This paper focuses on the major developments in the tungsten inert gas (TIG) welding technology for improving weld penetration depth during the welding process. TIG welding is an established arc ...welding process and it is extensively used for welding thin sections of almost all ferrous and non-ferrous material. However, the growing interest of industries in utilizing the process for welding mid-thick sections components led to numerous innovation in the TIG welding process. In this article, major variants of the TIG welding process i.e. pulse TIG, activated TIG, keyhole TIG, multi-electrode TIG welding process and its associated mechanism is described to understand the concept of improvement in weld penetration depth during the welding process. Furthermore, a systematic discussion on weld bead geometry obtained by different TIG welding process, starting from the mid of 2000 s to till date is presented. The major motive of this review paper is to explore the potential of the TIG welding process and provide a state-of-the-art to the industries as well as the academic world.
Stable keyhole welding process with K-TIG Liu, ZuMing; Fang, YueXiao; Cui, ShuangLin ...
Journal of materials processing technology,
December 2016, 2016-12-00, Letnik:
238
Journal Article
Recenzirano
Keyhole welding process was successfully achieved by using a self-made K-TIG torch. High quality welds were produced in 8mm-thick stainless steel plates. To evaluate the keyhole stability in the ...novel manufacturing process, keyhole behavior was observed by using a vision system from backside of the workpiece. Efflux plasma interference was eliminated by using a filter glass. Keyhole exit behavior was imaged in real time during the welding process, keyhole size and position were extracted from the keyhole image sequence. Keyhole behavior parameters, including keyhole length, width, length/width, and deviation distance were measured. It was found that keyhole exit was deviated away from the torch axis even though the arc current was very high in K-TIG welding process, keyhole exit had an oval shape. Continuous open keyhole welding were easily achieved in K-TIG process, without unstable keyhole stage when the keyhole firstly opens. Keyhole size, shape and position were all related to welding current. The observation results lay solid foundation to understand the thermal-physical behavior in K-TIG, and for the further optimizing of the welding torch.
A-TIG welding is a welding method in which TIG welding is conducted by covering a thin layer of activating flux on the weld bead beforehand. The most significant benefit of this process is the gain ...in weld penetration depth. A-TIG welds were produced on mild steel plates with TiO2 flux. The emphasis of this paper was laid upon introducing the effects of various process parameters, namely welding current, welding speed, powder/acetone ratio of the flux, arc length, and electrode angle on mild steel A-TIG welding. The weld penetration depth was measured metallographically. An optimum value was determined for each welding parameter.
This research manuscript explores the residual stress analysis, mechanical and metallurgical aspects of dissimilar welded joints between AISI 316 and Monel 400 developed by constant, pulse and ...Interpulse current TIG welding processes. The induced residual stresses have been measured experimentally by employing X-ray diffraction. The mechanical properties of welded joints have been determined by conducting tensile and Vickers hardness testing. The metallurgical properties of weldments have been analyzed by employing optical and scanning electron microscopy. From the experimental results, lower residual stresses have been observed in Interpulse current TIG weldment than the other two weldments. The tensile properties of the Interpulse current TIG weldment were observed to be higher than the other two weldments. In Interpulse TIG weldments, grain refinement and reduced heat affected zone near the fusion zone have been observed.
In this paper, high-temperature impact fatigue (HTIF) was carried out on a Co-based surface layer cladded by TIG welding, and cracks emerged at 400-cycle condition. The reasons for cracking were ...investigated from three aspects: microstructure, stress distribution, and crystal orientation. Crack generation was induced by high stress distribution in eutectic carbides at grain boundaries and the great disparity in orientations between grains on two sides of the crack path. The microstructural advantage for cracking behavior played a key role in emergence of cracks, which was verified by the investigation and comparison of three distances from the weld interface. Moreover, the interface microstructure of Co-based layer and FB2 substrate was characterized by transmission electron microscopy, and the phase composition of the weld interface comprised FeCo and M23C6. The results presented that the addition of Ni-based transition layer caused the acquisition of the crack-free surface layer after HTIF. Finally, microhardness test was conducted on samples with and without a transition layer. The hardness of Co-based surface layer without the transition layer was mainly affected by the transformation of carbides, dilution of Fe, and work hardening during HTIF. The hardness of Co-based surface layer with the transition layer showed minimal change during HTIF, and this finding was attributed to the slight variation in the microstructure.
