Showing papers on "Submerged arc welding published in 2019"

Investigating the effect of electrode preheating in novel water-cooled advanced submerged arc welding process:

Abstract: In this paper, a novel developed water-cooled advanced submerged arc welding (WASAW) process has been designed and established. The developed WASAW process can be utilized for higher preheating cur...

Design and development of submerged arc welding fluxes using TiO2-SiO2-CaO and SiO2-CaO-Al2O3 flux system:

Abstract: Submerged arc welding is widely used in pipeline manufacturing due to higher efficiency as compared to the other welding processes In present study, TiO2-SiO2-CaO and SiO2-CaO-Al2O3–based submerge

Variation of Mechanical Properties and Corrosion Properties with Mo Contents of Hyper Duplex Stainless-Steel Welds

Abstract: This study investigates the effect of the Mo content on the mechanical and corrosion properties of hyper duplex stainless-steel welds that are subjected to flux cored arc welding (FCAW). Conventional hyper duplex stainless steel has limited productivity owing to the welding position and welding equipment of gas tungsten arc welding (GTAW) and submerged arc welding (SAW). As such, the purpose of this study is to develop a weld material for FCAW, which is not subject to the limitations of GTAW and SAW, as well as to improve productivity and quality. FCAW was performed under the same conditions, except for the Mo content, which were varied to 3, 4.5, and 6 wt%. Tensile and impact tests were carried out to investigate the variation of the mechanical properties according to the Mo content. As the Mo content increased, the elongation decreased and the strength increased. It was confirmed that the δ-ferrite phase increased and the γ-austenite phase decreased as the Mo content increased. Secondary phase such as σ phase, χ phase were mainly distributed in ferrite grains or austenite–ferrite grain boundaries using EBSD. It was also increased as the Mo content increased. To evaluate the corrosion resistance, Potentiodynamic Polarization Tests and DL-EPR tests were conducted. As a result, all of specimens showed similar corrosion resistance.

Design of experiment based statistical approaches to optimize submerged arc welding process parameters.

Abstract: Joining of metals is very useful concept which is being utilized since Bronze Age and then gradual advancement gave rise to development of modern welding. And now welding is increasingly used in the fields of fabrication, manufacturing and construction. But productivity is the main concern in many manufacturing and industrial welding applications. Therefore selection of a welding process and its variables/parameters without sacrificing weld quality with respect to productivity and its quality is very important because an optimum blend of parameters which inevitably develop minimum or no defect will result in high productivity. For this study Submerge Arc Welding (SAW) process is selected for optimization because this versatile welding process is the first choice whenever good productivity with high quality requires in fabrication and manufacturing of Marine & pressure vessels, pipelines and offshore structures. Here Signal to noise (S/N) ratio analyses are used to find significant effects of key parameters on selected responses and then for optimization design of experiment based both quality loss function (OFM) and desirability function along with variance analyses by ANOVA are utilized. Moreover codes and standards provide a range for weld process parameters but author experienced that still there is a window to further optimize these parameters to produce the quality weld. Therefore this study is also useful to contribute in welding related research work by enhancing the knowledge of welding process and its analysis by utilizing advance statistical optimization techniques to find optimum zone within the acceptable zone from Code & Standard based tolerance Zone.

Comparative life cycle assessment of metal arc welding technologies by using engineering design documentation

