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.

scholarly journals Shielded Metal Arc and Thermite Welding Effect to Residual Stress, Hardness and Crack of R54-Rail Weld Joint

2020 ◽  
Vol 55 (4) ◽  
Author(s):  
Yurianto ◽  
Gunawan Dwi Haryadi ◽  
Sri Nugroho ◽  
Sulardjaka ◽  
Susilo Adi Widayanto
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Base Metal ◽  
Heat Affected Zone ◽  
Welded Joints ◽  
Arc Welding ◽  
Welding Process ◽  
Shielded Metal Arc Welding ◽  
Metal Arc Welding ◽  
Crack Susceptibility

The heating and cooling at the end of the welding process can cause residual stresses that are permanent and remain in the welded joint. This study aims to evaluate the magnitude and direction of residual stresses on the base metal and heat-affected zone of rail joints welded by the manual shielded metal arc and thermite welding. This research supports the feasibility of welding for rail. The material used in this study is the R-54 rail type, and the procedure used two rail samples of one meter long each, welded using manual shielded metal arc welding and thermite welding. The base metal and heat-affected zone of the welded joints were scanned with neutron ray diffraction. The scan produces a spectrum pattern and reveals the direction of the residual stress along with it. We found the strain value contained in both types of welded joints by looking at the microstrain values, which we obtained using the Bragg equation. The results show that the magnitude and direction of the residual stress produced by manual shielded metal arc welding and thermite welding are not the same. Thermite welding produces lower residual stress (lower crack susceptibility) than manual shielded metal arc welding. The melt's freezing starts from the edge to the center of the weld to create random residual stresses. The residual stress results of both the manual shielded metal arc welding and thermite welding are still below the yield strength of the base metal.

Numerical Analysis of Microstructure and Residual Stress in the Weld Zone of Multiwire Submerged Arc Welding

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Enlin Yu ◽  
Yi Han ◽  
Haixiang Xiao ◽  
Ying Gao
Keyword(s):  
Residual Stress ◽  
Temperature Measurement ◽  
Arc Welding ◽  
Large Diameter ◽  
Weld Zone ◽  
Submerged Arc Welding ◽  
Welding Parameters ◽  
Welding Quality ◽  
Welding Temperature ◽  
Submerged Arc

As oil and gas pipelines develop toward large throughput and high pressure, more and more attention has been paid to welding quality of oil pipelines. Submerged arc welding is widely applied in manufacturing of large-diameter welded pipes, and the welding quality has an impact on pipeline safety. With a multiwire submerged arc welding test platform and real-time temperature measurement system, temperature measurement has been done for multiwire submerged arc welding process with and without flux coverage, respectively. As a result, thermal cycling curves in both cases have been obtained, and convection and radiation coefficients of flux-covered X80 pipeline steel in air-cooled environment have been corrected. By using sysweld software, a finite-element computational model was set up for microstructure and residual stress in the weld zone of multiwire longitudinal submerged arc welding. Comparative experiment has been done to obtain welding temperature field with relatively high accuracy. Calculation and analysis of residual stress versus preheat residual stress decreased with increasing preheat temperature up to 100 °C, meanwhile content of bainite in microstructure fell, facilitating reduction in residual stress to some extent. This study provides quantitative reference for further optimization of welding parameters and improvement in weld mechanical properties.

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.

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.

Minimization of Residual Stresses in Submerged Arc Welding Process of Oil and Gas Steel Pipes by Committee Machine

2014 ◽  
Vol 564 ◽  
pp. 519-524
Author(s):  
Seyed Jafar Golestaneh ◽  
N. Ismail ◽  
M.K.A.M. Ariffin ◽  
S.H. Tang ◽  
Mohammad Reza Forouzan ◽  
...  
Keyword(s):  
Residual Stresses ◽  
Arc Welding ◽  
Oil And Gas ◽  
Traditional Approach ◽  
Welding Process ◽  
Submerged Arc Welding ◽  
Committee Machine ◽  
Steel Pipes ◽  
Input Variables ◽  
Submerged Arc

Submerged arc welding (SAW) is a well-known method to weld seam in manufacturing of large diameters steel pipes in oil and gas industry. The main subject of SAW design is selection of the optimum combination of input variables for achieving the desired output variables of weld. Input variables include voltage, amperage and speed of welding and output variables include residual stresses due to welding. On the other hand, main target in multi response optimization (MRO) problem is to find input variables values to achieve to desired output variables. Current study is a combination and modification of some works of authors in MRO and SAW subjects. This study utilizes an experiment design according to Taguchi arrays. Also a committee machine (CM) modeling the problem by CM using two approaches. The first CM consists eight experts with traditional approach in computation and second CM includes elite experts. Genetic algorithm was applied to find CM weights and desired responses. Results show that proposed approach in CM has a smaller root mean squire error (RMSE) than traditional approach. The validation of CM model is done by comparison of results with simulation of SAW process and residual stresses in a finite element environment. Finally, the results show few differences between the real case responses and the proposed algorithm responses.

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