Electron Beam Welding Research Articles

Review on High-Energy Beam Based Processing Technologies for Fabrication of Small Modular Reactor

The development of small modular reactors (SMRs) has attracted significant attention owing to the increasing interest in energy security and carbon neutrality worldwide. An SMR is an advanced nuclear reactor with a power capacity of up to 300 MWe per unit. To fabricate the SMR, innovative manufacturing technologies such as powder metallurgy hot isostatic pressing (PM-HIP), electron beam welding (EBW), and diode laser cladding (DLC) were introduced to reduce the fabrication cost and time. Particularly, this replaced arc-based welding and cladding with high-energy beam-based EBW and DLC. The EBW could provide one pass welding for extremely thick specimens. In addition, in the case of using the DLC, only one layer cladding was acceptable for corrosion protection owing to its low dilution rate. However, studies on the innovative manufacturing technologies were less reported because of technology security. In this study, recently reported research articles regarding the EBW and DLC were reviewed. In particular, local vacuum and reduced pressure electron beam studies were discussed by comparing their the arc welding results. Process parameter studies on the DLC were also reviewed to introduce appropriate optimized conditions for the industry application.

Study on the Comparison of Electron Beam Welding and Hybrid Laser-Arc Welding of Thick High-Manganese Steel Plate for Cryogenic Applications

Environmental protection policies have led to a focus on clean energy from Liquefied Natural Gas (LNG) and thus, its demand is increasing. Several studies for the development of cryogenic materials and fabrication technologies for storage and delivery of LNG are presented worldwide. Recently, International Maritime Organization (IMO) acknowledged that high-manganese steel was one such cryogenic material for application in LNG storage. Thus, high-manganese steel is expected to be increasingly used in the cryogenic storage industry because of its excellent material properties such as low-temperature toughness and tensile strength. A variety of researches on the welding technologies are available, including arc welding, laser welding and hybrid laser-arc welding. However, electron beam welding (EBW) has not been widely studied. In this work, EBW was investigated for the thick high-manganese steel plate and its mechanical properties were evaluated and compared with the characteristics of hybrid laser-arc welding. Our study indicates that EBW exhibits better mechanical properties than the hybrid laser-arc welding and it can be an effective potential candidate technology for welding of thick high-manganese steel plate with application in cryogenic storage tank.

Autogenous Dissimilar Welding of Copper-to-Stainless Steel via Electron Beam Welding: A Novel Strategy for Achieving Defect-Free Joints

Autogenous Dissimilar Welding of Copper-to-Stainless Steel via Electron Beam Welding: A Novel Strategy for Achieving Defect-Free Joints

Investigation of the influence of pulse parameters on the resulting weld seam quality in pulsed electron beam welding of AW 6061

Utilizing pulsed lasers in favor of a continuous wave in laser beam welding is a well-established method to achieve higher process efficiency and reduce heat input into the workpiece, which is especially useful for thin-walled workpieces (Steen, 2005). In addition, pulsed processes have shown to lead to smaller grain sizes due to higher cooling rates, which can lead to a reduction in hot cracks in some aluminum alloys (Beiranvand et al., 2019). Since an electron beam can also be pulsed, a technique industrially utilized in electron beam drilling, the same principles apply (Schultz, 2000). However, pulsed electron beam welding is rarely used in industrial welding applications due to the risk of pores, spiking and sputtering resulting from the pulsed process dynamic, especially in the deep welding regime (Kautz, 1991). This study aims to develop a pulsed electron beam welding process for AW 6061 sheet metal, which is susceptible to hot cracking. The influence of the welding and pulse parameters, as well as the combination of a pulsed beam with high frequency beam oscillation is discussed. Furthermore, suitable welding parameters for pulsed electron beam welding of AW 6061 are developed, and the increased efficiency of pulsed welding is shown by comparison to continuous welds.