Abstract: The paper aims to analyze and compare the environmental performances of metal arc welding technologies: gas metal arc welding (GMAW), shielded metal arc welding (SMAW), gas tungsten arc welding (GTAW), submerged arc welding (SAW), and flux-cored arc welding (FCAW). Welding is considered one of the most energy-intensive processes in manufacturing. This study was performed in accordance with the international standard ISO 14040/14044 by using attributional life cycle assessment (aLCA). The functional unit is defined as the “the development of 1 metre of welding seam (qualified by ASME section IX requirements) to join 25 millimetres thick of metal plates made in carbon steel material and considering a V-bevel configuration.” Different configurations of base/filler materials and standardized bevel geometries have been analyzed as welding scenarios. The inventory considers all inputs (e.g., electric energy and filler material) and outputs (e.g., fume emissions and slags) involved in each welding process. A framework for data collection starting from available project documentation is presented as an innovative solution for the inventory phase. The impact assessment includes the human health, resources (midpoints/endpoint), and ecosystems (endpoint) categories from the ReCiPe (H) and cumulative energy demand (CED) methods. This study reveals a notable dominance in terms of the environmental burdens of GTAW and SMAW processes, as they present higher impacts in most of the impact categories. SMAW is the most energy-consuming process, and this aspect is reflected in the environmental performance. Conversely, GMAW presents the least environmental load, accounting for less than one third compared with GTAW in terms of the CED indicator and performing very well in terms of the ReCiPe endpoint indicator. Via analysis of different scenarios, the main outcomes are the following: (i) the use of V bevels significantly increases the environmental load when the metal plate thickness increases and (ii) the use of specific materials such as Inconel alloy exacerbates the environmental concerns associated with welding processes. The use of project documentation allows robust analysis of welding activity. Sensitivity analysis shows how the range of values for specific parameters (e.g., volts and amps) affects each technology in a different manner. Indeed, those ranges have a limited impact on the result accuracy (up to 20%) for more automatized welding processes (e.g., GMAW, SAW, and FCAW), in which only a small number of parameters are set by the operator, and the operator skills are less influential on the quality of the weld.

Theoretical and Experimental Investigation of Temperature and Phase Transformation during SAW Overlaying

Abstract: The article presents the modeling of temporary temperature and phase share calculations during SAW (submerged arc welding) overlaying of steel elements. The input heat of a melted electrode and the heat of direct electric arc impact have been taken into consideration in the temperature field solution. The characteristic areas (fusion, full and incomplete transformation), have been determined by solidus, A3 and A1 temperatures, respectively. The limit temperatures of the phase trandformations during cooling, based on the cooling rate in the temperature range 800–500 °C according to S355 steel time-temperature-transformation welding diagram, have been determined. The JMAK (Johnson–Mehl–Avrami–Kolmogorov) law and KM (Koistinen–Marburger) formula were used in the phase change kinetic description. Theoretical considerations were illustrated with examples of temperature and phase share computations for welding overlaid S355 steel plate. The analysis of the history of changes in temperature and structural components (phases) was carried out based on the results of numerical simulations as well as metallographic examination after SAW overlaying. The dimensions of the HAZ (heat-affected zone), obtained experimentally, and the structure types confirmed the results of the computation.

A Comparative Analysis on Microstructure and Fracture Mechanism of X100 Pipeline Steel CGHAZ Between Laser Welding and Arc Welding

Abstract: The objective of this study is to compare and contrast the differences in microstructure and fracture mechanism between CGHAZ of laser welding and submerged arc welding in X100 pipeline steel. The single-pass welding thermal simulation test of laser welding and submerged arc welding was carried out in MMS-200 thermal simulation test machine using self-made fixtures. The results indicated that the microstructure of laser welding CGHAZ and submerged arc welding CGHAZ was lath martensite and granular bainite, respectively. The impact energy of laser welding CGHAZ was 27 J, and the fracture mode was ductile fracture; the impact energy of submerged arc welding CGHAZ was 7.7 J, and the fracture mode was brittle fracture. The nucleation and propagation mechanism of cracks in different welding modes was established. Microcracks nucleated at the position of dislocation accumulation and remained austenite suppressed crack nucleation in laser welding CGHAZ. The nucleation site was at the M–A constituents in submerged arc welding CGHAZ. The main crack of laser welding CGHAZ was formed by one or a small number of microcracks. The main crack in submerged arc welding CGHAZ was formed by a large number of microcracks. The difference between crack nucleation and propagation mechanism is the reason why the impact energy of laser welding CGHAZ is higher than of submerged arc welding CGHAZ.

Design and Development of Submerged Arc Welding Slags Using CaO-SiO2-CaF2 and CaO-SiO2-Al2O3 System

Abstract: The aim of present study is to investigate the physicochemical and thermophysical behaviour of submerged arc welding slags designed by CaO-SiO2-CaF2 and CaO-SiO2-Al2O3 system. Slag was produced during submerged arc welding using laboratory prepared agglomerated fluxes. By using mixture design and extreme vertices approach twenty one submerged arc welding slags were formulated. X-ray fluorescence technique was used to find the elemental weight percentage of each flux ingredient. The thermophysical behavior such as specific heat, thermal conductivity and thermal diffusivity of each slag was evaluated by hot disc technique. Density of submerged arc welding slags was evaluated at room temperature. FTIR technique was used to study the structural behaviour of submerged arc welding slags. Multi objective optimization technique was performed to derive the optimized slag formulations. Individual, binary and ternary slag constituents have been developed using various regression models for thermophysical and physicochemical properties. Significance level (upto 95%) has been checked for regression models by using F-test.

