plates were subjected to static shoulder FSW (SSFSW) and external cooling media FSW (ECFSW) using the indigenously developed tool. To investigate the effectiveness of the developed tool, microstructural and textural aspects of SSFSW were compared with that of ECFSW. Electron backscattered diffraction results revealed a significant reduction in the percentage of low angle grain boundaries from 61.4% (base material) to 28.4 % (ECFSW), and 8.6 % (SSFSW). The evolved texture components after FSW are completely different from base material and the overall texture strength increased after FSW. Pole figures of SSFSW revealed the presence of A, B components with maximum intensity of 10.489 while in ECFSW, presence of A 2 *, B ¯ components with maximum intensity of 7.913 were observed. Oriental distribution function showed strong orientations of {0 3 1} 〈2 1 3〉, {0 0 1} 〈1 1 0〉,{1 1 2} 〈0 1 1〉, {1 2 3} 〈6 3 4〉 and moderate Cube components in case of ECFSW. In the instance of SSFSW, there was dominant presence of γ fibre. Correlation between the microstructure and texture has revealed the occurrence of meta-dynamic recrystallization in ECFSW and continuous dynamic recrystallization in SSFSW.

Microstructure and mechanical properties of refill friction stir spot welded joints: Effects of tool size and welding parameters

A novel refill friction stir spot welding (RFSSW) technique employing large-sized tools is proposed. The microstructure and mechanical properties of joints produced with a large-sized welding tool and a conventional tool are compared. The results show that the exit line resulting from the sleeve becomes longer with increasing the plunge depth, and the diameter of nugget increases with higher rotational speed for the joints produced by both conventional and novel tools. The plunge depth increases from 2.0 mm to 2.2 mm, then to 2.4 mm, which affects the hook defect to bend upwards, almost parallel to the lap interface, to bend downwards, respectively. The joints produced with the novel tool have a flat hook compared to the conventional tool. The microstructure evolution of the conventional and novel joints is similar. The tensile-shear and tearing forces measured of the novel joints are higher than those of the conventional joints for the same welding parameters. For conventional joints, the maximum tensile-shear and tearing forces are 8.6 ± 0.1 kN and 4.4 ± 0.2 kN, respectively. The maximum tensile-shear and tearing forces for novel joints are 10.9 ± 0.1 kN and 5.6 ± 0.1 kN, respectively. After the tensile-shear test, there are three modes of fracture, the upper-mixed, the lower-mixed, and the shear fracture one. The plunge depth has a pronounced effect on the fracture mode of joints.

Joining of Polyethylene Using a Non-Conventional Friction Stir Welding Tool.

The objective of the current study was to butt-weld 6 mm-thick polyethylene (PE) plates by friction stir welding (FSW) using a non-conventional stationary shoulder tool. The welds were performed with an unheated shoulder and with a shoulder temperature of 85 °C. Additionally, rotational speeds of 870, 1140 and 1500 rpm; welding speeds of 60 and 120 mm/min; and plunge depths of 5.5 and 5.7 mm were used. The influence of these parameters on morphology, hardness, ultimate tensile strength, elongation at break and fracture modes was evaluated. Shoulder heating proved to be crucial for the optimization of PE joints by FSW, as it clearly improved joint efficiency. Furthermore, shoulder heating promoted the reduction in internal and external defects, such as porosity and surface burning. Defect-free weld seams were obtained with higher rotational speeds and a lower welding speed. A maximum joint efficiency of about 97% was achieved with a shoulder temperature of 85 °C, a rotational speed of 1500 rpm, a welding speed of 60 mm/min and a plunge depth of 5.7 mm. A weld with the average joint efficiency of 92% was produced at 120 mm/min, which based on the literature found is the highest welding speed reported that achieved a joint efficiency above 90%.

