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9 pages, 4885 KiB

Open AccessCommunication

Extrinsic-Riveting Friction Stir Lap Welding of Al/Steel Dissimilar Materials

by Xiangchen Meng, Jiaze Gao, Yuming Xie, Tifang Huang, Jihong Dong, Xiaotian Ma, Naijie Wang and Yongxian Huang

Materials 2024, 17(8), 1830; https://doi.org/10.3390/ma17081830 - 16 Apr 2024

Viewed by 279

Abstract

To obtain high-quality joints of Al/steel dissimilar materials, a new extrinsic-riveting friction stir lap welding (ERFSLW) method was proposed combining the synthesis advantages of mechanical riveting and metallurgical bonding. SiC-reinforced Al matrix composite bars were placed in the prefabricated holes in Al sheets [...] Read more.

To obtain high-quality joints of Al/steel dissimilar materials, a new extrinsic-riveting friction stir lap welding (ERFSLW) method was proposed combining the synthesis advantages of mechanical riveting and metallurgical bonding. SiC-reinforced Al matrix composite bars were placed in the prefabricated holes in Al sheets and steel sheets, arranged in a zigzag array. The bars were stirred and mixed with Al sheets under severe plastic deformation (SPD), forming composite rivets to strengthen the mechanical joining. SiC particles were uniformly dispersed in the lower part of the welding nugget zone (WNZ). The smooth transition between the SiC mixed zone and extrinsic-riveting zone (ERZ) ensured the metallurgical bonding. The maximum tensile shear load of the joints reached 7.8 kN and the maximum load of the weld per unit length was 497 N/mm. The fracture occurred at the interface between the rivets and steel sheets rather than the conventional Al/steel joining interface. Moreover, ERFSLW can prolong the service life of joints due to three fracture stages. This method can be further extended to the welding of other dissimilar materials that conform to the model of “soft/hard”. Full article

(This article belongs to the Special Issue Advances in Materials Joining and Additive Manufacturing)

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16 pages, 11339 KiB

Open AccessArticle

Online Detection of Laser Welding Penetration Depth Based on Multi-Sensor Features

by Kun She, Donghui Li, Kaisong Yang, Mingyu Li, Beile Wu, Lijun Yang and Yiming Huang

Materials 2024, 17(7), 1580; https://doi.org/10.3390/ma17071580 - 29 Mar 2024

Viewed by 407

Abstract

The accurate online detection of laser welding penetration depth has been a critical problem to which the industry has paid the most attention. Aiming at the laser welding process of TC4 titanium alloy, a multi-sensor monitoring system that obtained the keyhole/molten pool images [...] Read more.

The accurate online detection of laser welding penetration depth has been a critical problem to which the industry has paid the most attention. Aiming at the laser welding process of TC4 titanium alloy, a multi-sensor monitoring system that obtained the keyhole/molten pool images and laser-induced plasma spectrum was built. The influences of laser power on the keyhole/molten pool morphologies and plasma thermo-mechanical characteristics were investigated. The results showed that there were significant correlations among the variations of the keyhole–molten pool, plasma spectrum, and penetration depth. The image features and spectral features were extracted by image processing and dimension-reduction methods, respectively. Moreover, several penetration depth prediction models based on single-sensor features and multi-sensor features were established. The mean square error of the neural network model built by multi-sensor features was 0.0162, which was smaller than that of the model built by single-sensor features. The established high-precision model provided a theoretical basis for real-time feedback control of the penetration depth in the laser welding process. Full article

(This article belongs to the Special Issue Advances in Materials Joining and Additive Manufacturing)

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25 pages, 21311 KiB

Open AccessArticle

Residual Stress Measurement Using X-ray Diffraction in Friction Stir-Welded Dissimilar Titanium Alloys

by Kapil Gangwar and M. Ramulu

Materials 2024, 17(7), 1482; https://doi.org/10.3390/ma17071482 - 24 Mar 2024

Viewed by 546

Abstract

Surface residual stresses in welded specimens significantly influence properties such as fatigue resistance, fracture toughness, and the superplasticity of joints. In this study, we employed friction stir welding, a well-established joining method, to weld dissimilar titanium alloys. By combining two distinct titanium alloys, [...] Read more.

