Search

Carbon and low-alloy steel plates clad with stainless steel or other metals are a good choice to meet the demand for cost-effective materials to be used in many corrosive environments. Numerous technical solutions are developed for the production of clad steel plates, as well as for their joining by fusion welding. For thick plates, a careful strategy is required in carrying out the multiple passes and in choosing the most suitable filler metals, having to take into account the composition of the base metal and the cladding layer. The specificity of the different processes and materials involved requires an adequate approach in the study of the metallurgical characteristics of clad steel, thus arousing the interest of researchers. Focusing mainly on ferritic steel plates clad with austenitic steel, this article aims to review the scientific literature of recent years which deals with both the production and the fusion welding processes. The metallurgical issues concerning the interfaces and the effects of microstructural characteristics on mechanical behaviour and corrosion resistance will be addressed; in particular, the effects on the fusion and thermally affected zones that form during the fusion welding and weld overlay processes will be analysed and discussed. [ABSTRACT FROM AUTHOR]

Photic retinopathy (PR) is due to retinal phototoxicity, especially affecting the macula, resulting from exposure to sun, welding devices and lasers. It leads to oxidative damage to the retinal pigment epithelium (RPE) and the surrounding photoreceptors. Early recognition of this visual threatening condition, follow-up lesion evolution, and prevention of prolonged ocular exposure to lights is warranted. We herein report the three principal types of retinal burns due to solar retinopathy, laser pointer-induced maculopathy and arc welding maculopathy. [ABSTRACT FROM AUTHOR]

Welding processes are widely used technologies in the industrial context for creating permanent connections between mechanical components. This popularity is due to their versatility, which arises from the numerous available process variants and the multiple advantages they offer compared to other joining techniques. In the manufacturing context, where devices often operate in extreme conditions, the quality of welds becomes a critical factor in ensuring the safety and reliability of the manufactured products. Furthermore, a sound joint requires careful compliance with the increasingly stringent design specifications demanded by customers who require industry-standard conformity in order to achieve defect-free, robust, and durable welds. To address these needs and to define the optimal roadmap for the investigated process condition, an experimental investigation was conducted on the submerged arc welding process. The experimental trials involved butt joints of ASTM A516 Gr.70 carbon steel plates with different thicknesses in a flat position, utilizing a U-shaped chamfer and a multi-pass welding technique. For each weldment, the effects of the main process parameters on the qualitative characteristics of the manufactured products were evaluated from a metallurgical perspective. This evaluation included an in-depth metallographic analysis of the heat-affected zone of the carbon steel joint and involved both the measurement of the dimensions of these areas as well as the amount of ferrite and pearlite that resulted as the phases observed in the final microstructure of the steel joint following its solidification. Furthermore, the joint quality was assessed with regard to mechanical strength through hardness measurements. By analysing the experimental data, the paper provides a valuable contribution for increasing the productivity of the investigated welding process, while simultaneously meeting the specified industrial quality requirements for the products made of medium-thickness carbon steels. [ABSTRACT FROM AUTHOR]

This study aims to investigate the effect of the laser beam overlap rate on the mechanical properties of Al3003 aluminum alloy arc weldment with laser peening. To determine the optimal laser beam overlap rate for laser peening of the weldment, peening experiments were conducted on bead-welded and butt-welded specimens with varying overlap rates, and the effect of the beam overlap rate was analyzed. As the overlap rate increased, the residual stress changed from tensile to compressive, with the highest level of compressive residual stress at the overlap rate of 75%. Laser peening was performed on the aluminum weldment of the prototype, applying the optimal peening conditions identified earlier. As a result of comparing the residual stress, hardness, and tensile strength of the weld before and after laser peening, it was found that the tensile residual stress in the weldment was improved to a compressive residual stress of about −50 MPa or more. The hardness and tensile strength of the weld increased after peening, and the mechanical properties were also improved. [ABSTRACT FROM AUTHOR]

