Welding Tests Research Articles

Research on the Weldability and Service Performance of 7075 Aluminum Alloy Welding Wire Prepared by Spray Forming–Extrusion–Drawing

A large number of MIG welding tests were carried out on a 3 mm thick 7075 aluminum alloy plate prepared by the self-developed jet forming–extrusion–drawing process of 7075 high-strength aluminum alloy welding wire, and the welding process of the welding wire and the change in the performance of the welded joint after T6 heat treatment were studied. The results show that the self-developed wire has a good forming joint and a wide welding process window: the welding speed is 5–7 mm/s, and the welding current is 100–150 A. The main precipitated phases in the joint were η(MgZn2), S(CuMgAl2), Mg2Si, and Al13Fe4, which were continuously distributed at the grain boundaries in the form of coarse networks or long strips, which was an important reason for the weak performance of the joints. After the heat treatment of T6, the precipitated phase in the joint was greatly reduced, the element segregation phenomenon was improved, and the residual precipitated phase was mainly Al13Fe4 and a small amount of insoluble phase Fe and Si, and the recrystallization size of the heat-affected zone was refined. Through heat treatment, the average microhardness of the joint was increased from 110 HV to 150.24 HV, and the tensile strength was increased from 326 MPa to 536 MPa, reaching 97.5% of the strength of the base metal, indicating that the softening phenomenon was significantly improved after heat treatment, and the joint had excellent performance.

Joining UFG Copper by Means of the W2Mi Machine

Joining metals with ultra-fine grains (UFG) is very difficult. UFG metals have a grain size of less than 1 µm. Exceeding the recrystallization temperature causes the growth of ultra-fine grains and degradation of the material’s mechanical properties. The process temperature is influenced by the amount of energy supplied to the joint, which depends on the power and time. Conventional machines are not adapted to effectively conduct the process in extremely short friction times. For this reason, this article presents the welding process on the W2Mi prototype machine. The design of this machine allows the joining of UFG metals in less than 100 ms. UFG material produced using the hybrid SPD (Severe Plastic Deformation) process from technically pure CW004A(Cu-ETP) copper was used for welding tests. The joint obtained on the W2Mi machine did not show any significant degradation signs of mechanical properties. At the same time, an increase in microhardness in the joint area by approximately 4% was noticed. The obtained results prove that the process of joining UFG metals was successfully carried out.

Oxy-hydrogen gas as a sustainable fuel for the welding industry: Alternative for oxy-acetylene gas

The urgent need to address climate change has prompted researchers to explore sustainable power generation methods using low or net-zero fuels and energy storage. Historically, gases derived from acetylene or LPG have been used for welding in factories. Despite its negative effects on the environment and human health, acetylene gas remains widely used. Examples of pollutants released from acetylene gas include carbon dioxide and carbon monoxide, both of which contribute to the greenhouse effect and global warming. There is a need for an alternative gas that is environmentally friendly, economically viable, and readily available. Hydrogen gas is currently used across various industries and is increasingly considered a potential primary fuel source for the future. In this study, a hydrogen fuel cell was used to produce HHO (brown) gas as a replacement for acetylene through electrolysis. The HHO gas was used to weld a randomly selected test piece, which was then evaluated alongside an acetylene-welded test piece. The integrity of both welds was assessed using dye-penetrant and radiographic testing, showing that welds from both gases were strong. Welding with HHO gas, followed by non-destructive inspection, also proved effective, with any defects attributed to inexperience in welding. The adoption of HHO gas in the welding industry is recommended due to its potential socio-economic benefits, health advantages, and environmental friendliness. Challenges related to initial investment costs may be mitigated as technology advances. Further research should focus on qualitative weld testing, economic and environmental impact assessments, and developing a business model for HHO systems.

Estimation of Quality of Seam Welds in AlMgSi(Cu) Extrusion by Using an Original Device for Weldability Testing.