The Influence of the Tool Tilt Angle on the Heat Generation and the Material Behavior in Friction Stir Welding (FSW)

To improve the accuracy of numerical simulation of friction stir welding (FSW) process, the tool tilt angle must be considered as a significant parameter. In this study, specific considerations for mechanical boundary conditions in Eulerian domain is employed to investigate the tool tilt angle influence on the thermomechanical behavior in FSW. Aluminum 6061-T6 with a thickness of 6 mm under a rotational speed of 800 RPM, a transverse speed of 120 mm/min, and a plunging depth of 0.1 mm were employed for the simulations. Results showed an almost symmetric temperature profile predicted by the model without considering the tool tilt angle, while after incorporating the tool tilt angle, the peak temperature point is moved to the tool backside (around 400 °C), resulting in better material bonding, enhancing the weld joint quality. Without accounting for the tool tilt angle, the highest temperature of 389 °C is observed, while with the tilt angle the maximum temperature of 413 °C is achieved. The temperature variations at different points of the leading (around 360 °C) and the trailing sides (around 400 °C) of the welding tool were measured. It was observed that, after considering the tilt angle, as the tool moves, a smooth and quick increase for the temperature at the tool trailing side is achieved. This smooth and quick increasing of the temperature at the trailing side results in reducing the possibility of the formation of defects, cracks, and voids. Finally, comparisons showed that the model computational time is acceptable, and using Eulerian formulation leads to achieving a remarkable accuracy.

The Design and Implementation of a Subway Monitoring System

This design takes STM32 single chip microcomputer as the core, and uses keil as the compiling environment of single chip microcomputer program in the software. The circuit schematic diagram of subway monitoring system is drawn on Altium designer.STM32 single chip microcomputer, infrared monitoring, temperature and humidity sensor, pressure sensor, LCD display, voice broadcasting system, alarm system Switches and other hardware are connected together by hand welding tools according to the schematic diagram and the functional requirements.

Effect of Welding Parameters and Tool pin features on Mechanical Properties of Dissimilar Aluminum Alloy Friction Stir Welds

ABSTRACT The present work describes the effect of welding parameters and tool pin features during friction stir welding of dissimilar AA6082 and AA7050. Mechanical behaviour of dissimilar joints fabricated by using two distinct tool pin features, welding speed (WS), and rotary speed (RS) were compared for superior weld properties. All joints fabricated from tool having threaded cylindrical (TC) pin feature were defect-free, whereas welds fabricated by the plain cylindrical (PC) pin tool at 800 rpm RS using different WS were found defective. At the same RS and WS parameters combinations, the width of the softened region was found comparatively less in PC tool welds. The highest ultimate tensile strength (UTS) and elongation of 187.33 MPa and 7.55% were obtained for weld fabricated from TC tool at 180 mm.min−1 WS and 800 rpm RS. However, the highest yield strength (YS) value of 168.8 MPa was obtained for dissimilar joints produced using the PC tool at 180 mm.min−1 WS and 1600 rpm RS. The tensile specimens of defect-free dissimilar joints were fractured from respective minimum hardness locations in ductile mode.

Analysis of Temperature Distribution and Mechanical Properties of Friction Stir Welding of Al-Cu Joints Using Hardened H13 Steel Tools

Friction Stir Welding (FSW) is a superior metal joining technique for joining similar and dissimilar metals. The various materials acceptable for the FSW techniques were magnesium alloys, mild steel, stainless steel, copper alloys, titanium alloys, aluminium alloys, etc. In this method, the frictional heat generated by the tool on metal workpieces was used for joining, and the workpieces were joined below the upper critical temperature. The substantial benefit of this technique is that it is capable of welding unweldable alloys by the conventional fusion welding method. The welding tool was rotated, traversed, and penetrated into the joint between two base plates. A suitable tool design with appropriate process parameters will result in high-quality welding on workpieces. In these experiments, the tools were designed with different pin profiles. The welding tools required for FSW are designed using SOLIDWORKS, and temperature distributions across the weld regions were analyzed using Ansys software. The fixture needed for FSW is fabricated according to machine requirements. The tool material used was hardened H13 steel, and the base plates were aluminium alloy 6101 and copper alloy C11000. The temperature distributions are noted in each trial during FSW of Al-Cu joints along the weld line region. Due to maximum temperature at weld joints, high ultimate tensile strength and impact strength were obtained at 1200 rpm tool rotational speed and 20 mm/min feed rate with the square pin profile of a hardened H13 steel tool. The obtained ultimate tensile stress (UTS) at joints was less than that of the base plates Al and Cu. The microhardness value was higher at the nugget zone than at the base plates, giving high strength at the joint area and unevenly distributed.

