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23 pages, 11652 KiB

Open AccessArticle

Immune Optimization of Welding Sequence for Arc Weld Seams in Ship Medium-Small Assemblies

by Mingxin Yuan, Suodong Liu, Yunqiang Gao, Hongwei Sun, Chao Liu and Yi Shen

Coatings 2022, 12(5), 703; https://doi.org/10.3390/coatings12050703 - 20 May 2022

Viewed by 1462

The arc weld seam is a common form in ship medium-small assemblies. In order to reduce the deformation of the welded parts with an arc weld seam, and then improve the welding quality, research on the optimization of welding sequences based on the [...] Read more.

The arc weld seam is a common form in ship medium-small assemblies. In order to reduce the deformation of the welded parts with an arc weld seam, and then improve the welding quality, research on the optimization of welding sequences based on the artificial immune algorithm is carried out in this paper. First, the formation mechanism of welding deformation is analyzed by the thermo-elastic-plastic finite element method; next, the reduction in the welding deformation is taken as the optimization goal, and the welding sequence optimization model for the arc weld seam is constructed under the condition of boundary constraints; then, an immune clonal optimization algorithm based on similar antibody similarity screening and steady-state adjustment is proposed, and its welding sequence optimization ability is improved through antibody screening and median adjustment. Finally, the welding sequence optimization tests are carried out based on the Ansys platform. Numerical tests of a typical arc weld seam show that different welding sequences will cause different welding deformations, which verifies the importance of welding sequence optimization. Furthermore, the numerical test results of four different types of welds in ship medium-small assemblies demonstrated that the use of distributed optimization algorithms for welding sequence optimization can help reduce the amount of welding deformations, and the immune clonal algorithm, based on antibody similarity screening and steady-state adjustment, achieves the optimal combination of the welding sequence. Compared with the other three optimization algorithms, the maximum welding deformation caused by the welding sequence optimized by the proposed immune clonal algorithm is reduced by 3.1%, 4.0%, and 3.4%, respectively, the average maximum welding deformation is reduced by 3.5%, 5.5%, and 4.7%, respectively, and the convergence generation of the optimization algorithm is reduced by 16.8%, 13.1% and 14.5%, respectively, which further verifies the effectiveness and superiority of the proposed immune clonal algorithm in the optimization of welding sequences. Full article

(This article belongs to the Special Issue Progress in Coatings Deposition by Advanced Welding and Welding-Related Processes)

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12 pages, 6022 KiB

Open AccessArticle

Effect of Low Chloride and Sulfate Concentrations on Corrosion Behavior of Aluminum and Zinc Arc Thermal Sprayed Coatings

by Cezary Senderowski, Wojciech Rejmer and Piotr Bilko

Coatings 2022, 12(5), 653; https://doi.org/10.3390/coatings12050653 - 10 May 2022

Cited by 6 | Viewed by 1649

Abstract

The aim of this study was to determine the suitability of arc sprayed zinc and aluminum coatings as materials for protective coatings of different heating systems. The most aggressive chemical agents occurring in heating water are chloride and sulfate anions. Both ions are [...] Read more.

The aim of this study was to determine the suitability of arc sprayed zinc and aluminum coatings as materials for protective coatings of different heating systems. The most aggressive chemical agents occurring in heating water are chloride and sulfate anions. Both ions are responsible for the corrosion of metals due to their high electronegativity and standard electrochemical potential. Water in heating systems should not contain more than 150 mg/L anions, including no more than 50 mg/L of chlorides and 100 mg/L of sulfates. To determine the corrosion resistance of three types of zinc and aluminum coatings, open circuit potential and linear polarization resistance (LPR) tests were conducted in eight alkaline solutions with different sulfate and chloride contents. The SEM/EDS structural properties of sprayed coatings at specific arc process parameters were investigated. Zinc coatings exhibit the most stable corrosion potentials in varying environments but have higher corrosion current density. Aluminum coatings exhibit much higher potential values in a chloride environment than in any other. A chloride environment also causes the lowest corrosion rates for aluminum-coated samples. A small addition of aluminum to the zinc coating (15 wt.%) does not appear to affect the stability of the corrosion potential but does result in a reduction in corrosion rates in chloride solutions. Full article

