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A photon absorber, as a critical component of a synchrotron front‐end, is mainly used to handle high‐heat‐load synchrotron radiation. It is mostly made of dispersion strengthened copper or CuCrZr which can retain high performance at elevated temperatures. Joining processes for vacuum, including tungsten inert gas welding (TIG) and electron beam welding (EBW), are novel ways to make a long photon absorber from two short ones and reduce power density. The mechanical properties of TIG joints and EBW joints of CuCrZr to the same material are obtained by tensile tests at 20°C, 100°C, 200°C, 300°C and 400°C. Testing results indicate that the tensile strength and yield strength of both vacuum joints decline as temperature increases. Compared with TIG joints, EBW joints have higher strength, better ductility and a more stable performance. An engineering conservative acceptance criteria of the vacuum joints is created by the polynomial fitting method. A novel welded photon absorber with a total length of 600 mm has been successfully designed and manufactured. Finite‐element analysis by ANSYS shows that the maximum temperature, equivalent stress and strain are only 31.5%, 36.2% and 1.3%, respectively, of the corresponding thresholds. The welded photon absorbers with EBW joints will be applicable in the highest‐heat‐load front‐end in the Shanghai Synchrotron Radiation Facility Phase‐II beamline project. A novel welded photon absorber with a total length of 600 mm has been successfully designed and manufactured, and will be applicable in the highest‐heat‐load front‐end in the Shanghai Synchrotron Radiation Facility Phase‐II beamline project.

Electron beam welding–brazing (EBWB) was applied to join TA2 and 2024Al alloys with Al-Mg filler wire. The effect of gap clearance on interfacial microstructures and mechanical properties of the butt Ti/Al joint was discussed. Three types of intermetallic compound (IMC) layers, including discontinuous cellular shape, continuous serrated shape, and discrete club shape, were presence at the TA2 interface. With the increase of gap clearance, the thickness of the IMC layer increased gradually, and the morphology of IMC layer changed from cellular shape to serrated shape and ultimately to club shape. The IMC layer was mainly TiAl 3 compound, while the weld zone (WZ) comprised the predominant α -Al and bits of Al-Cu eutectic. The tensile strength of Ti/Al joint first increased and then decreased with the increased gap clearance. When the gap clearance of the butt configuration was 0.4 mm, the Ti/Al joint 3# exhibited the highest strength (316.4 MPa), about 73.7% of that of the 2024Al matrix, which is due to the formation of a continuous serrated-shaped IMC layer with a thickness of 1.36-2.3 μm.

To enhance welding quality and performance, preheating and post-heating are usually employed on high-temperature materials, concurrently with welding. This is a novel technique in vacuum chamber electron beam welding (EBW). TC17 and Ti2AlNb alloys are the hot topics in aero-engine parts, and the welding of dissimilar materials is also a broad prospect. To settle welding cracks of Ti2AlNb, EBW with preheating and post-heating was investigated on TC17 and Ti2AlNb dissimilar alloy, which improved the manufacturing technology on high-temperature materials. The dissimilar joint no longer had cracks after preheating, which exhibited excellent welding stability and metallurgical homogeneity, and preheating and annealing had an important effect on mechanical properties. The joint strength after 630 °C annealing is higher than that of TC17 alloy base metal (BM) and other annealing temperatures, reaching 1169 MPa at room temperature and 894 MPa at 450 °C tensile condition. The joint plasticity after 740 °C annealing is equivalent to TC17 BM. EBW with preheating improved the microstructure characteristics and enhanced the plasticity of Ti2AlNb alloy weld and dissimilar joint, which would contribute to the application of Ti2AlNb alloy and Ti2AlNb dissimilar parts.