Joining of Ramor 500 Steel with SAW (Submerged Arc Welding) and its Evaluation of Thermomechanical Analysis in ANSYS Package Software

Abstract: ANSYS package software; it is a simulation simulation software which is preferred in engineering fields after the modeling stage and before the prototype is produced. Ramor 500 armor steel; it is classified as a high-strength ballistic protection steel with a hardness of 505–590 HV and a thickness of 2–30 mm. In this study, 3 mm thick and 65 × 55 mm Ramor 500 steel which is used as the main combat vehicle in armor steel and armed forces in the market, is used with submerged arc welding (SAW) method of 250 fixed amperes, 20, 25, 30 V voltages and 20, 25, 30 cm/min are combined at welding feed rates. The metallographic microstructure, radiographic examination test, SEM-EDS analysis and weld stitch geometry of the structures formed in the intersection after the joining were performed and the thermomechanical analyzes after the joining process were evaluated in the ANSYS package software. In the results of working; radiographic examination test showed that full penetration was achieved in all welded joints and therefore no macro and micro cracks were observed. In the microstructure analysis, a grain structure was observed. In the form of a homogeneous distribution from the weld stitch to the base material. SEM-EDS analysis showed that elemental phase structures were homogeneously distributed. As a result of the effect of welding stitch geometries on the current strength and velocity, welding width increased while welding width increased, while welding speed increased, width decreased. In the thermomechanical analysis results of ANSYS software, heat inputs in welding stresses increased and elastic and mechanical stresses were quite high and replaced by permanent stresses as a result of deformation.

Influence of Heat Input and Cold Wire Feeding Rate on Pitting Corrosion Resistance of Submerged Arc Welding Duplex Stainless Steel Welds

Abstract: Welding thermal cycles may severely impair duplex stainless steel (DSS) performance, especially local pitting resistance and toughness. The restricted welding energy between 0.5 and 2.5 kJ mm−1 represents a limiting factor for productivity increase in DSS welding, and the addition of cold wire is an interesting alternative to increase the welding deposition rate without adding extra heat. The aim of this work is to evaluate the influence of the cold wire feeding rate (CW) and heat input (HI) on pitting corrosion behavior of DSS UNS S32304 bead-on-plate welds obtained by submerged arc welding (SAW). Cyclic potentiodynamic polarization was carried out in transverse weld sections using 1 mol L−1 NaCl solution at room temperature. Most pitting corrosion spots were located on the heat-affected zone (HAZ), and the pitting potentials were lower than the base metal due to higher ferrite fractions and the presence of chromium nitrides. Considering the same CW, the HI increasing reduced Epit for 1.6, 1.9, 2.2 kJ mm−1, but increased Epit for 2.7 kJ mm−1, due to a balance between the HAZ width and the austenite fraction.

The Influence of Heat Input to Mechanical Properties and Microstructures of API 5L-X65 Steel Using Submerged Arc Welding Process

Abstract: API 5L-X65 steel is the type of high strength low alloy (HSLA) steel, widely used in the manufacture of pipe. Submerged arc welding (SAW) is widely used for the fabrication of the pipe, the extent of use submerged arc welding caused it could be done automatically and high reliability. The results of the welding process will lead to differences and changes in the microstructure in heat affected zone (HAZ) and weld metal that will affect the mechanical properties of the output, so as to obtain good welding results required the selection of welding parameters accordingly. As the use of the heat input during welding is very important influence on the mechanical properties and microstructure of the weld. The purpose of this study to determine the effect of heat input on the microstructure, hardness and toughness of welds in submerged arc welding. Welding currents used were 200, 300, 400 and 500 Ampere with a voltage were used 25, 27 and 30 Volt. The results showed that the higher heat input will result in a growing area of HAZ region width and grain size increased. Highest hardness values are the results of the weld heat input with a low of 244.69 HVN caused by the rapid cooling rate of the weld area. The highest toughness values are the results of the highest heat input that was dominated by acicular ferrite phase.