Surface residual stresses in welded specimens significantly influence properties such as fatigue resistance, fracture toughness, and the superplasticity of joints. In this study, we employed friction stir welding, a well-established joining method, to weld dissimilar titanium alloys. By combining two distinct titanium alloys, we aimed to harness their unique properties when subjected to cyclic loading, impact, or superplastic forming processes. Utilizing X-ray diffraction, macroscopic surface stresses were assessed in dissimilar titanium alloys (Ti-6242 standard grain (SG) and Ti-54M) welded via friction stir welding, assuming a linear lattice distortion. The study accounted for misalignment, significant distortion, and grain refinement in the stir zone. Macroscopic surface residual stresses were quantified on the weld surface and at a depth of 1.5 mm beneath it within a square cross-section (1 × 1 mm²) by oscillating the specimen in the (X-Y) direction. The sin²φ method, implemented through the LEPTOS^® (v7.8) software, was employed for residual stress measurement. The analysis of the results was conducted with respect to different rotation and traverse speeds. It was noted that at the center (CEN) of the weld, commonly referred to as the weld nugget, approximately 50 MPa of tensile stress was observed under the lowest values of both tool rotation speed and traverse speed. Tensile residual stresses were evident at the boundaries and within the stir zone. No discernible pattern was observed at the specified locations. Notably, the resultant values of residual stress, influenced by rotation and traverse speeds, exhibited asymmetry. Full article

(This article belongs to the Special Issue Advances in Materials Joining and Additive Manufacturing)

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22 pages, 18057 KiB

Open AccessArticle

The Effects of Processing Parameters during the Wire Arc Additive Manufacturing of 308L Stainless Steel on the Formation of a Thin-Walled Structure

by Bang Liu, Jun Lan, Hongqiang Liu, Xinya Chen, Xin Zhang, Zhengyi Jiang and Jian Han

Materials 2024, 17(6), 1337; https://doi.org/10.3390/ma17061337 - 14 Mar 2024

Viewed by 497

Abstract

Wire arc additive manufacturing (WAAM) excels in producing medium to large components with a high deposition rate. Process optimization is crucial for uniform, defect-free components. This research employs orthogonal experimental design and response surface methodology (RSM) to control TIG WAAM-ed 308L stainless steel [...] Read more.

Wire arc additive manufacturing (WAAM) excels in producing medium to large components with a high deposition rate. Process optimization is crucial for uniform, defect-free components. This research employs orthogonal experimental design and response surface methodology (RSM) to control TIG WAAM-ed 308L stainless steel components. Varied parameters, including tungsten electrode angle, welding current, and speed, target weld bead attributes. Analysis of variance (ANOVA) evaluates multi-processing parameter influence on weld bead formation. Comparison with experimental results confirms accurate modeling of the relationship between parameters and bead attributes. The study optimizes process parameters and swing to enhance dimensional accuracy in single-layer and multi-layer components, improving precision, quality, and accuracy in thin-walled structures. Full article

(This article belongs to the Special Issue Advances in Materials Joining and Additive Manufacturing)

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16 pages, 4283 KiB

Open AccessArticle

Accelerated First-Principles Calculations Based on Machine Learning for Interfacial Modification Element Screening of SiCp/Al Composites

by Xiaoshuang Du, Nan Qu, Xuexi Zhang, Jiaying Chen, Puchang Cui, Jingtao Huang, Yong Liu and Jingchuan Zhu

Materials 2024, 17(6), 1322; https://doi.org/10.3390/ma17061322 - 13 Mar 2024

Viewed by 605

Abstract

SiCp/Al composites offer the advantages of lightweight construction, high strength, and corrosion resistance, rendering them extensively applicable across various domains such as aerospace and precision instrumentation. Nonetheless, the interfacial reaction between SiC and Al under high temperatures leads to degradation in material properties. [...] Read more.