Extrusion welding of AlMgSi(Cu) alloys is carried out by using porthole dies, as a result of which hollow shapes are formed with longitudinal seam welds. In the case of the inappropriate selection of the chemical composition of the aluminium alloy or improper metal welding conditions, the weld may have reduced strength in relation to that of the base material, thus weakening the strength of structures based on aluminium extrudates. The prediction of metal welding conditions, depending on the chemical composition of the alloy, the temperature and the unit welding pressures, effectively supports the design of porthole dies, thus significantly reducing the number of necessary extrusion tests and die geometry corrections needed during its implementation in industrial practice, and consequently significantly reducing production costs. In this work, an original laboratory test device simulating the behaviour of metal in a welding chamber of a porthole die was applied to examine the ability of AlMgSi(Cu) alloys to produce high-quality joints. Two different chemical compositions of AlMgSi(Cu) aluminium alloys differing in Mg, Si and Cu contents were used: alloy no. 1A (0.68% wt. Mg, 1.04% wt. Si, 0.61% wt. Cu) and alloy no. 3A (0.8% wt. Mg, 1.21% wt. Si, 1.22% wt. Cu). The weldability tests were carried out under various welding temperatures of 450, 500 and 550 °C and under various welding pressures of 150 MPa, 250 MPa and 350 MPa. The microstructural changes in the produced welds were evaluated with the use of OM and SEM/EDS with chemical analysis in micro-areas, whereas the mechanical effects were evaluated by using a static tensile test. Samples after static tensile testing were subjected to fractographic tests to determine the nature of the fractures. The highest values of relative weld strength were obtained under the highest welding temperature of 550 °C and the highest unit welding pressure of 350 MPa: 87% for alloy number 1/1A (high-strength weld), and 62% for alloy number 6/3A (medium-strength weld). Finally, the extrusion tests were performed in industrial conditions with an examination of the EBSD structure and strength of the longitudinal welds. High values of relative weld strength for extrudates from alloy no. 1/1A and alloy no. 3A, 96% and 89%, respectively, were found, which confirmed the previous weldability testing results.

Research on welding copper components with galvanometer based on the synergy of annular spot laser and mechatronics technology

Abstract In modern industrial production, the demand for welding copper components is increasing day by day. With the continuous progress of science and technology, the requirements for welding quality and efficiency are also getting higher and higher. As a new welding method, the collaborative welding technology of annular spot laser and CF150/330 galvanometer has the advantages of high efficiency and precision and is expected to meet the current welding needs of copper components. This study focuses on the efficiency and feasibility of ring-shaped lasers and CF150/330 vibration mirrors. With the help of the ring-shaped light spot laser combined with the CF150/330 vibration mirror, the welding test of four specifications schemes was conducted, and the quality and micro-organizations of welding copper components were conducted through depth evaluation. Under the optimized welding process parameters, the appearance of the weld is smooth and coherent. There is no significant defect. Its width is uniform. The transition from the mother material is natural. As far as micro-organizations are concerned, the weld area presents a small shaft crystal, which is narrowed in the thermal influence area. At the same time, the influence of process parameters such as laser power, scanning speed, diameter of light spots, and vibration mirror scanning on welding quality was analyzed in depth. Research conclusions show that such collaborative welding technology has good application prospects and can provide strong support for improving the welding quality and efficiency of copper components.

Ultrasonic Welding Parameter Optimization for Electric Component Welding

Industrial requirements to establish metallic joints between dissimilar metals in the electric area. The ultrasonic welding process is an optimal process to joint thin sheets or foils. The goal of the research was to optimize the ultrasonic welding parameters to join thin nickel-coated copper sheets and aluminium sheets. It used a 0.5 mm thick high-purity copper (Cu-OF-R200) sheet coated with a 10 μm pure nickel layer and a 0.5 mm thick aluminium (1050A H24) sheet. The ultrasonic welding is made by a Branson Ultraweld L20 ultrasonic welder equipment. The mechanical properties and exacting geometrical tolerance of the joint were required. The welding parameter optimization is made empirically, with several welding tests. The optimal welding parameters were confirmed by non-destructive and destructive tests of the joints. The non-destructive tests were the visual inspection and geometrical measurements of the joint sizes. The destructive tests were tensile tests and macroscopic and microscopic tests. The completed test results confirmed the process applicability and the quality of the joint.

