Weld Material Research Articles

Inhomogeneous flow stresses in FSW jointed aluminum alloy sheets inversely identified by FE-VFM

Inhomogeneous plastic flow stresses are identified for the friction stir welded aluminum alloy 6061-T6 sheets using a new finite element-based virtual fields method (FE-VFM). The FE-VFM is an enhanced virtual fields method developed based on the formulations in a common FE scheme. In the present study, the following novel numerical schemes are newly adopted in the FE-VFM: (1) a two-step identification process, (2) partitioning of the whole domain of interest with an interpolation of the constitutive parameter within each subdomain, and (3) the normal distribution type virtual fields. The non-uniform stress method (nUSM) is also considered for comparison. Before applying the developed method to a real experiment, the FE-VFM is verified via numerical feasibility tests using ideal deformation data of the FE simulations conducted with the artificially generated target welding materials. The feasibility tests show that the proposed FE-VFM can calculate the inhomogeneous flow stresses of the welded aluminum sheets with reliable accuracy. In the experimental applications, plastic properties measured by FE-VFM and nUSM are compared in terms of the distributions of yield stress, uniform elongation, and ultimate tensile tests. Also, identified inhomogeneous flow stresses are validated by simulating the two tensile tests loaded parallel and perpendicular to the weld line. The validation reveals that the proposed FE-VFM can give more accurate measurements over the nUSM owing to its ability to capture the mechanical properties in the narrow thermo-mechanically affected zone (TMAZ).

STRUCTURAL-PHASE STATE AND METAL FRACTURE SURFACE OF WELDS MADE WITH THE USE OF NEW MATERIALS BASED ON TECHNOGENIC RAW MATERIALS

The structural-phase state and the metal fracture surface of 09G2S steel welds made using new welding materials based on technogenic raw materials of metallurgical production (silica manganese slag and aluminum electrofilter dust) were studied by scanning and transmission electron microscopy methods. The production of welded joints was carried out in laboratory conditions using welding wire of the Sv-08GA brand on the equipment of the scientific and production center "Welding Processes and Technologies" of SibSIU. Quantitative analysis of the parameters of the structure and dislocation substructure of the weld metal was performed, using the equipment of the Institute of High-current Electronics SB RAS (Tomsk). The contributions of scalar and excessive dislocation density to the strength of the weld metal are estimated. It is established that the main metal phase of the studied welds (regardless of the introduction of the additive) is a solid solution based on α-iron (ferrite, BCC crystal lattice, α-phase). In addition to α-iron, particles of iron carbide (cementite) and (mainly in the sample without additives) iron silicide of the composition Fe3S are present in the weld metal. Analyzing electron microscopic images of the structure of the weld metal, it was noticed that the narrowest contours are formed at the interfacial boundaries of the inclusion – matrix. Such inclusions detected by transmission electron microscopy methods may be cementite particles located in the volume and at the boundaries of ferrite grains, and iron silicide particles of rounded (spherical) shape located in the volume of ferrite grains. It is revealed that the inclusions of the second phase present in the weld metal are stress concentrators and can be centers of microcrack nucleation under mechanical action on the material.

Особливості зварювання висококонцентрованими джерелами нагрівання міцних сплавів на основі алюмінію і берилію (Огляд)

Automatic Welding, 2022, №12. Journal «AVTOMATICHESKAYA SVARKA» Monthly scientific-technical and production journal. ISSN: 0005-111X, Since 1948. Russian version of «The PATON Welding Journal» Text in Russian, contents and summaries in English. The Journal presents a wide range of scientific-technical and promotion information in the field of technologies, equipment and materials for welding, surfacing, brazing, and deposition of protective coatings.

Зміцнення зварних конструкцій зі сталі 25ХГНМТ обробкою імпульсним бар’єрним розрядом

Automatic Welding, 2022, №12. Journal «AVTOMATICHESKAYA SVARKA» Monthly scientific-technical and production journal. ISSN: 0005-111X, Since 1948. Russian version of «The PATON Welding Journal» Text in Russian, contents and summaries in English. The Journal presents a wide range of scientific-technical and promotion information in the field of technologies, equipment and materials for welding, surfacing, brazing, and deposition of protective coatings.