The stability of the arc in arc welding processes is primarily relevant to the joint quality. However, the influencing factors which determine the arc stability are still partly unknown. Combining arc welding with laser welding enhances arc stability. The laser-induced metal vapor is often named as one stabilizing factor. But this contradicts the presumptions of arc welding researchers who mentioned the metal vapor as a destabilizing factor especially when high amounts are present in the arc. This investigation analyzes the specific influence of metal vapor on arc conductivity as one aspect of arc stability by producing metal vapor using a laser process on a separately placed substrate material. Furthermore, the arc current was varied at a constant metal vapor amount. The investigations show that the metal vapor presence increases the arc voltage by at least 20% and its fluctuation amplitude by at least 51% which was presumed to mean a decreased electrical conductivity and therefore decreased arc stability. The arc instability was lower for higher arc currents at constant metal vapor amounts. Therefore, higher arc currents increase the arc stability of welding arcs in the presence of a constant metal vapor amount. [ABSTRACT FROM AUTHOR]

The effect of local high-speed intense dynamic action by a metal object (indenter) on the change in the structure of weld metal of high strength alloy steel welded with austenitic flux-cored wire with nitrogen is studied. It is established that after welding the weld metal structure consists of austenite and delta-ferrite (3 vol. %) with microhardness HV0.1 200–250. After intense dynamic action weld metal is strengthened by a γ → ε → α' mechanism due to work hardening and formation of deformation within the structure of α'-martensite in an amount of 10 vol.% and a small amount of ε‑martensite while maintaining the original amount of δ‑ferrite, and with an increase in microhardness by more than 1.7 times from the initial level. [ABSTRACT FROM AUTHOR]

Currently, the strength of hot-press-forming steel has been increased to produce lightweight vehicles, and in this study, the first arc welding investigation on a 2.0 GPa-strength hot-press-forming steel was conducted. Hot-press-forming steel sheets with thicknesses of 1.1 mm were butt-welded by gas tungsten arc welding without a filler metal, with the heat input controlled in the range of 140-260 J/mm. The weld metal, coarse-grained heat-affected zone (HAZ), and fine-grained HAZ had martensitic microstructures. The softened zone was composed of an intercritical HAZ (with polygonal ferrite and martensite/bainite) and a subcritical HAZ (with tempered martensite). The intercritical HAZ was softened the most during welding and fractured during tensile testing. The strengths of the arc welds were in the range of 1141-1264 MPa, which were 57-63% strength of the base metal. The equiaxed austenite on martensite or ferrite matrix was developed at the intercritical HAZ of gas tungsten arc welds, therefore transforming into the coarse martensite during quenching. However, the intercritical HAZ of laser welds indicated acicular austenite transforming into the fine martensite due to its high cooling rate. The intercritical HAZ softening was revealed to originate from carbon diffusion during the martensite to austenite transformation, which is unavoidable in arc welding and should be considered in the design of a welded structure. [ABSTRACT FROM AUTHOR]

Dissimilar welds between ferritic and austenitic steels represent a good solution for exploiting the best performance of stainless steels at high and low temperatures and in aggressive environments, while minimizing costs. Therefore, they are widely used in nuclear and petrochemical plants; however, due to the different properties of the steels involved, the welding process can be challenging. Fusion welding can be specifically applied to connect low-carbon or low-alloy steels with high-alloy steels, which have similar melting points. The welding of thick plates can be performed with an electric arc in multiple passes or in a single pass by means of laser beam equipment. Since the microstructure and, consequently, the mechanical properties of the weld are closely related to the composition, the choice of the filler metal and processing parameters, which in turn affect the dilution rate, plays a fundamental role. Numerous technical solutions have been proposed for welding dissimilar steels and much research has developed on welding metallurgy; therefore, this article is aimed at a review of the most recent scientific literature on issues relating to the fusion welding of ferritic/austenitic steels. Two specific sections are dedicated, respectively, to electric arc and laser beam welding; finally, metallurgical issues, related to dilution and thermal field are debated in the discussion section. [ABSTRACT FROM AUTHOR]

Arc magnetic field analysis is a valuable approach for assessing the stability of the arc welding process, yet existing methods lack the ability to effectively quantify the disorder within the process. Through an investigation into the characteristics of the arc magnetic field signal, it was observed that the occurrence of low-frequency random fluctuations in arc magnetic field power, induced by unstable factors such as bubbles or short circuits, contributed to increased complexity and randomness in the arc magnetic field signals. To visualise the arc magnetic field signals in a time-frequency domain, a spectrogram was employed, revealing a strong correlation between the distribution of maximum power spectral density (PSD) in the spectrogram and the stability of the arc welding process. Furthermore, a novel method based on sample entropy was introduced to provide a quantitative measure of this relationship. A comprehensive quantitative assessment indicator called arc magnetic field sample entropy (AMFSE) was proposed. This indicator effectively mitigates the influence of varying parameters on the quantitative results, enabling a more accurate and consistent representation of the stability of the arc welding process. The proposed method was validated through testing, yielding an accuracy rate exceeding 90%. [ABSTRACT FROM AUTHOR]