(This article belongs to the Special Issue Progress in Coatings Deposition by Advanced Welding and Welding-Related Processes)

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13 pages, 5221 KiB

Open AccessEditor’s ChoiceArticle

The Laser Alloying Process of Ductile Cast Iron Surface with Titanium Powder in Nitrogen Atmosphere

by Aleksandra Lont, Jacek Górka, Damian Janicki and Krzysztof Matus

Coatings 2022, 12(2), 227; https://doi.org/10.3390/coatings12020227 - 10 Feb 2022

Cited by 7 | Viewed by 1833

Abstract

The article presents the results of the laser alloying process of a ductile cast iron EN-GJS 350-22 surface with titanium powder in nitrogen atmosphere. The aim of this research was to test the influence of nitrogen atmosphere on the structure and properties of [...] Read more.

The article presents the results of the laser alloying process of a ductile cast iron EN-GJS 350-22 surface with titanium powder in nitrogen atmosphere. The aim of this research was to test the influence of nitrogen atmosphere on the structure and properties of the ductile cast iron surface layer produced by a laser alloying process with titanium. The laser alloying process was conducted using a Rofin Sinar DL020 2 kW high-power diode laser (HPDDL) with rectangular focus and uniform power density distribution in the focus axis. The tests of the produced surface layers included macrostructure and microstructure observations, X-ray diffraction (XRD) analysis, energy-dispersive spectroscopy (EDS) on scanning electron microscope (SEM) and transmission electron microscope (TEM), Vickers hardness and solid particle erosion according to ASTM G76-04 standard. As a result of the laser alloying process in nitrogen atmosphere with titanium powder, the in situ metal matrix composite structure reinforced by TiCN particles was formed. The laser alloying process of ductile cast iron caused the increased hardness and erosion resistance of the surface. Full article

(This article belongs to the Special Issue Progress in Coatings Deposition by Advanced Welding and Welding-Related Processes)

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15 pages, 6890 KiB

Open AccessArticle

Effect of Reversed Austenite on Mechanical Properties of ZG06Cr13Ni4Mo Repair Welded Joint

by Yunhai Su, Zuyong Wei, Gang Li, Xiangwen Zhang, Hedi Ci and Ying Zhi

Coatings 2022, 12(1), 1; https://doi.org/10.3390/coatings12010001 - 21 Dec 2021

Cited by 3 | Viewed by 2491

Abstract

In this work, gas tungsten arc welding (GTAW) was used to repair ZG06Cr13Ni4Mo martensitic stainless steel. Repair welding occurred either once or twice. The changes in the microstructure and properties of the repair welded joints were characterized by optical microscope (OM), scanning electron [...] Read more.

In this work, gas tungsten arc welding (GTAW) was used to repair ZG06Cr13Ni4Mo martensitic stainless steel. Repair welding occurred either once or twice. The changes in the microstructure and properties of the repair welded joints were characterized by optical microscope (OM), scanning electron microscope (SEM), electron backscattering diffraction (EBSD), tensile and impact tests. The effects of reversed austenite in repair welded joints on microstructure and mechanical properties were studied. The results show that the microstructure of the welded joint after repair welding consists of a large amount of martensite (M) and a small amount of reversed austenite (A), and the reversed austenite is distributed at the boundary of martensite lath in fine strips. With the increase in the number of welding repairs, the content of reversed austenite in the welded joint increases. The microstructure in the repair welded joints is gradually refined, the microstructure in the once and twice repaired joints is 45.2% and 65.1% finer than that in the casting base metal, respectively. The reversed austenite presented in the repair welded joints decreases the tensile strength by 4.8% and 6.7%, increases the yield strength by 21.3% and 26.4%, and increases the elongation by 25% and 56%, respectively, compared with the casting base metal. In addition, the reversed austenite mainly nucleates and grows at the boundary of lath martensite. The refinement of the martensite structure was due to the generation of reversed austenite and the refinement of original austenite grain by the welding thermal cycle. After repair welding, the reverse austenite appeared in the repair welded joints and the tensile strength decreased slightly, but the plastic toughness was significantly improved, which was conducive to the subsequent service process. Full article