Microstructure and mechanical properties correlation of weld joints of a high strength naval grade steel

Abstract: Low alloy steels of higher strength grades are conventionally used for pressure hull application. Strength required range from 560 MPa to 800 MPa and plate thickness requirement is often higher (40 mm or more). Welding of high strength steels with higher thicknesses is often a challenge. From the view point of structural integrity challenge is not only to obtain defect free weld joint but also to meet the strength and low temperature toughness requirement in both weld and HAZ. In hull construction, different types of welding processes are used depending upon the requirement, accessibility and criticality of the weld joints to be produced. Conventionally, welding processes include Shielded Metal Arc Welding (SMAW), Gas Metal Arc Welding (GMAW), Submerged Arc Welding (SAW) & Gas Tungsten Arc Welding (GTAW). Number of weld consumables indigenously developed for a higher strength steel (YS~800 MPa), were used to develop the procedure, for producing weld joints, meeting the critical structural property requirements. Present study was focused on structural property correlation of weld joints made using these indigenous consumables. Weld joints were characterized in terms of impact toughness, Ductile Brittle Transition Temperature (DBTT), tensile properties and quantitative metallography. DBTT of weld joint is important from the aspect of structural integrity at sub-zero temperature. Impact toughness at -40° C varied from 39 J for SMAW process to 191 J for GTAW process. Yield strength of weld joints varied from 534 MPa for SMAW process to 907 MPa for GTAW process. Quantitative metallography was carried out to determine volume fraction of acicular ferrite (AF) in different welds. Heat input (HI) to produce a weld joint varied with welding processes used. HI for SMAW was 1.3 kJ/mm while it was 2.2 kJ/mm for SAW process. At HI of 1.85 kJ/mm (GTAW), a higher % fraction of AF (~77%) having Impact toughness of 191 kJ/mm at -40° C.

Arc Welding Process Selection through a Quality and Costs

Abstract: This paper presents a methodology to compare three welding processes, namely SAW (submerged arc welding), SMAW (shield metal arc welding) and GMAW (gas metal arc welding) and to select the best one for a given application. Study is the selection of arc welding process for improving quality and welding cost case in MIE and proposes a method for determining the welding process by comparing time, quality and cost, against one over the other of the three types of Arc welding. The welds were carried out in MIE training center. The selection was based on double criteria: operational costs and non-quality costs. The former is related to the normal costs evaluated in such kind of decision, like consumable cost, labor cost, etc. The is the financial loss suffered by the client every time response variable drifts away from its target value or presents variability. The results indicated that the non-quality and operational costs for the SAW process are slightly lower in comparison to the GMAW and SMAW. SAW is selective among them for quality wise. Therefore, it is the best process for the given application. However; cost incurs little high for GMAW.

Joining of Ramor 500 Steel by Submerged Welding and its Examination of Thermal Analysis in ANSYS Package Program

Abstract: ANSYS is a simulation software program used in the engineering fields. This program is used after the modeling phase and allows to test in the virtual, i.e. program, environment before the prototype is generated. Simulation of the welded structure is one of the most important subjects of the studies conducted on welding process. In this study, the complex situations encountered in the welded structures are tried to be solved with the help of computers by using Ansys finite elements method and numerical analysis and mathematical models. After the submerged welding; mechanical properties of the samples were investigated by using tensile test and SEM weld metal fracture surface. SEM-XRD analyses were carried out for the structures of the samples which showed characteristic in the weld metal. The fracture surfaces of the samples of the welded joints subjected to tensile test were investigated by using SEM and thus the fracture type was determined. Thermal analyses were performed by generating the model of the welded joints in ANSYS packaged software. In terms of the intensity of the joints, 250 A were found to have full intensity at all joints. As a result of the studies, it was determined that the results of the experimental studies and the results of the finite element solutions were compatible with each other.