Purpose: The paper shows the problem of surface cracks from welding (TIG welding) to welding stainless steel pipe (heat-affected zone: HAZ). The study is an experiment of preparing welding with non-heating workpieces and preheating the workpiece using the principle of induction, heating with a fluid inverter circuit that can adjust power by frequency control, pulse frequency density modulation (PFDM) to maintain temperature for industrial. Design/methodology/approach: The control circuit is responsible for regulating the functioning of different devices and the speed of operation of the switch device. It divides the control into two closed loops: phase-angle feedback and current feedback. The phase-angle feedback loop ensures frequency tracking during the phase check angle, enabling the inverter to operate at frequencies higher than the resonant frequency throughout its operation. The process of arc welding was employed in the fusion of stainless-steel materials. Preheating is a crucial step in the welding process, as it serves to uphold the integrity of the weld and mitigate the occurrence of undesirable outcomes such as cracking and the subsequent requirement for rework. The Welding Process Specification (WPS) about the task at hand will delineate the lower and upper limits of preheating temperatures and the requisite period for preheating. Highquality products should be devoid of these imperfections and possess comprehensive welding reinforcement. Additional welding certifications encompassed a tensile testing procedure, a microhardness testing procedure, and a comprehensive microstructure analysis. Findings: Applying an alternating voltage to an induction coil generates an alternating current (AC) within the coil circuit. The induced currents exhibit a frequency identical to that of the coil current, although they possess an opposite direction to the coil current. These currents facilitate heat generation through the phenomenon known as the Joule effect. The temperature range of 250°C-400°C can be effectively regulated for preheating stainless steel by using high-frequency electric process heating in induction welding, hence achieving the desired welding preheat. There are two primary classifications for inverters: voltage-source inverters and current-source inverters. Research limitations/implications: The main research limitation is comparing preheat and non-preheat. The size of the heat-affected zones is influenced by the rate of heating and cooling brought on by machining processes. By influencing the microstructural changes in that area, precise control of the variables can impact the integrity of the weld zones. The microstructural characteristics of the metal are different from the rest of the subject because welding heats the metal. The topic is heated up beforehand to ensure smooth welding and structural integrity. Because there is less of a temperature difference between the weld zone and the base material, preheating during welding results in less shrinkage stress. Distortions and crack flaws might result from higher shrinkage stress. Practical implications: NDT, or non-destructive testing, is a weld integrity test to find defects that occur in the weld without damaging that welding line and continuing to use it safely. For the welding line to be strong according to the design of that welding line (conformance to design), the test will use the principles of physical properties, such as light, X or gamma rays, magnetic fields, and high-frequency sound waves. Originality/value: In the research, stainless steel was successfully welded to preheat using induction heating (IH). [ABSTRACT FROM AUTHOR]

In this study, the influence of W, Cr, and Mo on the microstructure and mechanical properties of the arc-welded interface of TiC cermet and low-carbon steel was investigated. MIG arc welding was employed to deposit muti-alloyed low-carbon steel flux-cored wire onto the surface of the TiC cermet to create the arc-welded interface. Analysis of the microstructure, phase composition, and shear fracture of the interface were conducted by OM (optical microscopy), SEM (scanning electron microscope), EMPA (Electron Probe X-ray Micro-Analyzer), and XRD (X-ray diffraction) methods. The results indicate that the order of influence on the performance of the welded interface is perceived as Cr > W > Mo. The preferred ratio of element content is W at 1.0 wt.%, Cr at 0.5 wt.%, and Mo at 2.0 wt.%. During the arc-welding process, W and Mo formed a rim structure of TiC particles to inhibit the dissolution of TiC particles, while Cr formed dispersed carbides in the bonding phase. The synergistic impact of these components resulted in the simultaneous enhancement of both the TiC particles and the bonding phase. This led to a significant increase in the shear strength of the TiC cermet welded interface to 787 MPa, marking an 83% improvement compared to the welded interface without reinforcement, which exhibited a shear strength of 430 MPa. [ABSTRACT FROM AUTHOR]

