Welding Conditions Research Articles

Monitoring laser weld penetration status from the optical signal

Spectrometers have demonstrated their value in laser welding by facilitating the comprehension of welding dynamics and the identification of defects. However, the complex interaction between the laser beam and the material being welded makes it difficult for spectrometers to accurately capture the depth and extent of weld penetration, predominantly because plasma formation during welding interferes. This study presents an innovative approach that integrates laser technology, spectrometers, and advanced data analysis methods to classify and characterize various penetration types in pulse laser welding procedures, with notable computational efficiency. The research entailed the execution of an experiment on a boron steel plate, wherein peak power (1000-1200 kW), pulse duration (2-4 ms), and pulse repetition rate (25-50 Hz) were systematically varied to achieve diverse penetration conditions. Two categories of joints were identified based on their depth of penetration through careful analysis of the collected data. The investigation demonstrated a positive correlation between the depth of weld penetration and the increment of laser energy, with peak power ranging from 1000 kW to 1200 kW. Consequently, an elevation in light intensity was observed related to deeper weld penetration. The information is essential for understanding the relationship between laser energy and weld penetration, highlighting the importance of controlling laser parameters to achieve desired welding results. The spectrums were analyzed using Principal Component Analysis (PCA) to distinguish between different welding conditions. Overlap was observed between data from different weld conditions due to limitations imposed by the restricted dataset. Expanding the sample size can rectify this limitation and improve the accuracy and dependability of analytical outcomes. This study’s results provide valuable insights into optimizing welding parameters and improving understanding of the welding process, specifically in Tailor Weld Blanks. The findings offer potential for improving welding quality and strengthening lightweight components in high-performance industries like aerospace and automotive engineering.

Hazards associated with blue light emitted during gas metal arc welding of mild steel using various shielding gases and currents.

Blue light emitted during arc welding is known to potentially cause photoretinopathy. To help prevent retinal injury, it is important to identify the hazards associated with various welding conditions. The present work conducted experiments involving gas metal arc welding of mild steel under various conditions, and measured the spectral radiance of the arcs. The effective radiance values, as used by the American Conference of Governmental Industrial Hygienists (ACGIH) to quantify exposure level of blue light, were subsequently calculated from the data. The resulting values were in the range of 5.0-118 W/cm2/sr, corresponding to hazardous levels according to ACGIH guidelines. The effective radiance was increased at higher welding currents and when pulsed currents were used rather than steady currents. The blue light hazard was also affected by the type of shielding gas employed. These data confirm that it is very hazardous to stare at arcs during gas metal arc welding of mild steel. As such, appropriate eye protection is necessary during arc welding, and directly staring at the arc should be avoided.

Characteristics of welding laser beam and its influence on weld forming coefficient

Laser welding is a very complicated process. At present, there is no systematic research on the relationship between welding parameters and forming coefficient. By studying the internal relationship between laser parameters and the characteristics of welding laser, laser beam indexes, such as focusing index, are defined. They are simplified to a few laser parameters so as to facilitate the study of the influence of welding parameters on the forming coefficient. The results show that material, assembly gap, laser power and welding speed have great influence on weld penetration. When the laser power density reaches 106J/cm2, the characteristics of deep penetration welding appear. Under the condition of constant clearance, the weld depth increases with the increase of t/b. The weld penetration increases with the increase of laser power and tends to be stable when the welding speed is 12mm/s. Different materials also have a certain influence on the weld penetration depth. Under the same conditions, X6CrNiTi1810 obtains greater penetration depth, indicating that physical and chemical properties of materials are also one of the factors affecting the penetration depth. The mechanism and condition of laser welding were analysed. The relationship between laser absorptivity of sheet surface and physical properties of the materials is also studied and then obtained. The study will provide theoretical guidance for laser welding process design and welding parameter selection of steel plate.

