Performance Evaluation of Alternating Current Square Waveform Submerged Arc Welding as a Candidate for Fabrication of Thick Welds in 2.25Cr-1Mo Heat-Resistant Steel

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Uttam Kumar Mohanty ◽  
Yohei Abe ◽  
Takahiro Fujimoto ◽  
Mitsuyoshi Nakatani ◽  
Akikazu Kitagawa ◽  
...  
Keyword(s):  
High Pressure ◽  
Arc Welding ◽  
Submerged Arc Welding ◽  
Pressure Vessels ◽  
Heat Consumption ◽  
Welding Parameters ◽  
Resistant Steel ◽  
Heat Resistant Steel ◽  
Flux Consumption ◽  
Submerged Arc

Abstract The paper evaluates the performance of alternating current (AC) square waveform submerged arc welding (SAW) as a candidate technology for manufacturing thick welds for high-pressure vessels. A new mathematical formulation for calculating melting efficiency in square waveform arc welding is presented. The melting efficiency and the heat consumption are presented as a mathematical model of welding parameters, namely welding current, welding speed, current frequency, and electrode negativity (EN) ratio. The proposed approach is demonstrated through the welding of 2.25Cr-1Mo heat-resistant steel performed over a wide range of welding parameters. The investigation provides deeper insights into the interplay between process parameter, total heat consumption, and melting efficiency. The effect on flux consumption is also explained. The melting efficiency is inversely proportional to flux consumption. The welding heat does not necessarily promote the plate melting. Improper use of welding heat may lead to decreased melting efficiency and increased unwanted melting and consumption of welding flux. Compared to the conventional direct current (DC) power sources, the AC square waveform welding achieves almost the same order of melting efficiency with added advantages of better weld bead shape and flux consumption in a desirable range. The two additional parameters (frequency and EN ratio) of the AC square waveform power source provide more freedom to fine-tune the process and thereby efficiently use welding heat. The results of this investigation will be advantageous to the designers and fabricators of high-pressure vessels using AC square waveform welding.

Feasibility Studies on the Modeling and Evaluation of Residual Stresses in Arc Welded Butt Joints

2006 ◽  
Author(s):  
K. Satyambabu ◽  
N. Ramachandran
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Arc Welding ◽  
Thermal Loading ◽  
Submerged Arc Welding ◽  
Pressure Vessels ◽  
Welding Parameters ◽  
Shielded Metal Arc Welding ◽  
Metal Arc Welding ◽  
Submerged Arc

Many important engineering applications such as nuclear reactors, ships, pipes and pressure vessels are shell-like structures made with weldments. For such a structure, a major problem is the development of residual stress and distortion due to welding. Residual stresses in weldments significantly affect stress corrosion cracking, hydrogen-induced cracking and fatigue strength in welded structures. As-welded components generally have certain amount of residual stresses caused by the application of intense heat or thermal loading at the weld joint, formed due to non-uniform cooling rates at different points in the weld metal and heat affected zones. Presence of residual stresses in a component is detrimental as they may lead to failure below the design stress value and also affect many important properties including the life of a welded component. Welding induced residual stresses can significantly increase the fracture driving force in a weldment and also contribute to brittle fracture. The thermal cycle imposed on any welded object causes thermal expansions and contractions which are not uniform. Quantitative measurement of residual stresses is essential to take remedial measures such as change in the welding technique, optimizing welding parameters (heat input, electrode diameter etc,), change in the weld groove design and post-weld heat treatment for minimizing the residual stresses. Residual stress measurements after post-weld treatment would also ensure the adequacy of stress relief treatment. To have an investigation into these aspects, residual stresses due to Manual Metal Arc Welding and Submerged Arc Welding were measured nondestructively with Ultrasonic technique. Residual stress distribution for Shielded Metal Arc Welding and Submerged Arc Welding were compared and the present studies emphasized, that Shielded Metal Arc Welding gave higher compressive stresses than Submerged Arc Welding. Further, to substantiate the studies, commercial finite element analysis software ANSYS 5.6 was used for modeling of manual metal arc welded joint. The results obtained by ANSYS were compared with those by Ultrasonic method.

Design of CaO–SiO2–CaF2 and CaO–SiO2–Al2O3 Based Submerged Arc Fluxes for Series of Bead on Plate Pipeline Steel Welds—Effect on Carbon and Manganese Content, Grain Size and Microhardness

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Lochan Sharma ◽  
Rahul Chhibber
Keyword(s):  
Grain Size ◽  
Arc Welding ◽  
Welding Process ◽  
Submerged Arc Welding ◽  
Pressure Vessels ◽  
Constant Current ◽  
Welding Parameters ◽  
Chemical Compositions ◽  
Optimization Approach ◽  
Submerged Arc

Submerged arc welding is mainly used to weld high thickness steel plates in various applications such as offshore oil drilling platforms, bridges, building construction, and pressure vessels. Suitable flux composition and welding parameters play an important role in determining the good bead quality, which further affects the mechanical properties of welded joint. Agglomerated fluxes were formulated based on CaO–SiO2–CaF2 and CaO–SiO2–Al2O3 flux system using constrained mixture design and extreme vertices design approach. The chemical compositions of the bead on plate have been studied using formulated fluxes. Twenty one beads on plate experiments were conducted at constant current, voltage, and welding speed using submerged arc welding process. In the present study, chemical composition, grain size, and microhardness properties of series of bead on plate weld deposits (for API 5 L X70 grade pipe line) were optimized by using multiobjective optimization approach.