Investigation of the Inhibition Mechanism of Process Porosity in Laser-MIG Hybrid-Welded Joints for an Aluminum Alloy

In this paper, 4 mm thick 7075 aluminum alloy was utilized for conducting laser-MIG hybrid welding tests to investigate the correlation between the dynamic behavior of keyholes and process-induced porosity. Additionally, the generation and inhibition mechanisms of process porosity were elucidated. Utilizing a high-speed camera test system of our own design, the formation position and movement characteristics of keyholes in the molten pool under different welding parameters were captured using a “sandwich” method. The dynamic behavior of keyholes during the hybrid welding process was analyzed, and the porosity of each welded joint was quantified, revealing an intrinsic relationship between keyhole dynamics and aluminum alloy laser-MIG hybrid welding porosity. The findings indicate that variations in the defocusing amount can influence both the morphology and stability of keyholes in the molten pool, consequently impacting welding porosity. The dynamic behavior of keyholes under different defocusing amounts can be categorized into five types: no keyhole formation, collapse of the keyhole root, complete instability of the keyhole, instability of the keyhole root, and stability of the keyhole. At a defocus of +12 mm, stable keyholes were observed, and no defects in the welded joints were identified.

Analysis of projection welding in relation to the non-parallelism of electrodes

The article contains the analysis of projection welding in relation to the non-parallel location (non-parallelism) of electrodes. For a thin-walled flat element, e.g., sheet metal with two embossed projections, calculations were conducted for different angles between the upper electrode and the lower electrode. The calculation involved the use of the SORPAS 3D software. The analysis included the distribution of temperature, power density, electrode displacement, the volume of molten metal in the weld nugget, nugget diameters, and energy supplied to the weld. The article presents the comparison of results obtained for various angles between the electrodes of the welding machine. The results of numerical calculations were verified experimentally through technological welding tests and destructive tests (peeling/metallographic). The convergence of the experimental and numerical results was satisfactory. The tests involved a typical element used in the automotive industry, i.e., a nut with two embossed projections in the flat part. The article represents quite an innovative new approach to multiple-projection welding from a numerical calculation point of view. Such an approach allows the researcher to identify the phenomena taking place in the process. The article also presents a new approach to the analysis of multi-projection welding as regards the non-parallelism of electrodes. The results enabled the determination of phenomena taking place in the multi-projection welding process as well as the boundary conditions in relation to which the process became improper (unstable).

Understanding the Effect of Corrosion Resistance in Welded AA2198‐T8 Alloy: Microstructural‐Electrochemical Insights

ABSTRACTIn this study, we explore the corrosion resistance of AA2198‐T8 alloy in friction stir‐welded zones, focusing on microstructure changes and resulting corrosion susceptibility. Macrogalvanic coupling effects are observed in weldment under corrosive conditions, particularly in the welding joint (WJ), heat‐affected zones, and base metal (BM). Severe localized corrosion is prevalent in anodic zones, revealing intricate trenching patterns around micrometric particles in cathodic domains. Investigating isolated zones exposes SLC across all welding‐affected regions and BM, underscoring the involvement of microgalvanic cells in corrosion. The novel utilization of a syringe cell as an electrochemical tool proves to be instrumental in delineating the electrochemical characteristics of welding testing zones. Notably, stir zone within WJ emerges as the region depicting the lowest corrosion resistance, a critical finding substantiated by localized electrochemical impedance spectroscopy. These insights into the interplay of electrochemical phenomena and microstructural attributes have implications for advancing corrosion mitigation strategies and alloy engineering in materials science.

Research on heat exchanger tube sheet to shell fillet weld testing and engineering application using total focusing phased array technique

Abstract According to structure of the heat exchanger tube sheet to shell fillet weld, the total focusing phased array technique was adopted to settle down this testing difficulty. Firstly, the inspection background and detection difficulties of the fillet weld was introduced in this paper. Secondly, the sound field simulation and typical flaw response simulation was carried out using CIVA software, and the special blocks were manufactured on the base of the simulation result. Thirdly, the total focusing phased array testing study was carried out in laboratory, and the drilled holes, grooves, as well as the typical flaws of incomplete fusion, incomplete penetration and crack in blocks were successfully detected. Finally, the total focusing technique engineering application of one heat exchanger in chemical device was put into effect, the incomplete fusion and incomplete penetration flaws were successfully detected. The total focusing phased array technique was successfully applied to the heat exchanger inspection project, the research result of this paper have high practical value for ensuring the safe and reliable operation of heat exchanger, and can be popularized and applied in the engineering project.

