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8 pages, 11149 KiB

Open AccessCommunication

Eliminating Cu–Cu Bonding Interfaces Using Electroplated Copper and (111)-Oriented Nanotwinned Copper

by Tsan-Feng Lu, Yuan-Fu Cheng, Pei-Wen Wang, Yu-Ting Yen and YewChung Sermon Wu

Materials 2024, 17(14), 3467; https://doi.org/10.3390/ma17143467 - 13 Jul 2024

Viewed by 924

Abstract

Cu–Cu joints have been adopted for ultra-high-density packaging for high-end devices. However, the atomic diffusion rate is notably low at the preferred processing temperature, resulting in clear and distinct weak bonding interfaces, which, in turn, lead to reliability issues. In this study, a [...] Read more.

Cu–Cu joints have been adopted for ultra-high-density packaging for high-end devices. However, the atomic diffusion rate is notably low at the preferred processing temperature, resulting in clear and distinct weak bonding interfaces, which, in turn, lead to reliability issues. In this study, a new method for eliminating the bonding interfaces using two types of Cu films in Cu–Cu bonding is proposed. The difference in grain size was utilized as the primary driving force for the migration of bonding interfaces/interfacial grain boundaries. Additionally, the columnar nanotwinned Cu structure acted as a secondary driving force, making the migration more significant. When bonded at 300 °C, the grains from one side grew and extended to the bottom, eliminating the bonding interfaces. A mechanism for the evolution of the Cu bonding interfaces/interfacial grain boundaries is proposed. Full article

(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)

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18 pages, 4919 KiB

Open AccessArticle

Evolution of Material Properties and Residual Stress with Increasing Number of Passes in Aluminium Structure Printed via Additive Friction Stir Deposition

by Vladislav Yakubov, Halsey Ostergaard, James Hughes, Evren Yasa, Michail Karpenko, Gwénaëlle Proust and Anna M. Paradowska

Materials 2024, 17(14), 3457; https://doi.org/10.3390/ma17143457 - 12 Jul 2024

Cited by 2 | Viewed by 1408

Abstract

Additive friction stir deposition (AFSD) is an emerging solid-state additive manufacturing process with a high deposition rate. Being a non-fusion additive manufacturing (AM) process, it significantly eliminates problems related to melting such as cracking or high residual stresses. Therefore, it is possible to [...] Read more.

Additive friction stir deposition (AFSD) is an emerging solid-state additive manufacturing process with a high deposition rate. Being a non-fusion additive manufacturing (AM) process, it significantly eliminates problems related to melting such as cracking or high residual stresses. Therefore, it is possible to process reactive materials or high-strength alloys with high susceptibility to cracking. Although the residual stresses are lower in this process than with the other AM processes, depending on the deposition path, geometry, and boundary conditions, residual stresses may lead to undesired deformations and deteriorate the dimensional accuracy. Thermal cycling during layer deposition, which also depends on the geometry of the manufactured component, is expected to affect mechanical properties. To this day, the influence of the deposit geometry on the residual stresses and mechanical properties is not well understood, which presents a barrier for industry uptake of this process for large-scale part manufacturing. In this study, a stepped structure with 4, 7, and 10 passes manufactured via AFSD is used to investigate changes in microstructure, residual stress, and mechanical property as a function of the number of passes. The microstructure and defects are assessed using scanning electron microscopy and electron backscatter diffraction. Hardness maps for each step are created. The residual stress distributions at the centreline of each step are acquired via non-destructive neutron diffraction. The valuable insights presented here are essential for the successful utilisation of AFSD in industrial applications. Full article

(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)

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11 pages, 8775 KiB

Open AccessArticle

Modification of Microstructure and Mechanical Properties of Extruded AZ91-0.4Ce Magnesium Alloy through Addition of Ca

by Fengtao Ni, Jian Peng, Xiangquan Liu, Pan Gao, Zhongkui Nie, Jie Hu and Dong Zhao

Materials 2024, 17(13), 3359; https://doi.org/10.3390/ma17133359 - 8 Jul 2024

Cited by 1 | Viewed by 810

Abstract

The effect of the addition of alkali earth element Ca on the microstructure and mechanical properties of extruded AZ91-0.4Ce-xCa (x = 0, 0.4, 0.8, 1.2 wt.%) alloys was studied by using scanning electron microscopy, transmission electron microscopy, and tensile tests. The results showed [...] Read more.