SiCp/Al composites offer the advantages of lightweight construction, high strength, and corrosion resistance, rendering them extensively applicable across various domains such as aerospace and precision instrumentation. Nonetheless, the interfacial reaction between SiC and Al under high temperatures leads to degradation in material properties. In this study, the interface segregation energy and interface binding energy subsequent to the inclusion of alloying elements were computed through a first-principle methodology, serving as a dataset for machine learning. Feature descriptors for machine learning undergo refinement via feature engineering. Leveraging the theory of machine-learning-accelerated first-principle computation, six machine learning models—RBF, SVM, BPNN, ENS, ANN, and RF—were developed to train the dataset, with the ANN model selected based on R² and MSE metrics. Through this model, the accelerated computation of interface segregation energy and interface binding energy was achieved for 89 elements. The results indicate that elements including B, Si, Fe, Co, Ni, Cu, Zn, Ga, and Ge exhibit dual functionality, inhibiting interfacial reactions while bolstering interfacial binding. Furthermore, the atomic-scale mechanism elucidates the interfacial modulation of these elements. This investigation furnishes a theoretical framework for the compositional design of SiCp/Al composites. Full article

(This article belongs to the Special Issue Advances in Materials Joining and Additive Manufacturing)

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16 pages, 4098 KiB

Open AccessArticle

Development of Computational Approach for Analyzing In-Process Thermal-Mechanical Condition during Friction Stir Welding for Prediction of Material Bonding Defect

by Gaoqiang Chen, Huijie Liu and Qingyu Shi

Materials 2023, 16(23), 7473; https://doi.org/10.3390/ma16237473 - 01 Dec 2023

Viewed by 689

Abstract

Unlike the conventional fusion welding process, friction stir welding (FSW) relies on solid-state bonding (SSB) to join metal surfaces. In this study, a straightforward computational methodology is proposed for predicting the material bonding defects during FSW using quantitative evaluation of the in-process thermal-mechanical [...] Read more.

Unlike the conventional fusion welding process, friction stir welding (FSW) relies on solid-state bonding (SSB) to join metal surfaces. In this study, a straightforward computational methodology is proposed for predicting the material bonding defects during FSW using quantitative evaluation of the in-process thermal-mechanical condition. Several key modeling methods are integrated for predicting the material bonding defects. FSW of AA2024 is taken as an example to demonstrate the performance of the computational analysis. The dynamic sticking (DS) model is shown to be able to predict the geometry of the rotating flow zone near the welding tool. Butting interface tracking (BIT) analysis shows a significant orientation change occurring to the original butting interface, owing to the material flow in FSW, which has a major impact on the bonding pressure at the butting interface. The evolution of the interfacial temperature and the interfacial pressure at the butting interface was obtained to analyze their roles in the formation of material bonding. Four bonding-quality indexes for quantifying the thermal-mechanical condition are tested to show their performance in characterizing the bonding quality during FSW. When the BQI is below a critical value, a bonding defect will be generated. The paper indicates that the simulation-based prediction of a material bonding defect is highly feasible if the developed methodology is extended to quantitatively determine the critical value of the bonding quality index for successful SSB for various alloys. Full article

(This article belongs to the Special Issue Advances in Materials Joining and Additive Manufacturing)

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11 pages, 12248 KiB

Open AccessArticle

Enhancing Mechanical Properties: Exploring the Effect of Annealing Temperature on Wire Arc Additively Manufactured High-Strength Steel

by Yi Chen, Zhizhuang Hao, Yang Li, Chao Liu, Yongkang Liu, Zhen Luo and Sansan Ao

Materials 2023, 16(21), 6969; https://doi.org/10.3390/ma16216969 - 30 Oct 2023

Viewed by 862

Abstract

This study investigates the mechanical properties of exceptionally high-strength steel produced by wire and arc additive manufacturing (WAAM), using the 304 stainless steel wire and the low carbon wire (LCS). The study found that annealing treatment can enhance the steel’s mechanical properties. The [...] Read more.

