The geometric parameters of the deposited layer include the width, height, and penetration depth of the deposited layer. The welding current, wire feeding speed, and torch travel speed during the additive manufacturing process of TC4 titanium alloy have the greatest impact on the geometric parameters of the deposited layer. In order to study how the deposition layer width, deposition layer height, and penetration depth are affected by the welding current, wire feeding speed, and torch travel speed, this article uses Design Expert 8.0.6 software for Box−Behnken design response surface experiments. During the experimental design, the welding current, wire feeding speed, and torch travel speed are used as input variables. The deposition layer width, deposition layer height, and penetration depth are selected as the responses. We designed 17 response surface experiments that were conducted using GTAW-AM. The results show that as the welding current increases, the penetration depth and width of deposition layer gradually increase, and the deposition layer height gradually decreases. As the wire feeding speed increases, the deposition layer height and penetration depth gradually increase, and the wire feeding speed has a minimal effect on the deposition layer width. As the torch travel speed increases, the penetration depth, width and height of deposition layer gradually decrease. The response surface method experimental design can also optimize the matching of three process parameters: welding current, wire feeding speed, and torch travel speed, thereby obtaining the optimal matching range of process parameters. Within the optimized matching range of process parameters, a welding current of 90 A, a wire feeding speed of 900 mm/min, and a torch travel speed of 200.18 mm/min were selected to prepare TC4 titanium alloy thin-walled part. The microstructure of the top, middle and bottom are all basketweave structure. The α phase gradually becomes coarse from the top to the bottom. The microhardness of the top, middle, and bottom of the thin-walled parts is 362.7 HV, 352.7 HV, and 340.5 HV, respectively. The horizontal tensile strength is 926.1 MPa, with an elongation of 12.22%, and the vertical tensile strength is 938.1 MPa, with an elongation of 14.41%. Full article

Laser–arc composite additive manufacturing holds significant potential for a wide range of industrial applications, and the control of morphological dimensions in the deposited layer is a critical aspect of this technology. The width and height dimensions within the deposited layer of laser–arc hybrid additive manufacturing serve as essential indicators of its morphological characteristics, directly influencing the shape quality of the deposited layer. Accurate prediction of the shape dimensions becomes crucial in providing effective guidance for size control. To achieve precise prediction of shape dimensions in laser–arc composite additive manufacturing and ensure effective regulation of the deposited layer’s shape quality, this study introduces a novel approach that combines a particle swarm algorithm (PSO) with an optimized support vector regression (SVR) technique. By optimizing the SVR parameters through the PSO algorithm, the SVR model is enhanced and fine-tuned to accurately predict the shape dimensions of the deposited layers. In this study, a series of 25 laser–arc hybrid additive manufacturing experiments were conducted to compare different approaches. Specifically, the SVR model was built using selected radial basis function (rbf) kernel functions. Furthermore, the penalty factors and kernel parameters of the SVR model were optimized using the particle swarm optimization (PSO) algorithm, leading to the development of a PSO-SVR prediction model for the morphological dimensions of the deposited layers. The performance of the PSO-SVR model was compared with that of the SVR, BPNN, and LightGBM models. Model accuracy was evaluated using a test set, revealing average relative errors of 2.39%, 7.719%, 9.46%, and 5.356% for the PSO-SVR, SVR, BPNN, and LightGBM models, respectively. The PSO-SVR model exhibited excellent prediction accuracy with minimal fluctuations in prediction error. This performance demonstrates the model’s ability to effectively capture the intricate and non-linear relationship between process parameters and deposition layer dimensions. Consequently, the PSO-SVR model can provide a foundation for the control of morphological dimensions in the deposition layer, offering an effective guide for deposition layer morphology dimension control in laser–arc composite additive manufacturing. Full article

One of the challenges regarding the application of laser polishing in injection mold manufacturing is to eliminate the tensile residual stress on a polished cavity surface without the extra expenses of an annealing vacuum furnace. This study aims to develop a fast laser annealing method using a dual-beam laser system by which a mold cavity can be laser-polished and then laser-annealed. Fourteen mold steel specimens were laser-polished by a dual-beam laser, resulting in a roughness reduction from the initial state, Sa 1.11 μm, to Sa 0.16 μm, a smoother surface finish. A numerical simulation of laser annealing using the current CW laser was implemented to optimize the laser annealing parameters to guide the experiment of CW laser annealing. XRD measurement results showed that the tensile residual stress dropped from an initial 638 MPa to 10 MPa in an annealing cycle time of 40 min at 750 °C; therefore, fatigue cracks or stress corrosion cracks (SCC) on the mold cavity will no longer occur. Confocal microscopy, X-ray diffraction, and scanning electron microscopy were used to obtain the microstructure and phase composition of the microstructures, demonstrate that laser polishing and laser annealing by a dual-beam laser is a fast and effortless technique which can be effectively employed in injection mold manufacturing. Full article