The effect of the addition of alkali earth element Ca on the microstructure and mechanical properties of extruded AZ91-0.4Ce-xCa (x = 0, 0.4, 0.8, 1.2 wt.%) alloys was studied by using scanning electron microscopy, transmission electron microscopy, and tensile tests. The results showed that the addition of Ca could significantly refine the second phase and grain size of the extruded AZ91-0.4Ce alloy. The refinement effect was most obvious when 0.8 wt.% of Ca was added, and the recrystallized grain size was 4.75 μm after extrusion. The addition of Ca resulted in the formation of a spherical Al₂Ca phase, which effectively suppressed the precipitation of the β-Mg₁₇Al₁₂ phase, promoted dynamic recrystallization and grain refinement, impeded dislocation motion, and exerted a positive influence on the mechanical properties of the alloy. The yield strength (YS), ultimate tensile strength (UTS), and elongation (EL) of the AZ91-0.4Ce-0.8Ca alloy were 238.7 MPa, 338.3 MPa, and 10.8%, respectively. Full article

(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)

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16 pages, 29047 KiB

Open AccessArticle

Comparison between Mechanical Properties and Joint Performance of AA 2024-T351 Aluminum Alloy Welded by Friction Stir Welding, Metal Inert Gas and Tungsten Inert Gas Processes

by Miodrag Milčić, Damjan Klobčar, Dragan Milčić, Nataša Zdravković, Aleksija Đurić and Tomaž Vuherer

Materials 2024, 17(13), 3336; https://doi.org/10.3390/ma17133336 - 5 Jul 2024

Cited by 1 | Viewed by 764

Abstract

The aim of this work is to study joining Al 2024-T3 alloy plates with different welding procedures. Aluminum alloy AA 2024-T351 is especially used in the aerospace industry. Aluminum plates are welded by the TIG and MIG fusion welding process, as well as [...] Read more.

The aim of this work is to study joining Al 2024-T3 alloy plates with different welding procedures. Aluminum alloy AA 2024-T351 is especially used in the aerospace industry. Aluminum plates are welded by the TIG and MIG fusion welding process, as well as by the solid-state welding process, friction stir welding (FSW), which has recently become very important in aluminum and alloy welding. For welding AA2024-T35 with MIG and TIG fusion processes, the filler material ER 4043—AlSi₅ was chosen because of reduced cracking. Different methods were used to evaluate the quality of the produced joints, including macro- and microstructure evaluation, in addition to hardness and tensile tests. The ultimate tensile strength (UTS) of the FSW sample was found to be 80% higher than that of MIG and TIG samples. The average hardness value of the weld zone of metal for the MIG- and TIG-produced AA2024-T3511 butt joints showed a significant decrease compared to the hardness of the base metal AA2024-T351 by 50%, while for FSW joints, in the nugget zone, the hardness is about 10% lower relative to the base metal AA2024-T3511. Full article

(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)

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25 pages, 10756 KiB

Open AccessArticle

A Methodology for Shielding-Gas Selection in Wire Arc Additive Manufacturing with Stainless Steel

by Felipe Ribeiro Teixeira, Vinicius Lemes Jorge, Fernando Matos Scotti, Erwan Siewert and Americo Scotti

Materials 2024, 17(13), 3328; https://doi.org/10.3390/ma17133328 - 5 Jul 2024

Cited by 1 | Viewed by 882

Abstract

The main objective of this work was to propose and evaluate a methodology for shielding-gas selection in additive manufacturing assisted by wire arc additive manufacturing (WAAM) with an austenitic stainless steel as feedstock. To validate the proposed methodology, the impact of multi-component gases [...] Read more.

The main objective of this work was to propose and evaluate a methodology for shielding-gas selection in additive manufacturing assisted by wire arc additive manufacturing (WAAM) with an austenitic stainless steel as feedstock. To validate the proposed methodology, the impact of multi-component gases was valued using three different Ar-based blends recommended as shielding gas for GMA (gas metal arc) of the target material, using CMT (cold metal transfer) as the process version. This assessment considered features that potentially affect the building of the case study of thin walls, such as metal transfer regularity, deposition time, and geometrical and metallurgical characteristics. Different settings of wire-feed speeds were conceived to maintain a similar mean current (first constraint for comparison’s sake) among the three gas blends. This approach implied different mean wire-feed speeds and simultaneously forced a change in the deposition speed to maintain the same amount of material deposited per unit of length (second comparison constraint). The composition of the gases affects the operational performance of the shielding gases. It was concluded that by following this methodology, shielding-gas selection decision-making is possible based on the perceived characteristics of the different commercial blends. Full article

(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)

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29 pages, 41374 KiB

Open AccessArticle

Continuous Drive Friction Welded Al/Cu Joints Produced Using Short Welding Time, Elevated Rotational Speed, and High Welding Pressures

by Veljko Milašinović, Ana Alil, Mijat Milašinović, Aleksandar Vencl, Michal Hatala, Stefan Dikić and Bojan Gligorijević

Materials 2024, 17(13), 3284; https://doi.org/10.3390/ma17133284 - 3 Jul 2024

Viewed by 1089

Abstract

The present study aimed to enhance the efficiency and efficacy of the Al/Cu joint production process implemented by the company VEMID Ltd., Jagodina, Serbia, by attaining sound joints within a very short welding time. For this purpose, the present study aimed at investigating [...] Read more.