Research on welding defect examination technique based on phased array ultrasonic for high voltage transformer oil tank welds

Oil tank of high voltage transformer plates. During welding and operation, defects such as incomplete fusion, incomplete penetration , air holes and cracks may be produced which influence the integrity and density of the welds and the whole tank. In order to test the integrity of the shell weld of high-pressure transformer box and ensure no leakage of transformer oil, the phased array testing technology is used to detect the defects of the butt weld of the transformer oil tank. The characteristics of weld defect detection under the condition of incomplete penetration were studied, and the sound beam accessibility, process selection principle and probe selection principle were theoretically analyzed. The test tests were carried out on the artificial samples of the butt weld of the transformer oil tank plate. The results show that the phased array can effectively detect the defects in the weld of transformer tank shell under the condition of incomplete welding, and the imaging results are intuitive and easy to judge, which can effectively evaluate the integrity of transformer tank weld. During the process selection, the probe-wedge combination with appropriate front distance and detection Angle should be selected according to the wall thickness, weld penetration depth and crown width of the transformer oil tank. During defects judgment, the interference of structure echo wave and incomplete penetration area should be considered. The assistant defect positioning analysis based on incomplete penetration is also suggested.

Fabrication progress of the prototype spoke cavity for the JAEA-ADS linac

The Japan Atomic Energy Agency (JAEA) has been proposing an accelerator-driven nuclear transmutation system (ADS) as a future nuclear system. In preparation for the actual design of the CW proton linac for the JAEA-ADS, we are now prototyping a low-β (≈ 0.2) single-spoke cavity. The cavity fabrication started in 2020. Most of the cavity parts were shaped in fiscal year 2020 by press-forming and machining. In 2021, we started welding the shaped cavity parts together. By preliminarily investigating the optimum welding conditions using mock-up test pieces, each cavity part was joined together with smooth welding beads. So far, we have fabricated the body section and the beam port sections. By measuring the resonant frequency of the temporarily assembled cavity, it was confirmed that there were no significant problems with the cavity fabrication.

Enhancing Friction Stir Spot Welding of Al 5754 and Al 6111 Joints Using Taguchi’s Technique

The present study investigates the impact of varying process parameters on the mechanical properties of friction stir spot welding (FSSW) joints involving Al 5754 and Al 6111. Taguchi’s L16 design of experiment approach was employed to conduct experiments and optimize the process parameters. Key parameters, including tool pin profile, dwell time (5–30 sec), rotating speed (250–1400 rpm), and plunge depth (1.5–1.8 mm), were systematically considered. The results indicated that the optimized welding conditions for attaining higher tensile‐shear strength are a spindle speed of 1400 rpm, dwell time of 10 sec, plunge depth of 1.7 mm, and a tool pin profile of a triangular pyramid. As for bending strength, the optimal conditions are a spindle speed of 250 rpm, dwell time of 30 sec, plunge depth of 1.8 mm, and a tool pin profile of a square pyramid, representing higher bending strength. The analysis of variance technique revealed that the tool pin profile and plunge depth significantly influenced the tensile‐shear strength and bending strength of the developed FSSW joint, respectively. Regression analysis was employed to formulate mathematical models predicting tensile and bending strength, and the predicted values closely matched experimental results with 80% accuracy.

Development of a T-Joint Welding Fixture for Enhanced Friction Stir Welding Performance

Welding, a crucial manufacturing process across various industries, involves forming permanent component joints. Friction stir welding (FSW), an efficient technique is employed for this purpose. FSW requires a fixture to securely hold the workpiece during welding, ensuring precise alignment, minimal deformation and effective heat dissipation. This work focuses on designing a fixture tailored for T-joint configuration FSW of aluminum alloys. Initial concept design was refined for optimal performance with material selection (Mild Steel and EN8) based on requirements. Real-time welding conditions were considered for analysis, leading to the choice of EN8 due to reduced deformation. This paper outlines the steps involved in designing, analyzing and manufacturing a T-joint welding fixture, guaranteeing proper alignment, clamping and heat management during welding.

Temporal power modulation in high power laser beam welding of round bars

Temporal power modulation bears an enormous potential for high power laser beam welding of round bars since all its specific challenges are faced. They can be summarised as deviating welding conditions towards the round bar‘s centre. Accordingly, a tailored amount of energy would be provided to that area. The investigations are conducted on 30 mm diameter bars of 1.4301 stainless steel with the use of a 16 kW disk laser. The modulation parameters comprise 6/12/50/100/200 Hz modulation frequency and 0.30/0.47/0.73 modulation depth or power modulation ratio. Post analysis focuses on metallographic longitudinal sections and calculations. The modulation‘s outstanding capability is creating deeper and narrower weld seams due to higher peak power and more intense evaporation of protrusions along the keyhole front wall. Therefore, more laser power is provided to the weld root and despite applying lower average power, the same weld depth is achieved. Finally, more ecological and economical welding as well as welding of more temperature sensitive materials is enabled.

