Multi-pass Welding Research Articles

Microstructure and mechanical property assessment of stainless steel–clad plate joint made by hybrid SMAW-GTAW multi-pass welding process

Microstructure and mechanical property assessment of stainless steel–clad plate joint made by hybrid SMAW-GTAW multi-pass welding process

Deep Neural Networks for Defects Detection in Gas Metal Arc Welding

Welding is one of the most complex industrial processes because it is challenging to model, control, and inspect. In particular, the quality inspection process is critical because it is a complex and time-consuming activity. This research aims to propose a system of online inspection of the quality of the welded items with gas metal arc welding (GMAW) technology through the use of neural networks to speed up the inspection process. In particular, following experimental tests, the deviations of the welding parameters—such as current, voltage, and welding speed—from the Welding Procedure Specification was used to train a fully connected deep neural network, once labels have been obtained for each weld seam of a multi-pass welding procedure through non-destructive testing, which made it possible to find a correspondence between welding defects (e.g., porosity, lack of penetrations, etc.) and process parameters. The final results have shown an accuracy greater than 93% in defects classification and an inference time of less than 150 ms, which allow us to use this method for real-time purposes. Furthermore in this work networks were trained to reach a smaller false positive rate for the classification task on test data, to reduce the presence of faulty parts among non-defective parts.

Study of Residual Stress Evolution in SUS304/Q235 Bimetallic Clad Plate Butt-Welded Joints Considering Welding Sequence

Abstract Residual stress prediction and controlling is important for structural integrity assessment of weldments. In this work, finite element (FE) and experimental methods were integrated to study the influence of welding sequence on the SUS304/Q235 bimetallic clad plate (BCP) joints during multilayer and multipass welding. The results show that the peak residual stress values on flyer plate surface are weakly affected by welding sequences but the width of high surficial longitudinal stress area of joint with base layer welded first is bigger. Meanwhile, welding sequence has a great influence on the longitudinal residual stress evolution law inside joints. When base seam layer is welded first, the highest stress concentration appears in the transition layer. However, it would be transferred into the first base seam layer due to martensite phase transformation when flyer seam layer is welded first. Residual stress controlling in the BCP joint should attract more attention from researchers.

Microstructural and Impact Considerations of Heat Affected Zone in Gas Tungsten Arc Welding of Armor Steel

Abstract Gas tungsten arc welding is a preferred welding process due to its excellent heat control which provides high quality joinings of various metals. Welded armor steels are widely used in armored vehicles for the ease of production. Thus, characterization of gas tungsten arc welding of armor steels reveals important data on both present applications and potential uses of gas tungsten arc welding in future. In this study, microstructural and mechanical properties of welded armor steel were investigated. Optimal welding parameters depending on a previous research were used to eliminate welding defects. The results have shown that application of pre-heating and/or multi-pass welding on armor steel could provide fine and homogeneously dispersed carbides in heat affected zone.

Experimental validation on multi-pass weld distortion behavior of structural offshore steel HSLA S460 using FE-based inherent strain and thermo-mechanical method

Experimental validation on multi-pass weld distortion behavior of structural offshore steel HSLA S460 using FE-based inherent strain and thermo-mechanical method

A new numerical model to predict welding-induced sensitization in SUS304 austenitic stainless steel joint

In this paper, a SUS304/P92 dissimilar metal butt-welded joint was fabricated, and the welding-induced sensitization of SUS304 austenitic stainless steel in this joint was investigated via the numerical simulation and experiment. In the proposed new numerical model, the time–temperature-precipitation diagram and the time–temperature-sensitization diagram were used to simulate the region and the degree of sensitization, respectively. The predicted degree of sensitization (DOS) in the weld decay zone matched the electrochemical measurements well. Based on the simulation results, the evolution of DOS at the austenitic stainless steel side during the multi-pass welding process was examined in detail. The obtained results can help evaluate the material susceptibility to stress corrosion cracking in austenitic stainless steel joints.

Problems encountered in underwater welding and remedies- a review

Wet underwater welding has proved to be the most suitable solution for underwater repairs and fabrication works. However, number of difficulties are faced that are specifically depicted in the testing and analysis of welds obtained while welded underwater. Major issues that are faced include immediate contact of workpiece with water leading to severe quenching effect, hydrogen diffusion due to dissociation of water which causes hydrogen induced cracking, arc instability, porosity in welds due to infused gases, loss of alloying elements leading to degradation of mechanical properties and microstructure of weld metal, increased hardness of HAZ and associated cracking. Since its inception during world war I, number of researchers have worked on finding the way out to control the harmful effects due to problems encountered during underwater welding. This paper discusses the experimental works conducted for detailing the problems encountered and the solutions suggested by researchers to overcome them. Controlling the input parameters during welding, addition of alloying elements into the electrode coating and multipass welding are the suggested solutions for obtaining desired characteristics in the welds.

