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Stainless steel is one of the most important elements in structural design and application, and due to its excellent properties, it is widely used in industries for conventional structural engineering applications, such as thermal power plants, nuclear power plants, civil constructions, etc. (Mishra et al., 2014). A traditional tensile testing machine cannot determine the transversal stress–strain curves (Olden, 2002, 2013).

In the present study, identical mild steel specimen parts are welded at different intervals and then subjected to tensile loading. Welding is carried along the length of the specimen. Induced stresses are determined at the welded intervals and the stress–strain curve is obtained.

By considering the temperature of the weld at the interface, thermal stresses are determined. Brinell hardness number is determined at the interface and the base metal. Also, the change in the hardness at the heat-affected zone (HAZ) is found. Validation is carried out by comparing the results with the original stress–strain curve.

In the HAZ, there is a drop in the hardness number, which means that there is a change in the material property due to welding. The thermal stresses which develop at the interface can also play a very important role for property change. Results show that the stress developed due to the rise in temperature is lesser than that of normal stresses.

The purpose of this study is to explore the importance of vibrations during welding process. In recent years, welding has gained its supremacy in the field of production. The main set back of the welding process is induced residual stresses, which is a major cause for many welding defects. These defects can be minimized by post-weld heat treatment methods, which is a time consuming and laborious process. In the recent past, a technique of exciting the weld-pool by vibrating the work-pieces was also adopted to minimize the above-mentioned stresses. A novel technique of electrode vibration is another effective way of transferring the vibrations to the weld-pool to influence the induced residual stress.

In this research, the electrode is vibrated with the help of an electric motor. The specimens were prepared as per American Society for Testing and Materials standards and welded with varying frequencies and voltages. The weldments are tested for hardness along the weld bead and heat affected zone, also the microstructure of the fusion zone is analyzed.

It is observed that there is an improvement in the hardness because of the grain refinement, which is a result of proper excitation of the weld-pool. It is observed that there is an improvement in hardness test up to 28.69% when compared with the conventional welding process. The peak value of hardness is observed at a frequency of 4,450 Hz. This is because of fine grain structure at this frequency, which is observed through the microstructure analysis.

A novel technique is introduced to refine the weld-pool through electrode vibrations. To improve the hardness of the welded joints, vibrations play a major role by refining the grain structure. The vibrations are imparted with the help of a special equipment attached to the electrode.

The primary objective of this investigation is to optimize the constricted arc tungsten inert gas (CA-TIG) welding parameters specifically welding current (WC), arc constriction current (ACC), ACC frequency (ACCF) and CA traverse speed to maximize the tensile properties of thin Inconel 718 sheets (2 mm thick) using a statistical technique of response surface methodology and desirability function for gas turbine engine applications.

The four factor – five level central composite design (4 × 5 – CCD) matrix pertaining to the minimum number of experiments was chosen in this investigation for designing the experimental matrix. The techniques of numerical and graphical optimization were used to find the optimal conditions of CA-TIG welding parameters.

The thin sheets of Inconel 718 (2 mm thick) can be welded successfully using CA-TIG welding process without any defects. The joints welded using optimized conditions of CA-TIG welding parameters showed maximum of 99.20%, 94.45% and 73.5% of base metal tensile strength, yield strength and elongation.

The joints made using optimized CA-TIG welding parameters disclosed 99.20% joint efficiency which is comparatively 20%–30% superior than conventional TIG welding process and comparable to costly electron beam welding and laser beam welding processes. The parametric mathematical equations were designed to predict the tensile properties of Inconel 718 joints accurately with a confidence level of 95% and less than 4.5% error. The mathematical relationships were also developed to predict the tensile properties of joints from the grain size (secondary dendritic arm spacing-SDAS) of fusion zone microstructure.

The purpose of this paper is to predict and optimize the width of heat affected zone (HAZ) with better mechanical properties using suitable welding process and parameters for the fabrication of jet blast deflector (JBD) (high strength low alloy material of grade A588-B was used for fabrication) so that the JBD can sustain high exhaust parameters, because there are different welding zones formed due to the rapid cooling of weld metals. Out of the various zones of welding, HAZ remains the weakest zone in the entire weldment.

The present work describes the modeling, simulation, Modeling of three-dimensional plate and mess generation process are carried out using ICEM CFD software. FLUENT 16.0 software is used for ANSYS simulation where various models are used for analysis and results are validated with the experimental outcomes. High strength low alloy plates are welded by using shielded metal arc welding and tungsten inert gas (TIG) welding processes with two different electrodes. Optical microscopy and scanning electron microscopy were used for metallurgical study. The mechanical properties were evaluated by tensile strength test, vickers microhardness test and impact test. The corrosion resistance was evaluated by performing the potentiodynamic polarization test.