(This article belongs to the Special Issue Progress in Coatings Deposition by Advanced Welding and Welding-Related Processes)

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8 pages, 6395 KiB

Open AccessArticle

A Novel Technique for Controllable Fabrication of Multilayer Copper/Brass Block

by Jiansheng Li, Zhongchen Zhou, Tong Liu, Yu Zhao, Yan Lu, Ming Chen, Xiaozhen Wang, Gang Wang and Qingzhong Mao

Coatings 2021, 11(11), 1416; https://doi.org/10.3390/coatings11111416 - 20 Nov 2021

Cited by 3 | Viewed by 2205

Abstract

Fabricating a dissimilar-metal block with micro/nano-multilayered structures is usually used by engineers and scientists because of their excellent mechanical properties. In the current work, multilayered copper/brass blocks were effectively fabricated by a synthetical DWFR technique, which includes the processes of diffusion welding, forging [...] Read more.

Fabricating a dissimilar-metal block with micro/nano-multilayered structures is usually used by engineers and scientists because of their excellent mechanical properties. In the current work, multilayered copper/brass blocks were effectively fabricated by a synthetical DWFR technique, which includes the processes of diffusion welding, forging and rolling. Diffusion welding was used as the first operation to metallurgically bond the copper and brass sheets, with a Zn diffusion transition layer (thickness of ~100 μm), which can guarantee the bonding strength of copper/brass interfaces during the subsequent forging and rolling processes. After diffusion welding, the original copper/brass blocks were required to be forged, with its total thickness reduced to ~10 mm. This can further restrain the delamination of copper and brass layers during the final rolling process. Rolling was utilized as the ideal operation that can precisely tune the thickness of copper/brass laminate. This novel DWFR technique can easily tune the multilayered copper/brass blocks with controllable layer thickness (from ~250 to ~800 nm). The copper/brass interfaces were well-bonded, and the utilization efficiency of raw materials was very high (>95%). Full article

(This article belongs to the Special Issue Progress in Coatings Deposition by Advanced Welding and Welding-Related Processes)

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13 pages, 13606 KiB

Open AccessArticle

FEM Research on Welding Thermal Deformation of Copper Alloy Sheet and Optimization of Welding Sequence

by Mingxin Yuan, Suodong Liu, Hongwei Sun, Yunqiang Gao, Xianling Dai and Weibin Chen

Coatings 2021, 11(11), 1287; https://doi.org/10.3390/coatings11111287 - 23 Oct 2021

Cited by 4 | Viewed by 1591

Abstract

To reduce the residual stress and deformation of the copper alloy sheet after welding, and improve the welding quality of the copper alloy sheet, the finite element method (FEM) research on welding thermal deformation and welding sequence optimization was carried out. First, a [...] Read more.

To reduce the residual stress and deformation of the copper alloy sheet after welding, and improve the welding quality of the copper alloy sheet, the finite element method (FEM) research on welding thermal deformation and welding sequence optimization was carried out. First, a finite element model of copper alloy sheet welding was established based on ANSYS, the mechanical property parameters of the model at high temperature were determined, and the thermal–structural coupling calculation was performed on the model. Then, the change trend and magnitude of the residual stress and deformation of the model after welding were analyzed. Finally, different welding sequence schemes were designed, and numerical simulation calculations were carried out. The results of the welding sequence solution show that the change trend of the residual stress after welding of the base metal under different welding sequences is basically the same; repeated heating of the base metal at the same position causes large residual stress; the weldment vertical plate is subjected to opposing forces in the x-axis and y-axis directions at the same time. Among four welding schemes, the welding scheme that alternately welds symmetrically from the start and end positions of the weld seam to the middle position of the plate causes the least welding deformation. Compared with the other three schemes, its deformation reduces by 26.6%, 18.3%, and 19.4%, respectively. Full article

(This article belongs to the Special Issue Progress in Coatings Deposition by Advanced Welding and Welding-Related Processes)