Taguchi-based design of experiments to optimize the parameters of Hydrogen-Hydrogen-Oxygen based welding

This study discusses the design of a hydrogen-hydrogen-oxygen (HHO) based welding tool, which uses the concept of water electrolysis through a dry cell generator. To determine the optimal design of the HHO dry cell generator, a design experiment was carried out using the Taguchi method by taking into account several parameters, namely the configuration of the electrode plate, the duty cycle Pulse Width Modulation (PWM), the type of catalyst, the electrolyte concentration, and the thickness of the gasket of the electrode plate. Each parameter is varied in 4 levels so that 16 kinds of experiments are obtained with an orthogonal array. In addition, the Combustion temperature data was collected after determining the optimal design. The experimental results show that this HHO-based welding tool is able to produce an average temperature reach of 1063.85 °C.

Heat generation, plastic deformation and residual stresses in friction stir welding of aluminium alloy

The interactions among thermal history, plastic deformation and residual stresses in the friction stir welding (FSW) process under different welding parameters have been widely considered a crucial issue and still not fully understood. In the present study, a novel three-dimensional fully coupled thermo-mechanical finite element (FE) model based on Coupled Eulerian-Lagrangian approach (CEL) has been developed to simulate the FSW process of aluminium alloy AA 6082-T6 and to analyse the thermo-mechanical interaction mechanisms under different welding conditions. The numerical model successfully simulates the plunge, dwell, and welding steps in FSW and captures the evolution of temperature, plastic deformation, and residual stresses in the welded joint. The obtained results were validated by experimental testing with observed cross-weld thermal history, optical macrography and residual stress measurement using the neutron diffraction technique. The results reveal that the tool rotation speed governs the temperature evolution; the peak temperature increased from 740 to 850 °K when the tool rotation speed rose from 800 to 1100 rpm. The rotational speed also affected the plastic deformation, material flow, and the volume of material being stirred during the welding process. Higher plastic deformation is formed in the stirring zone by increasing the tool angular velocity. This behaviour led to an increase in the stirring effect of the welding tool, reduction of the tunnel defect size and enhancing the quality of weldments. The distribution of residual stresses in different zones of the FSW joints has been found to have an M-shaped profile. A significant tensile residual stress is characterised in the edge of the nugget zone in both longitudinal and transverse directions, balanced by compressive stresses in the thermo-mechanically affected zone, heat-affected zone and base metal. The presented FE modelling provides a reliable insight into the effects of the welding parameters on the weld quality of FSW joints and process optimisation with minimised experimental trials.

Information Needs of Blue‐Collar Workers: Welding Challenges and the Potential of Smart Welding Tools

AbstractResearch on work and occupations in the information field have largely focused on white‐collar jobs. Little is known about the information and technology experiences and behaviors of workers in blue‐collar jobs. This study examines the user experiences of current welding tools and welding training and asks how integration of information feedback through smart technology in welding tools can help welders do their jobs safer, easier, and faster. We conducted 14 in‐depth interviews with members of Longhorn Racing, a student organization that designs, builds, and tests race cars. Participants experienced frustrations with the dangerous and technical setup and the limited vision and information feedback from welding tools. Many argued that the integration of smart technology into welding tools could improve their experience. These innovations could lead to faster training and reduced attrition in the welding industry. Further, this research points to the urgent need for more research on blue‐collar workers in the information field.

Tools for Friction Stir Welding in the Aviation Industry: Morphological Analysis

Tools for Friction Stir Welding in the Aviation Industry: Morphological Analysis

The Simulation of the Dynamic Characteristics of Friction Stir Welding and the Structural Deflection of Base Materials

Friction stir welding requires an optimized process because the quality of the weld can vary depending on the dynamic characteristics of the welding tool. In addition, controlling the structural deflection of the base material according to the load of the welding tool is important. In this study, the structural deflection of thin base material according to the dynamic characteristics of the welding tool was confirmed using dynamic simulation. The generated deflection was controlled through the fixing clamp, and the results according to the rotation and progress speed of the welding tool were compared and analyzed through finite volume analysis. Thus, factors of the welding tools were obtained based on computational data without accompanying experimental data, and a process guide for efficient friction stir welding for thin base materials was presented.