This study investigates the mechanical properties of exceptionally high-strength steel produced by wire and arc additive manufacturing (WAAM), using the 304 stainless steel wire and the low carbon wire (LCS). The study found that annealing treatment can enhance the steel’s mechanical properties. The microstructure in the LCS layer changed from ferrite to bainite and then to a mixture of austenite, pearlite, and bainite with increasing annealing temperature. In contrast, the SS layer retained its martensitic structure, albeit with altered lath sizes. The annealing treatment also improved the orientation of the grains in the steel. The optimal annealing temperature observed for the steel was 900 ℃, which resulted in a maximum tensile strength of 1176 MPa along the Y direction and 1255 MPa along the Z direction. Despite the superior mechanical properties, the LCS layer still exhibited failure during tensile testing due to its lower hardness. The study suggests that annealing treatment can be a useful technique for enhancing the mechanical properties of high-strength steel in WAAM applications. Full article

(This article belongs to the Special Issue Advances in Materials Joining and Additive Manufacturing)

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11 pages, 4453 KiB

Open AccessArticle

Additive Manufacturing of SS316L/IN718 Bimetallic Structure via Laser Powder Bed Fusion

by Asif Mahmud, Nicolas Ayers, Thinh Huynh and Yongho Sohn

Materials 2023, 16(19), 6527; https://doi.org/10.3390/ma16196527 - 01 Oct 2023

Viewed by 1133

Abstract

Laser powder bed fusion (LPBF) is a popular additive manufacturing (AM) technique that has demonstrated the capability to produce sophisticated engineering components. This work reports the crack-free fabrication of an SS316L/IN718 bimetallic structure via LPBF, along with compositional redistribution, phase transformations and microstructural [...] Read more.

Laser powder bed fusion (LPBF) is a popular additive manufacturing (AM) technique that has demonstrated the capability to produce sophisticated engineering components. This work reports the crack-free fabrication of an SS316L/IN718 bimetallic structure via LPBF, along with compositional redistribution, phase transformations and microstructural development, and nanohardness variations. Constituent intermixing after LPBF was quantitatively estimated using thermo-kinetic coefficients of mass transport and compared with the diffusivity of Ni in the austenitic Fe-Ni system. Full article

(This article belongs to the Special Issue Advances in Materials Joining and Additive Manufacturing)

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18 pages, 4640 KiB

Open AccessArticle

In Situ, Real-Time Temperature Mapping and Thermal FE Simulations of Large-Format 3D Printed PETG/CF Vertical Wall

by Felipe Robles Poblete, Matthew Ireland, Lucinda Slattery, William G. Davids and Roberto A. Lopez-Anido

Materials 2023, 16(19), 6486; https://doi.org/10.3390/ma16196486 - 29 Sep 2023

Cited by 1 | Viewed by 890

Abstract

This work focuses on simulating the thermal history of a vertical wall consisting of a thermoplastic composite material, poly(ethylene terephthalate) glycol (PETG) with short carbon fiber reinforcement, manufactured using a Big Area Additive Manufacturing (BAAM) system. The incremental deposition process used in additive [...] Read more.

This work focuses on simulating the thermal history of a vertical wall consisting of a thermoplastic composite material, poly(ethylene terephthalate) glycol (PETG) with short carbon fiber reinforcement, manufactured using a Big Area Additive Manufacturing (BAAM) system. The incremental deposition process used in additive manufacturing, which corresponds to the repeated deposition of hot material onto cooler material, contributes to the presence of residual stresses and part warping. The prediction of these mechanisms is dependent on thermal history of the part, and the major motivation of this work was to improve the accuracy of finite element (FE) models used to quantify the thermal history of large-format additively manufactured parts. Thermocouples were placed throughout the part at varying heights to measure temperature as a function of time. The FE model developed found a thermal contact conductance between the printed part and the bed of 10 W/m²K and convection coefficient values that linearly varied from 3 to 15 W/m²K through the wall height when making a temperature comparison with the output from the thermocouples. It is also demonstrated that the FE model with a constant convection coefficient under-predicts model temperature at the beginning of the manufacturing process when compared against the model with a variable convection coefficient. The impact of this difference was seen in the stress values, which were larger for the model with a constant convection coefficient. Finally, a correlation equation was derived which allows the findings to be generalized to other vertical structures manufactured on the BAAM. In summary, this work offers valuable insights on material characterization, real-time thermocouple placement, and FE modeling of large-format additively manufactured parts. Full article