Вплив термічної обробки на підвищення механічних властивостей зварних з’єднань економнолегованого титанового сплаву Ti–2,8Al–5,1Mo–4,9Fe

Automatic Welding, 2022, №12. Journal «AVTOMATICHESKAYA SVARKA» Monthly scientific-technical and production journal. ISSN: 0005-111X, Since 1948. Russian version of «The PATON Welding Journal» Text in Russian, contents and summaries in English. The Journal presents a wide range of scientific-technical and promotion information in the field of technologies, equipment and materials for welding, surfacing, brazing, and deposition of protective coatings.

Основні напрями досліджень і розробок у галузі зварювання наукових центрів та провідних виробників зварювальної техніки

Automatic Welding, 2022, №12. Journal «AVTOMATICHESKAYA SVARKA» Monthly scientific-technical and production journal. ISSN: 0005-111X, Since 1948. Russian version of «The PATON Welding Journal» Text in Russian, contents and summaries in English. The Journal presents a wide range of scientific-technical and promotion information in the field of technologies, equipment and materials for welding, surfacing, brazing, and deposition of protective coatings.

Отримання паяних з’єднань з нітинолу (Огляд)

Automatic Welding, 2022, №12. Journal «AVTOMATICHESKAYA SVARKA» Monthly scientific-technical and production journal. ISSN: 0005-111X, Since 1948. Russian version of «The PATON Welding Journal» Text in Russian, contents and summaries in English. The Journal presents a wide range of scientific-technical and promotion information in the field of technologies, equipment and materials for welding, surfacing, brazing, and deposition of protective coatings.

Корозійна тривкість плазмових покриттів на основі композиційних порошків з інтерметалідом FeAl

Automatic Welding, 2022, №12. Journal «AVTOMATICHESKAYA SVARKA» Monthly scientific-technical and production journal. ISSN: 0005-111X, Since 1948. Russian version of «The PATON Welding Journal» Text in Russian, contents and summaries in English. The Journal presents a wide range of scientific-technical and promotion information in the field of technologies, equipment and materials for welding, surfacing, brazing, and deposition of protective coatings.

Зварювання алюмінієвого сплаву Д16 плавким електродом з мікролегуванням металу шва

Automatic Welding, 2022, №12. Journal «AVTOMATICHESKAYA SVARKA» Monthly scientific-technical and production journal. ISSN: 0005-111X, Since 1948. Russian version of «The PATON Welding Journal» Text in Russian, contents and summaries in English. The Journal presents a wide range of scientific-technical and promotion information in the field of technologies, equipment and materials for welding, surfacing, brazing, and deposition of protective coatings.

The Effect of Tool Rotation on Structure and Mechanical Properties in Friction Stir Welding Of Aluminum AA5052

Abstract: Welding of aluminum alloy materials is often used in the industrial world, including those engaged in shipping, aircraft, and others. The welding method used to bind aluminum materials is Friction Stir Welding (FSW). Friction Stir Welding (FSW) is a simple welding method, namely by utilizing the heat energy generated from the friction of the shoulder tool with the material being welded. This study aimed to determine the effect of tool rotation on the physical and mechanical properties of Friction Stir Welding of Aluminum AA5052. The material used in this study was aluminum with the series AA5052 as the primary material. The friction stir welding process was carried out using CnC milling with parameters of the tool rotation speed of 1000, 1200, and 1500 rpm and a feed rate of 25 mm/minute. Physical analysis was carried out using macro photo observations with a USB Digital Microscope and microstructural observations with optical metallography. Mechanical observations were carried out using tensile testing and hardness testing. The microstructure in the weld nugget area shows good results with fine and dense grains that occur due to the dynamic recrystallization process. The highest tensile strength is 102.49 MPa in the 1000 rpm parameter. This is due to the material mixing process and good heat transfer.

