Search Results (65)

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

The effective welding of a 6 mm thick TA2 pure titanium medium-thickness plate was achieved by laser–arc hybrid welding (LAHW) with helium–argon mixed shielding gas. Conducted research on the influence of helium–argon mixed shielding gas on plasma and arc characteristics during welding, and its further impact on the microstructure, internal porosity defects, tensile properties, and corrosion resistance of welded joints was explored. The study demonstrated that under the shielding gas with 75% helium, the arc width narrowed significantly from 6.96 mm to 2.61 mm, achieving a 63% reduction, which enhanced the concentration of arc heat flux density. Achieved a well-formed weld with no surface spatter and significantly reduced the internal porosity rate from 3.02% to 0.47%, which is an 84% decrease. Tensile fractures are located in the base material, all exhibiting plastic failure. The corrosion resistance of the welded joint initially increased and then decreased with the increase of helium content in the shielding gas, peaking at 75% helium content. Full article

The aim of this study was to determine the microstructural evolution, tensile characteristics, and strain-hardening response of AZ31B magnesium alloy welds as influenced by post-weld heat treatment (PWHT). Thus, the AZ31B alloy was welded by using a low-power pulsed Nd:YAG laser-arc hybrid welding equipped on the six-axis welding robot in the present study. Microstructure, mechanical properties and strain-hardening behaviors of the AZ31B joints under various post-weld heat treatment (PWHT) temperatures were characterized. As the heat treatment temperature increases, the grain size of the welded joint gradually increases, and the amount of β-Mg₁₇AI₁₂ phase noticeably decreases. The mechanical properties of the welded joint specimens showed a significant enhancement when subjected to heat treatment at 300 °C and 350 °C for 20 min. Especially, after 350 °C heat treatment for 20 min, the ultimate tensile strength (UTS) and elongation (EL) of specimen were 339.6 MPa and 20.1%, respectively, which were up to 99.5% and 98.5% of the AZ31B base material (BM). The strain-hardening capacity of specimens is significantly influenced by the grain size. Due to having the largest grain size, the 400–20 min specimen exhibited the highest hardening capacity and strain hardening exponent. In Kocks-Mecking type curves, both stage III and stage IV were observed in BM and joint specimens. At higher net flow stresses, the strain hardening rate in the 400–20 min joint specimen was higher due to the larger grains, which allowed for more dislocation accommodation and improved the capacity for dislocation storage. Full article

A Q345 steel butt-welded joint was manufactured using laser–arc hybrid welding (LAHW) technology, and its microstructure, microhardness, and residual stress (RS) distribution were measured. Using ABAQUS software, a sequentially coupled thermo-metallurgical-mechanical finite element method was employed to model the welding RS distribution in the LAHW joint made of Q345 steel. The effects of solid-state phase transformation (SSPT) and transverse restraint on the welding RS distribution were explored. The results show that a large number of martensite phase transformations occurred in the fusion zone and heat-affected zone of the LAHW joint. Furthermore, the SSPT had a significant effect on the magnitude and distribution of RS in the LAHW joint made of Q345 steel, which must be taken into account in numerical simulations. Transverse restraints markedly increased the transverse RS on the upper surface, with a comparatively minor impact on the longitudinal RS distribution. After the transverse restraint was released, both the longitudinal and transverse RS distributions in the LAHW joint reverted to a level akin to that of the welded joint under free conditions. Full article

This paper focuses on the mathematical and numerical modeling of the electric arc + laser beam welding (HLAW) process using an innovative model of the Yb:YAG laser heat source. Laser energy distribution is measured experimentally using a UFF100 analyzer. The results of experimental research, including the beam profile and energetic characteristics of an electric arc, are used in the model. The laser beam description is based on geostatistical kriging interpolation, whereas the electric arc is modeled using Goldak’s distribution. Hybrid heat source models are used in numerical algorithms to analyze physical phenomena occurring in the laser–arc hybrid welding process. Thermal phenomena with fluid flow in the fusion zone (FZ) are described by continuum conservation equations. The kinetics of phase transformations in the solid state are determined using Johnson–Mehl–Avrami (JMA) and Koistinen–Marburger (KM) equations. A continuous cooling transformation (CCT) diagram is determined using interpolation functions and experimental research. An experimental dilatometric analysis for the chosen cooling rates is performed to define the start and final temperatures as well as the start and final times of phase transformations. Computer simulations of butt-welding of S355 steel are executed to describe temperature and melted material velocity profiles. The predicted FZ and heat-affected zone (HAZ) are compared to cross-sections of hybrid welded joints, performed using different laser beam focusing. The obtained results confirm the significant influence of the power distribution of the heat source and the laser beam focusing point on the temperature distribution and the characteristic zones of the joint. Full article