The present study aimed to enhance the efficiency and efficacy of the Al/Cu joint production process implemented by the company VEMID Ltd., Jagodina, Serbia, by attaining sound joints within a very short welding time. For this purpose, the present study aimed at investigating the accuracy and the quality of the continuous drive friction welding (CDFW) process, as well as the optimum combination of CDFW parameters with highest joint efficiency in terms of investigated properties. The accuracy was estimated through an analysis of temperature–time curves recorded during CDFW using an infrared camera. The quality was evaluated through an investigation of the properties of Al/Cu joints produced using different friction (66.7, 88.9, and 133.3 MPa) and forging (88.9, 222.2, and 355.6 MPa) pressures and a constant total welding time (4 s) and rotational speed (2100 rpm). Thermal imaging with an infrared camera demonstrated that the actual total welding time was 15% longer compared to the nominal value. This was attributed to the slow pressure response of the pneumatic brake system. The relative changes in the maximum surface temperature (T_MS) during the CDFW process corresponded to changes in welding pressures, indicating the potential of the thermal imaging method for monitoring and assessing this process. A preliminary investigation demonstrated that Al/Cu joints produced using welding pressures less than 88.9 MPa often displayed the presence of non-joined micro-regions at the Al/Cu interface and a significant thickness of interfacial Al₂Cu (up to 1 µm). However, when friction pressure was set at 66.7 MPa, an increase in the forging pressure to 222.2 MPa eliminated the presence of non-joined micro-regions and reduced the thickness of Al₂Cu to 0.5 µm on the average level. These Al/Cu joints achieved the highest joint efficiencies in terms of strength (100%) and ductility (61%). They exhibited an electrical conductivity higher than 92% of the theoretical value. A further increase in any welding pressure produced similar or deteriorated properties, accompanied by an increase in the consumption of raw materials and energy. Such turn of events was counterproductive to the original goal of increasing the efficiency and efficacy of the CDFW process. Full article

(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)

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10 pages, 2246 KiB

Open AccessArticle

Enhancement of Abnormal Grain Growth by Surface Quenching Treatment to Eliminate Cu–Cu Bonding Interfaces Using (111)-Oriented Nanotwinned Copper

by Tsan-Feng Lu, Yu-Ting Yen, Yuan-Fu Cheng, Pei-Wen Wang and YewChung Sermon Wu

Materials 2024, 17(13), 3245; https://doi.org/10.3390/ma17133245 - 2 Jul 2024

Viewed by 775

Abstract

Cu–Cu joints have been adopted for ultra-high density of packaging for high-end devices. However, the processing temperature must be kept relatively low, preferably below 300 °C. In this study, a novel surface modification technique, quenching treatment, was applied to achieve Cu-to-Cu direct bonding [...] Read more.

Cu–Cu joints have been adopted for ultra-high density of packaging for high-end devices. However, the processing temperature must be kept relatively low, preferably below 300 °C. In this study, a novel surface modification technique, quenching treatment, was applied to achieve Cu-to-Cu direct bonding using (111)-oriented nanotwinned Cu. The quenching treatment enabled grain growth across the Cu–Cu bonding interface at 275 °C. During quenching treatment, strain energy was induced in the Cu film, resulting in a wrinkled surface morphology. To analyze the strain energy, we utilized an electron backscattered diffraction system to obtain crystallographic information and confirmed it using kernel average misorientation analysis. Full article

(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)

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11 pages, 9743 KiB

Open AccessArticle

Effect of Compressive Stress on Copper Bonding Quality and Bonding Mechanisms in Advanced Packaging

by Tsan-Feng Lu, Ping-Yang Lee and YewChung Sermon Wu

Materials 2024, 17(10), 2236; https://doi.org/10.3390/ma17102236 - 9 May 2024

Cited by 1 | Viewed by 1114

Abstract

The thermal expansion behavior of Cu plays a critical role in the bonding mechanism of Cu/SiO₂ hybrid joints. In this study, artificial voids, which were observed to evolve using a focused ion beam, were introduced at the bonded interfaces to investigate the [...] Read more.