(This article belongs to the Special Issue Advances in Materials Joining and Additive Manufacturing)

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17 pages, 7956 KiB

Open AccessArticle

Accelerating First Principles Calculation of Multi-Component Alloy Steady-State Structure and Elastic Properties in Full Component Space

by Zhixuan Yao, Yan Zhang, Yong Liu, Mingwei Li, Tianyi Han, Zhonghong Lai, Nan Qu, Jingchuan Zhu and Boyuan Yu

Materials 2023, 16(18), 6226; https://doi.org/10.3390/ma16186226 - 15 Sep 2023

Viewed by 854

Abstract

The FeNiCrAlCoCuTi alloy system has great advantages in mechanical properties such as high hardness and toughness. It has high performance potential and research value and the key in research is designing alloy compositions with target properties. The traditional method, experimental analysis, is highly [...] Read more.

The FeNiCrAlCoCuTi alloy system has great advantages in mechanical properties such as high hardness and toughness. It has high performance potential and research value and the key in research is designing alloy compositions with target properties. The traditional method, experimental analysis, is highly inefficient to properly exploit the intrinsic relationship between material characteristics and properties for multi-component alloys, especially in investigating the whole composition space. In this work, we present a research way that uses first principles calculation to obtain the properties of multi-component alloys and uses machine learning to accelerate the research. The FeNiCrAlCoCuTi alloy system with its elastic properties is used as an example to demonstrate this process. We specifically design models for each output, all of which have RMSE values of less than 1.1, and confirm their effectiveness through experimental data in the literature, showing that the relative error is below 5%. Additionally, we perform an interpretable analysis on the models, exposing the underlying relationship between input features and output. By means of spatial transformation, we achieve the prediction of the full-component spatial performance from binary to multiple components. Taking the FeNiCrAlM (M = Co, Cu, Ti) quinary alloy system as an example, we design a single-phase BCC structure composed of an Fe_0.23Cr_0.23Al_0.23Ni_0.03Cu_0.28 alloy with a Young’s modulus of 273.10 GPa, as well as a single-phase BCC structure composed of an Fe_0.01Cr_0.01Al_0.01Ni_0.44Co_0.53 alloy with a shear modulus of 103.6 GPa. Through this research way, we use machine learning to accelerate the calculation, which greatly shortens research time and costs. This work overcomes the drawbacks of traditional experiments and directly obtains element compositions and composition intervals with excellent performance. Full article

(This article belongs to the Special Issue Advances in Materials Joining and Additive Manufacturing)

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20 pages, 6357 KiB

Open AccessArticle

A New Method of Predicting the Parameters of the Rotational Friction Welding Process Based on the Determination of the Frictional Heat Transfer in Ti Grade 2/AA 5005 Joints

by Piotr Lacki, Janina Adamus, Wojciech Więckowski and Maciej Motyka

Materials 2023, 16(13), 4787; https://doi.org/10.3390/ma16134787 - 03 Jul 2023

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Abstract

The article presents an original approach to determining the basic parameters of rotational friction welding (RFW) based on the analysis of friction heat transfer at the faying surfaces. Dissimilar Ti Grade 2/AA 5005 joints were used to demonstrate the method. The work established [...] Read more.

