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The weldability of a developed high‐strength hull structure steel is investigated using a coarse‐grained heat‐affected zone (CGHAZ) thermal simulation and duplex double welding under a heat input of ≈20 kJ cm−1. From the results, the average impact test energy at −50 °C for the simulated CGHAZ samples is 142 J and for samples with V‐notch position 0.5 mm from the fusion line (FL) was 152 J. The impact test energies for the V‐notch position at the FL also show good toughness. The simulated samples and samples from the weld joint are machined into standard sizes to test their tensile strengths, which meet the request high strength. It is concluded that the high strength of the CGHAZ is mainly due to phase transformation and is supplemented by solid solution strengthening. The good low‐temperature toughness is mainly due to the high Ni content. All the results are comparable to the reported mechanical property test results of the weld joint of navy HSLA‐100 steel under a similar heat input. This suggests that the developed high‐strength hull structure steel exhibits satisfactory weldability. [ABSTRACT FROM AUTHOR]

The article describes properties of welds made of high wear resistance X120Mn12 steel obtained by the hybrid PTA-MAG (plasma transferred arc – metal active gas) method. The specimens were 8 mm thick rectangular (200 mm × 350 mm) sheets metal. The analyzed butt welds were made with the parameters selected according to the criterion of smallest cross-sectional area of welds and the narrowest HAZ (heat affected zone). The outcome of metallographic tests of weld, HAZ and parent material, hardness distribution and XRD (X-ray diffraction) patterns of selected areas are presented. The IIT (Instrumented Indentation Test) method was used to describe the distribution of mechanical properties shaped by thermal cycle annealing of the welding process. The investigation shows that the application of the PTA-MAG hybrid heat source for welding manganese steel enables the use of the filler material ER307 (AWS-A5.9). The hybrid PTA-MAG welding system has the relatively high potential to be an efficient alternative to welding standard processes for X120Mn12 steel due to the HAZ overheating limitation. The zone of high-risk weld cracking is the part of the HAZ close to the fusion area that has been reheated during weldment formation. Heat input about 0.6 kJ/mm is needed to provide full deep penetration butt weld without defects and with a vapor capillary of wide enough to cover the weld gap. The increase of hardness in the welded joint is smooth distributed and going up to 10% compared to the base material. The width of HAZ was <1 mm. Intensive carbides precipitation in HAZ has been avoided successfully. [ABSTRACT FROM AUTHOR]

Dissimilar welding of duplex stainless steel (DSS) with high-strength low alloy (HSLA) was more complicated since they were utilized in automotive and aerospace design, which needed components with lower weight, higher tensile strength (TS), hardness, corrosion resistance. In this research paper, the main objective was to establish a gas tungsten arc welding process, on a 60∘ angle double groove on both sides of DSS and HSLA, using three different filler metals ER2594, ER70S2 and ER304. The welded surfaces of the specimens were analyzed to assess the microstructural characterization using SEM and Edax, and they were also tested to determine their mechanical and corrosion characteristics. In comparison to microstructural characterization, Mn and Si combination decreased the surface defects in the weldment made by ER2594. The determination of mechanical properties revealed that specimen A produced by ER2594 was superior to other specimens B and C, in terms of yield stress, TS and hardness. Similarly, improved corrosion resistance was achieved by the larger presence of Cr along with Ni in ER2594. In the welded joint, Ni combined with an appropriate proportion of other alloying elements in ER2594 enabled effective control over the ferrite-austenite phase balance, which was crucial for achieving the necessary combination of properties and weldability designed for particular applications. Among the three filler metals, ER2594 showed better microstructure uniformity, enhanced TS, hardness and superior corrosion resistance. [ABSTRACT FROM AUTHOR]

Extrusion welding of AlMgSi(Cu) alloys is carried out by using porthole dies, as a result of which hollow shapes are formed with longitudinal seam welds. In the case of the inappropriate selection of the chemical composition of the aluminium alloy or improper metal welding conditions, the weld may have reduced strength in relation to that of the base material, thus weakening the strength of structures based on aluminium extrudates. The prediction of metal welding conditions, depending on the chemical composition of the alloy, the temperature and the unit welding pressures, effectively supports the design of porthole dies, thus significantly reducing the number of necessary extrusion tests and die geometry corrections needed during its implementation in industrial practice, and consequently significantly reducing production costs. In this work, an original laboratory test device simulating the behaviour of metal in a welding chamber of a porthole die was applied to examine the ability of AlMgSi(Cu) alloys to produce high-quality joints. Two different chemical compositions of AlMgSi(Cu) aluminium alloys differing in Mg, Si and Cu contents were used: alloy no. 1A (0.68% wt. Mg, 1.04% wt. Si, 0.61% wt. Cu) and alloy no. 3A (0.8% wt. Mg, 1.21% wt. Si, 1.22% wt. Cu). The weldability tests were carried out under various welding temperatures of 450, 500 and 550 °C and under various welding pressures of 150 MPa, 250 MPa and 350 MPa. The microstructural changes in the produced welds were evaluated with the use of OM and SEM/EDS with chemical analysis in micro-areas, whereas the mechanical effects were evaluated by using a static tensile test. Samples after static tensile testing were subjected to fractographic tests to determine the nature of the fractures. The highest values of relative weld strength were obtained under the highest welding temperature of 550 °C and the highest unit welding pressure of 350 MPa: 87% for alloy number 1/1A (high-strength weld), and 62% for alloy number 6/3A (medium-strength weld). Finally, the extrusion tests were performed in industrial conditions with an examination of the EBSD structure and strength of the longitudinal welds. High values of relative weld strength for extrudates from alloy no. 1/1A and alloy no. 3A, 96% and 89%, respectively, were found, which confirmed the previous weldability testing results. [ABSTRACT FROM AUTHOR]

5356 aluminum alloy welding wire is widely used in automotive, aerospace, and marine, due to its excellent corrosion resistance, high strength-to-weight ratio, and excellent weldability. The properties of aluminum alloys are primarily determined by their microstructure. This study investigates the microstructure evolution, mechanical properties, and texture of 5356 aluminum alloy welding wire produced using the continuous casting direct rolling (CCDR) method. The results show that continuous rolling led to an increased generation of dislocations in the matrix, and dynamic recovery plays an important role in reducing dislocation density. As a result of dynamic recovery, the microstructures of 3RPs consist of extensive deformed grains and numerous substructures. The continuous casting direct rolling textures are characterized to be cube and shear textures. After 10 rolling processes, the 5356 aluminum alloy welding wire shows a highest tensile strength of 365 MPa with a lowest elongation of 8.8%. This research provides theoretical guidance to produce high-performance 5356 aluminum alloy welding wires, paving the way for their more efficient and reliable applications. [ABSTRACT FROM AUTHOR]

Copyright of Foundry Technology (1000-8365) is the property of Foundry Technology 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.)