In situ localised post-weld heat treatment with electron beam welding of S690QL steel

The objective of this research is to assess the influence of in-situ localised electron beam post-weld heat treatment (LEB-PWHT) on the microstructure and mechanical properties of high-strength S690QL steel welded joints utilising highly sophisticated electron beam welding (EBW) technology. Although EBW is well-known for creating high-quality welds, the addition of the novel LEB-PWHT technique may significantly improve the characteristics of the welded joints. To systematically analyse the impacts of PWHT on the welded joints, the study employs microstructural analysis like optical microscopy and mechanical properties like microhardness testing, bending, tensile, and impact tests. Furthermore, tensile fractography analysed by scanning electron microscopy (SEM) to provide detailed insights into the fracture behaviour of the welded joints. The results show that the in-situ PWHT approach improves the microstructure and mechanical characteristics of the welded joints, such as a lower hardness peak in the heat affected zone (HAZ), increased tensile strength (5%), and improved toughness by 7 times. LEB-PWHT fractured surface revealed smaller, more sharply defined dimples and micro-voids. These results suggest that in-situ PWHT is an attractive option for improving the quality and performance of welds in a wide range of applications incorporating S690QL steel.

In-situ investigation of microstructure-dependent deformation behavior of an electron-beam welded Ni-Co based superalloy

In order to clarify the strengthening mechanism of an electron-beam welded (EBW) Ni-Co based superalloy, the local deformation behavior in different regions across the weld joint was investigated by the in-situ micro-tensile test in the scanning electron microscope and analyzed by the micro digital image correlation (μDIC). The microstructures across the weld joint were systematically investigated on multiscale levels. The micro-hardness profiles were also determined across the weld joint. Significant changes in the grain size, γ’ phase, MC carbides and dislocation configurations were observed within 2.0 mm from the weld line as a result of the steep temperature gradient and the resultant Marangoni flow occurring during EBW process. Furthermore, the micro-hardness profiles and microstructure-dependent mechanical properties were influenced by the variation of grain size, γ’ particle size and the dislocation density in the weld joint. The cracks preferred to initiate and propagate on the blocky MC carbides, rather than the ultrafine MC carbides and the liquefaction cracks. This study proposes a method for high throughput measurement of microstructure-dependent mechanical properties, and shows a certain guiding significance for optimization of microstructure and improvement of mechanical properties of electron-beam welded Ni-Co based superalloys.

Electron beam weldability of TiZrNbTa refractory high-entropy alloy and TC4 titanium alloy

Welding is a crucial process for the application of new materials in engineering. By welding refractory high-entropy alloys with other alloys, a composite structure can be formed that not only combines the advantages of both materials but also reduces costs. This paper focuses on evaluating the electron beam weldability of TiZrNbTa refractory high-entropy alloy. Additionally, it presents an innovative approach to achieve dissimilar electron beam welding of TiZrNbTa and TC4 titanium alloy, resulting in defect-free welded joints. The microstructure of the two groups of welds was analyzed, and the relationship between microstructure evolution and the mechanical properties of the joint was studied. The microstructure characterization of the two sets of welds was carried out after welding, and the relationship between the weld tissue evolution and the mechanical properties of the joints was investigated. It was found that the grains in the fusion zone of TiZrNbTa were significantly refined and the casting holes were significantly reduced. Although macroscopic segregation was found in the dissimilar welds, the subsequent tensile tests revealed a 10% increase in tensile strength over TiZrNbTa at 389 MPa. In addition, the dissimilar joints exhibited excellent compression strength and compressive yield strain (1280 MPa, 23.5%). However, both had poor tensile plasticity, a typical brittle fracture mode, and the fracture occurred on the TiZrNbTa parent material side, and the reason for the fracture was explained. This study confirms for the first time the good weldability of TiZrNbTa and TC4 titanium alloy, which provides theoretical support for the engineering application of refractory high-entropy alloys.

