TIG Arc Research Articles

Improved Adhesion Strength of Metal Textile Composites by Surface Texturing Using TIG Arc or CW Laser Process

Within the framework of the bilateral CORNET projects MeTexCom and MeTexCom2, new approaches were developed and tested to improve the adhesion strength of metal textile composites, with a focus on the targeted roughening of aluminum surfaces and the development of new acoustically insulating nonwovens. The metal textile composites were produced by melting thermoplastic components of the textile composites without a separately applied adhesive.For improved adhesion strength between metal and textile, roughness was generated on the metal surface by means of a novel arc treatment by an anodic polarized TIG process or a cw (continuous wave) fiber laser process. On the one hand, the goal was to produce uniformly rough, untercut surface structures in micro-and nanodimension by means of a highly dynamic arcing process. On the other hand, a similar approach was pursued with the cw laser method by using a single-mode as well as a multi-mode laser.

The effect of TIG arc brazing current on interfacial structure and bonding strength of tin-based babbit

The interfacial structure of the tin-based babbit obtained by TIG arc brazing was studied through the OM, XRD, SEM and EDS and the bonding strength was investigated by the Electronic Universal Testing Machine. It can be found that interfacial layers, unequal in thickness, ranged from 10.26 to 34.27 μm and IMCs layers formed at the interface, ranged from 1.5 to 4 μm as the welding current increased from 50 to 90 A. Also, the bonding strength apparently increased from 73 to 155 Mpa and shear fractures which occurred at the interface near iron substrate side were mainly brittle cleavage fracture. On the brazed interface, the higher element concentration of Fe was helpful to promote the metallurgical reaction and ensured the bonding property. The phase constituents of IMCs were FeSn, FeSn2 and Fe3Sn2. Moreover, the FeSn layer was plate shape, FeSn2 layer and Fe3Sn2 layer were branched shape which staggered with the plastic Sn-based solid solution so that the bonding strength was improved. Physical model of the Fe–Sn IMC layers formation mechanism was proposed, the experimental results further showed that the model was scientific and effective.

A novel arc heat treatment technique for producing graded microstructures through controlled temperature gradients

This paper introduces a novel arc heat treatment technique to produce samples with graded microstructures through the application of controlled temperature gradients. Steady state temperature distributions within the sample can be achieved and maintained, for times ranging from a few seconds to several hours. The technique reduces the number of samples needed to characterize the response of a material to thermal treatments, and can consequently be used as a physical simulator for materials processing. The technique is suitable for conventional heat treatment analogues, welding simulations, multi-step heat treatments, and heat treatments with controlled heating and cooling rates. To demonstrate this technique, a super duplex stainless steel was treated with a stationary TIG arc, to confirm the relationship between generated steady-state temperature fields, microstructure development, hardness, and sensitization to corrosion. Metallographic imaging and hardness mapping provided information about graded microstructures, confirming the formation of secondary phases and microstructure sensitization in the temperature range 850–950°C. Modelling of temperature distributions and thermodynamic calculations of phase stabilities were used to simulate microstructure development and associated welding cycles.

Disk-laser Welding of Ti-6Al-4V Titanium Alloy Plates in T-joint Configuration

Titanium alloys are employed in a wide range of applications, ranging from aerospace to medicine. In particular, Ti-6Al-4V is the most common, thanks to an excellent combination of low density, high specific strength and corrosion resistance. Laser welding has been increasingly considered as an alternative to traditional techniques to join titanium alloys. An increase in penetration depth and a reduction of possible welding defects is indeed achieved; moreover a smaller grain size in the fused zone is benefited in comparison to either TIG and plasma arc welding, thus providing an increase in the tensile strength of the welded structures.The aim of this work is to study disk-laser welding of 3.2mm thick Ti-6Al-4V plates in T-joint configuration without using a filler wire, defining the influence of different process parameters. The issue concerning the clamping of the plates is discussed and a proper device is developed to carry out welds.A structured plan has to be carried out in order to characterize the process thus discussing the response variables. Power and welding speed are considered as crucial input variables since they determine the thermal input to the work-piece; furthermore, given the particular configuration analyzed, tilt angle is considered as a further variable, whereas focus position is fixed below the upper surface to obtain a full penetration.Welding beads have been first examined with a coordinate measuring machine to study distortions, and then from a morphological point of view. Eventually, Vickers microhardness testing has been conducted to discuss structural changes in fusion and heat affected zone due to welding thermal cycles.

