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It is difficult to join dissimilar material which has different thermal and mechanical properties using conventional arc welding, which is prone to the formation of intermetallic compounds (IMCs). In the present work pure copper (Cu) and aluminium (Al) alloy (Al-6061) is lap joined by conventional TIG Welding. At optimal operating condition, a successful weld is achieved as observed from mechanical testing. The metallurgical properties of joints are investigated by Back Scattered Electron (BSE) image, spot Energy Dispersive X-ray Spectroscopy (EDS) and line EDS. IMCs layers formed for joints varied from 9 μm to 80 μm thickness obtained at different welding parameters. Two different layers of IMCs are formed at the interface and the failure occurred near the copper side of the joint. The mechanical property is investigated by tensile shear test, and the average maximum load-carrying capacity found 1876 N, which is comparable to other non-conventional welding processes. [ABSTRACT FROM AUTHOR]

Activating flux is made up of inorganic material mixed with a volatile medium. The objective of this study is to identify and review the literature in activating flux, and different type of welding techniques. For that purpose, a structured review method is adopted and the Scopus database is used as a primary source for the selection of papers. The papers were identified using the string term of "Activating flux" OR "Activated flux" in the title of papers. And a total of 238 papers were identified for the study. Besides the above few other papers were also reviewed and the materials used, the type of flux used, and the findings of different combinations were highlighted in the form of tables. The findings of the study provide a comprehensive understanding of the different type of welding techniques focusing on TIG welding, and the different combination of flux used and their impact was summarized. [ABSTRACT FROM AUTHOR]

Aluminium alloys are widely used in the fields of electric module packaging, electronic technology, automotive body structure, wind and solar energy management, due to the advantages of high specific strength, high processability, predominantly anti-erosion, increased conductivity, eco-friendly nature and recoverability. The objective of the study is to review the previous papers on aluminium usages, application, and workability parameters. The methodology adopted for the study is to use the structure literature review technique, and the time period selected for the study is 2008–2019 from the Scopus database. The findings of the study concluded that there are various types of aluminium alloys has been used by the previous researchers, and only 6061 is least explored aluminium alloy among all of them. The future scope of the study is to investigate using distinct activating fluxes for raising penetration & to understand consequences on mechanical components & rust behaviour of TIG-welded aluminium metal welds. [ABSTRACT FROM AUTHOR]

Copyright of Mechanics & Advanced Technologies is the property of National Technical University of Ukraine KPI and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Rare Metal Materials & Engineering is the property of Northwest Institute for Nonferrous Metal Research and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Laser-based joining is a potential key manufacturing process for realizing metal plastic hybrids. Therefore, surface preparation is essential to achieve a mechanical form fit. A new approach for surface preparation is based on a tungsten inert gas (TIG) arc process with anodic polarity. This TIG structure was characterized compared to fiber laser manufactured structures in cw and pw mode. The comparison of different preparations was based on pure ultimate tensile strength tests on spot joints. Finally, a transfer to overlap joints was successfully carried out and characterized by tensile shear tests using fiber reinforced plastics. [ABSTRACT FROM AUTHOR]

Welding is a way of heating pieces of metal using electricity or flame so that they melt and stick together. There are many kinds of welding processes, such as, for instance, MIG/MAG and MMA welding. However, such welding schemes require more electrodes during the process of welding. Hence, this paper intends to analyse the alternative tungsten inert gas (TIG) welding tech- nology using Response Surface Methodology (RSM), and to identify the effect of TIG welding process parameters on the weld bead pro- file of 15CDV6 high strength low alloy (HSLA) steel. Moreover, the methodology applied allows for identification of the optimal weld- ing conditions by means of multi-objective optimization using RSM to increase the depth of penetration (DOP) and reduce BW (bead width) and heat-affected zone (HAZ) width. The variables taken for the model-based investigations are: welding current (Wc), torch speed (Ts), gas flow rate (Gr), torch angle (Ta) and arc gap (Ag). Moreover, the responses taken are DOP, BW and HAZ width. Fur- ther, the results from the proposed model optimisation can be seen as highly beneficial for the rocket-motor hardware program, indus- tries and fabrication of pressure vessels, which are using 15CDV6 steel. [ABSTRACT FROM AUTHOR]