In the present study, considering the features and advantages of solid-state welding methods as compared with fusion welding methods such as arc welding, laser welding induction welding, and solid-state welding, they are used to connect CK45 steel to AISIS 304L steel to achieve the desired mechanical and metallurgical properties through experimental and practical tests, by trial and error, suitable parameters of distance, depth, and advance are obtained for welding, and finally a healthy and desirable weld is obtained. The purpose of the present study is to evaluate the weldability of CK45 steel to AISIS 304L steel by friction stir welding method. The distance, advance, and penetration depth parameters were experimentally determined as 950 rpm, 24 mm/min, and 0.35 mm, respectively, to obtain a healthy weld in terms of appearance. Then, through mechanical and metallurgical tests, the effect of the input parameters on the friction stir welding process was determined. The mechanical and metallurgical properties were also evaluated. The results show that the structure of the onion rings in the welding area is caused by the friction stir welding process, which is caused by the massive plastic deformation and the heat generated during the process. The scanning electron microscope image of the welded section of the steel sample shows the formation of a pearlite structure. Considering the severe plastic deformation and dynamic recrystallization in the friction stir welding process, the results obtained from the welding of dissimilar CK5 and AISI304 L show better mechanical properties and acceptable strength. [ABSTRACT FROM AUTHOR]

This study assessed the weldability and recyclability of four filler wires, two commercial (ER4047 and ER2319) and two experimental (ER2395 and J300), for laser beam welding of aluminum-Copper-lithium (Al–Cu–Li) aircraft panels. The results showed key differences in porosity and crack formation. The ER2319 filler exhibited a higher tendency for wormhole-type porosity compared to the others, which had similar pore area fractions. ER2395 displayed the longest crack length, likely due to its high lithium content. Chemical compatibility with the Al–Cu–Li base alloy AA2198 was confirmed for the ER2319, ER2395, and J300 filler wires, enabling 100% closed-loop recyclability without disassembly or alloy sorting. However, the high silicon content (around 11%) of ER4047 resulted in a recycled alloy that exceeded the allowable Si limit for AA2198, making it unsuitable for closed-loop recycling. Several end-of-life (EoL) strategies were explored for scrap fractions from ER4047-welded coupons. The 0C and 1C cutting strategies yielded hybrid fractions incompatible with AA2198 but suitable for the more Si-tolerant AA2196 alloy. The 3C strategy, involving weld seam separation before remelting, optimized recycling rates and minimized environmental impact. Additionally, a pre-scrap characterization method was developed to analyze weld seam composition, allowing for the prediction of recyclability issues and filler wire mass estimation in coupons where both the skin and stringer were made of the same alloy. This method provides a practical approach for evaluating welded structures in future recycling efforts.

The additive manufacturing method offers a number of advantages such as rapid prototyping, design flexibility and unique part production. However, compared to traditional production methods, the production volume is limited. Therefore, to meet large-volume production demands, additive manufacturing is not as effective as traditional methods. In order to overcome this disadvantage, scientists are conducting research on the assembly of parts produced by additive manufacturing method. This study focuses on investigating the MIG (Metal Inert Gas) weldability of AlSi10Mg SLM (Selective Laser Melting) plate to AlSi10Mg SLM plate and subsequently optimizing the welding parameters for welding zone hardness and tensile strength. The most suitable parameters obtained in the hardness optimization of the weld zone were determined as 20.6 V, 120 A, 5356 (AlMg5). The most suitable parameters for tensile strength optimization were determined as 20.6 V, 110 A and 4047 (AlSi12). In addition to all these, 4047 filler material is thought to be the most suitable weld filler material for this study, as it provides the best tensile strength performance, offers acceptable weld zone hardness and is relatively easily accessible in the market. [ABSTRACT FROM AUTHOR]

Powder metallurgy high chromium cast iron (PM HCCI) and low carbon steels (LCS) were welded by multi-pass manual gas tungsten arc welding (GTAW). The effects of welding current on the microstructure evolution and mechanical properties of the weld joints were systematically investigated, the microstructure evolution model of the weld joints was proposed, and the fracture mechanism of the solders was also discussed. In the results, the tensile strength of the welded joints reaches 538.1 MPa at 140 A welding current, which is 95.3% and 97.4% of the tensile strength for PM HCCI and LCS, respectively. The microhardness of the welded joints decreases from HCCI side to LCS side in the horizontal direction, whereas in the vertical direction, the microhardness distribution is of M-shape due to the secondary tempering and alloying element diffusion/segregation. The fusion zone (FZ) mainly consists of the austenite and tempered martensite at the welding current of 140 A, and there is a single austenite columnar crystals zone between FZ and LCS; while there is a HCCI columnar crystal zone between FZ and the sintered HCCI, in which the coarsen carbides with branches are distributed along the matrix’s grain boundary.