Wear and corrosion resistant properties of high entropy alloy coatings (HEAC) on H13 steel are of particular interest for industrial applications. The CoCrFeNi HEA/WC composite coatings (HEACC) developed in this study were successfully prepared by incorporating 10–40 wt.% WC into a matrix of CoCrFeNi HEA using laser cladding on an H13 steel substrate. Phase transformation, microstructure evolution, microhardness, wear and corrosion resistance of CoCrFeNi HEACC were investigated. According to the results, all CoCrFeNi HEACC exhibited higher wear and corrosion resistance than the H13 steel substrate. Wear resistance of CoCrFeNi HEACC first increases and then decreases with an increase in the concentration of WC particles, and the lowest coefficient of friction and the shallowest depth of wear groove were observed after adding 30 wt.%. Grain refinement strengthening and second-phase particle strengthening may contribute to enhanced hardness and wear resistance of coatings with WC additions. In addition, all the CoCrFeNi HEACC exhibited improved corrosion resistance. In particular, an addition of 10 wt.% WC helped to significantly improve the corrosion resistance and ease of passivation of CoCrFeNi HEACC. Full article

Several innovative mixed powders of Ti6Al4V and NiCr-Cr₃C₂ with different CeO₂ contents (0, 1, 2, 3, and 4 wt.%) were designed, and Ti₂C-reinforced CrTi₄-based composite coatings were prepared on the Ti6Al4V surface via laser cladding technology. The effects of CeO₂ amount on the forming quality, microstructure, hardness, and wear resistance of the composite coatings were studied. The results showed that the CeO₂ amount had a significant influence on the forming quality of the composite coatings. The cracks were eliminated completely when the CeO₂ content was 2 wt.%; furthermore, the lowest porosity was obtained with the addition of 3 wt.% CeO₂. The primary phase constituents of the coatings were non-stoichiometric Ti₂C and a β-type solid solution (CrTi₄) as the reinforcement and matrix, respectively. CeO₂ and a low quantity of Ce₂O₃ were re-precipitated at the Ti₂C/CrTi₄ interface and CrTi₄ grain boundary in the coatings with CeO₂ addition. In addition, the average hardness of the composite coatings was 1.28–1.34 times higher than that of the Ti6Al4V substrate. The wear resistance of the composite coatings was significantly higher than that of the substrate. However, both the composite coatings and the Ti6Al4V substrate exhibited a mixed-wear mode, i.e., abrasive and adhesive wear. Full article

A micro/nano surface structure can produce specific properties, such as super hydrophilicity, low reflectance property, etc. A femtosecond laser-induced periodic surface structure is an important manufacturing process for the micro/nano structure. This research investigated the effects of scanning intervals and laser power on the surface morphology, wetting properties, and reflectance properties of LIPSS based on a silicon wafer. The results showed that the laser power had a significant effect on the surface morphology and wettability of silicon. With the increase of laser power, the surface roughness, etching depth and surface hydrophilicity increased. However, the laser power had little effect on the surface reflectance. The scanning interval had a great influence on the wettability and reflectance property of silicon. With the decrease of the scanning interval, the surface hydrophobicity and reflectance of silicon first decrease and then remain basically stable from 10 μm. Full article

This study proposes an ultrafast laser ablation method for improving the depth uniformity of microgrooves in bursting discs. Under a lower laser fluence, the influence of the spot overlap rate on the depth uniformity of microgrooves was studied. The results show that 80% of the spot overlap ratio has good performance in ablation efficiency and depth uniformity of microgrooves. On this basis, the relationship between the number of laser scanning layers and the depth of microgrooves was studied, and the number of scanning layers needed to ablate 70 µm microgrooves was obtained. Based on the combination of the process parameters and the optimization of the laser scanning path, laser ablation of bursting disc microgrooves with a specific shape was realized. The depth uniformity of microgrooves in different sections of the bursting disc was not worse than 4 µm. The preliminary bursting test shows that the bursting pressure between the discs was no more than 0.06 Mpa. Compared with the results of the traditional processing method, the microgroove depth uniformity of bursting discs was greatly improved. Therefore, femtosecond laser ablation technology provides an advanced manufacturing method for bursting disc microgroove machining. Full article