Study of Influences of Groove Type on Welding Residual Stress Evolution in Bimetallic Clad Plate Joints during Multi-layer and Multi-pass Welding

Study of Influences of Groove Type on Welding Residual Stress Evolution in Bimetallic Clad Plate Joints during Multi-layer and Multi-pass Welding

Intelligent Design of Robotic Welding Process Parameters Using Learning-Based Methods

With the wide application of multi-layer and multi-pass welding in industry, the traditional manual welding method is difficult to meet the needs of manufacture. Welding Robot has the advantages of stable productivity, ensuring welding quality even in special environment, so the welding robots are used at a growing trend in manufacturing fields to complete different welding tasks. In this paper, an intelligence learning method for welding robot is designed, aiming at the prediction of welding process parameters and bead geometry parameters in the welding process, deep and machine learning algorithms are used for realization. It provides an instruction for the design of process parameters to realize the intellectualization and automation of welding robot. The experimental results show that automatic parameters learning based on machine learning are effective and different learning methods should be selected for different process parameter prediction tasks in order to achieve the best prediction effect.

Residual stress and distortion in thick-plate weld joint of AF1410 steel: finite element simulations and experimental studies

The quantification of the residual stress and distortion in the thick-plate weld joint of AF1410 steel has great significance, which is the basis for the safety and process design of the component. Therefore, this paper systematically investigated the welding residual stress and distortion distribution in the 10 mm thick welded plate for AF1410 steel by tungsten inert gas welding. The residual stress measurements were carried out by the X-ray diffraction method and advanced contour method, and the distortion was determined by coordinate measuring machine. The developed thermo-metallurgical-mechanical finite element model was applied to predict the residual stress and distortion in multi-pass welding considering solid-state phase transformation (SSPT) and transformation plasticity. The measured residual stress and distortion distribution were in good agreement with the finite element simulation results. The comparison results revealed that the residual stresses in the upper and lower parts of the welding plate were small, and there was apparent stress concentration in the center of the welding joint. SSPT and the subsequent thermal cycle had a significant influence on the magnitude of final residual stress. The accurate finite element model and the understanding of stress formation mechanism are helpful to control the residual stress and distortion distribution of aviation parts reasonably.

Welding, mechanical properties and microstructure of different grades of austenitic stainless steels: A review

Nowadays the power of the industry standard materials has gained a lot with the advancement in technology. The requirement for materials with high creep rupture strength, high thermal conductivity, and strong corrosion resistance rose dramatically when the power plant was operated at greater temperatures and pressures. Creep strength improved steels, nickel based alloys, and austenitic stainless steels are the most often utilised materials in high temperature and high pressure power plants. To meet the strength criteria, reduced cost investment, and service standards must be met, dissimilar welding between Stainless steels is required. This necessitates the combining of different metals. An effective weld among different metals is one which is as strong as that of the weakest of the two different metals being connected, that is, it has enough ductility and tensile strength to prevent the junction from failing during the weld. Such joins may be made from a number of metals and using a range of welding methods. Before selecting the best way to join the metals the evaluation of both the base metals and the filler material is to be done. Here the welding process done between steels is TIG welding. Challenges in the current research are to join the different materials without disturbing the properties of parent metals. Some of the frequently occurring problems are: wider HAZ (heat affected zone), Difference in coefficient of thermal expansions, Difference in chemical composition, Multi pass welds to weld high thickness materials. Current research deals with the Optimization the TIG Welding Process and To Understand the effect of Process Parameters on Mechanical Characteristics of the dissimilar joints and to carry out Numerical Investigation on the dissimilar welding of Austenitic Stainless Steel.

Prediction of angular distortion in austenitic stainless steel welds using finite element analysis

The present work was carried out with an aim of predicting angular distortion in AISI 304 welds fabricated using Shielded metal arc welding (SMAW) process. Since distortion results into loss of structural integrity which consequentially affects service performance of welded structures adversely, so studies on its prediction carry industrial significance to devise their preventing as well as controlling strategies. Experimental welds involved welding of 16.4 mm thick AISI 304 austenitic stainless steel plates using SMAW process using three different levels of welding heat input. Angular distortion was measured for each welded joint. Thereafter numerical analysis of the welds was done using Finite Element Method. This model was rather a simpler one as it did not consider temperature dependent properties of materials. A moving heat source was implemented to simulate the welding process which was modelled using Gaussian heat flux source. Owing to the simplicity of the model, filler material addition and multi-pass weld deposition were not considered. The whole analysis regime was divided into two steps, first a non-linear transient thermal analysis was performed to predict the temperature, and subsequently the predicted thermal load was then used as an input to perform non-linear transient structural analysis using ANSYS Workbench. To prevent the integrity of the plate in FE model, frictionless support was added as a boundary condition. For simulating the welding environment, the environment in simulation was chosen to be stagnant air and convective heat transfer loss was also considered. The numerical simulation data was then compared with the experimentally measured data. The results of this study reveal that the FE model was able to predict the angular distortion in welds to a reasonable extent, the fidelity of which can be further increased if temperature dependent property, filler metal addition and multilayer weld deposition are also taken in account.

