Search Results (69)

This study systematically investigates the behavior of droplet transfer and the characteristics of weld morphology in laser-cable-type welding wire (CWW) arc hybrid welding under varying Ar-CO₂ shielding gas compositions, utilizing AH36 shipbuilding steel. During the hybrid welding process, a comparative analysis was conducted on the welding process and weld formation using a high-speed camera system and a current–voltage waveform acquisition system. The experimental findings indicated that the arc width exhibited an upward trend, while the arc height demonstrated a decline as the CO₂ content increased. Additionally, the welding current experienced a decrease. Furthermore, the arc became more regular with an increase in the top arc width, which enhanced process stability. The peak intensity of the curve for 90% Ar + 10% CO₂ was the largest, and the peak range was the narrowest, indicating that the current was more stable compared to the other two shielding gas compositions. The droplet transfer frequency exhibited a decreasing trend with the increase in CO₂, while the diameter initially decreased and then increased. As the CO₂ content increased, the droplet transfer mode transitioned from a mixed mode involving both globular transfer and short circuits to predominantly globular transfer. The increase in CO₂ promoted weld penetration while reducing its width, with the penetration depth of the weld increasing by 12.3% when the CO₂ content rose to 18%. Full article

Stainless steels are widely used across many industrial sectors, including the fabrication of welded structures. The most common methods for joining these materials are arc welding processes. Increasing demands for higher weld quality and process efficiency have led to a growing adoption of laser-based technologies in industry. One of the most frequently applied techniques is hybrid laser–arc welding (HLAW), which combines two heat sources—the laser beam and the electric arc—acting simultaneously. For new, innovative joining technologies, a critical factor in their implementation is their impact on the environment and human health. This article presents the results of a study on the morphology of fumes emitted during the HLAW of X5CrNi18-10 (1.4301) stainless steel. Laser diffraction and scanning electron microscopy were used to characterize the fume morphology. The International Agency for Research on Cancer has classified welding fumes as a carcinogenic agent to humans. The results revealed that more than 20% of particles generated during hybrid welding belong to the most hazardous fraction, as they can penetrate beyond the laryngeal region. These particles exhibit a homogeneous elemental distribution, with the chromium content standing at approximately 20% and nickel nearly 10%. Full article

Maraging steels encounter tremendous aerospace applications, such as in landing gears, rocket motor casing, pressure vessels, satellite launch vehicles, etc. Laser welding is considered one of the most effective manufacturing processes due to its minimal instances of wider heat-affected zones (HAZs), precipitate accumulation, and other benefits. However, it should also be noted that their severe effect is still evident in terms of the tensile strength and fatigue strength of laser-welded maraging steel. This paper provides a critical review of the evolution of microstructural features and mechanical properties of laser-welded maraging steel, including corresponding factors in terms of microstructures and the formation of reverted austenite, as well as precipitation hardening from various studies on maraging steels. We examined the influence of precipitation, reverted austenite, welding, and post-weld heat treatment on mechanical properties like hardness, tensile strength, yield strength, elongation, and fatigue strength of laser-welded maraging steel. It is worth mentioning that the laser welding process is generally insufficient for welding sheets with a thickness over 10 mm or those requiring multi-pass welding. The reheating process becomes unfavorable for maraging steel in the multi-pass welding process since it may induce localized heat treatment. Although hybrid welding may resolve an arising thickness issue, the reversion of austenite and complexity are still difficult to overcome due to the dual nature of welding processes, resulting from the use of both arc and laser. Furthermore, maraging steel produced via additive manufacturing tends to avoid austenite reversion with effective heat treatment prior to any welding process. Post-weld heat treatment and cryogenic treatment have been found to be favorable for desired reverted austenite formation. Finally, the proposed constructive framework specifically applies to the welding process of maraging steel, particularly for aerospace applications. Full article

In this study, a processing platform based on hollow tungsten arc coaxially assisted by fiber laser (HTAAL) was developed. The HTAAL discharge process was analyzed through physical experiments and numerical simulations. The coupling effect between the laser and the hollow tungsten arc (HTA) was examined, the factors influencing HTAAL discharge stability were identified, and the coupling mechanism was explained separately. The findings showed that laser power had a significant impact on HTAAL discharge behavior. As laser power increased, the arc discharge exhibited different types. The variations in discharge were attributed to differences in several aspects, including discharge mode, current density distribution, high-temperature zone shape, arc conductivity, and the effect of laser plasma under different laser power conditions. Full article

Over the past 20 years, laser beam–electric arc hybrid welding has gained popularity, enabling high quality and efficiency standards needed for steel welds in structures subjected to severe working conditions. This process enables single-pass welding of thick components, overcoming issues concerning the individual use of traditional processes based on an electric arc or laser beam. Therefore, thorough knowledge of both processes is necessary to combine them optimally in terms of efficiency, reduced presence of defects, corrosion resistance, and mechanical and metallurgical features of the welds. This article aims to review the technical and metallurgical aspects of hybrid welding reported in the scientific literature mainly of the last decade, outlining possible choices for system configuration, the inter-distance between the two heat sources, as well as the key process parameters, considering their effects on the weld characteristics and also taking into account the consequences for solidification modes and weld composition. Finally, a specific section has been reserved for hybrid welding of clad steel plates. Full article