In this study the cold cracking (CC) susceptibility of naval grade high strength steel (HSS) welds developed using flux core wires of different yield strength levels was analyzed for lightweight shipbuilding structures. The steel plates of the PCE500 TM grade were welded in T-joint configuration using automatic flux core arc welding under the shielding gas. The CC susceptibility of weld metals was evaluated using Tekken weldability test. The microstructure of weld metal and the hardness of welded joint were analyzed using optical microscope and Vickers microhardness tester, respectively. Software package Sysweld was used for finite element simulation of CC susceptibility of weld metals. Results showed that the probability of CC increases with increase in the strength of filler wires, especially under conditions of limited welding deformations and exposure to low temperatures. The maximum resistance to the formation of cold cracks (CCs) in microstructure of the weld metal is observed in the presence acicular ferrite of at least 60%. To assess the structural strength of T-joint with soft welds, a calculation method has been developed, which allows ranking various structural and technological solutions of the T-joint from the condition of resistance to various types of fracture. Numerical calculation showed that the margin for brittle fracture at 11–23% and the gain in fatigue durability at 40% for welded joint with soft weld greater than for a welded joint with an equally strong weld. The use of low strength filler wires for welding thick plates of HSSs can successfully resolve the problem of CCs and ensure structural strength of joints.

The replacement of traditional materials like steel and Fe with lightweighted solutions, such as Al, Mg and composites has rapid development in science and technology. This study looks into Mg alloys which is expected to have rising impact on industrial trends in the future with material consumption, balanced performance and economic effects. Joining dissimilar materials together has never been easy and so the paper gives a brief theory of the advanced joining methods, laser beam welding (LBW) of distinct lightweight materials like Mg alloys, and its influences on laser parameters. Additionally, all experimental analyses of interlayer or filler materials reinforced by the weld joint of Mg alloys are studied. Their imitating results on the Mg alloys’ microstructure and properties to advance the weldability of the joint to repel failure, as well as their knowledge of the fundamentals, current trends and future approaches in the advanced joining of lightweight materials. [ABSTRACT FROM AUTHOR]

This study aims to clarify the effect of oxygen in shielding gas on weldability in the plasma-GMA (Gas Metal Arc) hybrid welding process of high-tensile strength steel plates. The difference in keyhole profile and bead formation, when the GMA shielding gas was pure Ar, Ar + 2% O2, or Ar + 20% CO2, was investigated for plate thicknesses of 6 and 9 mm for the first time. It was found that the weld beads were in good condition for 6 mm thickness plates for all shielding gases, which implied that the window of welding conditions for this thickness is wide. In contrast, for 9 mm thickness plates, a fully penetrated weld bead was achieved only in Ar + 20% CO2, and weld bead penetration in Ar + 20% CO2 is higher than in pure Ar and Ar + 2% O2 in the same welding condition. Due to decreased surface tension caused by sufficiently increased oxygen absorbed into the weld pool, the keyhole diameter increased to penetrate the bottom side of the plate, and the depressing weld pool surface under GMA allowed the heat input from the GMA to be directly applied to a deeper position. Consequently, the plasma-GMA hybrid welding process with Ar + 20% CO2 achieved a complete penetration for a plate of 9 mm thickness, owing to the effects of both phenomena. It proved a potential to increase penetrability in welding thicker plates by controlling oxygen content in shielding gas of GMA adequately. [ABSTRACT FROM AUTHOR]

Nonwovens have wide application areas due to their advantageous properties like low cost, high production efficiency, and tuneable properties. They are mostly used for disposable products. Combining bicomponent fiber spinning with hydroentanglement method is one of the innovative methods to obtain nonwovens for durable applications. On the other hand, ultrasonic welding is an alternative assembling method for disposable products made of low weight nonwovens. In this study, the ultrasonic weldability of relatively heavier weight and thicker nonwoven fabrics made of polyester: polyamide bicomponent microfilaments were examined in order to combine the advantages of nonwovens and ultrasonic welding. Relatively higher thickness and weight, and also fiber composition of the nonwoven fabrics were compelling effects of the study that drove the motivation. Overall 60 samples were produced using five nonwoven fabrics with varying unit masses and 12 selected ultrasonic welding types. Seam strength and strain assessments were supported with stereomicroscope and visual inspections in evaluating the welds. Results showed that despite having thick seam lines up to 1.6 mm, successful welded seams could be obtained. Depending on the welding parameters, seam lines of some samples exhibited waviness, color changes, and deformations but these situations did not drastically affect the seam strength of samples. [ABSTRACT FROM AUTHOR]

Automotive industries have seen increased demands for indirect hot-stamped pre-coated ultra-high-strength steel 22MnB5 due to its excellence. This paper presents the results of experimental investigation of the effect of Al-Si coating weights AS150 (150 g/m2) and AS80(80 g/m2) and spot-welding process parameters of indirect hot-stamped Usibor 1500 to further understand which coating weight perform better for automotive application. The resistance spot welding experiments were conducted with a medium-frequency direct control (MFDC) machine. The MFDC resistance spot-welding machine had two G20 electrodes with a 458 truncated cone designed with a diameter of 4.9 mm. The results show that the nugget diameter increases with increasing weld current, better spot-weld nugget diameter is recorded at weld currents above 7.5 kA for both AS80 and AS150 coating weights, and the weld current range decreases with increase in coating weight and with increase in the interdiffusion layer. Heat treatment dwell time has a remarkable influence on weld current range for both AS150 and AS80 coating weights. AS80 coating weight has a slightly higher weld current range of 2.1 KA than AS150 coating weight with weld current range of 1.8 KA. Tensile shear strength for AS150 and AS80 increases nonlinearly with increase in weld diameter. [ABSTRACT FROM AUTHOR]

Herein, innovative cast Ni‐based superalloys that not only withstand temperatures up to 800 °C but also offer superior weldability, robust tensile strength at both room and elevated temperatures, and a reduced density are introduced. The new Ni‐based superalloys are optimized via calculation of phase diagrams‐based high‐throughput thermal calculation and program‐controlled composition screening. A new multiperformance‐oriented criterion is devised, encompassing quantitative weldability indices, volume fraction of γ′, electron vacancy number, density, solidus temperature, and freezing range to optimize the alloy composition. Weldability indices, rooted in the solidification crack initiation mechanisms, prove equally applicable to both current interested alloys and commercial superalloys. The crack length of the optimized alloy after the constrained welding test is only 3.08% of the total weld length. It is unveiled that solidification cracking (SC) emerges as the pivotal factor governing the weldability of these alloys. The mechanism of SC for such superalloys is originated from the addition of Nb, Ti, Mo, and W, which results in the microsegregation of the composition and the precipitation of (Nb, Ti)‐rich constituents or M(Ta, Nb, Ti)C carbides in the liquid film of the central interdendritic region. This work hopefully helps to find promising candidates for the combustion chamber of aeroengines and other high‐temperature casts. [ABSTRACT FROM AUTHOR]