Analysis of Multi-Pass welding by using design of experiment on the maintenance of ASTM A131 Grade A steel

RESUMO O estudo consiste na análise da relação entre a soldagem multipasse e os valores de corrente elétrica utilizada na soldagem de manutenção de um aço ASTM A 131 grau A. Por meio do processo de soldagem de eletrodo revestido e um delineamento experimental buscou-se identificar quais os fatores mais influentes e se existe relação entre os fatores estudados. Entre os principais resultados, a zona afetada pelo calor das amostras atravessou a espessura da chapa, entretanto os valores de dureza para as extremidades afetadas demonstraram dureza idêntica ao metal de base. Para uso em uma situação de reparo, a configuração mais indicada seria a configuração com dois cordões de solda do CP4 (1,15 kJ/mm e 1,37 kJ/mm) por apresentar os menores valores de microdureza na junta soldada.

Characterization of nanoscale precipitates and enhanced mechanical properties of high strength weld metals containing Cu additions after PWHT

In order to match rapidly development of high strength low alloy steels, the new metal cored wire contained copper was designed. The multi-pass weld metals were obtained by gas metal arc welding. Results show that microstructure of weld metals is bainite with M-A constituents, and there are nano-9RCu precipitates after PWHT. The weld metal as welded achieves 737 MPa of yield strength (YS) and 1097 MPa of ultimate tensile strength (UTS), with an elongation 8%. After PWHT, the YS and UTS are 725 MPa and 968 MPa, respectively, and elongation increases to 16%. The lower dislocations density and reduction of Cu element at solid solution state hence for the decrease of YS. As well, the nano-Cu precipitates and reduction of effective grain size make it increase. The combined effect of these factors makes YS decrease by only 12 MPa after PWHT. Besides, a good impact performance (46.6 J) can be obtained after PWHT, while it is only 27.7 J of weld metals as welded. The improved toughness of weld metals after PWHT is obtained by the contributions of finer effective grain size, soft bainite, and dispersed nano-9RCu precipitation. The nano-Cu precipitates can improve strength without damage to toughness of weld metal after PWHT.

3D Computational Welding Mechanics applied to IN625 Nickel-Base Alloy

Design for sustainability asks for higher and higher performance materials and enhanced techniques devoted to realizing their joints. For advanced applications, the emphasis is on high-temperature strength, long-term creep life, phase stability, oxidation resistance, and robust and flexible welding processes. In this scenario, Ni-based superalloy Inconel 625 is successfully used for mechanical components operating at high temperatures and stresses, conditions that however may cause surface cracks. In the frame of circular economy, fusion welding is therefore used as a convenient repairing technique, as well. However, correct process parameters avoiding metallurgical and mechanical defects need to be known for each case-study. Computational welding mechanics is a proper tool used to avoid expensive trials, provided that the used numerical model can capture the main phenomena involved in welding process. In this work, a 3D numerical model of Inconel 625 multi-pass welding process is developed and validated through residual stresses X-Ray diffraction measurements. The model showed a good accuracy and was therefore proved to be a powerful tool for welding process design of such alloy.

Dissimilar joining of different grades of ferritic stainless steel: A review

In the recent times the power of the industry standard materials has gained a lot with the advancement in technology. To run the power plants at a required temperature and pressure, the demand for the material with high strength, high thermal conductivity and high corrosion resistance increased significantly. The large number of materials that are mostly used in power plants which are operating at high temperature and high pressure are creep strength enhanced steels, nickel based alloys and austenitic stainless steels. To fulfill and to satisfy the strength requirements, lower cost investment and service conditions, dissimilar welding between Stainless steels is required. And here we can see how important is the need joining dissimilar metals in such cases. A successful joining of two dissimilar metals is as strong as the weaker of the two metals being joined using different welding techniques, i.e., having enough and sufficient tensile strength and ductility so that the joint will not fail in the weld. These joints can be used in a variety of different metals and by several welding processes. The filler material and both metals need to be evaluated before choosing the best way to connect the metals. Here the welding process done between steels is TIG welding. Challenges in the current research are to join the different materials without disturbing the properties of parent metals. Some of the frequently occurring problems are: wider HAZ (heat affected zone), Difference in coefficient of thermal expansions, Difference in chemical composition, Multipass welds to weld high thickness materials. Current research deals with the Optimization the TIG Welding Process Parameters using RSM (Response surface Methodology) and To Understand the effect of Process Parameters on Mechanical Characteristics of the dissimilar joints and to carry out Numerical Investigation on the dissimilar welding of Ferritic Stainless Steel by joining the different materials using tungsten inert gas welding.