Abstract In the paper, a self-made water-cooled copper plate device was used to measure and analyze the welding arc pressure of alternate argon supply under different frequencies of 1 Hz, 2 Hz, 4 Hz and argon and helium supply alternately under different frequencies of 1 Hz, 4 Hz. The experimental results indicated that in the process of alternate argon supply, the maximum arc pressure produced significant fluctuation in a diameter of 1 mm range of the arc center, resulting in the molten pool surface exposed to the acting of pulsating pressure. Besides, the arc center pressure changed with the convert of argon-arc and helium-arc during argon gas and helium gas supply alternately. And the weld seam subjected the pulsating pressure from the process of argon-arc and helium-arc stroked alternately, leading to the change of welding surface formation. Furthermore, under the condition of alternating gas supply, the weld surface presented the typical distribution pattern of fish scale. [ABSTRACT FROM AUTHOR]

After several years of service under high temperatures and high pressure, the Ti-6Al-4V aero-engine components may need to be repaired by Tungsten Inert Gas (TIG) welding to prevent crack growth. However, the material properties tend to worsen after TIG welding due to residual stresses developed adjacent to the fusion zone (FZ) and the heat affected zone (HAZ). It can lead to premature failure of the repair area resulting in a shortened service life of the components. Post weld heat treatment (PWHT) is generally adopted to reduce the residual stresses and to improve the mechanical properties. A comprehensive study of the effects of PWHT on the mechanical properties of Ti-6Al-4V was conducted in this paper. The residual stresses, micro-hardness, tensile strength and low cycle tensile fatigue life of as-welded Ti-6Al-4V before and after PWHT were compared and analyzed. The results indicate that the PWHT at 700 °C for 1 hour increases the yield strength of weld metal around 2.1% and improves the low cycle tensile fatigue life significantly under fatigue loads from 750 MPa to 950MPa by reducing residual stresses to close to 0 MPa. [ABSTRACT FROM AUTHOR]

The paper presents a numerical analysis of deformations of TIG welded flat made of stainless steel 0H18N9. Numerical simulations of temperature field, stress and deformations of welded joints is carried out using Abaqus/FEA engineering software. Goldak's mathematical model is used to describe the distribution of moveable heat source power. The numerical analysis takes into account temperature dependant thermo-mechanical properties of welded steel. Presented results of calculations include temperature field, stress and deformations in welded joint. The results of numerical calculation are compared with experimental results. [ABSTRACT FROM AUTHOR]

Copyright of Mechanics & Advanced Technologies is the property of National Technical University of Ukraine KPI and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper deals with the effects of weld parameters on residual stress developed during TIG welding of pipes. Circumferential TIG welding is widely used in industries such as piping, oil refineries, power stations, etc. The 3D numerical simulation ANSYS code is used to predict the residual stress distribution developed during circumferential TIG welding. Due to non-uniform distribution of plastic and thermal strains in and around the weld pool, large amounts of residual stresses and deformations are present in all welded structures. The simulated results are validated using experimental results available in the literature. The effects of welding current and pipe thickness on residual stress and temperature fields at different locations were assessed. [ABSTRACT FROM AUTHOR]