Study on TIG Arc Preheating Auxiliary Aluminum-copper Ultrasonic Seam Welding

Study on TIG Arc Preheating Auxiliary Aluminum-copper Ultrasonic Seam Welding

Numerical Analysis of Heat Source Characteristics of a Constricted TIG Arc for Welding of Aluminium

Numerical Analysis of Heat Source Characteristics of a Constricted TIG Arc for Welding of Aluminium

Effects of Alloyed Fluxes on Spreading Behavior and Microstructures of Aluminum–Titanium TIG Brazing Interface

Alloyed fluxes consisting of the non-corrosive aluminum brazing potassium fluoroaluminate flux and alloyed elements Cu, Zr and Ni were firstly developed and studied for aluminum–titanium TIG arc brazing. Not only the alloyed fluxes can promote wetting of molten aluminum filler on the titanium, but suppress the formation of the intermetallic compound (IMC) layer as well. Results indicated that the alloyed fluxes exerted different influences on spreading areas. Comparing with the unalloyed flux, the spreading area of aluminum on titanium with Cu alloyed flux increased significantly, from 116 to 143 mm2. Moreover, evident differences in IMC thickness were observed corresponding to various fluxes. The IMC thickness rose dramatically at first and then declined with the increasing concentration of alloying element. The IMC can be reduced effectively by employing the fluxes with 50% Cu or Ni. The root cause is attributed to the Cu and Ni distribution in the aluminum brazing joint.

Influence of low current auxiliary TIG arc on high speed TIG-MIG hybrid welding

Arc shape, droplet transfer, weld pool behavior and temperature fields were studied to investigate the influence of low current auxiliary TIG arc on weld formation and microstructure in TIG-MIG hybrid welding and compared with conventional MIG welding. Results indicated that the MIG arc is stabilized by a leading TIG arc while it is destabilized by a trailing TIG arc. Regardless of the TIG arc leading or trailing, it decentralized the MIG arc force and reduced the impingement of droplet. The backward fluid flow in the hybrid welding was decelerated relative to the conventional MIG welding. The slower backward fluid flow in hybrid welding impeded the accumulation of high temperature filler metal in the tail of weld pool and provided the molten metal more time to fill the weld toe which resulted in suppression of the undercut defect. The top surface temperature gradient at the middle and tail of the hybrid weld pool was lower than that in the MIG weld pool, albeit the welding heat input was increased. Microstructure analysis showed evidence of prominent dendrite formation at higher welding speeds with no obvious grain coarsening in the weld zone of TIG-MIG hybrid weld joint while its HAZ became narrower.

Influences of welding conditions on the constricted TIG arcs

We investigate, how welding conditions affect the arc in TIG welding with a constricted nozzle by numerical simulation using an axial-symmetric two-dimensional model. When helium is used as a shielding gas, the effect of the constricted nozzle is more remarkable than argon. The heat flux to the centre of the anode surface increases more with a higher welding current. This feature is suitable for pulsed welding. Even if an electrode is consumed and its tip angle is changed, a stable arc plasma and heat intensity are obtained.

Gaseous Shielding Gas Additives as Flux Substitute for TIG Arc Brazing

Brazing is one of the key technologies in the field of joining of metal components. To improve the wetting of brazing material and work-piece surface, it is often required to fall back on the use of flux. The application of these substances requires accuracy and is often connected with considerable expenditure and it is, just as the removal of flux residues, often an additional working step which has to be carried out manually. Within the framework of a DFG research project it has been investigated to which degree gaseous substances as addition to the shielding gas may replace conventional flux in TIG arc brazing. To this end, investigations have been carried out using different combinations of base and filler materials. Mainly monosilane as a gaseous flux substitute has been added in low concentrations to the shielding gas volume flow. The resulting brazed joints have been quantified with regard to their geometry, their fusion conditions and their chemical compositions. These qualities were then correlated and evaluated with the provided quantity of monosilane in order to identify dependencies.

TIG Cladding + Laser Remelting of ZrAlNiCu Amorphous Coating

Abstract The present investigation focused on a new amorphous coating preparing technique which combined the advantages of both TIG arc and laser beam. After Zr 63.8 Ni 17.2 Al 11.4 Cu 7.6 powder bed was cladded on carbon steel surface by TIG arc, the coating was remelted using a CO 2 laser. The microstructure, the phase composition, the microhardness and the corrosion resistance of the present coating were analyzed. TIG arc helps the coating achieve a good bonding with substrate and a homogenous solidification. While laser beam contributes to a quick cooling rate to form an amorphous structure. The coating microstructure is complex, consisting of crystalline phase and amorphous phase. The XRD demonstrates a higher amorphous volume fraction of the present coating compared with traditional laser cladding. The present coating is 1330 MPa higher in microhardness, 0.07 V higher in corrosion potential and more than 10 times lower in corrosion current than traditional laser cladding.