The thermal expansion behavior of Cu plays a critical role in the bonding mechanism of Cu/SiO₂ hybrid joints. In this study, artificial voids, which were observed to evolve using a focused ion beam, were introduced at the bonded interfaces to investigate the influence of compressive stress on bonding quality and mechanisms at elevated temperatures of 250 °C and 300 °C. The evolution of interfacial voids serves as a key indicator for assessing bonding quality. We quantified the bonding fraction and void fraction to characterize the bonding interface and found a notable increase in the bonding fraction and a corresponding decrease in the void fraction with increasing compressive stress levels. This is primarily attributed to the Cu film exhibiting greater creep/elastic deformation under higher compressive stress conditions. Furthermore, these experimental findings are supported by the surface diffusion creep model. Therefore, our study confirms that compressive stress affects the Cu–Cu bonding interface, emphasizing the need to consider the depth of Cu joints during process design. Full article

(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)

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13 pages, 13869 KiB

Open AccessArticle

The Dominant Role of Recrystallization and Grain Growth Behaviors in the Simulated Welding Heat-Affected Zone of High-Mn Steel

by Yangwen Wang, Honghong Wang, Siyuan Peng, Bin Xia and Hai Zhu

Materials 2024, 17(10), 2218; https://doi.org/10.3390/ma17102218 - 8 May 2024

Viewed by 1070

Abstract

Single-pass-welding thermal cycles with different peak temperatures (T_p) were reproduced by a Gleeble 3800 to simulate the heat-affected zone (HAZ) of a Fe-24Mn-4Cr-0.4C-0.3Cu (wt.%) high manganese austenitic steel. Then, the effect of T_p on the microstructure and mechanical properties of [...] Read more.

Single-pass-welding thermal cycles with different peak temperatures (T_p) were reproduced by a Gleeble 3800 to simulate the heat-affected zone (HAZ) of a Fe-24Mn-4Cr-0.4C-0.3Cu (wt.%) high manganese austenitic steel. Then, the effect of T_p on the microstructure and mechanical properties of the HAZ were investigated. The results indicate that recrystallization and grain growth play dominant roles. Based on this, the HAZ is proposed to categorize into three zones: the recrystallization heat-affected zone (RHAZ) with a T_p of 700~900 °C, the transition heat-affected zone (THAZ) with a T_p of 900~1000 °C, and the coarse grain heat-affected zone (CGHAZ) with a T_p of 1000~1300 °C. The recrystallization fraction was 29~44% in the RHAZ, rapidly increased to 87% in the THAZ, and exceeded 95% in the CGHAZ. The average grain size was 17~19 μm in the RHAZ, slightly increased to 22 μm in the THAZ, and ultimately increased to 37 μm in the CGHAZ. The yield strength in the RHAZ and THAZ was consistent with the change in recrystallization fraction, while in the CGHAZ, it satisfied the Hall–Petch relationship with grain size. In addition, compared with the base material, the Charpy impact absorbed energy at −196 °C decreased by 22% in the RHAZ, but slightly increased in the CGHAZ. This indicates that the theory of fine grain strengthening and toughening is not entirely applicable to the HAZ of the investigated high-Mn steel. Full article

(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)

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12 pages, 40630 KiB

Open AccessArticle

Interfacial Reactions between Sn-Based Solders and n-Type Bi₂(Te,Se)₃ Thermoelectric Material

by Chao-Hong Wang, Chun-Wei Chiu and Mei-Hau Li

Materials 2024, 17(9), 2158; https://doi.org/10.3390/ma17092158 - 5 May 2024

Viewed by 991

Abstract

This study investigated the interfacial reactions between n-type Bi₂(Te,Se)₃ thermoelectric material, characterized by a highly-oriented (110) plane, and pure Sn and Sn-3.0Ag-0.5Cu (wt.%) solders, respectively. At 250 °C, the liquid-state Sn/Bi₂(Te,Se)₃ reactions resulted in the formation of [...] Read more.

This study investigated the interfacial reactions between n-type Bi₂(Te,Se)₃ thermoelectric material, characterized by a highly-oriented (110) plane, and pure Sn and Sn-3.0Ag-0.5Cu (wt.%) solders, respectively. At 250 °C, the liquid-state Sn/Bi₂(Te,Se)₃ reactions resulted in the formation of both SnTe and BiTe phases, with Bi-rich particles dispersed within the SnTe phase. The growth of the SnTe phase exhibited diffusion-controlled parabolic behavior over time. In contrast, the growth rate was considerably slower compared to that observed with p-type (Bi,Sb)₂Te₃. Solid-state Sn/Bi₂(Te,Se)₃ reactions conducted between 160 °C and 200 °C exhibited similar interfacial microstructures. The SnTe phase remained the primary reaction product, embedded with tiny Bi-rich particles, revealing a diffusion-controlled growth. However, the BiTe layer had no significant growth. Further investigation into growth kinetics of intermetallic compounds and microstructural evolution was conducted to elucidate the reaction mechanism. The slower growth rates in Bi₂(Te,Se)₃, compared to the reactions with (Bi,Sb)₂Te₃, could be attributed to the strong suppression effect of Se on SnTe growth. Additionally, the interfacial reactions of Bi₂(Te,Se)₃ with Sn-3.0Ag-0.5Cu were also examined, showing similar growth behavior to those observed with Sn solder. Notably, compared with Ag, Cu tends to diffuse towards the interfacial reaction phases, resulting in a high Cu solubility within the SnTe phase. Full article