Development of 16Cr8Ni low transformation temperature welding material for optimal characteristics under various dilutions due to all repair welding positions

A new low transformation temperature (LTT) welding material 16Cr8Ni was developed to satisfy the optimal characteristics in diluted welds due to all repair welding positions. Its good weldability for all welding positions was tested. The measured Ms temperature of weld metals with different dilutions was between 150°C and 250°C which is the optimal range for compressive residual stress generation and fatigue life extension. The in-situ observation of phase evolution by the synchrotron-based X-ray diffraction technique validated the solidification mode of LTT welds for the prevention of solidification cracks. Moreover, the mechanical properties in the diluted LTT welds were measured by miniature uniaxial tensile tests. Large compressive residual stresses at the welded joints due to all welding positions were confirmed numerical analyses.

Larson Miller Parameter for the Prediction of the Creep Life of Unweld and Welded P91 Steel

For structural components that operate at elevated temperatures, martensitic P91 steel is preferable. It is widely used in steam generators in the fossil-fired thermal and nuclear power generation sectors due to its creep endurance and corrosion resistance. Several creep laws, such as Monkman-Grant, Theta project, Wilshire and Sinh model, Omega technique, and the Larson Miller Parameter (LMP), have been developed over time to predict and failure of materials susceptible to the creep phenomenon. However, only the Omega Law and Larson-Miller Parameter are the only two methods approved in API 579-1. In this work, the creep test for welded and unwelded P91were conducted at temperatures of 600°C under stresses of 165, 175 MPa, and 190 MPa. In comparison to the welded specimens, the unwelded specimens displayed a continuously more substantial development of creep strain with time, resulting in a higher steady-state creep rate and a shorter rupture life. The increased magnitude of creep-rupture data has been observed to impact the dependability of creep life. Because of more significant changes in service temperature and stress conditions, the dependability of P91 steel has deteriorated, as well as an increase in creep life. The rupture life has been predicted using the LMP method, which utilizes the constant C parameter. At the same stress, the predicted creep life for weld material shows a higher value than that of the parent material, which is consistent with the experimental result.

Synthetical effect of material inhomogeneity and welding defects on fatigue behavior of 2205 duplex stainless steel cruciform welded Joints: Experiments and Life-prediction model

This paper performed experimental and analytical investigations on the synthetical effect of material inhomogeneity and welding defects on the fatigue behavior of 2205 duplex stainless steel cruciform welded joints. A series of experiments were performed, including microstructure characterization by the electron back-scattered diffraction, fatigue mechanical tests assisted by digital image correlation technique and fracture morphology observations by scanning electron microscope. Results show that fatigue life and failure location of cruciform welded joints depended heavily on their geometric configurations for lower cyclic amplitudes. However, with the elevation of loading, material inhomogeneity played a greater roles, leading to the change of fatigue failure mode with both geometric configuration and cyclic stress amplitude. To quantize the effects of welding defects and material inhomogeneity, a modified structure strain method was proposed by considering the heterogeneous plastic properties, to accurately predict both fatigue lifetime and failure location of cruciform welded joints at both low and high cycles fatigue. Lastly, a damage tolerance-based fatigue design method was discussed to guide the highly-reliable manufacture and damage detection of duplex stainless steel cruciform welded joints in the engineering.

Predicting residual stress in a 316L electron beam weld joint incorporating plastic properties derived from a crystal plasticity finite element model

Electron beam welding is an advanced joining technique which induces narrow weld region with minimal heat affected zone and weld-induced distortion. This reduces residual stresses in the joints which can be detrimental to structural performance of components in safety critical industries. Being an autogenous process, electron- beam welding generates a highly textured, columnar microstructure in the weld zone which have distinct properties when compared to the parent material region. Determining mechanical properties of the weld material assists in accurate assessment of the joint. However, extracting weld material specimens to determine plastic properties becomes increasingly cumbersome in thinner weld joints. An alternate approach has been demonstrated in this work wherein mechanical properties were derived using the weld microstructure in a crystal plasticity finite element (CPFE) framework. The initial calibration of the CPFE parameters was done using experimental data from thick weldment. These calibrated values were used to obtain the elastic and elastic-plastic properties of thinner weld materials by deforming corresponding synthetic microstructures whose attributes were determined by Electron Backscatter Diffraction analysis. The resultant properties were incorporated in a finite element (FE) based weld simulation to determine the residual strain. These results were compared with the residual strain data obtained using X-ray diffraction and good agreement was observed.

