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Accident Tolerant Fuels (ATF) have emerged as a promising solution to improve safety during reactor accidents by enhancing fuel performance in light water reactors (LWRs). This paper investigates the performance of different ATF concepts, including Chromium-coated Zircaloy (CrZry), advanced steel (FeCrAl), and Silicon Carbide (SiC) as cladding materials, paired with Uranium Dioxide (UO 2 ), Uranium Silicide (U 3 Si 2 ), and Uranium Nitride (UN) fuels, under spectrum shift regulation conditions in a VVER-S reactor. Using the GETERA program, a series of calculations were conducted to compare multiplying factors and isotopic concentrations under spectrum-shifted conditions. The results demonstrate significant differences in fuel cycle characteristics and isotopic behavior, with SiC emerging as the optimal cladding material for maximizing neutron economy and minimizing parasitic absorption.

Laser cladding is an environmentally friendly and reliable surface modification technology. The quality characteristics of the coating are directly affected by the process parameters of laser cladding. The reasonable selection of process parameters is essential to obtain high-quality coating. In this study, the single-track 15-5PH alloy coating was fabricated on the surface of 12Cr13 stainless steel. In view of the hybrid Genetic Algorithm and Ant Colony Optimization (GA-ACO) can effectively improve the prediction ability and robustness of Random Forest Regression (RFR), a prediction method of cladding layer quality characteristics based on GA-ACO-RFR was proposed. The fast non-dominated ranking genetic algorithm with elite strategy by introducing the Gaussian distribution crossover operator (GNSGA-II) was used to optimize the process parameters of laser cladding. The results showed that the multi-objective optimization method of laser cladding process parameters proposed in this paper can obtain high-quality laser cladding coating. This work demonstrated the potential of the proposed method in laser cladding process prediction and optimization.

To address the issue of wire detachment from the external surface of cladding tubes during operation, an integrated structure known as the ribbed cladding tube (RCT) has been introduced. Nonetheless, this novel form of cladding tube encounters challenges in fully filling the rib heights and is susceptible to inner wall depressions (IWDs) during the cold drawing process. In order to tackle these problems, a multiscale constitutive model incorporating multiple deformation mechanisms was developed and employed to establish a finite element model (FEM) for cold drawing of RCT. The credibility of the established FEM was verified by comparing the experimental and simulation results. Additionally, the influence of drawing process parameters on formability and microstructural evolution was investigated. The results indicate that under the conditions of a die semi-die angle of 6°, a rib-groove angle of 10°, a drawing speed of 5 mm/s, and a friction coefficient of 0.05, optimal filling effects for ribs can be realized. The resulting RCTs exhibit high contents of martensite and twins along with fine grain size on both inner and outer walls. Finally, by utilizing these optimized process parameters, RCTs that meet the dimensional specifications and exhibit reasonable microstructure distribution were successfully fabricated through multi-pass drawing. This research augments the forming theory associated with thin-walled shaped tube and provides theoretical guidance for the development and application of novel cladding tubes.

AlCoCrFeNi 2.1 eutectic high-entropy alloys (HEAs) are a new kind of alloy with high entropy and eutectic properties. Their advantages in terms of strength and shape matching can be fully exploited using extreme high-speed laser cladding (EHLA). In this paper, AlCoCrFeNi 2.1 eutectic HEA coatings were prepared by conventional laser cladding (CLA) and EHLA. The microstructures and phase compositions of the two coatings were analyzed by scanning electron microscopy, x-ray diffraction, and electron backscatter diffraction. The microhardness and wear resistance values of the coatings were tested using a microhardness tester and a friction and wear tester, respectively. The results showed that the surface qualities of both the CLA and EHLA coatings were good and had no cracks or defects. Compared with those of the CLA coating, the EHLA coating had finer grains and a more uniform distribution. Both coatings contained face-centered cubic (FCC) and body-centered cubic (BCC) phases, but the BCC phase of the EHLA coating was less precipitated than the CLA coating. The higher microhardness and better wear resistance of the EHLA coatings occurred in the presence of Hall–Petch strengthening. Graphical Abstract

Hybrid components, made of multiple materials, can meet the increasing demands for lightweight construction and functional integration in the automotive and aircraft industry. Hybrid semi-finished components are produced by applying a high-alloy cladding to a low-alloy base material before hot-forming and machining the workpiece. Throughout this process chain, workpiece deviations in the form of material distribution and material properties can occur that influence the component’s lifetime. This paper investigates whether such workpiece deviations can be detected within the process chain by analyzing process signals obtained from subsequent process steps. For this purpose, artificial workpiece deviations were introduced to hybrid semi-finished workpieces made of C22.8/X45CrSi9-3. Then, process signals during forming and machining were analyzed to determine their sensitivity to the artificial deviations. The results revealed that deviations in cladding size can be effectively monitored using signals from both forming and machining. Cladding position deviations can only be detected during machining, while forming signals are more responsive to detecting the introduced hardness deviations of approx. 100 HV0.1.