TC4 titanium alloy and 5083 aluminum alloy with different groove shapes were joined by laser-MIG hybrid welding–brazing using ER4043 filler wire. The effects of groove shape on the weld formation, intermetallic compounds and tensile property of the Ti/Al butt joints were investigated. The welds without obvious defects could be obtained with grooves of I-shape and V-shape on Ti side, while welds quality with grooves of V-shape on Al side and V-shape on both sides were slightly worse. The interfacial intermetallic compounds (IMCs) on the brazing interface were homogeneous in the joints with groove of V-shape on Ti side, and V-shape on both sides, which had similar thickness and were both composed of TiAl₃. Unlike the IMCs mainly composed of TiAl₃ at the I-shape groove interface, TiAl₃, TiAl, and Ti₃Al constituted the IMCs at the V-shape on Al side interface. The average tensile strength of Ti/Al joints with groove of I-shape was the highest at 238 MPa, and was lowest at 140 MPa with groove of V-shape on Al side. The tensile samples mainly fractured at IMCs interface and the fractured surfaces all exhibited mixed brittle–ductile fracture mode. Based on the above research results, I-shape groove was recommended for laser-arc hybrid welding–brazing of 4 mm thick Ti/Al dissimilar butt joints. Full article

In large welding structures, maintaining a uniform assembly condition and machined dimension in the pre-welding groove is challenging. The assembly condition and machined dimension of the pre-welding groove significantly impact the selection of the welding parameters. In this study, laser–arc hybrid welding is used to perform butt welding on 6 mm Q345 steel in various assembly conditions, and we propose an adaptive model of the BP neural network optimized by a genetic algorithm (GA) for laser–arc welding. By employing the GA algorithm to optimize the parameters of the neural network, the relationship between the pre-welding groove parameters and welding parameters is established. The mean square error (MSE) of the GA-BP neural network is 0.75%. It is verified via experiments that the neural network can predict the welding parameters required to process a specific welding morphology under different pre-welding grooves. This model provides technical support for the development of intelligent welding systems for large and complex components. Full article

To address the challenge of achieving an optimal balance between strength and toughness in ultra-high-strength steel welds, this study investigates ultrasonic vibration-assisted laser-arc hybrid welding. The influence of ultrasonic vibrations, applied to the lower surface of laser-arc hybrid welding specimens at powers ranging from 60 W to 240 W, on various aspects of the weld, including macroscopic morphology, porosity, microstructure, and mechanical properties, was systematically examined. Experimental findings reveal that as ultrasonic power increases, weld porosity initially diminishes before rising again. Simultaneously, the fusion ratio of the weld gradually enhances, and the cross-sectional morphology of the weld transforms from a “goblet” shape to an “inverted triangle”, with the transition boundary between the arc zone and laser zone becoming less distinct. Furthermore, an increase in ultrasonic power leads to a gradual rise in the microhardness of the weld, and the mechanical properties of the weld joint exhibit an upward trend. Notably, at an ultrasonic power of 180 W, the weld attains a tensile strength of 1380 MPa and an impact toughness of 10.5 J, highlighting the potential of this technique in optimizing the welding characteristics of ultra-high-strength steel. Full article

Laser–arc hybrid welding (LAHW) is an advanced welding technology that integrates both laser and arc heat sources within a single molten pool, achieving synergistic benefits that surpass the sum of their individual contributions. This method enhances the welding speed and depth of the fusion, stabilizes the process, and minimizes welding defects. Numerous studies have investigated the principles, synergistic effects, keyhole dynamics, joint performance, and various factors influencing the parameters of laser–arc hybrid welding. This paper begins with an introduction to the classification of LAHW, followed by a discussion of the characteristics of gas-shielded welding, argon arc welding, and plasma hybrid welding. Subsequently, the welding principles underlying laser–arc hybrid welding will be elucidated. To enhance weld integrity and quality, this paper will analyze keyhole behavior, droplet transfer dynamics, welding quality performance, and the generation and prevention of welding defects that affect laser–arc hybrid welding. Additionally, a detailed analysis of the effects of residual stress on the shape, microstructure, and phase composition of the weld will be provided, along with an exploration of the influences of various welding parameters on post-weld deformation and mechanical properties. Full article

During the all-position narrow-gap welding process of pipelines, welding defects tend to occur in non-flat welding positions, constraining the quality and efficiency of pipeline construction. This paper addresses the sidewall and interlayer lack of fusion defects that commonly arise in all-position pipeline welding. Based on the research achievements of scholars and engineering technicians at home and abroad in recent years, the paper summarizes the influence laws of droplet transfer characteristics, arc morphology, and molten pool behavior on weld seam formation under different welding positions during gas metal arc welding. Additionally, the paper explores strategies for optimizing weld bead formation, including optimizing welding process parameters, controlling the molten pool flow with an external magnetic field, and using laser–arc hybrid welding. The paper points out the development trends of all-position pipeline welding technology, providing technical guidance and problem-solving ideas for alleviating the flow of the molten pool and optimizing the formation of all-position weld seams in engineering practice. Furthermore, it offers direction for scientific research for relevant researchers. Full article

