MIG Hybrid Welding Research Articles

LASER-MIG Hybrid Welding of Thick Plates of Mild Steel in Single Pass

Laser hybrid welding combines the deep penetration capability of laser beam and edge gap bridging capability of an arc welding process such as MIG/MAG. In the present work, a 3.5 kW slab CO 2 LASER -MIG hybrid welding system was used to carry our laser hybrid welding studies with an aim to achieve butt welds of 12mm thick mild steel plates in single pass. Bead-on-plate studies were carried out to first understand the effect of parameters such as laser power, focal plane position of the laser, MIG wire feed rate, composition of shielding gas, distance between laser and MIG arc on the weld penetration. The optimized parameters were then applied on butt welds with Y-groove edge preparation with varying ischolar_main face height and groove angle to identify suitable joint design. Combining the results of bead-on-plate experiments and butt welding experiments, welding of 12 mm thick mild steel plates in single pass could be achieved. The LASER-MIG hybrid butt welds so fabricated showed 100% joint efficiency and high bend ductility.

Application of Plasma MIG Hybrid Welding to Dissimilar Joints Between Copper and Steel

Plasma MIG hybrid welding was developed several decades ago. This welding method is known to be suitable for aluminium. But cases of practical use were not reported so much. The combination of plasma and MIG arcs has recently been noticed again as a process appealing for heat source and arc phenomenon. Therefore, we examined the practical application, while the effectiveness of the plasma MIG hybrid welding was confirmed. This time, the result of examining the applicability to the copper contaminant welding is reported. The plasma MIG hybrid welding torch is coaxial with the MIG electrode placed in the centre, and the ring electrode in which the plasma arc is generated at the circumference. First, the weldability of copper was examined in order to confirm the basic characteristics of plasma MIG hybrid welding. The process was very effective for the application to the welding of copper in order to contribute not only to plasma preheating the base material but also stabilizing the MIG arc. Next, it was shown that copper-carbon steel dissimilar metal welding was possible by justifying the welding parameters. On the basis of these results, plasma MIG hybrid welding was applied to the copper-carbon steel contaminant welding of large structures for the nuclear waste storage, and the result was good.

Effect of Laser Beam on Double Wire Pulsed MIG Welding Process

Based on the coupling of laser beam and double arcs, a novel process was investigated. This research set up the laser-double wire pulsed MIG hybrid welding system. Meanwhile the current and voltage sensors were used to detect welding current and arc voltage wave-form and high-speed videography system was used to observe the metal transfer process and arc behavior. The three signals were acquired synchronously. The results showed that the synergic action of the three different heat sources leads to a change in metal transfer mode. It was revealed that the metal transfer mode was two droplets per pulse in laser-double wire hybrid welding process while one droplet per pulse in double wire welding process with the same certain experiment parameters. And we also discovered that the arcs were attracted strongly by the laser beam.

Development of Innovative MIG Welding Technology

In recent years, remarkable progress has been made in the field of MIG welding technology. In this paper, three kinds of innovative MIG welding technology were introduced － pulsed MIG welding, double wire MIG welding and MIG hybrid welding. Recent development and achievements were summarized, including features of the various processes and applications. In the end, the future tendency was discussed.

Effect of mechanical restraint on weldability of reduced activation ferritic/martensitic steel thick plates

As one of the reduced activation ferritic/martensitic steels, the weldability of thick F82H plate was experimentally examined using new heat sources in order to minimize the total heat input energy in comparison with TIG welding. A full penetration of 32mm thick plate could be produced as a combination of a 12mm deep first layer generated by a 10kW fiber laser beam and upper layers deposited by a plasma MIG hybrid welding with Ar+2%O shielding gas. Also, the effect of mechanical restraint on the weldability under EB welding of thick F82H plate was studied by using FEM to select an appropriate specimen size for the basic test. The appropriate and minimum size for the basic test of weldability under EB welding of 90mm thick plate might be 200mm in length and 400mm in width where the welding length should be about 180mm.