The current practice of reconstruction of oxidized turbine parts (due to hot corrosion) using arc welding methods facilitates restoration of the nominal shapes and dimensions, as well as other attributes and features. Intense development of 3D additive methods and techniques contributes to the repair/modification of different parts including gas turbine (GT) hardware. The article proves the viability of the concept of using a robotized additive arc welding metal active gas (MAG) process to repair and modify gas turbine diaphragms using different filler materials from the substrate. The industrialized robotic additive process (hybrid repair) shows that very good results were achieved if the diaphragm is cast of nickel-iron and the filler material for welding the passes is austenitic stainless steel (for instance 308 LSi). This is one of the novelties introduced to the repair process that was granted a patent (US11148235B2) and is already implemented in General Electric Service Centers. [ABSTRACT FROM AUTHOR]

The novel single-phase Cuk and Sepic power factor correction converter attracted toward arc welding application is highlighted in this paper. The preferred converter is outlined to function in DCM concealed by variations in load voltage and supply voltage to ensure better performance. The control strategy includes a voltage loop, which ensures arc welding process stability and improved input power quality. The designed system is validated with a hardware prototype of 100 W, 48 V, and Matlab/Simulink is used to simulate the arc welding power supply under different working conditions. The reduced input line total harmonic distortion of 1.527% with unity power factor is attained for the rated load in the investigational study. The experimental performance of the propounded converter is bestowed with operating conditions of AC mains (90–270 V) to cohere to the limits delineated by the IEC61000-3-2 standards. [ABSTRACT FROM AUTHOR]

SMAW (Shielded Metal Arc Welding) and GMAW (Gas Metal Arc Welding) are two of the most prominent welding processes commonly utilized in almost all types of modern industries. Among various aspects of these processes, some of the important parameters that govern the quality of the final weld product are the skill level of welders, welding consumables, and the role of shielding gases (in GMAW). Currently, the role of these parameters in determining the quality of the welded product is examined by evaluating the final weld produced and not by investigating how these factors affect the welding process. This is an indirect way to evaluate such welding parameters, which are both time-consuming and expensive. During the actual welding process, random variations in arc signals (voltage and current) take place. These dynamic variations are so short and rapid that ordinary ammeters and voltmeters cannot monitor the rate of such variations. However, the reliable acquisition of such variations and its subsequent analysis can provide very useful information in determining the quality of the final weld product. In this study, arc voltage and current were acquired at 100,000 samples/sec, filtered and subsequently analyzed using Continuous Wavelet Transform based on Fast Fourier Transform (CWT-FFT) technique to evaluate welding skill, welding electrodes (in SMAW process), and the effect of shielding gases (in GMAW process). Results thus obtained clearly differentiated the skill level of different trainee welders and welding electrodes in the SMAW process and the effect of shielding gases and arc current in the GMAW process. Very good correlation among the obtained results, its weld bead and its weld pool images were observed. Hence, this research proposes a simple yet effective methodology to evaluate the arc welding process parameters using CWT-FFT analysis of the welding signals. [ABSTRACT FROM AUTHOR]

This study aims to investigate the effect of the laser beam overlap rate on the mechanical properties of Al3003 aluminum alloy arc weldment with laser peening. To determine the optimal laser beam overlap rate for laser peening of the weldment, peening experiments were conducted on bead-welded and butt-welded specimens with varying overlap rates, and the effect of the beam overlap rate was analyzed. As the overlap rate increased, the residual stress changed from tensile to compressive, with the highest level of compressive residual stress at the overlap rate of 75%. Laser peening was performed on the aluminum weldment of the prototype, applying the optimal peening conditions identified earlier. As a result of comparing the residual stress, hardness, and tensile strength of the weld before and after laser peening, it was found that the tensile residual stress in the weldment was improved to a compressive residual stress of about −50 MPa or more. The hardness and tensile strength of the weld increased after peening, and the mechanical properties were also improved.

Carbon and low-alloy steel plates clad with stainless steel or other metals are a good choice to meet the demand for cost-effective materials to be used in many corrosive environments. Numerous technical solutions are developed for the production of clad steel plates, as well as for their joining by fusion welding. For thick plates, a careful strategy is required in carrying out the multiple passes and in choosing the most suitable filler metals, having to take into account the composition of the base metal and the cladding layer. The specificity of the different processes and materials involved requires an adequate approach in the study of the metallurgical characteristics of clad steel, thus arousing the interest of researchers. Focusing mainly on ferritic steel plates clad with austenitic steel, this article aims to review the scientific literature of recent years which deals with both the production and the fusion welding processes. The metallurgical issues concerning the interfaces and the effects of microstructural characteristics on mechanical behaviour and corrosion resistance will be addressed; in particular, the effects on the fusion and thermally affected zones that form during the fusion welding and weld overlay processes will be analysed and discussed.