Metallic materials have received special attention in the aerospace and defense areas. A few decades ago, Brazil was faced with technological challenges concerning the production and processing of ultra-high strength steels, such as AISI 4340 and SAE 300 M steels. The AISI 4130 steel had been also considered, since it is applied in landing gears, small aircrafts engine cradles, and besides general industries. In this work, as a comparative welding process, Laser Beam Welding (LBW) was used as an alternative to the traditional TIG (Tungsten Inert Gas) welding. For the mechanical characterization of laser and TIG welds, tensile and hardness tests were performed. Microstructural characterization through optical microscopy was realized as well, in the fusion zone (FZ) and heat-affected zone (HAZ). Martensite was found in the fusion zone for both processes. However the average grain sizes were different due to different heating and cooling rates. In the present study, the weld was autogenous and a post weld heat treatment was conducted to evaluate its influence on mechanical properties. This treatment proved to improve the ductility of the steel and reducing the embrittlement in the welded region. It was observed that the thicknesses of the FZ and HAZ in the TIG welds were ten times larger than in the laser. The hardness values observed in FZ and HAZ were similar in both cases. Tensile strength after heat treatment remained at levels similar to the base material. After the heat treatment, there was a recover in the material ductility, particularly after the laser welding, demonstrating the usefulness of the process. [ABSTRACT FROM AUTHOR]

In this paper, the high-temperature creep strengths and microstructures of laser beam and tungsten inert gas (TIG)-welded HR3C austenitic stainless steel joints were investigated. The results show that the high-temperature creep strengths of laser joints are increased compared with TIG joints with post-weld treatment. In laser welding joints, the microstructure is fine cellular austenite grains with a few fine globular austenite grains growing almost symmetrically along the bead centre, and no residual δ-ferrite is observed. However, about 8% of residual δ-ferrites occurred in the TIG joints. With a solution-annealing treatment, the δ-ferrites of TIG joints are dissolved, and the austenite grains are coarse in the weld bead. The improvement in creep strength of laser welding joint mainly comes from the low heat input and high welding speed, which can induce a fast solidification of the weld pool; therefore, no δ-ferrite is formed in this process. [ABSTRACT FROM AUTHOR]

Welding is widely used in all the fabrication processes for the development of structural components. An accurate and physically suitable heat flux simulation model is to be given as input for analysis of welding processes. The outcome of the heat input is structural deformation and residual stress formation. The temperature and residual stress modelling is one of the complex process which utilise the weld parameters and material properties at higher temperatures. A representation of heat flux model is developed using heat source with constant and uniformly applied condition. Present work is done with cylindrical heat flux model further a realistic model is possible by combining present with other heat flux models, such as Gaussian. The temperature distribution and stress analysis has been carried out with developed model by using the temperature dependent material properties for Stainless steel SS304. This work can be used for selecting process parameters for reducing structural distortion and residual stresses by simulation process. In this paper temperature and residual stresses are discussed. [ABSTRACT FROM AUTHOR]

The present work provides a microstructure examination of the weld zone (WZ) and heat affected zone (HAZ) associated with the low and high heat input tungsten inert gas (TIG) welding condition of used hastelloy X (HX). For both welding conditions, the segregation of the elements during solidification led to the formation of second phases (σ and P phases). In low heat input condition, the heat from the WZ caused the dissolution of carbide in the HAZ, whereas in high heat input condition, there was no enough time for carbide to dissolve but simply melt in the grain boundaries. Liquid phase in the HAZ during welding decreased the tensile properties of this alloy. Transmission electron microscopy (TEM) and scanning electron microscope (SEM) were used to evaluate the formation of phases and liquated product respectively. Additionally, the geometry analysis by using ANSYS software was introduced to ensure the different in stress concentration. [ABSTRACT FROM AUTHOR]

TIG welding tests were carried out on high nitrogen nickel-free austenitic stainless steel by solid solution treatment,with three kinds of self-developed high nitrogen alloyed flux cored wires obtained. The results show the microstructure of the welded joints is austenite in dendritic crystalwith strong corrosive resistance. The grains in HAZ zone hardly grew, and the bonding were perfect between weld and base metal. Furthermore, no obvious nitrogen pores are found in welds and fusion zone. Connector Rm of Mo-N Wire and Mo-Nb-N flux cored wire is higher than the base metal to 983 MPa. [ABSTRACT FROM AUTHOR]