The phenomenon of solidification cracking has been the subject of numerous research projects over the years. Great efforts have been made to understand the fundamentals of hot cracking. It is generally agreed that solidification cracks form in the solidification range between the liquidus and solidus temperatures under the combination of thermal, metallurgical and mechanical factors. There is still a need to determine the time‐resolved strain distribution in the crack‐sensitive region in order to analyse the local critical conditions for solidification cracking phenomena. This was a strong motivation for the development of a measurement system used in this study to estimate the local strains and strain rates in the zone where the solidification crack is expected to occur. The laser beam welding experiments were conducted using the Controlled‐Tensile‐Weldability test (CTW test) to apply an external strain condition during welding to generate solidification cracks. The CTW test is a test method for investigating the susceptibility of laser‐welded joints to solidification cracking, in which the sample can be subjected to a defined strain at a defined strain rate during welding. In combination with experimental investigations, numerical simulations provide spatially detailed and time‐dependent information about the strain development during the welding process, especially regarding the critical conditions for solidification cracking. Therefore, this tool was also used in the present study to evaluate the accuracy of measurement methods and to estimate experimentally derived values and their concrete influence on the formation of solidification cracks. By integrating experimental methods and numerical simulations, this study investigates the spatially resolved and temporally changing development of strain during welding, with a particular focus on the critical conditions that lead to the formation of solidification cracks. The use of numerical simulations serves a dual purpose by validating the accuracy of measurement methods and examining experimentally determined values for their actual influence on the formation of solidification cracks. A three‐dimensional finite element (FE) model implemented with ANSYS is used to simulate strains and stresses during welding. The credibility of the model was first established by validation using experimental temperature measurements. Subsequently, structural simulations were carried out under external load. The results of the simulations showed commendable agreement with the strain measurements performed using the developed technique. [ABSTRACT FROM AUTHOR]

Quality assurance of welded ETFE‐foils in building applications ETFE structures are an established construction method which are usually used as façade and roof constructions for wide‐span buildings. As membranes, they have a complex load‐bearing behaviour which is governed by the interaction of the load, shape and material behaviour. The material behaviour is characterised by the viscoelastic‐plastic short and long‐term tensile behaviour of the foil products used and must be taken into account for the design of ETFE structures. The production of the mostly double‐curved and individually designed surface structures is made possible by the weldability of the fluoropolymer. The weld seams are considered to be the weak point of the overall system and are significantly relevant for the overall structural safety. In two research projects, the uni‐ and biaxial short‐ and long‐term tensile load‐bearing behaviour of ETFE films and the load‐bearing behaviour of ETFE surface weld seams were investigated and procedures for standardising the design of ETFE weld seams were developed. Based on these findings, concepts and standards were developed that can be used for the quality assurance of ETFE structures. The basic findings developed as part of these research projects are summarised in the present contribution. [ABSTRACT FROM AUTHOR]

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) 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.)

Dissimilar welds between ferritic and austenitic stainless steels are widely used in industrial applications. Taking into account the issues inherent to arc welding, such as the high heat input and the need to carry out multiple passes in the case of thick plates, a procedure with two simultaneous laser beams (working in a single pass) and consumable inserts as filler metal has been considered. Particular attention was paid to the choice of the filler metal (composition and amount), as well as welding parameters, which are crucial to obtain the right dilution necessary for a correct chemical composition in the weld zone. The first experimental investigations confirmed the achievement of a good weldability of the dissimilar pair ASTM A387 ferritic/AISI 304L austenitic steel, having ascertained that the microstructure of the weld zone is austenitic with a little amount of residual primary ferrite, which is the best condition to minimize the risk of hot cracking. [ABSTRACT FROM AUTHOR]

Among Al-Zn-Mg alloys, A7003 alloy is considered to be an excellent alloy from the viewpoint of weldability because it is an alloy with relatively low Zn and low Mg composition. In this paper, changes in mechanical properties and microstructure during aging treatment are investigated by the addition of Si in the Al-5.6 mass%Zn-0.75 mass%Mg alloy containing Cu, Mn, Zr and Fe. Cast billets of alloys with different Si contents (Si: 0.05 mass%, 0.15 mass%, and 0.30 mass%) were prepared, and these cast billets were homogenized and extruded. After extrusion, four aging treatments were performed: one step aging at 423K for 8 hours, and two step aging at 373K for 3 hours, 6 hours, and 9 hours, followed by 423K for 8 hours. The higher the amount of Si, the smaller the thickness of recrystallization layer near the inner surface and near the outer surface, and the smaller the existence rate of recrystallized grains in the cross section. After one step aging at 423K for 8 hours, Si: 0.05 mass% showed lower strength than Si: 0.15 mass% and Si: 0.30 mass%. On the other hand, two-step aging resulted in Si: 0.05 mass%, Si: 0.15 mass%, and Si: 0.30 mass% with similar strength. The low strength of Si: 0.05 mass% after one step aging at 423K for 8 hours is thought to be due to the coarse η phase, which was precipitated in the grain boundaries and grains. In Si: 0.15 mass% and Si: 0.30 mass%, Al(Mn,Fe)Si which formed during homogenization process is present in the grain boundaries and grains after extrusion. It is thought to suppress the generation of the precipitate of the coarse η phase in the aging at 423K for 8 hours, which is a condition that the coarse η phase is easy to generate. [ABSTRACT FROM AUTHOR]