A fast crack-free bonding method for glass and silicon using laser transmission welding with a defocused beam

This paper presents a novel fast crack-free bonding method for glass and silicon based on the defocused beam laser transmission welding technique (LTW). The bonding and crack formation mechanisms during LTW are discussed in detail in this paper. It was shown that the LTW technique using a defocused beam could effectively reduce the temperature gradient during the process to avoid crack formation. Meanwhile, the defocused beam could increase the bonding width of a single scan, reducing the number of scans for large-area bonding and further improving the efficiency of the bonding process. To find the welding conditions for different dimension requirements, a regression model was developed to determine the width of the weld. The crack-free bonding conditions were found by using the support vector machine (SVM). The regression model and the boundaries for the crack-free bonding conditions were both validated under randomly selected processing parameters. Finally, a 7.54 mm × 12.5 mm large crack-free bonded area was fabricated using this technique to demonstrate the feasibility of this technique. The crack-free bonded part was fabricated within 2 min, which is 8 times faster than the conventional anodic bonding. This study showed that the defocused beam LTW is a much more efficient and competitive alternative to the conventional bonding methods for silicon and glass, holding a huge potential in applications like semiconductor packaging and MEMS fabrication.

Дослідження міцності вантажних вагонів з хребтовою балкою зварної конструкції

Due to the severe shortage of rolled zeta profile of increased strength class in the country as a result of the armed aggression of the russian federation, domestic enterprises were forced to manufacture freight cars with welded center sills. This article deals with the topical issue of researching the strength of freight cars with welded center sills. The models of freight cars with welded center sills that were subjected to scientific and experimental studies to assess strength are given. A comprehensive scientific and experimental studies of the strength of freight cars with center sills was carried out beams of a welded structure, which included execution of static strength tests, wedge tests within the tolerance range. Based on the results of the carried out tests types, the experimental and calculated value of the coefficient of fatigue safety factor in the structural elements of freight cars with welded center sills was obtained. The most stressed places in the metal structures of freight cars with welded have been determined. The service life of the researched freight cars with welded center sills installed by the manufacturing companies was confirmed based on the obtained values of fatigue safety factor in the structural elements of these cars. It has been established that the strength qualities of freight cars with welded center sills comply with the current regulatory requirements. Based on the results of comprehensive scientific and experimental studies, it is recommended to inspect the condition of structures and welds of center sills as part of each type of scheduled repair of freight cars.

A Study on a Novel Process Combines Cutting and Joining by an Automatic Lathe

The Swiss-type automatic lathe is designed for continuous mass production of the same product. In the research, the authors propose a combined turning process in which a joining process using the frictional welding method is introduced into the automatic lathe. If the joining process is performed with a Swiss-type automatic lathe, it is expected that the problem of a large amount of residual material due to the mechanical structure can be solved. Generally, the friction welding method is performed by a dedicated machine and is pressure controlled by a hydraulic power source, however in the case of an automatic lathe, friction welding is controlled by the feed length and feed rate. The low rigidity of automatic lathes is also concerned. In the study, the authors investigated the tensile strength and rotational bending fatigue strength of the A6061 bonding material to investigate and quantitatively evaluate the optimum friction welding conditions that can obtain good bonding results in the friction welding method using a multi-axis automatic lathe. Upset speed was the most influential factor for tensile strength and friction rotation speed was good at about 4000 rpm. This fact suggests that excessive heat input leads to a decrease in tensile strength. The tensile strength was equivalent to that of the annealed material. It also seems that the air-cooled annealing phenomenon occurs during the friction welding process. The results of rotational bending fatigue strength were similar to those of the annealed material. It is clarified that friction welding with an automatic lathe is feasible, however, the strength of the bonded material is reduced to the same level as that of the annealed material.