•The microstructural evolution of Stellite 6 layer was revealed.•Mechanisms of cracks generation during HTIF were illustrated.•Crack problem was solved by the addition of Inconel 625 transition layer.•The phase composition of interfacial layer was determined.•Reasons for hardness variation during HTIF was explained.
In this study, Stellite 6 and Stellite 12 claddings were deposited on 56NiCrMoV7 hot-worked die steel using the Tungsten Inert Gas (TIG) welding process. Initially, single tracks were deposited using ...a full factorial design varying two process parameters - current (65, 75, and 85 A) and scan speed (400, 600, and 800 mm/min). The single tracks were then optimized based on dilution rate and microhardness. The optimized parameters were used to develop Stellite 6 and 12 multi-pass clad layers on 56NiCrMoV7. The evaluation of the microstructure of the claddings was done using an optical microscope, XRD, FESEM, EDX, and EBSD. The microstructure of the claddings consists of α-Co matric with M7C3, M23C6, and W2C carbides precipitated along the grain boundaries. Further microhardness and tribological performance were analyzed using Vicker's hardness tester and ball-on-disc tribometer, respectively. Stellite 12 claddings exhibited superior wear resistance and indicated reduced wear volume by 51.3 % at room temperature, 69.2 % at 450 °C, and 32 % at 550 °C compared to the base material and 53.2 % at room temperature, 37.3 % at 450 °C, and 24.1 % at 550 °C compared to Stellite 6 claddings. The KAM mapping showed higher dislocation density for Stellite 12 cladding. The combination of finer grains, higher hardness, and higher dislocation density resulted in higher wear resistance.
•Stellite 6 and Stellite 12 claddings were fabricated with optimized process parameters on 56NiCrMoV7 die-steel substrate using a TIG cladding.•Variation in hardness occurred in multi-track clads compared to single tracks.•The friction coefficients of the cladded layers were reduced with an increase in temperatures.•Stellite 12 claddings exhibited reduced wear volume by 51.3 % RT, 69.2 % at 450 °C, and 32 % at 550 °C compared to the base material.•The FESEM images of worn-out surfaces revealed that adhesive and abrasive wear takes place and is further aggregated by oxidation at higher temperatures.
Geographic Information Systems (GIS) are key methodological tools for land management and to have databases of urban trees that help to make better decisions about biodiversity in a built ...environment. The construction of urban models with quality information is of high scientific and management value for diagnosis, evaluation and decision making. The objective of the present work was to establish the steps for the realization, design and modeling of a GIS for the management of urban trees in the city of Pigüé s and to provide the basis for a computerized system to support decision making. The GIS was planned in order to have a model of reality, establishing the geographic model, the representation model and the storage model. A tree census was carried out and updated, surveying 9,518 spaces. It was found that there is a high diversity of tree species. Of the total number of spaces with species, 7424 are in good health. Pigüé's urban trees have a high percentage of trees that obstruct or interfere with the wiring of public services.
This research manuscript explores the residual stress analysis, mechanical and metallurgical aspects of dissimilar welded joints between AISI 316 and Monel 400 developed by constant, pulse and ...Interpulse current TIG welding processes. The induced residual stresses have been measured experimentally by employing X-ray diffraction. The mechanical properties of welded joints have been determined by conducting tensile and Vickers hardness testing. The metallurgical properties of weldments have been analyzed by employing optical and scanning electron microscopy. From the experimental results, lower residual stresses have been observed in Interpulse current TIG weldment than the other two weldments. The tensile properties of the Interpulse current TIG weldment were observed to be higher than the other two weldments. In Interpulse TIG weldments, grain refinement and reduced heat affected zone near the fusion zone have been observed.
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