Features of arc welding of thin plates with various welding processes.

The Arctic region is expected to play an extremely prominent role in the future of the oil and gas industry as growing demand for natural resources leads to greater exploitation of a region that holds about 25% of the world’s oil and gas reserves. It has become clear that ensuring the necessary reliability of Arctic industrial structures is highly dependent on the welding processes used and the materials employed. The main challenge for welding in Arctic conditions is prevention of the formation of brittle fractures in the weld and base material. One mitigating solution to obtain sufficiently low-transition temperatures of the weld is use of a suitable welding process with properly selected parameters. This work provides a comprehensive review with experimental study of modified submerged arc welding processes used for Arctic applications, such as narrow gap welding, multi-wire welding, and welding with metal powder additions. Case studies covered in this article describe welding of Arctic steels such as X70 12.7-mm plate by multi-wire welding technique. Advanced submerged arc welding processes are compared in terms of deposition rate and welding process operational parameters, and the advantages and disadvantages of each process with respect to low-temperature environment applications are listed. This article contributes to the field by presenting a comprehensive state-of-the-art review and case studies of the most common submerged arc welding high deposition modifications. Each modification is reviewed in detail, facilitating understanding and assisting in correct selection of appropriate welding processes and process parameters.

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Analysis of circumferentially welded thin-walled cylinders to study the effects of tack weld orientations and joint root opening on residual stress fields

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1243/09544062jmes1191 ◽

2009 ◽

Vol 223 (5) ◽

pp. 1037-1049 ◽

Cited By ~ 3

Author(s):

N U Dar ◽

E M Qureshi ◽

A M Malik ◽

M M I Hammouda ◽

R A Azeem

Keyword(s):

Residual Stress ◽

Residual Stresses ◽

Arc Welding ◽

Operating Conditions ◽

Stress Fields ◽

Welded Structures ◽

Prime Concern ◽

Thin Walled ◽

Tack Weld ◽

Welding Processes

In recent years, the demand for resilient welded structures with excellent in-service load-bearing capacity has been growing rapidly. The operating conditions (thermal and/or structural loads) are becoming more stringent, putting immense pressure on welding engineers to secure excellent quality welded structures. The local, non-uniform heating and subsequent cooling during the welding processes cause complex thermal stress—strain fields to develop, which finally leads to residual stresses, distortions, and their adverse consequences. Residual stresses are of prime concern to industries producing weld-integrated structures around the globe because of their obvious potential to cause dimensional instability in welded structures, and contribute to premature fracture/failure along with significant reduction in fatigue strength and in-service performance of welded structures. Arc welding with single or multiple weld runs is an appropriate and cost-effective joining method to produce high-strength structures in these industries. Multi-field interaction in arc welding makes it a complex manufacturing process. A number of geometric and process parameters contribute significant stress levels in arc-welded structures. In the present analysis, parametric studies have been conducted for the effects of a critical geometric parameter (i.e. tack weld) on the corresponding residual stress fields in circumferentially welded thin-walled cylinders. Tack weld offers considerable resistance to the shrinkage, and the orientation and size of tacks can altogether alter stress patterns within the weldments. Hence, a critical analysis for the effects of tack weld orientation is desirable.

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Determination of Heat Input in Tungsten Inert Gas and Laser Welding of Type Optim 960 QC Structural Steel Using Adams’ Equation for 2-D Heat Distribution

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.750.45 ◽

2017 ◽

Vol 750 ◽

pp. 45-52

Author(s):

Sveto Cvetkovski

Keyword(s):

Laser Welding ◽

Heat Input ◽

Arc Welding ◽

Research Work ◽

Laser Beam Welding ◽

Peak Temperature ◽

Efficiency Coefficient ◽

Zone Recrystallization ◽

Welding Processes

The heat input during conventional arc welding processes can be readily calculated knowing the power taken from the power source. The efficiency coefficient can be taken from the appropriate literature standards. Here, the intention of the performed research work was to develop a procedure for determination of heat input in arc and laser welding processes implementing Adams equation - modified Rykalin equation for two dimensional heat distributions (2-D). To realize this idea, it is necessary to determine two characteristic temperatures points in the HAZ with known peak temperature, and to determine distance between them. Implementing measured values for distance in Adams’ equation, heat input in arc welding can be directly determined in arc welded joints.In laser beam welding, the absorption of the beam in the metal is not known, so that the welding heat input cannot be calculated directly, and direct implementation of Adam’s equation is not possible i.e. absorption coefficient has to be determined first, and after that calculation of heat input is possible.The peak temperatures corresponding to specific microstructures can be obtained by performing welding simulation, by the Gleeble 1500 simulator in our case. As one of the peak temperatures, the melting temperature can be used corresponding to the fusion line, so that at least one characteristic peak temperature such as coarse grain zone, fine grin zone, intercritical zone, recrystallization, has to be determined by the simulation.Performed research showed that obtained values for heat input using Adam’s equation correspond pretty well with standard equation for heat input in arc welding.

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