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16 pages, 7898 KiB

Open AccessArticle

Effects of Specimen Size and Welded Joints on the Very High Cycle Fatigue Properties of Compressor Blade Steel KMN-I

by Pengfei Wang, Weiqiang Wang, Ming Zhang, Qiwen Zhou and Zengliang Gao

Coatings 2021, 11(10), 1244; https://doi.org/10.3390/coatings11101244 - 13 Oct 2021

Cited by 6 | Viewed by 1686

Abstract

The effects of specimen size and welded joints on the very high cycle fatigue properties of compressor blade steel KMN-I were studied by ultrasonic fatigue testing. It was found that the S-N curve of large specimens had a slow decline above 10⁷ [...] Read more.

The effects of specimen size and welded joints on the very high cycle fatigue properties of compressor blade steel KMN-I were studied by ultrasonic fatigue testing. It was found that the S-N curve of large specimens had a slow decline above 10⁷ cycles, and fatigue failure still occurred in the very high cycle regime (>10⁷ cycles), while the very high cycle fatigue characteristics of welded specimens was less obvious, and the fatigue limit was observed. Metallographic observation and SEM analysis were carried out on the fracture of the specimens. The results showed that surface fractures were mostly observed in the large specimens, and only a small number of cracks initiated from non-metallic inclusions above 10⁷ cycles. The cracks of welded specimens initiated from the surface below 10⁷ cycles and initiated from the internal matrix above 10⁷ cycles. In addition, the formation mechanism of GBF (granular bright facet) was analyzed by the “dispersive decohesion of spherical carbide” theory, and the fatigue strength and fatigue life were predicted, which was consistent with the experimental results. Full article

(This article belongs to the Special Issue Progress in Coatings Deposition by Advanced Welding and Welding-Related Processes)

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Graphical abstract

20 pages, 13349 KiB

Open AccessArticle

Framework for Mitigation of Welding Induced Distortion through Response Surface Method and Reinforcement Learning

by Rehan Waheed, Hasan Aftab Saeed, Sajid Ullah Butt and Bilal Anjum

Coatings 2021, 11(10), 1227; https://doi.org/10.3390/coatings11101227 - 9 Oct 2021

Cited by 3 | Viewed by 1730

Abstract

Welding induced distortion causes dimensional inaccuracies in parts being produced and assembly fit-up problems during manufacturing. In this study, a framework is proposed to mitigate weld distortion at the design stage. A sequential approach is adopted to optimize the welding process. In the [...] Read more.

Welding induced distortion causes dimensional inaccuracies in parts being produced and assembly fit-up problems during manufacturing. In this study, a framework is proposed to mitigate weld distortion at the design stage. A sequential approach is adopted to optimize the welding process. In the first phase, welding process parameters are optimized through the response surface method. The effect of these parameters on the overall distortion of the welded part is observed by a simulation of the welding process. In the second phase, the weld sequence is optimized using the optimum weld parameters. A reinforcement learning-based Q-learning technique is used to select the optimum welding path by sequential observation of weld distortion at each segment being welded. The optimum process parameters and weld path sequence have been selected for 3 mm steel plates having a lap joint configuration and a 2 mm vent panel with a butt joint configuration. It is concluded that the combination of the optimum welding parameters and welding sequence yields minimum distortion. By applying this framework, a reduction of 19% is observed in overall welding induced distortion. Full article

(This article belongs to the Special Issue Progress in Coatings Deposition by Advanced Welding and Welding-Related Processes)

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12 pages, 9618 KiB

Open AccessArticle

Effect of Thermal Management Approaches on Geometry and Productivity of Thin-Walled Structures of ER 5356 Built by Wire + Arc Additive Manufacturing

by Leandro João da Silva, Henrique Nardon Ferraresi, Douglas Bezerra Araújo, Ruham Pablo Reis and Américo Scotti

Coatings 2021, 11(9), 1141; https://doi.org/10.3390/coatings11091141 - 20 Sep 2021

Cited by 13 | Viewed by 3103

Abstract

The present paper aimed at assessing the effect of two thermal management approaches on geometry and productivity of thin-walled structures built by Wire + Arc Additive Manufacturing (WAAM). Thin-walls of ER 5356 (Al5Mg) with different lengths and the same number of layers were [...] Read more.