Traditional polybenzoxazine thermosets cannot be reprocessed or recycled due to the permanent crosslinked networks. The dynamic exchangeable characteristics of imine bonds can impart the networks with reprocessabilities and recyclabilities. This study reported a weldable, reprocessable, and water‐resistant polybenzoxazine vitrimer (C‐ABZ) crosslinked by dynamic imine bonds. It was synthesized through a condensation reaction between an aldehyde‐containing benzoxazine oligomer (O‐ABZ) and 1,12‐dodecanediamine. The resulting C‐ABZ was able to be welded and reprocessed due to the dynamic exchange of imine bonds. The tensile strengths of the welded C‐ABZ and the reprocessed C‐ABZ after three cycles of hot‐pressing were 76.7, 81.3, 70.8, and 58.1 Mpa, with corresponding tensile strength recovery ratios of 74.1 %, 78.6 %, 68.4 %, and 56.1 %, respectively. Furthermore, the polybenzoxazine backbone significantly improved the water resistance of the imine bonds. After immersing in water for 30 days at room temperature, the weight gain of C‐ABZ was less than 1 % with corresponding tensile strength and tensile strength retention ratio of 59.5 Mpa and 57.5 %, respectively. Although the heat resistance of C‐ABZ decreased slightly with increased hot‐pressing cycles, a glass transition temperature (Tg, tanδ) of 150 °C was retained after the third hot‐pressing. Overall, these findings demonstrate that the C‐ABZ possesses excellent comprehensive performances. [ABSTRACT FROM AUTHOR]

When welding ultra-fine-grained metals using conventional methods, the microstructure in the joint area is degraded (mainly due to recrystallization) in the heat-affected zone and a significant deterioration of mechanical properties, including joint strength. The aim of the research presented in this article was to identify the possibility of obtaining joints with strength close to initial material using friction welding of metal materials with ultra-fine grain. For this purpose, UFG (ultra-fine-grained) material was produced from technically pure M1Ez4 copper using a hybrid SPD (severe plastic deformation) process. The welding process was carried out on a machine with a prototype design that allows minimizing the welding time, while generating high force. The process parameters used on the prototype machine resulted in an increase in the hardness of the material by 4% in the joint area. The strength of the joint compared to the base material decreased slightly by 2%. The tests carried out proved that, using appropriate process parameters, it is possible to obtain a UFG metal joint without a decrease in its mechanical strength. [ABSTRACT FROM AUTHOR]

In this study the cold cracking (CC) susceptibility of naval grade high strength steel (HSS) welds developed using flux core wires of different yield strength levels was analyzed for lightweight shipbuilding structures. The steel plates of the PCE500 TM grade were welded in T-joint configuration using automatic flux core arc welding under the shielding gas. The CC susceptibility of weld metals was evaluated using Tekken weldability test. The microstructure of weld metal and the hardness of welded joint were analyzed using optical microscope and Vickers microhardness tester, respectively. Software package Sysweld was used for finite element simulation of CC susceptibility of weld metals. Results showed that the probability of CC increases with increase in the strength of filler wires, especially under conditions of limited welding deformations and exposure to low temperatures. The maximum resistance to the formation of cold cracks (CCs) in microstructure of the weld metal is observed in the presence acicular ferrite of at least 60%. To assess the structural strength of T-joint with soft welds, a calculation method has been developed, which allows ranking various structural and technological solutions of the T-joint from the condition of resistance to various types of fracture. Numerical calculation showed that the margin for brittle fracture at 11e23% and the gain in fatigue durability at 40% for welded joint with soft weld greater than for a welded joint with an equally strong weld. The use of low strength filler wires for welding thick plates of HSSs can successfully resolve the problem of CCs and ensure structural strength of joints. [ABSTRACT FROM AUTHOR]

Copyright of Metal Working (1674-165X) is the property of Metal Working 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.)

Owing to their unique high-temperature mechanical properties and outstanding high-temperature oxidation resistance, superalloys have become key materials in aviation, aerospace, petrochemical, metallurgy, electric power, automotive, and other industrial fields. Due to the structural complexity and high manufacturing cost of the hot sections of aeroengines, vessel engines, and gas turbines, the development and practicality of superalloy welding technology are critical to satisfying the design and maintenance requirements of hot sections. In this work, the research progress of superalloy fusion welding is described. Its advantages and application scope, such as arc welding, electron beam welding, and laser welding, are elaborated. Common types of welding cracks are introduced, and the mechanisms and influencing factors of solidification cracks, liquation cracks, strain-age cracks, and ductility-dip cracks are summarized. The primary techniques to enhance the weldability of fusion welding are also examined in terms of heat input, material composition, microstructure, and welding residual stress. The requirements for the temperature-bearing level of superalloys in industrial development are constantly increasing; thus, the types of superalloys are also being iteratively updated. They have evolved from deformed superalloys to ordinary cast polycrystalline superalloys to novel superalloy materials such as directional solidification and single-crystal superalloys. Thus, continuously conducting welding research on emerging superalloys, traditional nonweldable superalloys, and dissimilar materials that are extremely incompatible with metallurgy is necessary. Because the composition and microstructure of the base material have an important bearing on weldability, it is necessary to strengthen the composition design of emerging superalloys and conventional nonweldable superalloys in future works. Moreover, it is critical to pay attention to the improvement of welding process technology and pre- and post-weld treatment methods. In particular, research on detection and elimination measures of welding residual stress should be strengthened, which is one of the most effective approaches for lowering the weld crack-sensitivity of superalloys. This is of great importance for synergistically enhancing the welding performance of superalloys. Moreover, monitoring and simulation techniques for the welding process can be used to perform in-depth research on scientific issues such as molten pool flow and welding heat and mass transfer during the fusion welding process. This is of great scientific value for promoting the development of fusion welding technology. Based on the foundation of enhancing welding processes, future work on automation and intelligence of welding processes should also gradually deepen, which is one of the important directions to improve welding stability and reliability and promote the widespread application of superalloy fusion welding.