Design of TiO2–SiO2–MgO and SiO2–MgO–Al2O3-Based Submerged Arc Fluxes for Multipass Bead on Plate Pipeline Steel Welds

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Lochan Sharma ◽  
Rahul Chhibber
Keyword(s):  
Arc Welding ◽  
Pipeline Steel ◽  
Welding Process ◽  
Submerged Arc Welding ◽  
Pressure Vessels ◽  
Welding Parameters ◽  
Chemical Compositions ◽  
Optimization Approach ◽  
Low Alloy Steels ◽  
Submerged Arc

High strength low alloy steels are extensively used in different applications like oil and gas transmission line pipes, pressure vessels and offshore oil drilling platforms. Submerged arc welding (SAW) is mainly used to weld high thickness steel plates. Flux composition and welding parameters play an important role in determining the adequate quality and mechanical properties of the weld. Agglomerated fluxes were formulated based on TiO2–SiO2–MgO and SiO2–MgO–Al2O3 flux system using constrained mixture design and extreme vertices design approach. The chemical compositions of the bead on a plate have been studied using formulated fluxes. Twenty-one beads on plates were applied using submerged arc welding process keeping the parameters: current, voltage, and welding speed constant. Regression models were developed for bead on plate content in terms of individual, binary, and ternary mixture flux constituents for submerged arc multipass bead on plate deposition for pipeline steel (API 5 L X70). In the present study, chemical composition, grain size, and microhardness properties of the multipass bead on a plate (for API 5 L X70 grade pipeline) were optimized using multi-objective optimization approach.

Development of Exothermic Flux for Enhanced Penetration in Submerged Arc Welding

2020 ◽  
Vol 19 (01) ◽  
pp. 131-146
Author(s):  
Aditya Kumar ◽  
Kulwant Singh
Keyword(s):  
Mathematical Model ◽  
Arc Welding ◽  
Welding Process ◽  
Submerged Arc Welding ◽  
Graphical Form ◽  
Welding Parameters ◽  
Weld Penetration ◽  
Agglomeration Process ◽  
Arc Welding Process ◽  
Submerged Arc

An exothermic flux for submerged arc welding process has been developed which is capable of enhancing weld penetration of the joint. For this purpose, thermit mixture in different proportions (20% and 40%) has been added to the parent flux by agglomeration process. Beads on plate were deposited using parent and developed exothermic fluxes for a comparative study. EH14 filler wires in combination with parent and exothermic fluxes were used in this investigation. The effects of welding parameters and exothermic flux on weld penetration were investigated and the results have been presented in this paper. It has been found that the penetration increases from 2.95 to 3.51[Formula: see text]mm with 40% thermit mixture addition to the parent flux. It is further observed that penetration increases with increase in the amount of thermit mixture added. A mathematical model has been developed to predict weld penetration or select suitable welding parameters to obtain the desired penetration. The significance of coefficients was tested using Student’s [Formula: see text]-test and the adequacy of developed model was tested using [Formula: see text]-test. The effects of various parameters on penetration have been presented in graphical form for better understanding.

Design of Experiment of High Pressure Steel Tank Using Tandem Submerged Arc Welding

2016 ◽  
Vol 848 ◽  
pp. 11-14
Author(s):  
Prin Boonkanit ◽  
Wittaya Pansong
Keyword(s):  
High Pressure ◽  
Arc Welding ◽  
Travel Speed ◽  
Submerged Arc Welding ◽  
Average Value ◽  
Steel Tank ◽  
Welding Line ◽  
Set Up ◽  
Submerged Arc ◽  
Tandem Submerged Arc Welding

The objective of this research is to investigate the appropriated Tandem Submerged Arc Welding (TSAW) by Punch through technique for high pressure steel tank in ship building industry. Electrode Type AWS A5.17 EM12K and powder flux type AWS A5.17 F7A6 have been applied with electric current at AC+ 550-700 Amp/DC 460-610 Amp. The welding travel speed is controlled between 515-590 mm/min with arc length between 25-30 mm which SM400 steel type is 25 mm thickness. The welding is in horizontal position without any bevel on the steel piece. Studying the suitable parameters from the experiment type 24 of this procedure experiment, the result has been found that the most suitable parameter set up for this welding is DC460, AC550, ST515, AL25. The experiment follows AWS D1.1 standard with 100% full penetration, tensile value at 542.61 N/mm2. Welding line supports impact test at 0°C with average value of 66 Joules, average hardness value at 156.4 HV, bending at 180°. With out any defected found. Moreover, this method can be reduced welding cost around18,482 baht/day and also increased the welding lenght around 168%.

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