The article presents an original approach to determining the basic parameters of rotational friction welding (RFW) based on the analysis of friction heat transfer at the faying surfaces. Dissimilar Ti Grade 2/AA 5005 joints were used to demonstrate the method. The work established that for the analyzed joint, the optimum temperature at the faying surface that allow for a good quality weld to be obtained should be ~505 °C. On this basis, a map of optimal parameters was developed to achieve this temperature. This approach could potentially allow for more precise control of the welding process, leading to better joint quality and performance. The paper includes both a description of the technological process of friction welding and an attempt to explain the mechanism of the phenomena occurring in the welding area. The numerical calculations presented in the article were carried out using the ADINA System v. 9.8.2, which allows for the consideration of heat friction in the axial symmetric thermo-mechanical model. Frictional resistance was determined by the temperature-dependent friction coefficient. The assumed thermo-mechanical model required the determination of elastic-plastic properties versus temperature for the analyzed materials. The simulations of the friction welding were carried out for the different welding parameters and time. The different variants of friction welding were modelled. Full article

(This article belongs to the Special Issue Advances in Materials Joining and Additive Manufacturing)

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16 pages, 4768 KiB

Open AccessArticle

Characterization of 5356 Aluminum Walls Produced by Wire Arc Additive Manufacturing (WAAM)

by Michal Wieczorowski, Alejandro Pereira, Diego Carou, Bartosz Gapinski and Ignacio Ramírez

Materials 2023, 16(7), 2570; https://doi.org/10.3390/ma16072570 - 23 Mar 2023

Cited by 5 | Viewed by 1906

Abstract

Wire arc additive manufacturing (WAAM) is renowned for its high deposition rate, enabling the production of large parts. However, the process has challenges such as porosity formation, residual stresses, and cracking when manufacturing aluminum parts. This study focuses on ana-lyzing the porosity of [...] Read more.

Wire arc additive manufacturing (WAAM) is renowned for its high deposition rate, enabling the production of large parts. However, the process has challenges such as porosity formation, residual stresses, and cracking when manufacturing aluminum parts. This study focuses on ana-lyzing the porosity of AA5356 walls manufactured using the WAAM process with the Fronius cold metal transfer system (Wels, Austria). The walls were machined to obtain specimens for tensile testing. The study used computed tomography and the tensile test to analyze the specimens’ porosity and its potential relation to tensile strength. The process parameters analyzed were travel speed, cooling time, and path strategy. In conclusion, increasing travel speed and cooling time significantly affects pore diameter due to the lower heat input to the weld zone. Porosity can be reduced when diminishing heat accumulation. The results indicate that an increase in travel speed produces a slight decrease in porosity. Specifically, the total pore volume diminishes from 0.42 to 0.36 mm³ when increasing the travel speed from 700 to 950 mm/min. The ultimate tensile strength and maximum elongation of the ‘back and forth’ strategy are slightly higher than those of the ‘go’ strategy. After tensile testing, the ultimate tensile strength and yield strength did not show any relation to the porosity measured by computed tomography. The percentage of the pore total volume over the measured volume was lower than 0.12% for all the scanned specimens. Full article

(This article belongs to the Special Issue Advances in Materials Joining and Additive Manufacturing)

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11 pages, 4163 KiB

Open AccessArticle

Low-Temperature Transient Liquid Phase Bonding Technology via Cu Porous-Sn58Bi Solid–Liquid System under Formic Acid Atmosphere

by Siliang He, Bifu Xiong, Fangyi Xu, Biyang Chen, Yinhua Cui, Chuan Hu, Gao Yue and Yu-An Shen

Materials 2023, 16(6), 2389; https://doi.org/10.3390/ma16062389 - 16 Mar 2023

Cited by 4 | Viewed by 1543

Abstract

This study proposes a low-temperature transient liquid phase bonding (TLPB) method using Sn58Bi/porous Cu/Sn58Bi to enable efficient power-device packaging at high temperatures. The bonding mechanism is attributed to the rapid reaction between porous Cu and Sn58Bi solder, leading to the formation of intermetallic [...] Read more.