Aluminum alloy and copper used in lithiumion batteries have low absorption and high reflectivity, so it is difficult to obtain stable joint strength when laser welding is applied. In order to overcome problems, this study has applied multi-seam weld to increase joint area of welded joints. AA1050-H18 and C11020P sheets with a thickness of 0.5 mm were welded by 2-kW fiber laser welding. The effect of the welding parameters of pitch (0, 1, 4, 8 mm) on weldability in welded joints has been investigated. As the pitch of multi-weld seam increased, the tensile-shear load tended to increase. The maximum tensileshear load in the multi seam weld of pitch 8 mm was 1.25 kN, which was about 108% compared to the single weld seam 0.6 kN. In addition, the minimum electrical resistance was 77 μΩ at the pitch of 8 mm, which decreased by approximately 49% compared to 115 μΩ of single seam welding. [ABSTRACT FROM AUTHOR]

This study advances the vibration-assisted welding (VAW) technique for joining medium-carbon, low-alloy steels, which are typically challenging to weld. Traditional welding methods suggest low linear energy and mandatory pre- and post-heating due to these steels' poor weldability. However, VAW employs a vibrating table to maintain part vibration throughout the automatic MIG/MAG welding process. This study tested the VAW technique on 42CrMo4 steel samples, achieving satisfactory weld quality without the need for pre- and post-heating treatments. This research revealed that while vibration frequencies between 550 Hz and 9.5 kHz minimally affect the appearance of the weld joint, the oscillation acceleration has a significant impact. The acceleration along the weld axis (ax), combined with the welding speed and vibration frequency, affects the weld surface's appearance, particularly its scaly texture and size. Lateral acceleration (ay) alters the seam width, whereas vertical acceleration (az) affects penetration depth at the root. Notably, if the effective acceleration (aef) surpasses 40 m/s2, there is a risk of molten metal expulsion from the weld pool or piercing at the joint's base. The quality of the joints was assessed through macroscopic and microscopic structural analyses, micro-hardness tests in the weld zone, and bending trials. The mechanical properties of the VAW samples were found to be acceptable, with hardness slightly exceeding that of the samples subjected to pre- and post-heating. Moreover, the VAW process significantly reduced energy consumption and operational time. The employed vibration system, with a power rating of 100 W, operates for just a few minutes, resulting in substantially lower energy usage compared to the traditional pre- and post-heating method, which typically requires a 5 kW electric furnace. [ABSTRACT FROM AUTHOR]

Robotic Friction Stir Welding (RFSW) technology integrates the advantages of friction stir welding and industrial robots, finding extensive applications and research in aerospace, shipbuilding, and new energy vehicles. However, the high-speed rotational process of friction stir welding combined with the low stiffness characteristics of serial industrial robots inevitably introduces vibrations during the welding process. This paper investigates the vibration patterns and impacts during the RFSW process and proposes an active vibration avoidance control method for variable speed welding based on constant heat input. This method utilizes a vibration feedback strategy that adjusts the spindle speed actively if the end-effector's vibration exceeds a threshold, thereby avoiding the modal frequencies of the robot at its current pose. Concurrently, it calculates and adjusts the welding speed of the robot according to the thermal equilibrium equation to maintain constant heat input. A simplified dynamic model of the RFSW robot was established, and the feasibility of this method was validated through simulation experiments. This study fills the gap in vibration analysis of RFSW and provides new insights into control strategies and process optimization for robotic friction stir welding. [ABSTRACT FROM AUTHOR]

The present study was conducted to investigate the root cause failure analysis of 316L stainless steel air tube inlets at the weld joint in a High-Speed Power turbine (HSPT). Fractography analysis revealed ratchet marks and striations on the fracture surfaces, indictive of vibration-induced fatigue in the heat affected zone of the tube-to-flange weld joint, resulting from the rotation of the HSPT at high speed, identified as the primary cause of failure. Additionally, radiography and visual inspection unveiled a sharp interface between the weld metal and parent metal within the inner wall, acting as a stress riser. X-ray diffraction analysis demonstrated that the parent metal predominantly consisted of austenite (γ), while the weld metal comprised a mix of austenite (γ, ≈ 90%) and delta ferrite (δ, ≈ %10). Hardness readings in the weld zone ranged from 260–302 HV, compared to ≈ 140 HV in the parent metal. Microstructural examination showed inclusions and impurities rich in manganese, and silicon, likely introduced during manufacturing and/or welding processes. Conclusively, the study attributes failure to the use of low-quality materials and consumables, poor welding practices, and insufficient vibration condition monitoring. [ABSTRACT FROM AUTHOR]

In order to improve the safety performance of projection welding joints during use, the finite element method and equivalent structural stress method were used to study the fatigue life prediction method for resistance projection welding joints of thin-walled cylindrical shells under internal pressure. A modeling method considering the influence of preloading on the shape of cylindrical shells was proposed, and the deformation of the cylinder and the fatigue life of projection welded joints under different preloading were calculated. The research results show that the deformation of thin-walled cylindrical shells at the projection welding joint has a significant impact on the fatigue life of the projection welding joint. It is recommended that measures shoud be taken to reduce the deformation of the cylindrical shell in the opening during the welding process, so as to obtain a higher fatigue life for the projection welded joint. [ABSTRACT FROM AUTHOR]

With the development of lightweight aerospace structures, the use of the high-quality and efficient laser welding of near-α titanium alloys has received widespread attention and favor thanks to its superior comprehensive performance. The welding experiment of 3 mm thick TA15 titanium alloy was carried out by YAG laser welding, and the material weldability, microstructure, microhardness, and mechanical properties of welded joints were systematically studied. The results indicated that laser welding of TA15 titanium alloy can produce well-formed welded joints without defects such as cracks and porosity. The welded metal used was a typical basket-weave microstructure composed of a large number of α′ martensitic phases and a small number of high-temperature residual β phases, and the heat-affected zone was a staggered arrangement of undissolved α phase and needle-like α′ martensite. The microhardness of the welded joint showed a hump distribution, and the hardness of WM fluctuated between 410 and 450 HV since the martensitic transformation occurred during the solidification of the weld under thermal cycling, and the β phase changed to the needle-like α′ phase. The tensile test indicated that the fracture position was located in the base metal area, and the fracture morphology showed the equiaxial dimple morphology of different sizes in a ductile fracture mode. The welded metal had the lowest impact performance (average value of 5.3 J) because the weld area was predominantly coarse α′ martensite. This experiment conducted systematic, in-depth, and extensive research on welding processes, hardness, tensile, impact, and fracture mechanisms. Based on the special product applications in the aerospace field, it was more targeted and conducive to promoting the application of the welding process in this material. [ABSTRACT FROM AUTHOR]