The effect of joint configuration on residual stress and distortion of the 304 stainless steel multi-pass welded joints

With the increasing of the dimension of engineering structures, the application of multi-pass welding is increasing. In this paper, numerical simulation of a thick plate’s multi-pass welding process is carried out based on thermal elastic-plastic FEM, MSC. Marc software is used. The influence of plate thickness and joint configuration on welding distortion and residual stress is investigated. The results show that once other parameters are fixed, the thicker the plate, the larger the welding residual stress. Double V-groove joint has apparent refraining effect on transverse residual stress, while its influence on longitudinal stress is slight. For the compressive stress of the structure’s bottom surface, double V-groove joint is better; while for the tensile stress of the structure’s top surface, V-groove joint is better. The distortions of cross-sections increase with the increase of the plate thickness. Using double V-groove joint cannot only refrain the angular deformation of the multi-pass welded plate effectively, but also refrain its longitudinal deformation.

Welding distortion prediction and mitigation in thick steel plate structures on ships

ABSTRACT In the ship fabrication process, welding distortion will affect the dimension accuracy. In this paper, an industrialisation prediction method for thick steel plate structures on ships is proposed based on a combination of thermal-elastic-plastic finite element method and inherent deformation theory to reduce the welding distortion in the design stage, and its applicability is verified through a comparison of measurements in the shipyard and numerical simulations. The thick plate models produced by multi-pass welding technology are selected to analyse the welding distortion. The results show that the numerical prediction results are in good agreement with the measurement on site. The transverse bending distortion is the main factor that affects the fabrication accuracy. To mitigate welding distortion, the influence of welding sequence and flame heating is examined. This research may provide a macro concept for understanding the distribution characteristics of welding distortion and serve as a mitigation reference for manufacturing engineers.

Strength mismatch effect on residual stress of 10CrNi3MoV steel considering the back-chipping process

The paper investigates the Welding Residual Stresses (WRS) of 10CrNi3MoV high strength steel multipass butt welded joints by experimental measurement and numerical calculation considering the effects of weld metal strength mismatch and back-chipping processing. Firstly, a thermo-metallurgical-mechanical simulation model was developed incorporating the Effect of Solid-State Phase Transformation (SSPT) to obtain multipass welding residual stress distributions after the back-chipping processing for evenmatched filler material. Phase transformation modeling of diffusionless transformation kinetics based on the Koistinen-Marburger formula was performed by a user subroutine implemented in ABAQUS. Additionally, strain transformation calculation due to volumetric and heating change during the SSPT was completed by the user-defined subroutine. Then, the effects of weldment mismatch and back-chipping processing on WRS for the multipass welds were analyzed. Comparing the calculated residual stress results (with and without consideration of SSPT) with experimental data shows that more accurate WRS predictions are obtained when the SSPT effect is incorporated in the simulation procedure. For evenmatched welded joints, the compressive WRS were distributed in the top and back weld layer due to the involvement of SSPT behavior. While the considerable tensile WRS in undermatched weldments was obtained without considering the SSPT, the magnitudes were lower than those in Heat Affected Zone (HAZ). The proposed finite element model can predict the WRS of high-strength steel multipass welded joints and provide a theoretical basis for conducting the structural integrity assessment.

Large-Scale Welding Process Simulation by GPU Parallelized Computing

The computational design of industrially relevant welded structures is extremely time consuming due to coupled physics and high nonlinearity. Previously, most welding distortion and residual stress simulations have been limited to small coupons and reduced order (from three-dimensional [3D] to two-dimensional [2D]), or inherent strain approximations were used for large structures. In this current study, an explicit finite element code based on a graphics processing unit was utilized to perform 3D transient thermomechanical simulation of structural components during welding. Laser brazing of aluminum alloy panels as representative of automotive manufacturing scenarios was simulated to predict out-of-plane distortion under different clamping conditions. The predicted deformation pattern and magnitude were validated by laser scanning data of physical assemblies. In addition, the code was used to investigate residual stresses developed during multipass arc welding of a nuclear industry pressurizer surge nozzle and subsequent welding repair where a 3D simulation was necessary. Taking the experimental data as reference, the 3D model predicted better residual stress distribution than a typical 2D asymmetrical model. Stress evolution in welding repair was also presented and discussed in this study. The efficient numerical model made it feasible to use integrated computational welding engineering to simulate welding processes for large-scale structures.