Thermal cycle and microstructure of backing weld in double-sided TIG arc horizontal welding of high-strength steel thick plate

Double-sided arc horizontal welding is a new process for high-strength steel thick plate. This study aims at studying thermal cycle and microstructure of backing weld. The special heating cycle with two peaks in double-sided double-arc welding is beneficial to the generation of microstructure with good strength and toughness, due to the effect of preheating and postheating. The microstructure was a mixture of ferrite and lath martensite. The heat-affected zone (HAZ) in the root area was overheated, owing to the shape of groove in the horizontal welding, resulting in meshes in the grain boundary. The meshes were analyzed to be the tempered martensite. Hardness tests showed that there were some softened regions in the HAZ on account of high-temperature tempering.

Effect of hot dip aluminising on interfacial microstructure and mechanical properties of Ti/Al joint by TIG arc welding brazing

The joint of Al 5A06 and aluminised Ti–6Al–4V dissimilar alloys was achieved by means of tungsten inert gas arc welding brazing. The effect of aluminized coating on the spreading behaviour of filler metal on Ti substrate was studied. The spreadability of liquid filler metal on the Ti substrate was enhanced obviously due to the presence of aluminised coating. The interfacial reaction layer was characterised by a uniform lamellar layer of TiAl3 intermetallic, with a thickness of 1 μm. Sound joints with well appearance were obtained, and the optimised tensile strength of the joint reached 216 MPa. The failure initiated from the interfacial layer at the root face and then propagated within the weld seam at the upper part of the joint. Capable welding parameters were broadened by the presence of aluminised coating for dissimilar metal joining of Ti/Al.

Study for the mechanism of TIG-MIG hybrid welding process

On TIG-MIG hybrid welding process (TIG: DCEN and MIG: DCEP), the stability of MIG arc can be kept even in pure inert shielding gas by the effect of hybridization with TIG arc, and it becomes possible to achieve the new welding method which has both merits of high quality as TIG welding process and high efficiency as MIG welding process. In this report, we performed two experiments mainly as follows to solve two problems: (1) Analysis of output from TIG power source in hybrid welding state to prove experimentally the existence of direct current path which flows between TIG cathode and MIG anode via in hybrid arc plasma. (2) Measurement of actual heat input based on evaporation amount of liquid nitrogen to investigate detailed heat source property of this process. As results, it was shown that output of TIG power source in hybrid welding condition is lower than it in single TIG welding, and the heat efficiency in hybrid welding condition decreases about 10 % rather than it in single heat source of TIG or MIG arc. Moreover, in specific condition that value of TIG current is lower than value of MIG current, output of TIG power source becomes entirely zero even though TIG arc shape is observed clearly, and thus, the stability of MIG arc is lost then. It can be said that these findings reveal the existence of direct current and explain one of mechanisms that TIG arc can control the arc stability and heat input of MIG arc.

Numerical Simulation of Weld Distortion and Residual Stress on the Basis of Heat Source Modeling for AC TIG Arc Welding Numerical Simulation of Weld Distortion and Residual Stress n the Basis of Heat Source Modeling for AC TIG Arc Welding

Numerical Simulation of Weld Distortion and Residual Stress on the Basis of Heat Source Modeling for AC TIG Arc Welding Numerical Simulation of Weld Distortion and Residual Stress n the Basis of Heat Source Modeling for AC TIG Arc Welding

Investigation and Optimization of Disk-Laser Welding of 1 mm Thick Ti-6Al-4V Titanium Alloy Sheets

Ti-6Al-4V joints are employed in nuclear engineering, civil industry, military, and space vehicles. Laser beam welding has been proven to be promising, thanks to increased penetration depth and reduction of possible defects of the welding bead; moreover, a smaller grain size in the fusion zone is better in comparison to either TIG or plasma arc welding, thus providing an increase in tensile strength of any welded structures. In this frame, the regression models for a number of crucial responses are discussed in this paper. The study has been conducted on 1 mm thick Ti-6Al-4V plates in square butt welding configuration; a disk-laser source has been used. A three-level Box-Behnken experimental design is considered. An optimum condition is then suggested via numerical optimization with the response surface method using desirability functions with proper weights and importance of constraints. Eventually, Vickers microhardness testing has been conducted to discuss structural changes in fusion and heat affected zone due to welding thermal cycles.