Study on friction properties of different abrasive materials and polylactic acid materials

In recent years, 3D printing technology is often used in various fields such as industry, medical care, and academia, because it can produce components with complex shapes at a lower cost than traditional processing. However, the size of 3D products is often limited by the printable range of printing equipment, so large objects often need to be disassembled and printed before joining. Friction stir welding is used to join different thermoplastics and has considerable potential for industrial applications, and the influence of the design of the welding tool on the formation of the welding zone is an important key. In this study, different abrasive materials and polylactic acid materials were used for friction, and the changes of friction coefficient and friction temperature during the friction process were discussed. The experimental results show the surface roughness of the abrasive tool has a significant effect on the coefficient of friction and temperature rise. As increasing the roughness of the abrasive tool, the wear scars, the cracks below the wear scar are both significant. It can be inferred from the crack shape that the PLA softens at high temperatures and then solidifies again, so the cracks are seen with a streamlined appearance, which means that the softened PLA can be carried by the abrasives tool with highly rough surfaces.

Detection of Microstructural Changes in Metastable AISI 347, HSS Z-M4 and Tool Steel Ferrotitanit WFN by Mechanical Loss Coefficient at Ultrasonic Frequencies.

Ultrasonic processes such as ultrasonic welding or ultrasonic fatigue testing use power ultrasound to stimulate materials with amplitudes in the range of 1–100 µm. The ultrasonic welding process is sensitive to any changes in the system or even the environment that may result in lower joint quality. The welding tools, so called sonotrodes, have to be accurately designed to endure high mechanical and thermal loads while inducing a sufficient amount of welding energy into the joining zone by oscillation with the Eigenfrequency of the whole system. Such sonotrodes are often made of thermally treated metals where the heat treatment is accompanied by microstructural changes. During ultrasonic stimulation, the material may further change its properties and microstructure due to cyclic loading. Both are expected to be recognized and identified by loss coefficients. Therefore, the loss coefficient was determined by modal analysis of rods and fatigue specimen made of different materials to correlate microstructural changes to attenuation. The determined loss coefficients indicated microstructural changes in all materials investigated, confirming results from previous investigations that showed an increasing attenuation due to cyclic loading for AISI 347. For the sonotrode materials Z-M4 PM and Ferrotitanit WFN, the loss coefficients decreased due to thermal treatments. Technically most relevant, changes in elastic modulus due to thermal treatments were quantitatively related to frequency changes, which can significantly simplify future sonotrode development.

Material Flow and Mechanical Properties of a Non-Keyhole Friction Stir Welded Aluminum Alloy with Improved Sleeve Bottom Geometry

Non-keyhole friction stir welding (N-KFSW) is a technique that can fabricate a welding joint without a keyhole through a one-time welding process. The Al–Mg–Si alloy was chosen as a research object, and the N-KFSW technique was investigated by numerical and experimental methods. Firstly, the sleeve bottoms of the N-KFSW welding tool system were innovatively optimized in this study. The optimal sleeve bottom with an 80° angle between the spiral groove and the sleeve inner side wall allowed avoiding the incomplete root penetration defect at the bottom of the stir zone (SZ), which was verified by numerical results and the C-shaped line height. Then, using a 3 mm-thick aluminum alloy as the experimental material, the material flow and joint formation characteristics and mechanical properties at 110, 150 and 190 mm/min welding speeds were studied and compared. The results showed that the SZ presented a drum shape due to the action of the clamping ring and the threads on the side wall of the sleeve. The SZ width decreased from 7.17 to 6.91 mm due to the decreased heat input. From 70 to 210 mm/min welding speed, the maximum tensile strength of the joint was 250 MPa at 190 mm/min, and the joint with relatively higher strength fractured at the heat-affected zone.