An austenitic metal-cored wire (diameter – 1.6 mm) with additional nitrogen alloying (0.25–0.40 wt.%) was developed for this study. Mechanical tests and metallographic studies of the deposited metal and welded joints made with austenitic metal-cored wire (composition – Cr20Mn5Ni4Mo2.5Cu3N0.3) were conducted. It was found that the values of σu and σ0.2 of the deposited metal obtained by using the developed wire were 20 to 30% higher compared to the utilized electrode materials, while the ductility characteristics were preserved (δ = 43%). It was shown that the use of metal-cored wire (Cr20Mn5Ni4Mo2.5Cu3N0.3) for welding of high-strength steel 20HGSNM (EN 1.6523) makes it possible to obtain defect-free welded joints with austenitic-ferritic structure, which have 20% higher strength characteristics compared to the analogues. [ABSTRACT FROM AUTHOR]

In arc welding technologies, arc welding machines and robots are widely used, which require application of tracking systems to orient the electrode relative to the product. Systematization and analysis of various tracking systems and description of their features and advantages are relevant. Tracking systems applied in automatic welding machines use various feedback signals, but the most accurate are signals picked up directly from the welding arc, when it is used as the measuring system sensor. The main principles of obtaining the feedback signals in arc welding are considered exactly for these systems, and their analysis is performed. 11 Ref., 15 Fig. [ABSTRACT FROM AUTHOR]

The simulation modeling for CMT arc-welded joints using shell elements applicable to full vehicle crash analysis was developed for predicting fracture behaviors. A measuring method of mechanical properties in welding induced heataffected zone was proposed by applying simulated thermal cycles to ultra-high-strength steel. The peak temperature range of several simulated thermal cycles with furnace heating and enforced cooling was from 773 to 1073K, where material softening occurs. The stress triaxiality dependent fracture strain was obtained using tensile test results at two stress states. The predicted results by developed shell model agreed well with the experimental force-stroke history and fracture location. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Polytechnic is the property of Journal of Polytechnic and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Results are presented for studies of deposited metal and welded joints of high-strength medium-alloy steels made by austenitic type flux-cored wire with nitrogen developed by the authors. It is found that use of this wire makes it possible to increase the strength of deposited metal by 20–30% with simultaneous retention of good ductility indices. Within the joint metal structure in the central part, after welding high-strength alloy steel, an austenitic-ferritic structure is formed with a delta-ferrite content of ~3 vol.% by an AF type crystallization mechanism, and a small amount of lower bainite is also present. Weld metal microhardness varies in the range HV0.1 200–250. As distance from the joint metal center towards the fusion line increases the structure transforms with an increase in bainite content. At the fusion line the phase composition is g-phase in an amount of 44.7 vol.%, and α-phase in an amount of 51.8 vol.%, as well as carbides of the order of 0.5 vol.%. The structure within the fusion line is represented by large grains of austenite in the central part and lower bainite, which has carbides within the volume of the α-phase, and δ-ferrite, the amount of which remains unchanged (3 vol.%). In the heat-affected zone, the length of which is 2–2.5 mm, a structure forms that is a mixture of lower bainite and lath package martensite (the total content of the α-phase is 98.6 vol.%) with microhardness of HV0.1 400–550. Use of austenitic class flux-cored wire with nitrogen for welding high-strength alloy steels makes it possible to obtain defect-free welded joints with an austenitic-ferritic structure. [ABSTRACT FROM AUTHOR]

Ceramics are difficult to machine into complex shapes due to their high hardness and brittleness. In practical applications, ceramics often need to be jointed to themselves or metals. Traditional joining processes such as brazing and diffusion bonding are inefficient and costly, greatly limiting their practical applications. To solve the problems, current work explores the characteristics, applications, and prospects of unconventional and efficient joining techniques of ceramics. The joining processes are classified by heat sources, including resistance brazing, flash joining, laser welding/brazing, arc welding, and microwave joining. Additionally, current work provides solutions for resistance brazing of non-conductive ceramics, microwave joining of low dielectric loss ceramics, and laser welding of transparent ceramics. Among these techniques, USP laser welding is one of the most promising rapid joining techniques due to its ability to effectively reduce heat affected zone and residual stress. [ABSTRACT FROM AUTHOR]