Weld toe versus root fatigue failure mode and governing parameters: A study of aluminum alloy load-carrying fillet joints

In load-carrying fillet welded connections, two fatigue failure modes are possible i.e. weld toe cracking and weld root cracking. The fatigue life associated with weld root cracking is typically much lower than weld toe cracking, exhibiting a wider scatter band, especially for welded aluminum alloys. This paper examines fatigue failure mode transition behaviors in load-carrying fillet welds made of aluminum and their governing parameters, among plate thickness, weld penetration, joint misalignment, weld material, and ultrasound impact peening(UIP). Through both experimental and theoretical studies, a quantitative fillet weld sizing criterion was proposed for avoiding weld root cracking in fillet-welded aluminum connections.

AISI 2205 DSS for body-in-white automotive structure: effect of welding current and time on the performance of spot welded joint

Duplex stainless steel is an ideal candidate in the automotive sector leading to a significant weight reduction and enhancement in product safety. In the present work, two major influencing process parameters i.e. welding current and welding time have been considered to investigate the mechanical and metallurgical performance of resistance spot welded duplex stainless steel. Other important process parameters, such as electrode force, squeeze time and hold time have been kept constant throughout the process. Results show that tensile shear strength (TSS) increases with an increase in welding current as well as welding time due to more amount of heat generation at interface. However, excessive value of both results in the expulsion of weld material which significantly alters the nugget diameter and cause decrease in TSS. Moreover, the failure mode is changed from interfacial failure (IF) mode to pull-out failure (PF) mode at the higher value of welding current and time. Microstructural observation reveals that the fusion zone (FZ) is consisted of columnar grain structure, whereas heat affected zone (HAZ) contains equiaxed grain structure. Furthermore, the phase balance of austenite and ferrite is completely disturbed in the FZ and HAZ.

Microstructure and mechanical properties of welded joints between nickel base alloy and 10Ni5CrMoV steel by MIG welding

• Welding of 10Ni5CrMoV steel using nickel-based alloy as filler metal. • The welding process adopted MIG welding and provided suitable welding parameters. • ERNiCrMo-4 had lower toughness, strength and higher hardness than ERNiCrMo-3. • The different precipitates will affect the mechanical properties of the weld. In order to solve the problem of cold cracks in welding of high strength steel with large thickness, austenitic stainless steel welding materials are usually selected in the industry, but there are few researches on the application of other austenitic welding materials such as nickel-based welding materials. In this paper, Metal Inertia Gas(MIG) welding was used to weld two typical nickel-based alloys (ERNiCrMo-3 and ERNiCrMo-4) with different contents of solid solution strengthening elements and 10Ni5CrMoV high-strength steel. The results showed that the welded joints of the two welding wires were well formed without obvious welding defects. In the impact toughness test, the average values of ERNiCrMo-3 and ERNiCrMo-4 welds at 73K were 134J and 96J respectively, while in the impact test of other parts, ERNiCrMo-3 was also higher than ERNiCrMo-4. In the tensile test, the tensile strength of both can reach 877MPa and 858MPa. In terms of precipitates, ERNiCrMo-4 containing more solid solution strengthening elements precipitated more TCP phase, which reduced the impact toughness of the weld to a certain extent. In the hardness test, it also proved that the hardness of ERNiCrMo-4 weld with more brittle and hard precipitates was higher. Overall, ERNiCrMo-3 welding wire has more advantages in welding large thickness 10Ni5CrMoV steel.