The present paper aimed at assessing the effect of two thermal management approaches on geometry and productivity of thin-walled structures built by Wire + Arc Additive Manufacturing (WAAM). Thin-walls of ER 5356 (Al5Mg) with different lengths and the same number of layers were deposited via the gas metal arc (GMA) process with the aid of an active cooling technique (near-immersion active cooling—NIAC) under a fixed set of deposition parameters. Then, the same experiment was performed with natural cooling (NC) in air. To characterize the thermal management approaches, the interpass temperature (i.e., the temperature at which subsequent layers are deposited) were monitored by a trailing/leading infrared pyrometer during the deposition time. Finally, thin walls with a fixed length were deposited using the NC and NIAC approaches with equivalent interpass temperatures. As expected, the shorter the wall length the more intense the deposition concentration, heat accumulation, and, thus, geometric deviation. This behavior was more evident and premature for the NC strategy due to its lower heat sinking effectiveness. The main finding was that, regardless of the thermal management technique applied, if the same interpass temperature is selected and maintained, the geometry of the part being built tends to be stable and very similar. However, the total deposition time is somewhat shorter with the NIAC technique due its greater heat sinking advantage. Thus, the NIAC technique facilitates the non-stop manufacturing of small parts and details via WAAM. Full article

(This article belongs to the Special Issue Progress in Coatings Deposition by Advanced Welding and Welding-Related Processes)

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20 pages, 6161 KiB

Open AccessArticle

Multi-Objective Optimization of MIG Welding and Preheat Parameters for 6061-T6 Al Alloy T-Joints Using Artificial Neural Networks Based on FEM

by Qing Shao, Fuxing Tan, Kai Li, Tatsuo Yoshino and Guikai Guo

Coatings 2021, 11(8), 998; https://doi.org/10.3390/coatings11080998 - 21 Aug 2021

Cited by 8 | Viewed by 3115

Abstract

To control the welding residual stress and deformation of metal inert gas (MIG) welding, the influence of welding process parameters and preheat parameters (welding speed, heat input, preheat temperature, and preheat area) is discussed, and a prediction model is established to select the [...] Read more.

To control the welding residual stress and deformation of metal inert gas (MIG) welding, the influence of welding process parameters and preheat parameters (welding speed, heat input, preheat temperature, and preheat area) is discussed, and a prediction model is established to select the optimal combination of process parameters. Thermomechanical numerical analysis was performed to obtain the residual welding deformation and stress according to a 100 × 150 × 50 × 4 mm aluminum alloy 6061-T6 T-joint. Owing to the complexity of the welding process, an optimal Latin hypercube sampling (OLHS) method was adopted for sampling with uniformity and stratification. Analysis of variance (ANOVA) was used to find the influence degree of welding speed (7.5–9 mm/s), heat input (1500–1700 W), preheat temperature (80–125 °C), and preheat area (12–36 mm). The range of research parameters are according to the material, welding method, thickness of the welding plate, and welding procedure specification. Artificial neural network (ANN) and multi-objective particle swarm optimization (MOPSO) was combined to find the effective parameters to minimize welding deformation and stress. The results showed that preheat temperature and welding speed had the greatest effect on the minimization of welding residual deformation and stress, followed by the preheat area, respectively. The Pareto front was obtained by using the MOPSO algorithm with ε-dominance. The welding residual deformation and stress are the minimum at the same time, when the welding parameters are selected as preheating temperature 85 °C and preheating area 12 mm, welding speed is 8.8 mm/s and heat input is 1535 W, respectively. The optimization results were validated by the finite element (FE) method. The error between the FE results and the Pareto optimal compromise solutions is less than 12.5%. The optimum solutions in the Pareto front can be chosen by designers according to actual demand. Full article

(This article belongs to the Special Issue Progress in Coatings Deposition by Advanced Welding and Welding-Related Processes)

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