A comparative study of laser beam welding and laser–MIG hybrid welding of Ti–Al–Zr–Fe titanium alloy

Ti–Al–Zr–Fe titanium alloy sheets with thickness of 4mm were welded using laser beam welding (LBW) and laser-MIG hybrid welding (LAMIG) methods. To investigate the influence of the methods difference on the joint properties, optical microscope observation, microhardness measurement and mechanical tests were conducted. Experimental results show that the sheets can be welded at a high speed of 1.8m/min and power of 8kW, with no defects such as, surface oxidation, porosity, cracks and lack of penetration in the welding seam. In addition, all tensile test specimens fractured at the parent metal. Compared with the LBW, the LAMIG welding method can produce joints with higher ductility, due to the improvement of seam formation and lower microhardness by employing a low strength TA-10 welding wire. It can be concluded that LAMIG is much more feasible for welding the Ti–Al–Zr–Fe titanium alloy sheets.

Analysis of Weld Formation Mechanism and Weld Pool Dynamic during Moving Laser-MIG Hybrid Welding

In order to better understand heat transfer and fluid flow pattern in the weld pool of laser-metal inert gas (MIG) hybrid welding aluminum-alloy process, weld formation mechanism and weld pool dynamic behavior were analyzed by a three-dimensional mathematical model for moving laser- MIG hybrid welding. The temperature and velocity distribution of weld longitudinal section for laser-MIG moving hybrid welding at different moment were discussed to explain flow dynamic behavior in the weld pool. In addition, weld formation mechanism was illustrated by a transverse section heat history evolvement. Moreover, the effects of laser welding parameter and MIG welding parameter on important weld geometry characteristic were quantitatively studied using the mathematical model, and the simulated weld bead geometry parameters were in good agreement with experimental measurements.

A study of the radiation of a Nd:YAG laser–MIG hybrid plasma

To study the coupling of a Nd:YAG laser beam and a MIG arc with the spectrum of the plasma, a new hollow probe method is used to collect radiation from specific points within the arc plasma. With the probe, the spatial distributions of the MIG arc radiation with and without the Nd:YAG laser hybrid plasma are collected and analyzed by a fiber spectrometer. Through analysis of the spectrum, radiation in the ultraviolet (Fe II dominated), visible (Fe I dominated) and infra (Ar I dominated) spectral zones are acquired for comparison of the difference between the MIG and Laser–MIG hybrid welding processes. The electronic temperature is calculated using the Boltzmann plot method and the electronic density is calculated using the Stark broadening method. The results show that the Laser–MIG hybrid welding processes cause the plasma energy to focus on the center of the welding arc and approach the welding pool. An ionizing duct abundant with Fe ions will be formed near the position of the impinging laser beam, which makes the welding arc stable. The electronic temperature of the Laser–MIG hybrid welding arc is a little higher than that of the MIG. The electronic density of Laser–MIG hybrid welding is higher than that of the MIG.

Circumferential welding of gas pipeline pipes using hybrid technology with fibre-delivered LASER beamPaper presented at the 4th National Welding Day, Workshop: “New frontiers in LASER beam welding, friction stir welding and electron beam welding processes” Genova, 25–26 October 2007.

In reducing the costs associated with the fabrication of new pipelines for transporting hydrocarbons (pipelines), circumferential joint welding activities have a significant impact on total cost per km. LASER–MIG hybrid welding (LB–GMAW), with fibre-optic LASER beam delivery, offers the opportunity for reducing fabrication costs, thanks to increased productivity, despite the higher initial investment. The aim of this work is to demonstrate the feasibility of pipeline fabrication using LB–GMAW hybrid welding technology for the circumferential welding of large diameter pipes (36″) for gas pipelines, on X100 high-grade steel with nominal thickness of 16 mm. Solid-state LASER systems with fibre-delivered LASER beam (Nd:YAG and Yb:SiO2) have been used in this study. The hybrid welding system has been shown to be of potential interest since, by guaranteeing adequate mechanical properties, it ensures increased productivity (reduced number of passes and increased welding speed).