This study proposes a low-temperature transient liquid phase bonding (TLPB) method using Sn58Bi/porous Cu/Sn58Bi to enable efficient power-device packaging at high temperatures. The bonding mechanism is attributed to the rapid reaction between porous Cu and Sn58Bi solder, leading to the formation of intermetallic compounds with high melting point at low temperatures. The present paper investigates the effects of bonding atmosphere, bonding time, and external pressure on the shear strength of metal joints. Under formic acid (FA) atmosphere, Cu₆Sn₅ forms at the porous Cu foil/Sn58Bi interface, and some of it transforms into Cu₃Sn. External pressure significantly reduces the micropores and thickness of the joint interconnection layer, resulting in a ductile fracture failure mode. The metal joint obtained under a pressure of 10 MPa at 250 °C for 5 min exhibits outstanding bonding mechanical performance with a shear strength of 62.2 MPa. Full article

(This article belongs to the Special Issue Advances in Materials Joining and Additive Manufacturing)

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18 pages, 7210 KiB

Open AccessArticle

Microstructure and Mechanical Properties of Solid-State Rotary Friction Welded Inconel 713C and 32CrMo4 Steel Joints Used in a Turbocharger Rotor

by Krzysztof Szwajka, Joanna Zielińska-Szwajka and Tomasz Trzepieciński

Materials 2023, 16(6), 2273; https://doi.org/10.3390/ma16062273 - 12 Mar 2023

Cited by 4 | Viewed by 1878

Abstract

The aim of this work was to determine the effect of selected parameters of friction welding, such as friction pressure and welding speed, on the mechanical properties and microstructure of friction-welded Inconel 713C-32CrMo4 joints. Tensile strength and hardness tests were carried out to [...] Read more.

The aim of this work was to determine the effect of selected parameters of friction welding, such as friction pressure and welding speed, on the mechanical properties and microstructure of friction-welded Inconel 713C-32CrMo4 joints. Tensile strength and hardness tests were carried out to determine the mechanical properties of the resulting welded joints. The results of the ultimate tensile strength, hardness, and microstructure were linked to the parameters of the welding process. It was found that the highest tensile strength was 1222 N/mm². There was a significant increase in the hardness value in the thermo-mechanically affected zone for all samples. However, as the friction pressure increased, the zone with the higher hardness value migrated towards the 32CrMo4 material. In all weld tests, the fracture was found on the 32CrMo4 steel side. A distinct band of carbide formation was observed between the thermo-mechanically affected zone and the Inconel 713C base material. Full article

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14 pages, 9664 KiB

Open AccessArticle

Joining Strategies for Double-Sided Self-Pierce Riveting

by Rafael M. Afonso and Luís M. Alves

Materials 2023, 16(3), 1191; https://doi.org/10.3390/ma16031191 - 30 Jan 2023

Cited by 3 | Viewed by 1274

Abstract

Double-sided self-pierce riveting (DSSPR) has been presenting itself as a proper alternative to self-pierce riveting (SPR) with many advantages for joining geometries of different thicknesses and cross-sections. To ensure its successful future industrial application, this paper presents a detailed comparison between different strategies [...] Read more.

Double-sided self-pierce riveting (DSSPR) has been presenting itself as a proper alternative to self-pierce riveting (SPR) with many advantages for joining geometries of different thicknesses and cross-sections. To ensure its successful future industrial application, this paper presents a detailed comparison between different strategies to produce mechanical joints by means of the DSSPR process and discusses its performance and feasibility. Results show that the use of flat-bottom holes in both sheets provide interesting results, since they allow for a precise positioning of the tubular rivet in specific pre-defined locations, thus avoiding an incorrect joining procedure. This strategy tightens the tolerances of the process, while keeping a suitable level of destructive performance as demonstrated by the lap shear tests. Pre-riveting of the sheet has also been shown to produce suitable results in combination with or without a flat-bottom hole in the opposite sheet. This strategy comes at a cost of a slightly lower performance than that obtained with flat-bottom holes in both sheets, although the requirements of force and energy to complete the joining process are smaller. The conclusions of this research work are essential for selecting the joining strategy with DSSPR according to the requirements of the intended application. Full article