(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)

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10 pages, 3506 KiB

Open AccessArticle

Effect of Cu Film Thickness on Cu Bonding Quality and Bonding Mechanism

by Tsan-Feng Lu, Kai-Ning Hsu, Ching-Chi Hsu, Chia-Yu Hsu and YewChung Sermon Wu

Materials 2024, 17(9), 2150; https://doi.org/10.3390/ma17092150 - 4 May 2024

Cited by 1 | Viewed by 1152

Abstract

In the hybrid bonding process, the final stage of chemical mechanical polishing plays a critical role. It is essential to ensure that the copper surface is recessed slightly from the oxide surface. However, this recess can lead to the occurrence of interfacial voids [...] Read more.

In the hybrid bonding process, the final stage of chemical mechanical polishing plays a critical role. It is essential to ensure that the copper surface is recessed slightly from the oxide surface. However, this recess can lead to the occurrence of interfacial voids between the bonded copper interfaces. To examine the effects of copper film thickness on bonding quality and bonding mechanisms in this study, artificial voids were intentionally introduced at the bonded interfaces at temperatures of 250 °C and 300 °C. The results revealed that as the thickness of the copper film increases, there is an increase in the bonding fraction and a decrease in the void fraction. The variations in void height with different copper film thicknesses were influenced by the bonding mechanism and bonding fraction. Full article

(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)

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13 pages, 2779 KiB

Open AccessArticle

Weldability and Mechanical Properties of Pure Copper Foils Welded by Blue Diode Laser

by Tim Pasang, Shumpei Fujio, Pai-Chen Lin, Yuan Tao, Mao Sudo, Travis Kuendig, Yuji Sato and Masahiro Tsukamoto

Materials 2024, 17(9), 2140; https://doi.org/10.3390/ma17092140 - 2 May 2024

Cited by 2 | Viewed by 1403

Abstract

The need to manufacture components out of copper is significantly increasing, particularly in the solar technology, semiconductor, and electric vehicle sectors. In the past few decades, infrared laser (IR) and green laser (GL) have been the primary technologies used to address this demand, [...] Read more.

The need to manufacture components out of copper is significantly increasing, particularly in the solar technology, semiconductor, and electric vehicle sectors. In the past few decades, infrared laser (IR) and green laser (GL) have been the primary technologies used to address this demand, especially for small or thin components. However, with the increased demand for energy saving, alternative joint techniques such as blue diode laser (BDL) are being actively explored. In this paper, bead-on-plate welding experiments on 0.2 mm thick pure copper samples employing a BDL are presented. Two sets of parameters were carefully selected in this investigation, namely Cu-1: Power (P) = 200 W; Speed (s) = 1 mm/s; and angle = 0°, and Cu-2: P = 200 W; s = 5 mm/s; and angle = 10°. The results from both sets of parameters produced defect-free full penetration welds. Hardness test results indicated relatively softer weld zones compared with the base metal. Tensile test samples fractured in the weld zones. Overall, the samples welded with Cu-1 parameters showed better mechanical properties, such as strength and elongation, than those welded with the Cu-2 parameters. The tensile strength and elongation obtained from Cu-1 were marginally lower than those of the unwelded pure copper. The outcomes from this research provide an alternative welding technique that is able to produce reliable, strong, and precise joints, particularly for small and thin components, which can be very challenging to produce. Full article

(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)

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24 pages, 11055 KiB

Open AccessArticle

Comparison of the Mechanical Properties of Hardfacings Made by Standard Coated Stick Electrodes and a Newly Developed Rectangular Stick Electrode

by Edvard Bjelajac, Andrej Skumavc, Gorazd Lojen, Mirza Manjgo and Tomaž Vuherer

Materials 2024, 17(9), 2051; https://doi.org/10.3390/ma17092051 - 27 Apr 2024

Viewed by 723

Abstract

Cladding with a stick electrode is one of the oldest arc processes for adding a deposit on a base material. The process is suitable for outdoor working, but the disadvantages are low productivity and large dilution rates. In this work, a simple solution [...] Read more.

Cladding with a stick electrode is one of the oldest arc processes for adding a deposit on a base material. The process is suitable for outdoor working, but the disadvantages are low productivity and large dilution rates. In this work, a simple solution is proposed, which would enable cladding of a larger area with one pass and decrease the dilution rate at the same time—a new type of electrode was developed, exhibiting a rectangular cross-section instead of a round one. Hardfacings, welded with E Fe8 electrodes according to EN 14 700 Standard were welded on mild steel S355 J2 base material with three different coated stick electrodes. The first one was a commercially available, standard, round hardfacing electrode, the second was the same, but with a thinner coating, and the third one was a newly developed rectangular electrode. All three types had equal cross-sections of the metallic core and the same type of coating. Manufacturing of the rectangular electrodes in the laboratory is explained briefly. One- and multi-layer deposits were welded with all three types. Differences were observed in the arc behavior between the round and rectangular electrodes. With the rectangular electrode, the microstructure of the deposit was finer, penetration was shallower, and dilution rates were lower, while the hardness was higher, residual stresses predominantly compressive, and the results of instrumented Charpy impact tests and fracture mechanics tests were better. Full article