Hot Tool Welding of Pipelines from Polyethylene for Gas Supply with a Diameter of 90-315 mm

Purpose of research. GOST P 55276-2012 applied in the Russian Federation does not regulate concrete data on the choice of this or that procedure under various conditions of welding and standard sizes of the applied pipes, leaving it to the discretion of the consumer. Unlike the procedure of the welding with only low pressure which is well fulfilled and widely applied in domestic practice, the welding according to the procedure with the only high pressure allowing to reduce three times time of a welding cycle is practically not used and specially intended welding machines in Russia are not issued. In this regard this work is devoted to development of the modes of hot tool welding of abutting connections of pipes from polyethylene with a diameter from 90 to 315 mm for SDR 13.6 - SDR 9.0 with the only high pressure, to the choice of possible domestic welding equipment and experimental check of the developed modes.Methods. In this article for butt welding by the heated tool of pipes from polyethylene with a diameter from 90 to 315 mm, using a design technique, main parameters of welding procedure are determined with the only high pressure. When choosing the welding machine necessary for tube welding of the considered range on welding procedure with the only high pressure, by results of the carried-out analysis of technical datas of domestic welding machines and features of their operation capabilities it is preferred as the welding machine with the hydraulic drive "Native of the Volga Region of SSPT-315". For experimental check of the executed payment of parameters of the procedure of welding under the cyclogram with the only high pressure four joints of pipes with a diameter of 110 mm with thickness of a wall of 10 mm from PE-100 (SDR 11.0) have been welded and visual and measuring quality control of the executed connections and short-term tests of technological samples on axial stretching by the R-50 machine is made.Results. Mechanical tests of technological samples of all joints of the pipes from PE-100 with a diameter of 110 mm (SDR 11.0) executed on the SSPT-315 welding machine on welding procedure with the only high pressure have shown 100% - ny result of plastic nature of destruction at the size of lengthening from 500 to 600%.Conclusion. The high quality of experimental joints of pipes from PE-100 assumes a possibility of use of the SSPT- 315 machine for hot tool welding of pipes from polyethylene of everything of the range regulated by technical datas on welding procedure with the only high pressure.

Coaxial one-side resistance spot welding for cross-lap joints of Al5052 and CFRP: Thermal process and strength evaluation

Coaxial one-side resistance welding (COS-RSW) is an advanced joining technology for the metal-plastic hybrid structure, which has great application potential in the lightweight design of body-in-white. In the present research, the Al5052-CFRP cross-lap joints were fabricated by COS-RSW with different welding conditions. The author-developed finite element (FE) code JWRIAN-RSW was employed to reproduce the multi-physics coupled phenomena of COS-RSW and predict thermal history. The influence of welding current and welding time on molten zone generation and joining strength was discussed in detail. The results showed that the developed FE model can predict temperature distribution and variation effectively, which were verified by the bonding zone observation and infrared thermal image measurement. Both welding current and welding time had a significant contribution to the Joule heat generation. While their influence on the molten zone growth during heating and cooling stage was distinct. The maximum joining strength of COS-RSW cross-lap joints can reach about 1380 N. The static tensile strength was improved significantly when the maximum interface temperature exceeded 340 °C and the failure mode altered into staged fracture. The strength degradation induced by significant CFRP decomposition was appeared when the predicted interface temperature reached 410 °C. For the COS-RSW joint of Al5052 and CFRP, it was better to improve the joining strength using longer welding time rather than higher welding current, which led to sufficient heat generation, persistent thermal conduction and elongated melting duration for sound joining.

Evolutionary Algorithm to Optimize Process Parameters of Al/Steel Magnetic Pulse Welding

The Magnetic Pulse Welding (MPW) process uses only electromagnetic force to create a solid-state metallurgical bond between a working coil and outer workpiece. The electromagnetic force drives the outer tube to collide with the inner rod, resulting in successful bonding. However, due to the dissimilarity of the MPW joint, only a portion of the interface forms a metallurgical bond, which affects the quality of the joint. Therefore, the purpose of this study is to analyze the effects of process parameters on joint quality through experimental work using RSM. Furthermore, an optimization algorithm is utilized to optimize the process parameters used in magnetic pulse welding. A1070 aluminum and S45C carbon steel were used as the materials, while peak current, gap between working coil and outer tube, and frequency were chosen as the process parameters for MPW. The welding conditions are determined through experimental design. After welding, the maximum load and weld length are measured to analyze the effect of the process parameters, and a prediction model is developed. Specifically, to achieve a high-quality joint, the process parameters are optimized using the Imperialist Competitive Algorithm (ICA) and Genetic Algorithm (GA). The results reveal that the peak current is a significant parameter, and the developed prediction model exhibits high accuracy. Furthermore, the ICA algorithm proves very effective in determining the process parameters for achieving a high-quality Al/Steel MPW joint.