Determination of the load acting on the probe by separating force and torque during FSW of AA 6060 T66

AbstractThe development of suitable welding processes is required to meet the ever-increasing demands on joining processes, particularly for lightweight construction and increasing environmental awareness. Friction stir welding (FSW) represents a promising alternative to conventional fusion welding processes, particularly for the joining of low-melting-point materials such as aluminium and magnesium alloys, which present a number of challenges, including the formation of pores and the occurrence of hot cracks. The central element of the process is the friction stir welding tool, which consists of a shoulder and a probe. The rotation and the simultaneous application of pressure during the joining process create a friction-based heat input through the tool. The excellent mechanical properties resulting from dynamic recrystallisation during the welding process are a major advantage of the process. As a result, strengths comparable to those of the base material can be achieved. However, FSW is subject to process-specific challenges, including high process forces, which result in the fabrication of complex and robust devices. Additionally, high dynamic loads on the friction stir welding tools must be considered. In many cases, the design of friction stir welding tools is based on empirical data. However, these empirical values are machine-, component- and material-specific, which often results in under- or overmatching of friction stir welding tools. Sudden probe failure, component scrap, and low process reliability are the direct consequences of undermatching. Overmatching results in enlarged tools with limited accessibility, high heat input, and high process forces, leading to component deformation. The aim of this study is to determine the load on the probe by separating the forces and torque of the shoulder and the probe in order to be able to make statements about the load acting on the probe and the resulting stress state. The knowledge of the stress state can be employed to design friction stir welding tools, both statically and dynamically, for a specific welding task. A strategy was devised to distribute the load exerted on the shoulder and probe. To this end, the length of the probe was gradually reduced between the welding tests. The investigations were carried out with a force-controlled robotized welding setup in which AA 6060 T66 sheets with a thickness of 5 mm were welded. A Kistler multicomponent dynamometer type 9139AA allows to measure the Cartesian forces to be recorded in the x-, y-, and z-directions with a sampling rate of 80 kHz. The weld seam properties were determined by visual and metallographic inspections as well as tensile and bending tests in accordance with DIN EN ISO 25239–5.

LNG storage tanks 9% Ni steel weld inspection via phased-coherent TFM and SVD enhancement

ABSTRACT 9% Ni steel is commonly utilised in liquefied natural gas storage tanks due to its strong resistance to corrosion and oxidation. However, the welds in these tanks are prone to serious defects, necessitating thorough non-destructive testing. Unfortunately, when inspecting nickel-based alloy welds using phased array ultrasonic testing (PAUT) technology the ultrasonic waves are scattered and attenuated because of the coarse columnar grains. To address this challenge, this paper introduces a based on SVD enhancement directivity corrected circular coherence factor weighted TFM imaging algorithm (SVD-DC-CCF). Initially, the CCF matrix is corrected by the directivity and energy attenuation compensation factors, then weighted with the TFM pixel point amplitude. Subsequently, the weighted amplitude matrix undergoes singular value decomposition (SVD), followed by the establishment of an enhancement factor to reconstruct the amplitude matrix. The proposed algorithm is evaluated through experiments on three types of defects in a 30.0 mm thick 9% Ni steel T-shaped fillet weld test block. Results demonstrate superior signal-to-noise ratio (SNR) and enhanced image resolution. Compared to TFM results, the SNR increases by 4.97 dB, 4.25 dB, and 4.96 dB, respectively, while the array performance index (API) decreases by 9.80%, 34.39%, and 22.22%, respectively.