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14 pages, 10062 KiB

Open AccessArticle

Effect of Process Parameters on Weld Quality in Vortex- Friction Stir Welding of 6061-T6 Aluminum Alloy

by Xiaochao Liu, Wentao Li, Yunqian Zhen, Luanluan Jia, Yongzhe Li and Xianjun Pei

Materials 2023, 16(2), 873; https://doi.org/10.3390/ma16020873 - 16 Jan 2023

Cited by 3 | Viewed by 1569

Abstract

Vortex- friction stir welding (VFSW) utilizes a stir bar made of an identical material to the workpiece to rub the workpiece’s top surface, which avoids the keyhole defect in conventional friction stir welding. It presents great potential in the repair field of aluminum [...] Read more.

Vortex- friction stir welding (VFSW) utilizes a stir bar made of an identical material to the workpiece to rub the workpiece’s top surface, which avoids the keyhole defect in conventional friction stir welding. It presents great potential in the repair field of aluminum alloys. In this study, the effect of stir bar diameter, rotation speed, and welding speed on the weld formation was investigated in the VFSW of 6061-T6 aluminum alloy. The weld macrostructure, penetration, and mechanical properties were characterized. The results show that a large diameter of the stir bar can enhance the vortex material flow, increase the heat input, and eliminate the incomplete-penetration defect. The increase in rotation speed within limits can enhance the weld penetration and the mechanical properties of the weld nugget zone (WNZ). However, too high a rotation speed reduces the weld penetration and weakens the mechanical properties of the WNZ. The increase in welding speed reduces the weld penetration but enhances the mechanical properties of the heat affected zone. The incomplete-penetration defect significantly weakens the ductility of the VFSW joint. It can be eliminated by enlarging the stir bar diameter and choosing a moderate rotation speed and a lower welding speed. Full article

(This article belongs to the Special Issue Advances in Materials Joining and Additive Manufacturing)

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Review

Jump to: Research

31 pages, 11510 KiB

Open AccessReview

A Comprehensive Review of Friction Stir Additive Manufacturing (FSAM) of Non-Ferrous Alloys

by Adeel Hassan, Srinivasa Rao Pedapati, Mokhtar Awang and Imtiaz Ali Soomro

Materials 2023, 16(7), 2723; https://doi.org/10.3390/ma16072723 - 29 Mar 2023

Cited by 7 | Viewed by 4213

Abstract

Additive manufacturing is a key component of the fourth industrial revolution (IR4.0) that has received increased attention over the last three decades. Metal additive manufacturing is broadly classified into two types: melting-based additive manufacturing and solid-state additive manufacturing. Friction stir additive manufacturing (FSAM) [...] Read more.

Additive manufacturing is a key component of the fourth industrial revolution (IR4.0) that has received increased attention over the last three decades. Metal additive manufacturing is broadly classified into two types: melting-based additive manufacturing and solid-state additive manufacturing. Friction stir additive manufacturing (FSAM) is a subset of solid-state additive manufacturing that produces big area multi-layered components through plate addition fashion using the friction stir welding (FSW) concept. Because of the solid-state process in nature, the part produced has equiaxed grain structure, which leads to better mechanical properties with less residual stresses and solidification defects when compared to existing melting-based additive manufacturing processes. The current review article intends to highlight the working principle and previous research conducted by various research groups using FSAM as an emerging material synthesizing technique. The summary of affecting process parameters and defects claimed for different research materials is discussed in detail based on open access experimental data. Mechanical properties such as microhardness and tensile strength, as well as microstructural properties such as grain refinement and morphology, are summarized in comparison to the base material. Furthermore, the viability and potential application of FSAM, as well as its current academic research status with technology readiness level and future recommendations are discussed meticulously. Full article

(This article belongs to the Special Issue Advances in Materials Joining and Additive Manufacturing)

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