Mechanical and structural behavior of high-strength low-alloy steel pad welded by underwater wet welding conditions

The aim of the paper was to determine the metallurgical and mechanical behaviors of a high-strength low-alloy (HSLA) steel pad-welded specimen used in the structures of industrial and naval parts. Then to predict the metallurgical consequences (nature of the phases present) and the mechanical properties (hardness and impact strength) of the pad-welded steel obtained by underwater wet welding with different heat input values. The XRD patterns clearly reveal a ferritic alpha steel S460N for both parameters. The ferritic quantification is above 70 wt% for low-alloy steel. The welded specimens are characterized by the presence of different phases. In a specimen performed with higher heat input, the complex oxide Mn2TiO4 was found to be around 7 wt%. Moreover, the solid solution formed with iron and manganese was observed. The hardness results obtained by indentation showed that the higher heat input resulted in higher hardness values (54 HRC) than for specimen performed with lower parameters (45 HRC). The impact test showed that the toughness of both pad-welded layers is greater than the toughness of the base material (40 kV for S2 and 34 kV for S1 about 27 kV for low-alloy steel). Moreover, it was observed that higher heat input results in increasing the impact strength of pad welds.

Welding of P355NH steel for the construction of a medium-pressure gas pipeline

AbstractThere is an increasing demand for welding of steel pipes meant for pressure purposes. P355NH (1.0473) steel became an important construction material used for structuring and restructuring of a medium-pressure gas pipeline due to its properties, such as significant tensile strength at the level of 600 MPa and increased yield point. These properties ensure appropriate service life of the principal pipeline structures. When welding P355NH steel, processes that enable high-quality welds without significant changes in the chemical composition of the base material, are applied. It is recommended to use the TIG welding process to produce joints, although P355NH steel joints are considered as difficult to weld. During welding, various welding defects might appear, which mainly include sticking and lack of fusion. Creation of joints with the desired properties, including those used in the construction of medium pressure gas pipelines, with the required class B quality, requires selection of appropriate parameters and compliance with the welding process practice. This is very important for the service life of the structure. Therefore, the article aims to select the most appropriate parameters and thermodynamic conditions for welding P355NH steel in order to obtain the best mechanical properties. The most important of the tested welding parameters of P355NH steel is welding speed, welding current, preheating temperature, interpass temperature and, above all, the role of various shielding gases. (Three different shielding gases containing argon and helium additives were tested.) The obtained joints were tested by: non-destructive tests, such as VT—visual examination; MT—magnetic particle testing, PT—penetration tests, UT—ultrasonic testing and by the destructive methods, such as tensile strength, impact toughness, bending test, light microscopy and scanning electron microscopy. The cause-and-effect relationships between the obtained joint structure and its mechanical properties were determined. The considerations were supported by the nucleation model and the mechanisms of formation of the acicular ferrite phase in the joint material. The chosen parameters of TIG process allow to obtain joint with adequate strength for the production of the gases pipeline, without welding defects. The results have a practical implication, the developed production technology for the obtaining the joints. The presented solution gives the possibility of producing correct welded joints, which can be used in the responsible steel construction. The originality of manuscript is the presentation the newly, uncomplicated solution of obtaining joint with good mechanical properties included the thin-walled tubular structure with a thickness of 3.6 mm. A novelty in the article is a clear indication of the importance of detailed thermodynamic welding conditions and obtained weld structure on the mechanical properties of the P355NH steel joint, which lead to the formation of various non-metallic titanium inclusions, which have a decisive impact on the mechanical properties of the joint, especially its strength and impact strength.

The Effect of Rotational Tool Speed on Dissimilar Joint Aluminum-Copper Plate Friction Stir Welded Joint

The study investigates the impact of rotational tool speed on the mechanical properties and microstructure of aluminum-cooper friction stir-welded joints. It found that higher rotational speed leads to increased grain size, possibly due to increased heat production. Higher hardness values in the stir zone result from uniform dispersion of smaller copper particles. The study found that 540 rpm yields the maximum hardness value in the stir zone, measuring 67 VHN. However, higher speed results in defects like voids, cracks, and intermetallic compounds (IMCs), which are linked to the formation of IMCs at elevated temperatures. The optimal welding conditions at 550 rpm balance grain refinement, hardness enhancement, and defect mitigation, contributing to the understanding of welding process parameters.