Improvement of the toughness and ductility of the weld beads by inducing growth of acicular ferrite with TiO2-nanoparticles during submerged arc welding

Abstract: This work was focused to relate the mechanical properties of weld beads with size and superficial density of the acicular ferrite (AF) needles changing by impregnating two different sizes of TiO2-nanoparticles at the bevel before the SAW process. Microstructure of weld metal with addition of TiO2-nanoparticles with 21 and 127 nm sizes, respectively, shows an increase of the density (61.3 and 75.4%) and length of AF needles formed (156.4 and 68.8%), in comparison to the weld metal without TiO2-nanoparticles, namely the WB-0. Moreover, chemical analyses at weld metal and inclusions of weld beads with TiO2-nanoparticles reveal and increase on their Ti contents respect to those in the WB-0. Tensile and yield strength of the weld bead fabricated with the smallest TiO2-nanoparticles diminished in comparison to other weld beads. Besides, it was found that the average Vickers microhardness of weld metal decreased by adding TiO2-nanoparticles. On the other hand, their Charpy V-notch toughness values were found to be 30.1 and 102.6% bigger respect to those of the WB-0, by adding TiO2-nanoparticles with 21 and 127 nm sizes, respectively. In general, it was found that by adding TiO2-nanoparticles before the SAW process, the density and dimensions of the AF needles increase, which could be associated with the improvement of toughness and ductility of weld beads.

The contribution of impurities to unexpected cold cracks in a thick C-Mn steel plate

Abstract: The internal cracking observed in a 6″-thick carbon-manganese steel plate after welding is discussed with respect to the presence of material impurities. The morphology and location of the cracks detected during fabrication of a heavy structure are typical of hydrogen-induced cracking (HIC) usually associated to hard untempered martensite. However, typically martensitic microstructures would not be expected for low carbon low alloy steels joints when a suitable welding procedure specification is adopted, which includes preheating and high heat input. This paper illustrates the morphology of the original cracks, which are unrelated to hard microstructures, and presents the results of the welding experiments conducted in samples cut from segregated regions of the 6″-thick plate. Through hydrogenation of thin slices containing impure regions and autogenous gas tungsten arc welding bead, it was possible to reproduce the same cracking characteristics formed during submerged arc welding, indicating that HIC may also be associated to softer phases. Hydrogen entrapment at the weld fusion line can be related to high impurities level due to the expected lower melting points at grain boundaries, explaining the HIC phenomenon. The present paper proposes a model for hydrogen cracking of bainitic structures at the welding heat affected zone that typically is not susceptible to crack.

Subjective Factors Consideration in the Selection of Welding Technique for Welded Tube Manufacturing

Abstract: In choosing the right welding process for an application like welded tube manufacturing, the manufacturing engineers have to take into account a large number of selection criteria. Choosing the right welding process for any application is difficult not only due to multiple factors affecting the decision but also due to a number of emerging new welding techniques becoming available as alternatives. Some of the alternative welding processes for manufacturing tubes have been Fretz-Moon process (FM), low-frequency (LF) as well as high-frequency (HF) alternating current resistance welding, direct current (DC)-based resistance welding in addition to gas metal arc welding (GMAW), and submerged arc welding (SAW) in some specific applications. A systematic examination of the decision situation may lead us to an appropriate choice rather than basing the decision on one factor or the other in stand-alone manner. This paper presents an analytic hierarchy process (AHP)- based decision analysis for the selection of welding process in a case of manufacturing small diameter steel tubes.

Recommendations for Improved Welding Procedures for Thick Steel Plates Through Thermo-Mechanical Analysis

Abstract: Welding of steel plates is accompanied by residual stresses that increase as the constraint provided by the welded components becomes greater. Consequently, crack initiation has been reported after welding thick plates due to the high residual stresses developed by the welding procedure. This is further exacerbated by the higher likelihood of imperfections present in thick steel plates due to the rolling and cooling process. The research described herein aims to develop improved submerged arc welding (SAW) procedures to reduce the residual stresses for steel plates of thickness > 50 mm. Acceptance criteria are developed for discontinuities present in the steel plates prior to welding, to limit the probability of crack initiation. A parametric study of SAW procedure parameters was conducted utilizing a validated finite element model. Two welding procedures were recommended for thick steel plates. Discontinuity acceptance limits were also recommended for each welding procedure using a fracture toughness database and an expression developed to calculate the probability of a crack to initiate.