Fe–Mn alloys have been identified as suitable candidates for structural applications that require damping. Damping is the ability of a material to convert mechanical vibrations into other forms of energy (usually heat), which is then dissipated in the material. Fe–Mn alloys do this by the oscillatory movement of various boundaries in their microstructure. Fabricating large structural damping components often requires fusion welding, so it is important that these alloys are weldable. The welding metallurgy and weldability of three high manganese steels were investigated using Varestraint testing, 3D heat flow and solidification modeling, electron probe microanalysis (EPMA), and scanning electron microscopy (SEM). The high manganese steels studied were found to have poor resistance to solidification cracking compared to existing weldable commercial alloys. Through heat flow and solidification modeling, it was established that the ranking of the alloys in the Varestraint test correlated to the size of the crack-susceptible solid + liquid region formed during welding. This was further investigated by tracking solute segregation behavior and its effects on secondary phase formation. Aggressive solute segregation and the concomitant formation of deleterious secondary phases degraded weldability in these alloys. Although it is useful for damping purposes, Si was found to be particularly detrimental to weldability in Fe–Mn systems. [ABSTRACT FROM AUTHOR]

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Within the context of reducing the environmental impact generated by the current generation, a constant challenge for the automotive industry is to produce vehicles with the lowest possible environmental impact. In this context, in order to reduce vehicle weight and, consequently, reduce fuel consumption and emissions of gases harmful to the environment, the automotive industries have been using advanced high-strength steels. These steels make it possible to reduce thickness without losing mechanical strength and, therefore, without compromising passenger safety. Among these steels, 22MnB5 steel stands out. Among the welding processes used to weld steel sheets, electrical resistance spot welding is the most widely used joining technique in the automotive industry. The main reasons for its wide application are that it is a process in which no material addition is required and it has a high processing speed and low processing costs. In this context, this study proposes a bibliometric and systematic review of electrical resistance spot welding of 22MnB5 steel. The main objective of this study was to identify current research trends and impacts, along with a comprehensive revision. The research was carried out using the Proknow-C method. A bibliographic portfolio of 50 articles was compiled. The bibliometric analysis revealed that articles related to this topic increased substantially between 2016 and 2023 compared to previous years. The systematic evaluation of the papers in the bibliographic portfolio made it possible to identify aspects such as the research problems addressed, the materials and methodologies used, the results evaluated, and the research gaps. It was found that most of the studies focused on the weldability and mechanical performance characteristics of similar two-plate joints with an average thickness of 1.5 mm and Al-Si coatings. Finally, this article provides a comprehensive overview of the research on electric resistance spot welding of 22MnB5 steel and can provide guidance for future studies to improve the process. [ABSTRACT FROM AUTHOR]

The presented work is focused on the influence of imposed strain on the weldability of Dievar alloy. Two mechanisms affecting the microstructure and thus imparting changes in the mechanical properties were applied—heat treatment (hardening and tempering), and rotary swaging. The processed workpieces were further subjected to welding with various welding currents. In order to characterize the effects of welding on the microstructure, especially in the heat-affected zone, and determine material stability under elevated temperatures, samples for uniaxial hot compression testing at temperatures from 600 to 900 °C, optical and scanning electron microscopy, and microhardness testing were taken. The testing revealed that, although the rotary swaged and heat-treated samples featured comparable microhardness, the strength of the swaged material was approximately twice as high as that of the heat-treated one—specifically 1350 MPa. Furthermore, it was found that the rotary swaged sample exhibited favorable welding behavior when compared to the heat-treated one, when the higher welding current was applied. [ABSTRACT FROM AUTHOR]

Supermartensitic stainless steel (SMSS) UNS S41426 is an extra-low carbon steel with 12–13%Cr-5%Ni-2%Mo (%wt.) and microadditions of Ti and V. This material offers an interesting combination of mechanical and corrosion resistance. Although the weldability was improved in relation to conventional martensitic steels, due to the drastic reduction of carbon content, post-weld heat treatments are still necessary to decrease the hardness of the heat affected zone (HAZ). The UNS S41426 is used to manufacture mandrels for chemical products or gas injection in the well in the oil and gas off-shore production. Those mandrels are constructed with forged parts and hot rolled seamless pipes joined by welding. The microstructure, hardness, toughness, and sensitization of simulated HAZ of SMSS UNS S41426 forged and hot rolled were investigated. The effect of single tempering at 650 °C for 5 min and at 620 °C for 1 h, as well as double tempering (670 °C/2 h + 600 °C/2 h), was analyzed. The short duration tempering treatments did not change considerably the microstructure, but provoked an undesirable decrease of toughness. The single tempering for 1 h and the double tempering promoted more important microstructural changes, accompanied by the decrease of hardness and the increase of the degree of sensitization. [ABSTRACT FROM AUTHOR]

The need to manufacture components out of copper is significantly increasing, particularly in the solar technology, semiconductor, and electric vehicle sectors. In the past few decades, infrared laser (IR) and green laser (GL) have been the primary technologies used to address this demand, especially for small or thin components. However, with the increased demand for energy saving, alternative joint techniques such as blue diode laser (BDL) are being actively explored. In this paper, bead-on-plate welding experiments on 0.2 mm thick pure copper samples employing a BDL are presented. Two sets of parameters were carefully selected in this investigation, namely Cu-1: Power (P) = 200 W; Speed (s) = 1 mm/s; and angle = 0°, and Cu-2: P = 200 W; s = 5 mm/s; and angle = 10°. The results from both sets of parameters produced defect-free full penetration welds. Hardness test results indicated relatively softer weld zones compared with the base metal. Tensile test samples fractured in the weld zones. Overall, the samples welded with Cu-1 parameters showed better mechanical properties, such as strength and elongation, than those welded with the Cu-2 parameters. The tensile strength and elongation obtained from Cu-1 were marginally lower than those of the unwelded pure copper. The outcomes from this research provide an alternative welding technique that is able to produce reliable, strong, and precise joints, particularly for small and thin components, which can be very challenging to produce. [ABSTRACT FROM AUTHOR]