The multi-track, multi-layer laser cladding process is influenced by critical parameters, yet research on optimizing these parameters remains limited. This study aims to address this gap by focusing on the optimization of process parameters for multi-track, multi-layer laser cladding of 316L stainless steel. Orthogonal experiment was firstly conducted on laser power, scanning speed, powder feed rate, overlap rate, and Z-axis lift amount, and gray relational analysis (GRA) assessed their impact on quality indicators such as porosity, surface smoothness, and height difference. A Gaussian process regression (GPR) model was then developed to predict the relationship between process and quality parameters. Using an improved multi-objective particle swarm optimization (IMOPSO) algorithm, optimal parameters were identified, reducing porosity, surface smoothness, and height difference by 53.7%, 76.1%, and 92.7%, respectively. A repair experiment on a damaged 316L stainless steel tooth rack demonstrated that the optimized parameters increased microhardness to 310 HV 1 , compared to 272 HV 1 for the substrate. The cladding formed a strong metallurgical bond, exhibited a uniform microstructure, and was free of cracks and pores. These results demonstrate the effectiveness of the proposed optimization approach in improving laser cladding repair quality.

In this study, the laser cladding process is used to deposit strengthening iron-chromium alloy (Fe–Cr alloy) coating on SS400 low carbon steel (SS400 steel) for improving its mechanical properties and prolonging the lifespan of materials. The laser cladding process parameters were optimized in single-track experiments using the Taguchi method to obtain the highest hardness coating. The optimized parameters were used to deposit pore-free multi-tracks of Fe–Cr alloy on SS400 steel to enhance its wear resistance. The results indicate a significant improvement in the wear resistance of SS400 steel with the Fe–Cr alloy coating from 1.96 × 10 −5 mm 3 /( N  ×  m ) to 0.0114 × 10 −5 mm 3 /( N  ×  m ). Overall wear resistance increased with an increase in the overlap rate. The optimal overlap rate determined in this study was 60%, as the wear morphology at 60% was not only comparable to that at 70% but also exhibited better cross-sectional quality of deposited than the 70% overlap rate. Therefore, this study confirms that employing the Taguchi method is effective in finding defect-free laser cladding optimization parameters, ultimately leading to improved mechanical performance and reduced experimental costs.

Due to the increased integration of functions, many components have to meet high and sometimes contradictory requirements. One way to solve this problem is Tailored Forming. Here, hybrid semi-finished products are manufactured by a joining or cladding process, which are then hot-formed and finished. For the design of hybrid components for a possible later industrial application, knowledge about properties of hybrid components is required. In this paper it is investigated how the respective process steps of the Tailored Forming process chain change the surface and subsurface properties of the applied cladding layer. For this purpose, shafts made of unalloyed steel are provided with a high-alloy austenitic steel X2CrNiMo19-12 cladding by laser hot-wire cladding. Subsequently, hot forming is carried out by cross-wedge rolling and the finishing by turning and deep rolling. After each process step, the subsurface properties of the cladding such as microstructure, hardness and residual stress state are examined. Thus, the influence of different process steps on the subsurface properties in the process chain of manufacturing hybrid shafts can be analyzed. This knowledge is necessary for the specific adjustment of defined properties for a required application behavior.

The powder-feed laser additive manufacturing method was applied to rebuild GTD 450 martensitic stainless steel specimens with Stellite 6. The H-factor parameter was defined as the controlling factor based on the values of the laser power, the cladding speed, and the powder feed rate. By depositing upper layers, cellular dendrites turned into columnar ones, which grew in the direction of heat transfer. A mixture of Co-rich γ and complex carbides of Cr, W, and Mo were found in the microstructure. The dilution was decreased with increasing the number of deposited layers; consequently, the increase in the hardness from the base metal to the cladded area was observed due to the less dilution by the base material as well as the less tempering effect of subsequent layers. The increased cladding speed decreased the H-factor. It was observed that, by controlling the H-factor, the wear properties of the cladded parts were increased by 8%.

LMD, an additive manufacturing technique, involves depositing projected powder using a laser beam that can be employed to either fabricate or repair components. Despite its capabilities, process feasibility assessment and choice of process parameters usually requires straightforward single track case studies. Some effects of process parameters such as laser power, powder flow rate or printing rate on printed single-track geometry are indeed critical to ensure the structural and metallurgical quality of the material produced. To identify the optimized process parameters, this study investigates an applicable robust strategy using single tracks to statistically investigate the process parameter effects on geometrical characteristics using a dedicated automated tool (named SAAMO). For different geometrical characteristics of the bead, the optimal process parameters are identified for a 316 L steel, enriched in Silicon. Particular focus is given to dilution analysis while an analytical disc model is used to correctly predict the geometries produced. Based on these findings, it is possible to provide high-quality deposition with needed deposition yield. The metallurgical bond between the produced material and the substrate is therefore optimal for structure build-up/reparation applications.