The present study indicated for better mechanical properties and improved corrosion resistance for TIG welded joints with type 308 L filler.

In aeronautical, defense, space and research organizations.

It can be shown from the scanning electron microscope technique that sound weld joint is produced with very good mechanical properties and joint also showed better corrosion resistance.

The Ni-base superalloy INC738LC is a precipitation strengthened alloy and is widely used in hot sections of gas turbine engines owing to its excellent high-temperature strength and high hot corrosion resistance. The purpose of this study is to determine the appropriate welding current of Ni-base superalloy INC738LC after two passes of applying the tungsten inert gas (TIG) welding technique.

Ni-base superalloy INC738LC plates were joined by TIG welding technique by varying the welding current (30, 40 and 50 A). Welded specimens were investigated using optical microscopy, tensile tests, Vickers’s micro-hardness tests and X-ray diffraction (XRD). Optical microscopy was used to characterize fusion zone, heat-affected zone and base metal. Tensile test was conducted to characterize weld strength by determining ultimate tensile strength. Scanning electron microscopy was used to investigate the fracture surfaces after tensile tests. Micro-hardness test was conducted to characterize the welded joint. XRD was applied to determine precipitates formed after welding.

The ultimate tensile strength results show that the optimum weld current out of the three weld currents was found to be 40 A, which is the closest to that of the base metal.

Many researchers have worked to optimize welding parameters such as current and speed from the microstructural observations and mechanical properties of welded joints. The optimum weld current out of the three weld currents was found to be 40 A.

The paper aims to report on a new welding technology, TIP TIG.

The principle of operation and benefits of the technology are described together with a typical application.

The study finds that the technology provides the quality of TIG welding at the speeds of MIG welding, providing significant cost savings to the user.

TIP TIG provides a good opportunity for all users of robotic MIG welding to improve the quality of their product and reduce their costs.

The paper introduces a new and useful technology to the robot industry.

Presently, the materials used in light combat aircraft structures are aluminium alloys and composites. These structures are joined together through riveted joints. The weight of these rivets for the entire aircraft is nearly one ton. In addition to weight, the riveted connection requires a lot of tools, equipments, fixtures and manpower, which makes it an expensive and time-consuming process. Moreover, Al alloy is also welded using tungsten inert gas (TIG) welding process by proper control of process parameters. This process has limitations such as porosity, alloy segregation and hot cracking. To overcome the above limitations, an alternative technology is required. One such technology is friction stir welding (FSW), which can be successfully applied for welding of aluminium alloy in LCA structures. Therefore, this paper aims to compare the load carrying capabilities of FSW joints with TIG welded and riveted joints.

FSW joints and TIG welded joints were fabricated using optimized process parameters, followed by riveted joints using standard shop floor practice in the butt and lap joint configurations.

The load-carrying capabilities of FSW joints are superior than those of other joints. FSW joints exhibited 75 per cent higher load-carrying capability compared to the riveted joints and TIG-welded joints.

From this investigation, it is inferred that the FSW joint is suitable for the replacement of riveted joints in LCA and TIG-welded joints.

Friction stir butt joints exhibited 75 per cent higher load-carrying capability than riveted butt joints. Friction stir welded lap joints showed 70 per cent higher load-carrying capability than the riveted lap joints. Friction stir butt joints yielded 41 per cent higher breaking load capabilities than the TIG-welded butt joints. Moreover, Friction stir lap weld joints have 57 per cent more load-carrying capabilities than the TIG-welded lap joints.

A lecture held in Paris the 22 April 1966 during an ESAB symposium on the subject of the development of methods for electrical welding, and originally published in Esab Svetsaren, no. 1, 1968 (Box 8850, S‐402 71 Göteborg 8, Sweden.)

Mathematical models of the metal‐inert gas (MIG) welding process may be used to study the influence of various welding parameters on weld dimensions, to assist in the development of welding procedures, and to aid in the generation of process control algorithms for automated applications. A three‐dimensional model for convection and heat transfer in MIG weld pools has been formulated and solved using the finite difference technique. The energy exchange between the pool and the molten filler metal droplets via spray transfer, and the interaction of electromagnetic, buoyant, surface tension, droplet impact and plasma jet forces were considered. MIG welding was carried out using mild steel plate with heat input from 7 to 17.5 KJ/cm. The calculated and experimentally observed weld bead dimensions were compared. Occurrence of finger penetration phenomena only in MIG welds are adequately explained through the application of the proposed model. Good agreement is demonstrated between predicted weld dimensions and experimentally measured ones.