In the wire and arc additive manufacturing technology, which involves melting and depositing metal wire materials by arc discharge, it is possible to use a wide variety of wire materials and change the composition locally. However, CuSn alloys with a high Sn content have poor ductility and are difficult to process into wires. In this study, we propose an accumulation method in which Sn wire is fed from the outside to the molten pool during the deposition process using a CuSn alloy wire with a low Sn content. This study investigated the relationship between wire feed rate and actual Sn content rate. Tensile and acoustic tests were conducted. Sn content of the additively manufactured materials was changed by varying the Sn wire feed rate. It was verified that Sn content influences the mechanical and acoustic characteristics of CuSn alloys.

The most challenging aspect of producing durable joints between titanium alloy and stainless steel (Ti/SS) is preventing the formation of brittle Ti–Fe intermetallic compounds, particularly the TiFe2 phase. In this paper, the interrupted pulsed arc welding (IPAW) was proposed to join TC4 and 304SS dissimilar metals. The joining mechanisms, microstructures and shear strength of the joints were investigated. The precise regulation of arc pulsed time in the millisecond range enabled the creation of a joint without the formation of the TiFe2 phase through contact reactive brazing. A Ti-rich reaction layer consisting of β-Ti and TiFe phases was formed in the brazing joint, and the shear strength of the joint reached 106.3 MPa. By increasing the arc pulsed current or time, the brazing joint was transformed into the fusion joint. The formation of two reaction layers was observed: Ti-rich phases (TiFe and β-Ti) near the TC4 and Fe-rich phases (TiFe2 and TiCr2) near the 304SS, which exhibited high brittleness. The presence of a high brittleness fusion zone resulted in immediate cracking post-welding.

Dissimilar welds between ferritic and austenitic steels represent a good solution for exploiting the best performance of stainless steels at high and low temperatures and in aggressive environments, while minimizing costs. Therefore, they are widely used in nuclear and petrochemical plants; however, due to the different properties of the steels involved, the welding process can be challenging. Fusion welding can be specifically applied to connect low-carbon or low-alloy steels with high-alloy steels, which have similar melting points. The welding of thick plates can be performed with an electric arc in multiple passes or in a single pass by means of laser beam equipment. Since the microstructure and, consequently, the mechanical properties of the weld are closely related to the composition, the choice of the filler metal and processing parameters, which in turn affect the dilution rate, plays a fundamental role. Numerous technical solutions have been proposed for welding dissimilar steels and much research has developed on welding metallurgy; therefore, this article is aimed at a review of the most recent scientific literature on issues relating to the fusion welding of ferritic/austenitic steels. Two specific sections are dedicated, respectively, to electric arc and laser beam welding; finally, metallurgical issues, related to dilution and thermal field are debated in the discussion section.

The possibility of using vibration technologies as an alternative to heat treatment, but having a shorter duration, low energy consumption, low capital costs and comparable efficiency, is substantiated. Priority areas of application of methods of vibration treatment of critical welded structures are highlighted: post-welding and related. The advantages and difficulties in the implementation of these methods are shown: the ability to control the efficiency of postwelding processing by changing the amplitude-frequency characteristics, increasing strength and plasticity and optimizing the geometric parameters of the weld, combining the processing time together with the welding production cycle with accompanying processing. Brief results of experimental work on the criteria of residual stresses and residual deformations for different types of welded joints, such as butt, T-bar and lap joints, and several groups of materials, such as aluminum alloys, carbon steels and stainless steels, are presented. The conclusion is made about the prospects of using post-welding vibration treatment for dimensional rigid, forming a closed contour, composed of their many parts and subassemblies of welded structures in assembly-welding special conductors or universal assembly devices, as well as about the initial reduction of residual deformations during concomitant vibration treatment of welded joints.