(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)

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16 pages, 5925 KiB

Open AccessEditor’s ChoiceArticle

Microstructure and Mechanical Properties of Ti-6Al-4V Welds Produced with Different Processes

by Sakari Tolvanen, Robert Pederson and Uta Klement

Materials 2024, 17(4), 782; https://doi.org/10.3390/ma17040782 - 6 Feb 2024

Cited by 3 | Viewed by 1204

Abstract

The effect of defects and microstructure on the mechanical properties of Ti-6Al-4V welds produced by tungsten inert gas welding; plasma arc welding; electron beam welding; and laser beam welding was studied in the present work. The mechanical properties of different weld types were [...] Read more.

The effect of defects and microstructure on the mechanical properties of Ti-6Al-4V welds produced by tungsten inert gas welding; plasma arc welding; electron beam welding; and laser beam welding was studied in the present work. The mechanical properties of different weld types were evaluated with respect to micro hardness; yield strength; ultimate tensile strength; ductility; and fatigue at room temperature and at elevated temperatures (200 °C and 250 °C). Metallographic investigation was carried out to characterize the microstructures of different weld types, and fractographic investigation was conducted to relate the effect of defects on fatigue performance. Electron and laser beam welding produced welds with finer microstructure, higher tensile ductility, and better fatigue performance than tungsten inert gas welding and plasma arc welding. Large pores, and pores located close to the specimen surface, were found to be most detrimental to fatigue life. Full article

(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)

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13 pages, 12227 KiB

Open AccessArticle

Microstructure and Mechanical Properties of the Joints from Coarse- and Ultrafine-Grained Al-Mg-Si Alloy Obtained via Friction Stir Welding

by Marta Lipińska

Materials 2023, 16(18), 6287; https://doi.org/10.3390/ma16186287 - 19 Sep 2023

Viewed by 1034

Abstract

In the present study, the welding of coarse- (CG) and ultrafine-grained (UFG) Al-Mg-Si alloy using friction stir welding (FSW) was attempted. The purpose of welding the UFG material was to check the possibility of applying FSW to materials with a thermally unstable microstructure, [...] Read more.

In the present study, the welding of coarse- (CG) and ultrafine-grained (UFG) Al-Mg-Si alloy using friction stir welding (FSW) was attempted. The purpose of welding the UFG material was to check the possibility of applying FSW to materials with a thermally unstable microstructure, which is achieved by severe plastic deformation. This group of materials has significant potential due to the enhanced mechanical properties as a result of the elevated number of structural defects. The CG sample was also examined in order to assess whether there is an influence of the base material microstructure on the weld microstructure and properties. To refine the microstructure, incremental equal channel angular pressing was used. Plastic deformation resulted in grain refinement from 23 µm to 1.5 µm. It caused an increase in the microhardness from 105 HV0.1 to 125 HV0.1 and the tensile strength from 320 MPa to 394 MPa. Similar welds obtained using an FSW method exhibited good quality and grain size in a stir zone of 5 µm. For both welds, a decrease in the microhardness occurred in the stir zone. However, for the weld of UFG Al-Mg-Si, the microhardness distribution was homogeneous, while for the weld of the CG, it was inhomogeneous, which was caused by different characteristics of the second-phase precipitates. The tensile strength of the welds was lowered and equaled 269 MPa and 220 MPa for the CG and UFG welds, respectively. Full article

(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)

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15 pages, 5661 KiB

Open AccessArticle

Ni-Al Bronze in Molten Carbonate Manufactured by LPBF: Effect of Porosity Design on Mechanical Properties and Oxidation

by Camila Arcos, Carolina Guerra, Jorge A. Ramos-Grez and Mamié Sancy

Materials 2023, 16(10), 3893; https://doi.org/10.3390/ma16103893 - 22 May 2023

Cited by 3 | Viewed by 1654

Abstract

Fuel cell technology has developed due to diminishing dependence on fossil fuels and carbon footprint production. This work focuses on a nickel–aluminum bronze alloy as an anode produced by additive manufacturing as bulk and porous samples, studying the effect of designed porosity and [...] Read more.