Nanomechanical, mechanical and microstructural characterization of electron beam welded Al2219-T6 tempered aerospace grade alloy: A comprehensive study

As compared to traditional fusion welding processes, electron beam welding (EBW) is known to produce structurally robust microstructures and narrow heat-affected zone (HAZ) in metals. The process becomes more significant for the tempered alloys vulnerable to heat exposure. In the present investigation, Al 2219-T6 alloy was joined using the EBW process. The microstructural, mechanical, and nanomechanical characteristics of the resulting joint were investigated. EBW resulted in a narrow HAZ (22 μm) with a 430 mm fusion zone (FZ). A dendritic structure was observed in the FZ zone, while second-phase particles were absent indicating their dissolution during welding and interesting formation of Al2Cu mixture around the dendrites. The limited content of Cu in the base metal (BM) resulted in the formation of a solid solution in the FZ, along with the presence of fine equiaxed grains in the HAZ and equiaxed dendritic grains in the FZ zone. The X-ray diffraction analysis confirmed the absence of peaks corresponding to incoherent phases in the FZ. Compared to the BM, micro-hardness measurements revealed a 12.7 % increase in the hardness in the HAZ, while a significant decrease of approximately 19 % was observed in the FZ. The joint exhibited reduced tensile strength, ultimate strength by 42.2 %, and yield strength by 47.3 % when compared to the BM. The fracture analysis indicated a ductile failure mode with the presence of microvoids. Nano-indentation tests at various loads demonstrated a decrease in the nanohardness from the BM to the HAZ and FZ regions. Atomic force microscopy (AFM) analysis revealed significant pile-ups in the FZ, indicating the occurrence of plastic deformation during the welding process. The presented findings are valuable for the joint and structure design of Al −2219T6 alloy in particular and other Al alloys in general.

Modeling of technological parameters of electron beam weldingfor rocket and space technology products

The article contains the results of scientific research on modeling the technological parameters of electron beam welding. The modeling used a material VT-14 with a thickness of 0.16 cm. The purpose of the simulation is to improve the quality of the weld due to the optimal shape and the absence of defects in the form of pores and cracks. A concentrated energy source equivalent to an electron beam is used in the calculations. During the study of the thermal process of heating the material, the authors developed and tested criteria that allow optimizing welding parameters such as welding speed and the position of the focal spot relative to the surface of the heated part. In their calculations, the authors applied an original method of finding the welding speed and the coordinates of the focal spot according to the functionals of the thermal model. The algorithm developed by the authors was successfully tested on AMG-6 material with a thickness of 10 cm. In the process of modeling welding for large thicknesses, results have been obtained that must be taken into account when optimizing the welding parameters of products with large thickness. The relevance of the presented material is confirmed by the demand for the quality of the technology of welding structures with an electron beam. Research by the authors of this direction will significantly expand the possibilities in the application of electron beam technology for rocket and space technology.

Formability characterization of steel tailor welded blanks formed through single point incremental forming

TWBs are being well formed by a simple, highly innovative method known as Incremental Sheet Forming (ISF). Both aluminum and steel sheets welded through friction stir welding (FSW), laser beam welding (LBW) or electron beam welding (EBW) have been explored, extensively, by researchers. However, no research is available on the formability characterization of selected steel sheets having thickness and strength differential, manually welded using Tungsten Inert Gas (TIG) welding technique and formed through Single Point Incremental Forming (SPIF). The same is addressed in this study. Variable wall angle truncated pyramid was used as test geometry. Tensile testing, microhardness and scanning electron microscope (SEM)/Energy Dispersive X-ray (EDX) analysis were performed before forming. Material selected for the study included deep drawing quality (DDQ) steel (DC06) and stainless steel (SS) (AISI 201). Because of huge difference in both strength and hardness values of DDQ steel and SS, low formability was achieved in case of strength differential with minimum and maximum forming depths of 1.8 mm and 3.6 mm, respectively. Whereas formability achieved in case of thickness differential was quite high with minimum and maximum values of forming depths of 27.8 mm and 36.6 mm, respectively since strength and hardness values were not varied much. Percentage thinning was used to assess formability achieved. Final thicknesses achieved during forming were verified by cosine law also. Research investigations may be applied in similar fashion for precise study of material characterization of various kinds of TWBs being used in multiple industries including automotive, vessel, medical, etc.