The current work is based on investigating the influence of different technological conditions of electron-beam welding on the microstructure and mechanical properties of joints between Ti6Al4V and Al6082-T6 dissimilar alloys. The plates were in all cases preheated to 300 °C. Different strategies of welding were investigated such as varying the electron-beam current/welding speed ratio (Ib/vw) and applying a beam offset towards the aluminum side. The heat input during the experiments was varied in order to guarantee full penetration of the electron beam. The macrostructure of the samples was studied, and the results indicated that using a high beam power and a high welding speed leads to an increased formation of defects within the structure of the weld seam. Utilizing a lower beam current along with a lower welding speed leads to the stabilization of the electron-beam welding process and thus to the formation of an even weld seam with next to no defects and high ductility. Using this approach gave the highest ultimate tensile strength (UTS) of 165 MPa along with a yield strength (YS) of 80 MPa and an elongation (ε) figure of 18.4%. During the investigation, improved technological conditions of electron-beam welding of Ti6Al4V and Al6082-T6 dissimilar alloys were obtained, and the results were discussed regarding possible practical applications of the suggested approach along with its scientific contribution to developing further strategies for electron-beam welding of other dissimilar alloys. The downsides and the economic effect of the presented method for welding Ti6Al4V and Al6082-T6 were also discussed.

The Ti2AlNb alloy is an intermetallic structural material with excellent properties, but it is limited in its uses due to the problem of welding cracks. The electron beam welding (EBW) procedure with preheating on Ti2AlNb alloy was examined in this research using multi-beam processing. The microstructures at the weld center were still constituted of a single B2 phase, and B2 and O phases were in heat affected zone (HAZ), despite the fact that the cooling rate of EBW decreased under electron beam preheating. Under ambient temperature and 650 °C high-temperature tensile tests, the tensile strength of Ti2AlNb alloy joints was respectively above 980 and 595 MPa, as determined by electron beam preheating of 550 °C. Welding with preheating increased the mechanical characteristics of Ti2AlNb alloy joints when compared to standard EBW, which was attributable to improved welding joint uniformity.

The ER5183 is used as filler metal, and the Al–Li alloy is welded by electron beam welding. The microstructure and mechanical property of welded joint are investigated. Results show that, under the proper welding procedure, the joint with good appearance of weld is obtained. The fusion zone is mainly composed of α-Al matrix phase and some strengthening phases involving θ′(Al 2 Cu), T 2 (Al 6 CuLi 3 ), T 1 (Al 2 CuLi) and δ′(Al 3 Li). The grains in weldment are refined by the addition of electron beam scanning. Compared with that of the base metal (BM), the microhardness in weld zone is decreased to a certain extent. Under the welding condition of square wave electron beam scanning, the tensile strength of welded joint is 352.2 MPa, which is 70.2% of that of the BM. There exists obvious dimple morphology on the joint fracture surface, and it presents the characteristic of intergranular fracture.

Vacuum roll-cladding (VRC) is an effective method to produce high-quality ultra-heavy AISI P20 plate steel. In the process of VRC, reasonable welding process of electron beam welding (EBW) can significantly avoid welding cracks and reduce the cost. In this paper, the electron beam welding process of AISI P20 tool steel was simulated by using a combined heat source model based on finite element method, and the temperature field and stress field under different welding parameters were studied respectively. The results showed that welding parameters have a greater effect on weld penetration than that of weld width, making the aspect ratio increases with the increase of welding current, and decrease with the increase of welding speed. The weld morphologies were consistent with those of the modeling, and the measured thermal heat curves were in good agreement with those of simulated, which verified the feasibility and effectiveness of temperature fields. The results of stress fields under different welding parameters indicated that welding speed of 300mm/min and welding current of 60mA result in lower residual stress at welded joint, which means lower risk of cracking after EBW. The results of this study have been successfully applied to industrial production.