Fuel cell technology has developed due to diminishing dependence on fossil fuels and carbon footprint production. This work focuses on a nickel–aluminum bronze alloy as an anode produced by additive manufacturing as bulk and porous samples, studying the effect of designed porosity and thermal treatment on mechanical and chemical stability in molten carbonate (Li₂CO₃-K₂CO₃). Micrographs showed a typical morphology of the martensite phase for all samples in as-built conditions and a spheroid structure on the surface after the heat treatment, possibly revealing the formation of molten salt deposits and corrosion products. FE-SEM analysis of the bulk samples showed some pores with a diameter near 2–5 μm in the as-built condition, which varied between 100 and −1000 μm for the porous samples. After exposure, the cross-section images of porous samples revealed a film composed principally of Cu and Fe, Al, followed by a Ni-rich zone, whose thickness was approximately 1.5 µm, which depended on the porous design but was not influenced significantly by the heat treatment. Additionally, by incorporating porosity, the corrosion rate of NAB samples increased slightly. Full article

(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)

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12 pages, 7663 KiB

Open AccessArticle

The Influence of MSR-B Mg Alloy Surface Preparation on Bonding Properties

by Katarzyna Łyczkowska, Damian Miara, Beata Rams, Janusz Adamiec and Katarzyna Baluch

Materials 2023, 16(10), 3887; https://doi.org/10.3390/ma16103887 - 22 May 2023

Cited by 2 | Viewed by 1513

Abstract

Nowadays, industrial adhesives are replacing conventional bonding methods in many industries, including the automotive, aviation, and power industries, among others. The continuous development of joining technology has promoted adhesive bonding as one of the basic methods of joining metal materials. This article presents [...] Read more.

Nowadays, industrial adhesives are replacing conventional bonding methods in many industries, including the automotive, aviation, and power industries, among others. The continuous development of joining technology has promoted adhesive bonding as one of the basic methods of joining metal materials. This article presents the influence of surface preparation of magnesium alloys on the strength properties of a single-lap adhesive joint using a one-component epoxy adhesive. The samples were subjected to shear strength tests and metallographic observations. The lowest properties of the adhesive joint were obtained on samples degreased with isopropyl alcohol. The lack of surface treatment before joining led to destruction by adhesive and mixed mechanisms. Higher properties were obtained for samples ground with sandpaper. The depressions created as a result of grinding increased the contact area of the adhesive with the magnesium alloys. The highest properties were noticed for samples after sandblasting. This proved that the development of the surface layer and the formation of larger grooves increased both the shear strength and the resistance of the adhesive bonding to fracture toughness. It was found that the method of surface preparation had a significant influence on the resulting failure mechanism, and the adhesive bonding of the casting of magnesium alloy QE22 can be used successfully. Full article

(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)

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20 pages, 10818 KiB

Open AccessArticle

Influence of Microstructure and Mechanical Properties of Dissimilar Rotary Friction Welded Inconel to Stainless Steel Joints

by Akhil Reddy Beeravolu, Nagumothu Kishore Babu, Mahesh Kumar Talari, Ateekh Ur Rehman and Prakash Srirangam

Materials 2023, 16(8), 3049; https://doi.org/10.3390/ma16083049 - 12 Apr 2023

Cited by 5 | Viewed by 2046

Abstract

The present study aims to evaluate the microstructure, grain size, and mechanical properties of the dissimilar AISI 316L/Inconel 718 (IN 718) rotary friction welded joints under both the as-welded and post-weld heat treatment (PWHT) conditions. Because of reduced flow strength at elevated temperatures, [...] Read more.

The present study aims to evaluate the microstructure, grain size, and mechanical properties of the dissimilar AISI 316L/Inconel 718 (IN 718) rotary friction welded joints under both the as-welded and post-weld heat treatment (PWHT) conditions. Because of reduced flow strength at elevated temperatures, the AISI 316L and IN 718 dissimilar weldments exhibited more flash formation on the AISI 316L side. At higher rotating speeds during friction welding, an intermixing zone was created at the weld joint interface due to the material softening and squeezing. The dissimilar welds exhibited distinctive regions, including the fully deformed zone (FDZ), heat-affected zone (HAZ), thermo-mechanically affected zone (TMAZ), and the base metal (BM), located on either side of the weld interface. The dissimilar friction welds, AISI 316L/IN 718 ST and AISI 316L/IN 718 STA, exhibited yield strength (YS) of 634 ± 9 MPa and 602 ± 3 MPa, ultimate tensile strength (UTS) of 728 ± 7 MPa and 697± 2 MPa, and % elongation (% El) of 14 ± 1.5 and 17 ± 0.9, respectively. Among the welded samples, PWHT samples exhibited high strength (YS = 730 ± 2 MPa, UTS = 828 ± 5 MPa, % El = 9 ± 1.2), and this may be attributed to the formation of precipitates. Dissimilar PWHT friction weld samples resulted in the highest hardness among all the conditions in the FDZ due to the formation of precipitates. On the AISI 316L side, prolonged exposure to high temperatures during PWHT resulted in grain growth and decreased hardness. During the tensile test at ambient temperature, both the as-welded and PWHT friction weld joints failed in the HAZ regions of the AISI 316L side. Full article