The microstructure and impact toughness of vacuum electron beam welded joints of a highly alloyed dual phase titanium alloy

Vacuum electron beam welding of 50 mm thick TC18 titanium alloy plates were carried out at different processing parameters, and full penetration welded joints were obtained. The welded joint presents three typical zones, namely, fusion zone, heat affected zone and base metal zone. It is found that processing parameters have no obvious influence on the width of heat affected zone. By using EBSD technology, the changes of phase composition, grain size and grain boundary density from the fusion zone to heat affected zone and then to base metal zone were clearly observed and quantitatively analyzed. The fusion zone shows coarse equiaxed/columnar β grains with an average diameter/width of more than 100 μm. The volume fraction of α phase in the heat affected zone decreases with the decrease of the distance to the fusion zone until it is completely dissolved into β phase. The formation mechanism of microstructure in different zones and its influence on impact toughness were discussed. The β grain size and undissolved/precipitated fine α grain on β grain boundary are two main factors affecting impact toughness.

Dynamic ideality for electron beam welding

Experimental methods for evaluating performance of electron beams are both time consuming and costly, with favourable parameters chosen based on a subjective standard. Correlation of the weld geometry against conventional machine input parameters such as voltage, focus, and current involves complex interaction phenomena. This renders it difficult to deconvolute the influence of these inputs against applied energy distributions within a setup. In this work, a process window was generated across a range of weld powers and speeds with focal positions adjusted to achieve the same nominal spot size and hence mitigate input parameter interaction phenomena. The variability of spot size using this method can be reduced by 90% against using the conventional method of optically acquiring weld focus. To reduce reliance on empirically derived heuristics in parameter selection, weld performance was quantified through an aggregated output quality termed ‘ideality’ as a function of conventional weld geometry, imperfections, and characteristic microstructural evolution/transformation. The ideality metric was shown as a method of achieving the least harmful compromise of parameter conflicts. A method of using a thermal process model to perform subsequent optimisation of ideality was presented. The ability to characterise inputs as a function of beam properties rather than machine inputs serves as a useful method to optimise weld procedures and serve as a basis for comparison between setups. While electron beam welding is used in this study to propose ideality, process outputs and inputs can be substituted for other process-specific outputs and inputs, enabling adoption for most manufacturing processes.

Microstructure evolution and strengthening mechanisms of electron beam welded 2219 aluminum alloy plate after hot spinning and heat treatment

To investigate the feasibility of spinning the welded aluminum alloys, hot spinning tests were conducted on the electron beam welded (EBWed) 2219 aluminum alloy thick plates at 400 °C and successfully obtained a 2.8 mm curved welded-spun plate with a total thickness reduction of 72 %. The abnormal grain growth (AGG) phenomenon of the base material during hot spinning could be observed due to the reduced pinning effect of the θ-Al2Cu phases and static recrystallization, while the fusion zone exhibited homogeneous recrystallized microstructure. After hot spinning, the yield strength of the base material increased from 89.3 MPa to 133.6 MPa and the yield strength of the joint increased from 93.1 MPa to 134.7 MPa. To further optimize the microstructure and improve the mechanical properties of the spun alloy, the subsequent solid solution and aging treatment were conducted. Most of the coarse θ particles dissolved into the matrix and a large quantity of needle-like θ′ precipitates were generated. The yield strengths of the base material and the joint increased to 213.1 MPa and 216.4 MPa, respectively, which was mainly attributed to the precipitation strengthening of the θ′ precipitates. The comparison between the calculated yield stress and the experimental results showed that the contributions of different strengthening mechanisms in strengths were reliable.

Comparative Analysis of Weld Microstructure in Ti-6Al-4V Samples Produced by Rolling and Wire-Feed Electron Beam Additive Manufacturing

The microstructure and phase composition of electron beam welded Ti-6Al-4V titanium alloy were studied by optical and scanning electron microscopy, backscattered electron diffraction, and X-ray diffraction analysis. Deep-penetration electron beam welds were made in a single pass on rectangular Ti-6Al-4V samples obtained by rolling and wire-feed electron beam additive manufacturing. It was found that the weld width in the 3D printed Ti-6Al-4V samples is greater than in the rolled material. The influence of the vapor capillary on the size, shape and structure of primary β grains formed in the fusion zone was shown. The variation of the penetration coefficient, volume fraction of the residual β phase, and residual stresses along the weld length was studied for Ti-6Al-4V samples obtained by both rolling and 3D printing.