Determination of self-adaptive slip rate at tool/workpiece interface in numerical model of friction stir welding

As a key parameter affecting the heat generation and the interface material velocity, the interface slip rate is a prerequisite for numerical simulation of friction stir welding of lightweight materials. The contact state on the tool/workpiece interface is related to friction stress and material yield strength, and a new calculation method of the self-adaptive interface slip rate was established. The interface velocity of material flow, heat generation due to friction and plastic deformation near the tool and temperature distribution were analyzed quantitatively. The calculated self-adaptive interface slip rate has a wider range than the previous used one, from a sticking dominant for the material near the inner part of the shoulder to a sliding dominant for the material near the edge of the shoulder. With application of this improved method determining the slip rate, the material flow velocity at the tool/workpiece interface is roughly in a "M" shape, which first increases and then decreases as the radial distance rises, and the maximum interfacial material velocity no longer appears at the shoulder edge. The experiments were made to validate the method. The slip rate distribution at tool/workpiece interface in (a) Previous mode; (b) Improved mode.

Optimization of process parameters for induction welding of composite materials based on NSGA-II and BP neural network

In this paper, a process parameter optimization method of induction heating temperature field was proposed, in which finite element simulation as data supply, back-propagation (BP) neural network as data prediction, and non-dominated sorting genetic algorithm II (NSGA-II) as data optimization. Firstly, the electromagnetic-thermal coupling analysis in COMSOL was used to calculate the temperature field of the welding interface of electromagnetic induction welding of CF/PEEK composites, and the temperature data of each point of the welding interface was obtained. Then, the BP neural network model based on the L-M algorithm was established to predict the temperature field of the welding interface, and train and test the established neural network model, got a prediction model that reasonably reveals the welding process parameters and the temperature field relationship of the welding interface. Then, the multi-objective optimization algorithm NSGA-II was used to optimize the design of welding process parameters, and according to the thermal properties of polyetheretherketone (PEEK) resin, based on the crowding calculation and combined with the priority solution analysis method, the priority solution non-dominated sorting genetic algorithm (pNSGA-II)was proposed. Finally, a set of process parameters was obtained that satisfies the optimal heating effect of the weld interface.

Analysis of Hydro Test Pressure Variations on A106 Grade B Carbon Steel Pipe Welded Joints with Welding Repair Method

Transportation of oil and gas through oil refinery pipelines is faced with problems, including corrosion problems. Corrosion is a natural phenomenon that occurs in metal materials, where corrosion is a process of material damage due to chemical or electrochemical reactions with its environment. The purpose of this study is the results of the analysis of HydroTest pressure variations on the Welding Joints of Carbon Steel Pipes (carbon steel) A106 Gr.B. In the study did not discuss the occurrence of corrosion and other tests, while the welding process in detail was shown in WPS. This experimental research method uses the Welding Repair Method on welded joints according to the ASME IX, ASME B31.3 standard. The research material is A106 GR carbon steel pipe. B is in the form of a U Tube Seal Deck that has undergone corrosion and damage, where later the fabrication process (pipe repair) especially welding (using SMAW and GTAW) has been determined in PQR and WPS (WPS / CS / EM / ASME / WPxxx). The focus of this research is on stage 9 (hydro testing stage) of the Welding Repair method. Free variables in pressures of 240 Psi, 435 Psi, 690 Psi, and 910 Psi, which have been planned based on the thickness and length of the Pipe joint. Variable fixed temperature test Hydrotest 28OC, holding time holding time (pressurizing) 10 minutes and holding time peak 60 minutes before (depressurizing). The results were obtained that the pressure change was divided into two stages, pressurizing with the highest pressure of 915 Psi is the 4th pressure variation this was obtained from the test observation that there were no leaks in the welded joints and pipe materials in accordance with the acceptance criteria. While the second stage is (depressurizing) with a decrease in pressure or called realese, where successively realese 100%, 75%, 50%, 25%, and 0% at pressures of 915 Psi, 690 Psi, 435 Psi, 240 Psi, 0 Psi with the results of no leakage and observation test results in accordance with the acceptance criteria. So it can be concluded that the welded joints of carbon steel pipes tested using hydrotest, no deformation occurs, there is no change in shape and there are no leaks in the welded joint layer of A106 Gr.B carbon steel pipe