Arc welding is a thermal plasma process widely used to join metals. An arc welding model that couples fluid dynamic and electromagnetic equations was initially developed as a research tool. Subsequently, it was applied to improve and optimise industrial implementations of arc welding. The model includes the arc plasma, the electrode, and the workpiece in the computational domain. It incorporates several features to ensure numerical accuracy and reduce computation time and memory requirements. The arc welding code has been refactored into commercial-grade Windows software, ArcWeld, to address the needs of industrial customers. The methods used to develop ArcWeld and its extension to new arc welding regimes, which used the Workspace workflow platform, are presented. The transformation of the model to an integrated software application means that non-experts can now run the code after only elementary training. The user can easily visualise the results, improving the ability to analyse and generate insights into the arc welding process being modelled. These changes mean that scientific progress is accelerated, and that the software can be used in industry and assist welders’ training. The methods used are transferrable to many other research codes.

The current practice of reconstruction of oxidized turbine parts (due to hot corrosion) using arc welding methods facilitates restoration of the nominal shapes and dimensions, as well as other attributes and features. Intense development of 3D additive methods and techniques contributes to the repair/modification of different parts including gas turbine (GT) hardware. The article proves the viability of the concept of using a robotized additive arc welding metal active gas (MAG) process to repair and modify gas turbine diaphragms using different filler materials from the substrate. The industrialized robotic additive process (hybrid repair) shows that very good results were achieved if the diaphragm is cast of nickel-iron and the filler material for welding the passes is austenitic stainless steel (for instance 308 LSi). This is one of the novelties introduced to the repair process that was granted a patent (US11148235B2) and is already implemented in General Electric Service Centers.

A novel wire arc additive manufacturing process is proposed to produce porous metal (PM). The innovation is to convert harmful welding pore defects into a beneficial structure of PM, and then the PM parts can be additive manufactured layer by layer. Air was transferred to the molten pool as pore promoters to maximize the formation of the welding pore defects. The triple-wire indirect arc process was used for fabricating multi-layer parts to reduce interlayer filling. The primary advantage is that the process can directly produce macro-pore structures rather than depositing pore walls along micro paths in laser additive manufacturing. The uniform diameter of the pore ranges from 500 to 2700 μm, and the typical porosity is 64%, 49%, and 87%. The process could achieve a high deposition rate of 11.5 kg/h. Due to martensite formation, the pore walls can achieve high microhardness of over 200 HV.

The objective of this work is to study the microstructure and the texture evolution in welded joint of X70 steel with duplex stainless steel joined by gas tungsten arc welding (GTAW) process and heat treated at 200 °C and 600 °C. Then, the microstructural evolutions are correlated to their hardness mechanical property. The characterization techniques used are optical microscopy, scanning electron microscopy, EDS, Vickers microhardness, tensile tests, X-ray diffraction, and electron backscatter diffraction (EBSD) technique. Two heat affected zones were observed in welded joint with different microstructures. Heat affected zone on the X70 steel side and another on the duplex stainless steel side. A solidification microstructure was observed in the fusion zone such elongated ferritic grains and a growth direction < 100 > was found. The most microstructural transformations were observed in the vicinity of the interface which connects the heat affected zone to the fusion zone either on the X70 steel side or on the duplex stainless steel side. The effect of heat treatment on the hardness of the welded joint was noticed in the side of the duplex stainless steel. The fusion zone is the hardest zone of the welded joint (309.4 Hv) and which is not affected by the applied heat. X-ray diffraction analysis did not reveal the formation of new phases after the heat treatments applied to the welded joint. The tensile tests have shown that the welded joint treated at 200 C presents the highest value of ultimate tensile strength (667 MPa). [ABSTRACT FROM AUTHOR]

The article presents results of research on fume emission in relation to various arc welding methods (MAG standard, CMT, ColdArc and ColdArc Puls) and laser welding techniques (heat conduction and deep penetration welding). Research - related tests involved manifold elements and a turbine housing made of cast stainless steel. The shielding gas used during arc welding was a mixture containing 97,5 % of Ar and 2,5 % of CO2. In turn, laser welding processes were shielded by argon. The analysis of test results aimed to identify the effect of arc/laser welding methods on the total emission of welding fume. [ABSTRACT FROM AUTHOR]