(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)

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19 pages, 7623 KiB

Open AccessArticle

Effect of Heat Treatment on the Microstructure and Mechanical Properties of Rotary Friction Welded AA7075 and AA5083 Dissimilar Joint

by Aditya M. Mahajan, Nagumothu Kishore Babu, Mahesh Kumar Talari, Ateekh Ur Rehman and Prakash Srirangam

Materials 2023, 16(6), 2464; https://doi.org/10.3390/ma16062464 - 20 Mar 2023

Cited by 4 | Viewed by 1616

Abstract

The present work aims to investigate the changes in the microstructural and mechanical properties of various pre- and post weld heat treatments (PWHTs) on rotary friction welded dissimilar (AA7075 and AA5083) aluminum alloys. The investigation focused on the evolution of weld macro- and [...] Read more.

The present work aims to investigate the changes in the microstructural and mechanical properties of various pre- and post weld heat treatments (PWHTs) on rotary friction welded dissimilar (AA7075 and AA5083) aluminum alloys. The investigation focused on the evolution of weld macro- and microstructures, as well as the changes in hardness and tensile properties resulting from friction welding. The joint integrity was studied through various characterization techniques, and no cracks or incomplete bonding was observed. The study found that the dissimilar joints of the AA7075 and AA5083 alloys displayed higher flash formation on the AA7075 side, which has a lower melting temperature compared to the AA5083 alloy. Various zones were identified in the weld region, including the dynamic recrystallized zone (DRZ), the thermomechanically affected zone (TMAZ) consisting of TMAZ-1 (elongated grains) and TMAZ-2 (compressed/distorted grains), the heat-affected zone (HAZ), and the base metal (BM) zone. The rotary friction welded sample AA5083/AA7075-PWHT joint exhibited the highest strength (yield strength (YS): 195 ± 3 MPa, ultimate tensile strength (UTS): 387 ± 2 MPa) among all the other welded conditions, and this may be attributed to the major strengthening precipitates MgZn₂ (of AA7075) formed during postweld aging. All dissimilar welds failed in the HAZ region of the AA5083 side due to the formation of coarse grains, indicating the weakest region. Full article

(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)

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Review

Jump to: Research

35 pages, 12255 KiB

Open AccessReview

A Review on Multiplicity in Multi-Material Additive Manufacturing: Process, Capability, Scale, and Structure

by Ayush Verma, Angshuman Kapil, Damjan Klobčar and Abhay Sharma

Materials 2023, 16(15), 5246; https://doi.org/10.3390/ma16155246 - 26 Jul 2023

Cited by 7 | Viewed by 3987

Abstract

Additive manufacturing (AM) has experienced exponential growth over the past two decades and now stands on the cusp of a transformative paradigm shift into the realm of multi-functional component manufacturing, known as multi-material AM (MMAM). While progress in MMAM has been more gradual [...] Read more.

Additive manufacturing (AM) has experienced exponential growth over the past two decades and now stands on the cusp of a transformative paradigm shift into the realm of multi-functional component manufacturing, known as multi-material AM (MMAM). While progress in MMAM has been more gradual compared to single-material AM, significant strides have been made in exploring the scientific and technological possibilities of this emerging field. Researchers have conducted feasibility studies and investigated various processes for multi-material deposition, encompassing polymeric, metallic, and bio-materials. To facilitate further advancements, this review paper addresses the pressing need for a consolidated document on MMAM that can serve as a comprehensive guide to the state of the art. Previous reviews have tended to focus on specific processes or materials, overlooking the overall picture of MMAM. Thus, this pioneering review endeavors to synthesize the collective knowledge and provide a holistic understanding of the multiplicity of materials and multiscale processes employed in MMAM. The review commences with an analysis of the implications of multiplicity, delving into its advantages, applications, challenges, and issues. Subsequently, it offers a detailed examination of MMAM with respect to processes, materials, capabilities, scales, and structural aspects. Seven standard AM processes and hybrid AM processes are thoroughly scrutinized in the context of their adaptation for MMAM, accompanied by specific examples, merits, and demerits. The scope of the review encompasses material combinations in polymers, composites, metals-ceramics, metal alloys, and biomaterials. Furthermore, it explores MMAM’s capabilities in fabricating bi-metallic structures and functionally/compositionally graded materials, providing insights into various scale and structural aspects. The review culminates by outlining future research directions in MMAM and offering an overall outlook on the vast potential of multiplicity in this field. By presenting a comprehensive and integrated perspective, this paper aims to catalyze further breakthroughs in MMAM, thus propelling the next generation of multi-functional component manufacturing to new heights by capitalizing on the unprecedented possibilities of MMAM. Full article

(This article belongs to the Special Issue Welding, Joining, and Additive Manufacturing of Metals and Alloys)

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