Numerical Study on Welding Structure of Connecting Fin Used in Thermal Power Plant

The background of deep peak-shaving poses demanding requirements for the performance of metal components in thermal power plants. The cracking of the connecting fins on the side wall of the flue seriously endangers the safe operation of the system. Herein, welding simulations were carried out using the finite element method to understand the cracking process of the connecting fins. By changing the welding process and fin size, their effect on stress and deformation was explored. The results showed that increasing the welding rate would decrease the flexural deformation of the flue-side wall. Additionally, the yield range of the connecting fin depended more on width than thickness, and increased with increasing width. As for the relationship between fin size and flexural deformation, the maximum deformation decreased with the increase in thickness, while it first decreased and then increased with increasing width. Overall, the post-welding stress and deformation of the boiler flue side wall exhibited more sensitivity to the fin width compared with the fin thickness and welding rate. This article clarifies the stress distribution status of the connecting fins in the flue side wall under different welding conditions, providing a basis for analyzing its cracking phenomenon, and further providing theoretical guidance for optimizing the structural parameter design of the side wall.

Achieving an improved performance in double-sided friction stir weld joints by adjusting the welding conditions during the passes of AA6061-T6 aluminium alloy

The present study aims at investigating the effect of interaction between the process parameters of each weld pass (1st pass and 2nd pass) to improve the joint performance during the double-sided friction stir welded joints of AA6061-T6 aluminium alloy. Experimental designs were conducted following a design matrix developed using response surface methodology to investigate the impact on the microstructural changes and tensile properties. Pronounced interaction between the process parameters of each weld pass of the joint was observed and indicated a strong interdependency between them. The detailed microstructural study conducted through EBSD insights into the extent of homogenization, and abnormal grain refinement and reflects a vast transformation of low-angle grain boundaries into high-angle grain boundaries within the stir zone. The profound examination through scanning electron microscopy and transmission electron microscopy analysis validated the uniform homogeneous distribution of Al-Fe and Al-Si-rich precipitates. The significant improvement in the grain refinement and distribution of the strengthening precipitates within the stir zone led to a substantial enhancement in the microhardness, along with achieving a maximum ultimate tensile strength of 223 MPa and a percentage elongation of 14%. A study of the fracture morphology ensures the ductile fracture behavior of the tensile fracture specimen by observing the presence of numerous dimples within a well-bonded joint.

Distribution and reinforcement effect of carbon fiber at the interface in injection welding of polyamide 6 composites

AbstractTo meet the lightweight production requirements of automobiles and achieve high strength, reinforced thermoplastic composite materials are gradually replacing metal materials. Injection molding is the preferred manufacturing method to enable the production of complex‐shaped parts, facilitate production, and reduce costs. In this study, carbon fiber (CF) was added to the commonly used resin‐reinforcing material, polyamide (nylon) PA6, to create a CF‐reinforced thermoplastic composite (polyamide 6 [PA6]/CF) that was welded using injection molding. This study not only investigates the impact of different welding conditions on shear strength but also discusses the sequence of welding. Achieving 85% of the shear strength of the PA6 base material under ideal circumstances. The CF distribution and reinforcement mechanism were analyzed by observing the connection interface and cross section using a polarizing microscope and a scanning electron microscope. When PA6/CF was used as the secondary molded body, the welding results were better. The addition of CF had a significant strengthening effect on the strength of the PA6 injection welding.Highlights Carbon fiber‐reinforced thermoplastic composite materials were prepared, and welding with PA6 was achieved using the injection molding method. The optimal welding parameters were determined by varying the mold, injection speed, injection temperature, and order of injection. The maximum welding shear strength reached 85% of the base material shear strength. The positive effect of specific fiber distribution on welding strength was analyzed by observing the interface using a scanning electron microscope and a polarizing microscope. This study provides valuable insights into the optimization of welding processes for carbon fiber thermoplastic composite materials, offering possibilities for connecting dissimilar materials with poor compatibility.