Fatigue crack usually initiates at welded joints of structural elements. For a high-responsibility aeronautic component, called “Motor-Cradle” - critical to the flight safety -, successive weld repairs are carried out toward restoring the original condition of the aircraft and extending the in-service life of them. Motivated by the high fracture incidence on this particular component an extensive research program to evaluate the effects of maintenance weld repairs on the structural integrity, mechanical properties and microstructural changes has been developed. In this research-work, a maintenance weld repair procedures widely employed along the useful life of aircrafts, characterized by overlapping the weld bead by gas tungsten arc welding with filler metal was investigated. From the data obtained with fatigue crack growth laboratorial tests in base material (BM), heat affected zone (HAZ) and weld metal (WM) the effects of successive TIG welding repairs on the structural integrity of AISI 4130 aeronautical steel were analysed. After TIG welding and re-welding processes, specimens were prepared in accordance with ASTM 647 standard and fatigue tested with constant amplitude (R=0,1) at 10 Hz frequency and room temperature. The obtained results were associated to the micro hardness and microstructure variations, as well as to the residual stresses field generated by the successive weld cycles. Key-conclusion is that welding repair increase the fatigue crack growth resistance in the weld metal and in the HAZ. [ABSTRACT FROM AUTHOR]

Abstract: The article deals with determining of fatigue lifetime of structural materials during by multiaxial cyclic loading. The theoretical part focuses on fatigue and criterions for evaluation of the multiaxial fatigue lifetime. The experimental part deals with modeling of combined bending -torsion loading and determining the number of cycles to fracture in region low-cycle fatigue and also during of the loading with the sinusoidal wave form under in phase φ = 0°. Based on the experimental results the fatigue design curves are compared to fatigue data from base metal and weldments. [Copyright &y& Elsevier]

Abstract: Samples of Al-Mg-Mn-Zr-Er alloys were welded by the method of TIG welding. Microstructures of base metal and welded zones were analyzed by optical microscopy (OM), electron probe micro-analyzer (EPMA) and transmission electron microscopy (TEM). Particular emphasis was laid on the existence form of Er and its effect on the microstructure and the phase composition of the fusion zone. Results reveal that the trace rare earth element Er mainly exists in the form of primary and secondary Al3Er phase, which play significant roles of refining and strengthening the fusion zone. A characteristic Equiaxed Zone (EQZ) is obtained beside the fusion boundary between the partially melted zone and the fusion zone (FZ) due to the addition of Er. [Copyright &y& Elsevier]

Abstract: This paper explains an integrated method with a new approach using experimental design matrix of experimental designs technique on the experimental data available from conventional experimentation, application of neural network for predicting the weld bead geometric descriptors and use of genetic algorithm for optimization of process parameters. The properties of the welded joints are affected by a large number of welding parameters. Modeling of weld bead shape is important for predicting the quality of welds. In an attempt to model the welding process for predicting the bead shape parameters (also known as bead geometry parameters) of welded joints, modeling and optimization of bead shape parameters in tungsten inert gas (TIG) welding process has been tried in the present work. Multiple linear regression technique has been used to develop mathematical models for weld bead shape parameters of TIG welding process, considering the effects of main variables as well as two factor interactions. Also by using the same experimental data, an attempt has been made to predict the bead shape parameters using back-propagation neural network. To optimize the process parameters for the desired front height to front width ratio and back height to back width ratio, genetic algorithmic approach has been applied. [Copyright &y& Elsevier]

Abstract: Structures critical to the flight-safety are commonly submitted to several maintenance repairs at the welded joints in order to prolong the in-service life of aircrafts. The aim of this study is to analyze the effects of Tungsten Inert Gas (TIG) welding repair on the structural integrity of the AISI 4130 aeronautical steel by means of experimental fatigue crack growth tests in basematerial, heat-affected zone (HAZ) and weld metal. The tests were performed on hot-rolled steel plate specimens, 0.89 mm thick, with load ratio , constant amplitude, at 10 Hz frequency and room temperature. Increase of the fracture resistance was observed in the weld metal but decreasing in the HAZ after repair. The results were associated to microhardness and microstructural changes with the welding sequence. [Copyright &y& Elsevier]

Copyright of Teknoloji is the property of Engineering Science & Technology, an International Journal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)