Copyright of Automobile Technology & Material is the property of Automobile Technology & Material Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Automobile Technology & Material is the property of Automobile Technology & Material Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Arc welding is a thermal plasma process widely used to join metals. An arc welding model that couples fluid dynamic and electromagnetic equations was initially developed as a research tool. Subsequently, it was applied to improve and optimise industrial implementations of arc welding. The model includes the arc plasma, the electrode, and the workpiece in the computational domain. It incorporates several features to ensure numerical accuracy and reduce computation time and memory requirements. The arc welding code has been refactored into commercial-grade Windows software, ArcWeld, to address the needs of industrial customers. The methods used to develop ArcWeld and its extension to new arc welding regimes, which used the Workspace workflow platform, are presented. The transformation of the model to an integrated software application means that non-experts can now run the code after only elementary training. The user can easily visualise the results, improving the ability to analyse and generate insights into the arc welding process being modelled. These changes mean that scientific progress is accelerated, and that the software can be used in industry and assist welders' training. The methods used are transferrable to many other research codes. [ABSTRACT FROM AUTHOR]

Hot-dip galvanizing performances of various filler metals were investigated in this study. S355JR grade structural steel plates were joined with four different filler wires in solid, flux-cored, and metal-cored forms in different chemical compositions, then cooled at ambient temperature. Later, specimens were subjected to a hot-dip galvanizing process. Coating metallography, soundness analysis, and microstructural characterizations were conducted by optical and scanning electron microscopes (SEM). The coating thicknesses of the specimens were also measured. The chemical composition of weld metal after galvanizing was analyzed by Energy-dispersive X-ray spectroscopy (EDS). The mechanical properties of the coatings were also interpreted by hardness tests. As a result of these examinations, it was determined that the galvanized coating properties of the samples joined with E70C-6M and ER70S-2 filler wires were comparably better. [ABSTRACT FROM AUTHOR]

This study experimentally assessed the effect of microadditives of the Ti–TiC system modifier on the functional properties of the deposited metal of 25Kh5FMS semi-heat-resistant tool steel. The used Ti–TiC system modifier powders were obtained by high-voltage electric discharge treatment of Tipowder, which resulted in changes in its structural, chemical, and phase composition. It was determined that modification of the deposited metal with titanium carbides in an amount of ≈ 0.01% did not impair the quality of the formation of welded rollers and slag crust detachment. It was experimentally determined that introducing titanium carbide micro-additives in the amount of 0.01% to the deposited metal increased its heat resistance and wear resistance at elevated temperatures by 15–50%, depending on the modifier additive used. The obtained results can be useful in selecting materials for welding parts operated under abrasive wear and cyclic thermomechanical loads. [ABSTRACT FROM AUTHOR]

The work presents the results of investigations of cold cracking susceptibility of welded joints on modern high hardness armour steels and gives recommendations on their prevention. Investigations were performed using a calculation method according to EN 1011-2:2001 -- the Implant method to determine the delayed fracture resistance of the HAZ metal and rigid technological test in welding multilayer joints. It is found that in arc welding the joints of high hardness armour steels have a higher susceptibility to cold cracking in the HAZ metal. In welding with low-alloyed consumable of Sv-10gsmt type application of preheating allows avoiding them. the preheating temperature can be calculated by CET and PT indices in keeping with the armour steel composition. In the presence of steel raisers in the welded joints the calculated preheating temperature should be increased by 50-70 °C. the welded joints made with high-alloyed consumable of Sv-08Kh20n9G7T type have higher delayed fracture and cold cracking resistance. In manufacture of light armoured vehicles, it is recommended to select armour steel with carbon content of not more than 0.26 %. In welding such armour steel by low-alloyed consumables sufficiently high cold cracking resistance of welded joints is ensured, even in the presence of stress raisers, due to preheating up to the temperature of 150 °C, as well as in welding without preheating at application of high-alloyed consumables. [ABSTRACT FROM AUTHOR]

Aluminium castings have been widely used in many industries, including automotive, aerospace, telecommunication, construction, consumer products, etc., due to their lightweight, good electric and thermal conductivity, and electromagnetic interference/radio frequency interference (EMI/RFI) shielding properties. The main applications of aluminium castings are in automotive industry. For lighweighting purposes, more and more aluminium castings are used in the automotive vehicle structures to reduce weight, improve fuel efficiency, and reduce greenhouse gas emissions. However, due to the features of cast aluminium, such as porosity, poor surface quality, a tendency toward hot cracking, and low ductility, joining these materials is problematic. In this paper, the joining technologies for aluminium castings and the related issues, mainly cracking and porosity, are reviewed. The current state-of-the-art of joining technologies is summarized, and areas for future research are recommended. [ABSTRACT FROM AUTHOR]