Laser-arc hybrid welding was applied to Q355 medium-thick steel plates to improve weld tensile properties, with experimental verification comparing welds to the base material. Numerical simulations identified optimal process parameters, analyzing the effects of heat source distance, welding speed, laser power, and arc power on temperature field distribution and molten pool morphology. Heat source distance had the greatest influence, followed by welding speed, laser power, and arc power. Maintaining a peak welding temperature of 900–1000 K refined the weld grain structure, enhancing the tensile performance. Under optimal parameters (laser power: 800 W, arc power: 1200 W, wire distance: 5 mm, welding speed: 15 mm/s), the weld achieved a 77% elongation rate compared to the base material’s 73% at a loading rate of 0.5 mm/min, demonstrating superior tensile properties. These results comply with the Code for Welding of Steel Structures. SEM analysis showed uniform, deep dimples in both the weld and base material, indicating a dense structure, excellent plasticity, and strong fracture resistance. This study offers theoretical and experimental insights for optimizing laser-arc hybrid welding processes. Full article

In this study, the melt pool formation behavior of high-speed laser-arc hybrid welding of aluminum plates was simulated using finite element analysis (FEA). To evaluate the heat input efficiencies of the laser and arc, standalone laser or arc welding experiments were conducted using the same arc or laser processing parameters as those employed in hybrid welding. These experiments were also simulated using FEA to calibrate the laser and arc heat adsorption parameters. The melt pool shapes were measured from cross-sectional optical microscope (OM) images of the specimens and subsequently used to develop a thermal analysis simulation of the laser and arc welding processes. A simulation model for the laser-arc hybrid welding process was developed by combining the heat input models of the laser and arc welding processes. The FEA model successfully predicted the melt pool shapes observed in the experiments. The accuracy of the developed model was evaluated, yielding average errors in the melt pool sizes of the laser, arc, and hybrid welds of 5.43%, 6.89%, and 4.51%, respectively. Full article

The welding of the bottom-locking structure in a detector receptacle plays an essential role in ensuring the safety of nuclear equipment. A pulsed TIG–laser hybrid welding method is proposed to address the problem of welding pores in locking structural parts. The effects of the pulse frequency on the escape of porosity and of porosity on the mechanical properties of the hybrid welding joint were investigated. The results were compared to those of direct current (0 Hz), showing that the pulse frequency affects the stability of the arc. With an increase in pulse frequency, the grain size of the fusion zone gradually decreases, and the flow in the middle area of the molten pool increases. This subjects bubbles in the molten pool to a thrust force, which causes the bubbles to escape to the surface of the molten pool. Compared with 0 Hz, the tensile strength of the joint increased by 67%. This provides a new solution for obtaining reliable welded joints for the bottom-locking structure of detector storage tanks. Full article

Super duplex stainless steel UNS S32750 is widely used in marine industries, pulp and paper industries, and the offshore oil and gas industry. Welding manufacturing is one of the main manufacturing processes to make material into products in the above fields. It is of great importance to obtain high-quality welded UNS S32750 joints. The austenite content and ferrite content in UNS S32750 play an important role in determining UNS S32750 properties such as mechanical properties and corrosion resistance. However, the phase proportion between the ferrite phase and austenite phase in the welded joint will be changed during welding. Lots of research has been done on how to weld UNS S32750 and how to obtain welded joints with good quality. In this work, the recent studies on welding UNS S32750 are categorized based on the welding process. The welding process for UNS S32750 will be classified as gas tungsten arc welding, submerged arc welding, plasma arc welding, laser beam welding, electron beam welding, friction stir welding, and laser-MIG hybrid welding, and each will be reviewed in turn. The microstructure and properties of the joints welded using different welding processes will also be discussed. The critical challenge of balancing the two phases of austenite and ferrite in UNS S32750 welded joints will be discussed. This review about the welding process for UNS S32750 will provide people in the welding field with some advice on welding UNS S32750 super duplex stainless steel. Full article

Laser beam welding is the most modern and promising process for the automatic or robotized welding of structures of the highest Execution Class, EXC3-4, which are made of a variety of weldable structural materials, mainly steel, titanium, and nickel alloys, but also a limited range of aluminum, magnesium, and copper alloys, reactive materials, and even thermoplastics. This paper presents a systematic review and analysis of the author’s research results, research articles, industrial catalogs, technical notes, etc., regarding laser beam welding (LBW) and laser hybrid welding (LHW) processes. Examples of industrial applications of the melt-in-mode and keyhole-mode laser welding techniques for low-alloy and high-alloy steel joints are analyzed. The influence of basic LBW and LHW parameters on the quality of welded joints proves that the laser beam power, welding speed, and Gas Metal Arc (GMA) welding current firmly decide the quality of welded joints. A brief review of the artificial intelligence (AI)-supported online quality-monitoring systems for LBW and LHW processes indicates the decisive influence on the quality control of welded joints. Full article