Study on temperature measurement of two-electrode TIG arc plasma

Measurements of arc plasma are important for determining the associated physical properties. Such measurements usually involve the use of spectroscopic techniques to measure temperature distribution in free-burning arcs. Most studies have reported the temperature of axially symmetric arc plasma using Abel inversion. This method cannot be used for axially asymmetric arc plasma such as two-electrode TIG arc plasma. It is a complex phenomenon because the arc plasma generated from each electrode is affected by the other due to electromagnetic force. We measured the temperature distribution of tandem TIG arc plasma three dimensionally with a one camera rotation system. The measurement method includes the multi-directional detections and the image reconstruction technique: maximum likelihood–expectation maximization. We evaluated the influence of the number of detection directions on the reconstruction by virtual intensity distribution and found that the sufficient direction number is 6. As a result, we could measure the temperature distribution of the inclined, drawn and coupled arc plasma provided by a two-electrode TIG arc.

Effect of hot-wire on microstructure and mechanical property in weld metal formed with CO2 gas shielded arc welding method

The new welding method known as F-MAG, which has been developed based on the CO2 gas-shielded arc welding method (MAG), increases deposition rate of weld metal. The F-MAG welding method is combined with hot-wire, as has been used in TIG arc- and laser-welding methods. F-MAG is performed using hot-wire which is inserted into the rear part of the weld pool made with the leading electrode. Hot-wire melts by both electrical heating of itself and heat of the weld pool. Multi-layered weld metals were prepared using F-MAG and MAG. Microstructures and mechanical properties of both as-weld and reheated zones in the uppermost layer of the multi-layered weld metals formed with F-MAG and MAG were examined and the effects of hot-wire on microstructures and mechanical properties were analysed. Both the as-weld and reheated zones of the weld metal formed with F-MAG consisted of acicular ferrite (AF), equiaxed ferrite and so on. Both strength and elongation in as-weld and reheated zones formed with F-MAG were superior compared with those formed with MAG. It could be suggested that strength increased by refinement of AF due to increase in the concentration of alloying elements being contained in the hot-wire. Larger elongation of the weld metal in F-MAG compared with that in MAG could be analysed in terms of the Aggregate of AF Laths with nearly Parallel Slip systems between neighboring AF laths (ALPS). The number of AFs contained in an ALPS formed with FMAG is larger than that with MAG, in spite of the sizes of ALPSs formed with MAG and F-MAG being almost same. Deformation occurs over a lot of AFs in the case of finer AF formed with F-MAG through the rotation of the tensile test piece during deformation, resulting in the larger elongation.

Effect of auxiliary TIG arc on formation and microstructures of aluminum alloy/stainless steel joints made by MIG welding-brazing process

A new hybrid welding process was successfully used to join aluminum alloy and stainless steel. In the MIG welding-brazing process, the lower thermal conductivity of steel can cause dramatic change of temperature gradient on steel surface, while the auxiliary TIG arc can change this phenomenon by heating the steel side. The auxiliary TIG improved the wettability of molten metal, resulting in the molten metal spreading fully on upper surfaces, front and back surface of steel, forming a sound brazing joint; the content of Cr and Ni elements in IMCs layer was increased, which can enhance the quality of the layer; and the microstructure of IMCs layer also was improved, increasing the bonding strength with the weld seam. The average tensile strength of the joint obtained with auxiliary TIG arc (146.7 MPa) was higher than that without auxiliary TIG arc (96.7 MPa).

Effects of Phase Matching Pattern on Pulse Laser-Arc Hybrid Welding Process

This paper proposed a method on accurate phase matching control between the pulse laser and the AC TIG arc in real time, and a pulse laser-arc hybrid heat source phase matching control system is developed as well. With the utilization of this system in two typical matching cases that the pulse laser acts on the peak and the trough of the arc welding current waveform, effect regulations on weld formation, weld penetration depth and hybrid plasma shape are studied during welding on magnesium alloy AZ61. Results indicate that, when the pulse laser acting on the peak of arc welding current waveform, the weld formation is better than that of on the trough. However, when pulse laser act on the arc trough the weld penetration depth is deeper than that of on the peak.