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Stress relaxation cracking (SRC) is considered one of the major failure mechanisms for 347H stainless steel welds at elevated service temperatures or during post weld heat treatment (PWHT), especially within the heat-affected zone (HAZ). This work focuses on the characterization of SRC susceptibility within 347H physically simulated arc welded HAZ at elevated temperatures. A four-step SRC thermomechanical test in combination with finite element modeling (FEM) of the welding and testing processes is developed to establish a susceptibility map for HAZ. The test first runs a thermal cycle with three different peak temperatures (1335, 1275, and 1150 °C) to duplicate representative HAZ subzone microstructures, followed by time-to-failure examination under a variety of pre-stress (260–600 MPa) and pre-strain conditions (0.03–0.19) as a function of reheat temperatures between 750 and 1050 °C. With the aid of FEM, SRC susceptibility maps are generated to identify the threshold stress, plastic strain, and creep strain as a function of test temperature. It was found out that HAZ subzone with a lower peak temperature (1150 °C) appears to be slightly less susceptible to SRC than the other two subzones that experienced higher peak temperatures. Generally, time-to-fracture reduces with increasing initially applied stress and strain for all test temperatures. The pre-stress thresholds decrease from about 500 to 330 MPa as the testing temperature increases from 800 to 1050 °C, while the corresponding initial plastic strain thresholds reduces from 0.15 to 0.06. The SRC susceptibility was also evaluated through the Larson–Miller Parameter (LMP) analysis as a function of plastic strain, initial stress and starting stress upon reaching the testing temperature, respectively. The 1050 °C test with a high pre-applied strain (0.1) exhibits an extremely short time to failure (t = 3 s) that lies outside the general trend in LMP analysis. Additionally, it was identified that a plastic strain above 0.07 is identified to significantly reduce the bulk creep strain tolerance to fracture and therefore increases SRC susceptibility. Hardness measurement and fractography analysis indicated that the strain aging of niobium carbonitrides and other potential phases in conjunction with intergranular precipitates contributes to an increase in microhardness and increased intergranular cracking susceptibility. [ABSTRACT FROM AUTHOR]

Investigation explores the weldability of Niobium stabilized TP347H austenitic stainless steel tubes through the application of optimized welding parameters using Auto TIG welding. This research investigates the influence of post weld heat treatment conditions on microhardness, microstructures, sensitization due to Cr23C6 precipitation, presence of Niobium carbides and formation of twin boundaries in the weldment. Extended post weld heat treatment duration resulted in notable decline in microhardness from 280 to 180 VHN within initial 5-h of soaking. Nevertheless, further prolongation of soaking time (10–15 h) exhibited subsequent rise in microhardness levels to 200 VHN in base, weld and heat affected zone. Increase in hardness is attributed to the emergence of annealing twins in base metal and the precipitation of Niobium carbides within weld and heat affected zone, confirmed by advanced analytical scanning electron microscope. Energy dispersive spectrum line mapping reveals presence of Cr23C6 precipitation following 1-h soak at 720 °C. Subsequent prolongation of soaking time (5-h) demonstrates desensitization in the base metal. Additionally, cooling rate of 300 °C/hr during post weld heat treatment reduces required time for microstructure homogenization, resulting in increased hardness compared to 100 °C/hr rate in the weldment. However, beyond a 5-h soaking time, the cooling rate has a negligible impact on microhardness. Ultimate Tensile Stress of 674.82 and 665.28 N/mm2 for TP347H was achieved against the minimum requirement of 515 N/mm2 as per American Society of Mechanical Engineers Section IX standard. [ABSTRACT FROM AUTHOR]

This work discusses several aspects of the weldability of AA5083-H116 butt-welded joints, using ER5183 filler material, automated GMAW-P process, and 80Ar19He1O2 shielding gas. The used methodology included the characterization of base metal, the development of welded joints using two different heat inputs, the microhardness profiles analysis on the cross section of the welded joint, and the microstructural evolution using microscopy. The above-mentioned measurements were complemented with residual stress evaluation using the x-ray diffraction technique, together with analysis of transversal and longitudinal tensile tests of the welded joints. The obtained results in welded joints indicated that yield strength, ultimate tensile strength, and ductility behavior have been influenced by heat input compared to base metal and reported values for similar alloys. Residual stress results showed that both the weld metal and adjacent coarse grain zone were subjected to tensile stresses, while the refined grain zone (FGZ) and base metal adjacent to the FGZ were subjected to compressive stresses. Additionally, the magnitude of residual stresses was smaller than maximum tensile stresses, and its behavior was related to both heat input and mechanical properties along welding regions. [ABSTRACT FROM AUTHOR]

Copyright of FME Transactions is the property of University of Belgrade, Faculty of Mechanical Engineering 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.)

The weldability of a CoCrFeMnNi high-entropy alloy (HEA) and 304 stainless steel (304 SS) was investigated to determine their potential for application in the nuclear and aerospace fields. Autogenous dissimilar butt welding was performed using gas tungsten arc welding, and the resulting joint was complete with no defects. SEM/XRD analysis showed that the fusion zone microstructure consisted of a single fcc phase without the formation of intermetallic compounds. However, there is an unmixed zone near the 304 SS side, which can be attributed to subcooling of the composition caused by the lower liquidus temperature of the bulk weld metal than that of the base metal. Furthermore, a small increase in the hardness of the fusion zone compared with that of the CoCrFeMnNi HEA was observed. These results can be attributed to the grain refinement of the weld and the strengthening effect owing to the incorporation of carbon. The joints exhibited a tensile strength of ~ 465 MPa and ductility of 38%, where the strength was comparable to that of the CoCrFeMnNi HEA, and a joint fracture was found at the side of the CoCrFeMnNi HEA. This indicates that the weldments are suitable for room temperature structural applications. [ABSTRACT FROM AUTHOR]