Future application and prospect of space electron beam processing technology

Technological advances in space electron beam processing could fundamentally alter how spacecraft and space stations are built. The primary topics covered in this essay are the application circumstances for electron beams in space, the research situations for electron beam welding, additive manufacturing, and surface modification, and an analysis of the potential future applications for this technology. It demonstrates the viability of space applications of electron beam processing technologies.

Effect of post-welding heat treatment on microstructure and properties of electron beam welding joint of new high-strength TB18 titanium alloy

Effect of post-welding heat treatment on microstructure and properties of electron beam welding joint of new high-strength TB18 titanium alloy

Electron-Beam Welding Joint Strength of Dissimilar Materials

This paper provides an in-depth discussion of the joint strength of electron beam welding of dissimilar materials. The effect of welding parameters and material properties on the joint strength was analyzed, and an argument for the optimal parameter combination is presented. Electron-beam welding technology offers several advantages, including high energy density and the ability to create fine weld seams. However, it also presents certain challenges, such as the complexity of welding parameters and the potential generation of brittle phases. The analysis conducted in this paper holds significant importance in enhancing the quality and efficiency of dissimilar material welding processes.

High Energy Density Welding of IN792 Ds Superalloy

Ni base superalloys are commonly employed in the industrial fields of aerospace, automotive and energy production due to their excellent mechanical properties and corrosion resistance at high temperature. Superficial defects and cracks may occur during both manufacturing process of components and their service life. High energy density welding techniques, electron beam (EBW) and laser beam (LBW) welding, can be used to create efficient repairs. Joints, obtained by EBW and LBW of IN792 directionally solidified (DS) superalloy, have been investigated to determine the presence of defects, and evaluate the mechanical properties related to specific microstructural features. The results showed that a pre-heating temperature (PHT) higher than 200 °C is always necessary to prevent the formation of hot cracks in the molten zone (MZ) and heat affected zone (HAZ). The process parameters have been optimized to get a good quality of the seams (lack of macro-defects, a good penetration depth and width). Some preliminary test of post-welding heat treatments (PWHTs) have been investigated to homogenize as far as possible the microstructure and the mechanical properties across the seams. The results obtained by the two techniques, EBW and LBW, have been compared and discussed.

The Application of Electron-Beam Welding in Pellet Mold Preparation

This paper provides insight into the application of electron-beam welding in pellet mold preparation, highlighting the importance of the combination of electron-beam welding and pellet mold preparation in the fields of microstructure joining and micro- and nanostructure preparation. Precise material joining and microstructure fabrication can be achieved by the precise control of electron-beam welding and the shape adjustment of pellet molds. These applications hold significant potential in the modern industrial field, providing robust support for the development of new materials and the growth of the petrochemical industry. This paper asserts that in the future, the ongoing development of electron-beam welding and pelletizing template technology will unlock new possibilities in the field of petrochemicals, fostering progress in science and technology.

Annealing Heat Treatment for Homogenizing the Microstructure and Mechanical Properties of Electron-Beam-Welded Thick Plate of Ti-6Al-4V Alloy

In the application of Ti-6Al-4V to aerospace structural components, when welding thick plates similar of the thickness of the components, microstructure and hardness gradients emerge between the base material (BM) and the joint. This leads to the issue of significant stress concentration in the BM under tensile stress. To address this problem through post-welding heat treatment, this study conducted heat treatments at temperatures both below (mill annealing, MA) and above the beta-transus temperature (beta annealing, BA) on electron-beam weldments of 18 mm thickness Ti-6Al-4V plates. Subsequently, microstructures and hardness were analyzed at different depths from the upper surface and areas (fusion zone (FZ), heat-affected zone (HAZ), and BM), and tensile properties were measured at various depths. The results indicated that α′ observed in FZ and HAZ was resolved through both MA and BA. Particularly after BA, the microstructural gradient that persisted even after MA completely disappeared, resulting in the homogenization of widmanstätten α + β. Consequently, after BA, the hardness gradient in each zone also disappeared, and the tensile strength was higher than in just-welded and MA heat-treated plates.