Optimizing Sample Preparation for Destructive Testing in Resistance Spot Welding

Abstract The integrity and reliability of resistance spot welding, a crucial process in various manufacturing industries, are significantly influenced by the quality of sample preparation. This study focuses on advancing the methodologies and practices in the preparation of samples for resistance spot welding destructive tests, aiming to improve the precision and repeatability of the results. We discuss comprehensive approaches encompassing material selection, surface treatment, dimensional accuracy, and alignment procedures, emphasizing the importance of meticulous handling and preparation techniques, A significant focus is placed on the utilization of sophisticated alignment and measurement tools to enhance the consistency of the welding area subjected to destructive testing. our study demonstrates a significant improvement in the reliability and accuracy of welding machine calibration, ultimately contributing to the overall quality of the welding process. By integrating these refined processes, the study highlights a significant improvement in the reliability of welding tests, contributing to enhanced welding quality and performance in practical applications. Our findings underscore the critical role of detailed and standardized sample preparation in achieving accurate and reliable resistance spot welding destructive test outcomes, providing valuable insights for both industrial applications and further research in welding technology.

Thermo-mechanical characterization of pinless friction stir welding in AA6060-T4 thin sheets

Friction Stir Welding (FSW) is a solid-state welding method, offering superior weld quality for aluminum alloys. Despite its advantages, the thermo-mechanical characteristics of pinless FSW, especially for AA6060-T4 aluminum thin sheets, remain underexplored. This study aims to fill this gap by examining the effects of different welding parameters on the mechanical properties and thermal distribution in pinless FSW of 2 mm AA6060-T4 sheets. Experimental welding tests were conducted using high alloy steel tools and a modified milling machine, with variations in rotation and feed rates. The results show that higher rotation speeds correlate with lower maximum temperatures, and increased feed rates further reduce temperatures. Optimal welding parameters achieved efficiency coefficients as high as 84%. Microhardness profiles indicated minimum hardness in the Thermo-Mechanically Affected Zone (TMAZ) and a significant increase on the advancing side. These findings enhance the understanding of pinless FSW, emphasizing the interaction between welding parameters and mechanical properties. This research advances the application of AA6060-T4 in various industrial sectors by providing valuable insights into optimizing weld quality and mechanical performance.

Design and implementation of power socket soldering robot arm system

Abstract In order to solve the problem of high cost and low efficiency in manual welding of power socket welding components, a soldering robot arm system was developed. The gripper, 5-DOF manipulator, clamp, support, and control system were designed. The coordinate system of the robot arm was constructed, and the working space of the robot arm was analyzed by using the MATLAB robot toolbox. It was concluded that the x0 coordinate range of the welding working area was [175mm, 215mm], the y0 coordinate range was [55mm, -55mm], and the z0 coordinate was 90mm. At the same time, the motion trajectory of the robot arm was determined. Using Raspberry PI as a controller, the control system is developed by programming Python language. The prototype is made, and a welding test is carried out. The test shows that the system has completed the welding operation, and the welding effect is good.

Weld-joint design to optimize groove weld depth and mechanical properties for welding of nozzle onto pressure vessel

Full and partial set-in weld-joints connect the nozzle to pressure vessels to prevent lamellar tearing. This investigation aims to compare full and partial set-in weld-joints through computer simulations, numerical modelling, welding experiments, nondestructive examination and destructive testing. The nozzle-to-shell opening connection’s weld-joint design model is DN20, with a 50 mm shell wall thickness. The optimal groove weld depth, at a safety factor of 3.5, ranges from 20 to 50 mm. We investigated weld-joint design variations using design-of-experiment, which included actual welding and mechanical testing. The inter-run temperature and its interaction with the heat input were found to be statistically significant. The mechanical properties of welded joint are better than those of the specified material, A516 Grade 70, which include an average impact toughness of 89.5 J at -50 °C, a microhardness of 195 Hv10, an ultimate tensile strength of 533 MPa, a yield strength of 391.5 MPa and an elongation of 56.5%. The coefficients of determination of impact toughness and microhardness, which have R2 values of 88.73% and 76.65%, respectively, conclude a successful welding experiment. The design and mechanical testing results conclude the reliability of the weld-joints.

Ultrasonic Non-Destructive Testing and Evaluation of Stainless-Steel Resistance Spot Welding Based on Spiral C-Scan Technique.