In recent years, ultra-high-strength structural (UHSS) steel in quenched and tempered (Q+T) conditions, for example, S960QL has been found in wider application areas such as structures, cranes, and trucks due to its extraordinary material properties and acceptable weldability. The motivation of the study is to investigate the unique capabilities of electron beam welding (EBW) compared to conventional gas metal arc welding (GMAW) for a deep, narrow weld with a small heat-affected zone (HAZ) and minimum thermal distortion of the welded joint without significantly affecting the mechanical properties. In this study, S960QL base material (BM) specimens with a thickness of 15 mm were butt-welded without filler material at a welding speed of 10 mm/s using the high-vacuum (2 × 10−4 mbar) EBW process. Microstructural characteristics were analyzed using an optical microscope (OM), a scanning electron microscope (SEM), fractography, and an electron backscatter diffraction (EBSD) analysis. The macro hardness, tensile strength, and instrumented Charpy-V impact test were performed to evaluate the mechanical properties. Further, the results of these tests of the EBW joints were compared with the GMAW joints of the same steel grade and thickness. Higher hardness is observed in the fusion zone (FZ) and the HAZ compared to the BM but under the limit of qualifying the hardness value (450 HV10) of Q+T steels according to the ISO 15614-11 specifications. The tensile strength of the EBW-welded joint (1044 MPa) reached the level of the BM as the specimens fractured in the BM. The FZ microstructure consists of fine dendritic martensite and the HAZ predominantly consists of martensite. Instrumented impact testing was performed on Charpy-V specimens at −40 °C, which showed the brittle behavior of both the FZ and HAZ but to a significantly lower extent compared to GMAW. The measured average impact toughness of the BM is 162 J and the average impact toughness value of the HAZ and FZ are 45 ± 11 J and 44 ± 20 J, respectively.

The structure is considered for a typical system to control electron beam welding deposition with supplying feed (wire). This approach is used today to implement additive technologies. The main features of the process are described. It is shown that the temperature of the underlying layer changes during surface deposition; therefore, it destabilizes the process through changing the temperature of the melt bath as well as the transverse dimensions of the formed layer. The need to use a feedback control system to stabilize the temperature of the welded layer is substantiated and an approach to its technical implementation is described. The results obtained for a prototype of a temperature stabilizer based on a microcontroller are presented. The fundamental potential is demonstrated to ensure the repeatability of the height of the welded layer and to prevent the wire from detaching the liquid melt bath during welding deposition of a multilayer cylindrical contour made of 316L steel.

Vacuum electron-beam welding (EBW) was used to join the precipitation-strengthened GH4169 superalloy and a new nickel-based superalloy IC10 to fabricate the turbine blade discs. In this study, a solid solution (1050 °C/2 h for GH4169 and 1150 °C/2 h for IC10) and different heat-exposure temperatures (650 °C, 750 °C, 950 °C and 1050 °C/200 h, respectively) were used to study the high-temperature tensile properties and microstructure evolution of welded joints; meanwhile, the formation and evolution of the second phases of the joints were analyzed. After EBW, the welded joint exhibited a typical nail morphology, and the fusion zone (FZ) consisted of columnar and cellular structures. During the solidification process of the molten pool, Mo elements are enriched in the dendrites and inter-dendrites, and that of Nb and Ti elements was enriched in the dendrites, which lead to forming a non-uniform distribution of Laves eutectic and MC carbides in the FZ. The microhardness of the FZ gradually increased during thermal exposure at 650 °C and reached 300–320 HV, and the γ′ and γ″ phases were gradually precipitated with size of about 50 nm. Meanwhile, the microhardness of the FZ decreased to 260–280 HV at 750 °C, and the higher temperature resulted in the coarsening of the γ″ phase (with a final size of about 100 nm) and the formation of the acicular δ-phase. At 950 °C and 1050 °C, the microhardness of FZ decreased sharply, reaching up to 170~190 HV and 160~180 HV, respectively. Moreover, the Laves eutectic and MC carbides are dissolved to a greater extent without the formation of γ″ and δ phases; as a result, the absent of γ″ and δ phases are attributed to the significant improvement of segregation at higher temperatures.