In order to achieve the non-destructive testing and quality evaluation of stainless-steel resistance spot welding (RSW) joints, a portable ultrasonic spiral C-scan testing instrument was developed based on the principle of ultrasonic pulse reflection. A mathematical model for the quality evaluation of RSW joints was established, and the centroid of the ultrasonic C-scan image in the nugget zone of the RSW was determined based on the principle of static moment. The longest and shortest axes passing through the centroid in the image were extracted, and the ratio of the longest axis to the shortest axis (RLS) factor and the average of axis (AOA) factor were calculated, respectively, to evaluate the quality of the joint. To study the effectiveness of the detection results, tensile tests, and stereo analysis were conducted on the solder joints after sampling. The results indicate that this detection method can realize online detection and significantly improve the detection efficiency; the detection value of internal defect size is close to the true value with an error of 0.1 mm; the combination of RLS and AOA factors can be used to evaluate the mechanical properties of RSW joints. This technology can be used to solve the NDT, evaluate problems of RSW joints, and realize engineering applications.

Numerical Simulation of the Laser Welding Process for Diamond Saw Blades

The development and application of laser welding transition layer technology is pivotal for manufacturing high-performance diamond saw blades. Despite its importance, there is a need for more precise modeling to optimize welding parameters and enhance blade performance. This study employs SYSWELD software to simulate the laser welding process, demonstrating high accuracy in predicting the molten pool shape. A cross-scale multi-field coupling model was established using the finite element method, incorporating temperature field, phase transformation, grain morphology, stress field, and fatigue performance. A comprehensive life cycle assessment identified optimal welding parameters. The results indicate that a laser welding speed of 26 mm/s and a power of 1700 W minimize weld stress, reduce the digital volume correlation (DVC) value, and enhance fatigue resistance. Additionally, welding tests confirmed that using 1700 W produced the highest tooth strength of 1200 MPa, validating the simulation results. This study addresses existing gaps in modeling accuracy and parameter optimization, offering a robust framework for improving the performance and reliability of laser-welded diamond saw blades.

Laser Welding of ARMOX 500T Steel.

The article describes the results of the study on laser welding of armor plates with a nominal thickness of 3.0 mm. The plates were made of Armox 500T steel characterized by a hardness of up to 540 HB, a minimum yield strength of 1250 MPa, an ultimate strength of up to 1750 MPa, and an elongation A5 minimum of 8%. The laser used for the welding tests was a solid state Yb:YAG laser. The influence of basic parameters such as laser output power, welding speed, and focal plane position on the weld geometry was determined during bead-on-plate welding tests. The optimal conditions for butt joint welding were determined, and the test joints were subjected to mechanical and impact tests, metallographic analysis, and hardness measurements. It has been shown that it is possible to laser weld Armox 500T armor plates, and at the same time it is possible to provide high quality butt joints, but this requires precise selection of welding parameters. A decrease in HAZ hardness of about 22-35% in relation to the hardness of the base material, ranging from 470 to 510 HV0.2, was found. The ultimate tensile strength of the test joints was approx. 20% lower than the Armox 500T steel. The bending tests revealed the low plasticity of the tested joints because the bending angle was just 25-35°. The results of Charpy V-notch test revealed that the impact toughness of the weld metal at -20 °C was approx. 30% lower than at room temperature.

Design and manufacturing of Welded Vacuum Testing (WVT) tool

To ensure the quality of welded joints in the hull area, welding testing is very important and must be carried out. But unfortunately, currently the quality testing process of welded joints was still limited to penetrant tests and lime tests. The purpose of this study was to obtain a portable welding testing machine that was able to obtain fairly accurate test results on hull welding defects using a vacuum system. The research method is experimental by involving data collection through field experiments, testing is carried out with the resulting weld defect research subjects and the length of testing time on 1G and 3G position welding. The results of the study by compared tests among Welded Vacuum Testing (WVT) machines, Magnetic Particle tests (MP), and Penetrant Tests (PT). The three experiments detected leaking weld defects, spark sparks, pinholes, overlaps, and undercuts. For test results with machines made, welding defects that were successfully detected were leaks in the 1G position welding workpiece and undercut in the 3G position welding workpiece. Air bubbles at a vacuum pressure of 0.2 bar are detected, meaning that there is a defect in the welded joint. This tool can be used in bilge testing.