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Metals
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Mechanical Characteristics of Brazed Joints in Metallic Materials
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Mechanical Characteristics of Brazed Joints in Metallic Materials

A special issue of Metals (ISSN 2075-4701). This special issue belongs to the section "Welding and Joining".

Deadline for manuscript submissions: closed (31 October 2021) | Viewed by 16550

Special Issue Editor

Prof. Dr. Boris A. Kalin

E-Mail Website
Guest Editor
National Research Nuclear University MEPhI, Moscow, Russian Federation
Interests: metals and alloys; ultra-fast solidification; amorphous and nanocrystalline brazing alloys; nuclear materials; radiation resistance

Special Issue Information

Dear Colleagues,

Manufacturing reliable brazed joints out of various materials is of great importance nowadays, especially in high-performance structures. The assessment of the strength of the joints is carried out depending on the operating conditions, and the following may be important: tensile and shear strength, thermal resistance during thermal cycling, fracture toughness, corrosion resistance, and so on. According to the fundamentals of Materials Science, strength depends on the microstructure. It is crucial to consider the relationship between the mechanical properties and the microstructure of a seam. High mechanical properties can be obtained in the absence of heterogeneity, which depends on the composition of the brazing alloy, brazing modes, and subsequent heat treatment. The selection of these parameters makes it possible to carry out precision brazing in order to obtain a microstructure without sharp interfaces, with the absence of large intermetallic compounds, which ultimately provides high mechanical properties and corrosion resistance.

In the upcoming Issue of the journal, it is advisable to consider the relationship between the mechanical properties and microstructure of a brazed seam with the use of high-end methods. We encourage authors to provide studies of high-quality and dissimilar joints (metal/metal, metal/ceramics, etc.) by means of accurate microstructural analysis, elemental composition, and the composition of phases in the brazed seam and in the diffusion zone. The application of computation assessment methods to predict the mechanical properties, microstructure, and corrosion resistance are also of great interest, however other potential topics are not limited.

Prof. Dr. Boris A. Kalin
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Metals is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • brazing
  • joint
  • mechanical properties
  • microstructure
  • filler alloy
  • finite element analysis
  • corrosion resistance
  • thermocycling

Published Papers (7 papers)

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Research

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13 pages, 4221 KiB  
Article
Joining of Zirconia to Ti6Al4V Using Ag-Cu Sputter-Coated Ti Brazing Filler
by Sónia Simões, Omid Emadinia, Carlos José Tavares and Aníbal Guedes
Metals 2022, 12(2), 358; https://doi.org/10.3390/met12020358 - 20 Feb 2022
Cited by 2 | Viewed by 1538
Abstract
The joining of zirconia (ZrO2) to Ti6Al4V using Ag-Cu sputter-coated Ti brazing filler foil was investigated. Brazing experiments were performed at 900, 950, and 980 °C for 30 min under vacuum. The microstructural features of the brazed interfaces were evaluated by [...] Read more.
The joining of zirconia (ZrO2) to Ti6Al4V using Ag-Cu sputter-coated Ti brazing filler foil was investigated. Brazing experiments were performed at 900, 950, and 980 °C for 30 min under vacuum. The microstructural features of the brazed interfaces were evaluated by optical microscopy (OM) and by scanning electron microscopy (SEM). The chemical composition of the brazed interfaces was analyzed by energy dispersive X-ray spectroscopy (EDS). Room temperature shear tests and Vickers microhardness tests performed across the interfaces were used to evaluate the mechanical strength of the joints. Multilayered interfaces were produced for all brazing temperatures, consisting essentially in α-Ti + Ti2(Ag, Cu), TiAg. Joining to ZrO2 was promoted by the formation of a hard layer, reaching a maximum of 1715 HV0.01, possibly consisting mainly in α-Ti and Ti oxide(s). Joining to the Ti6Al4V was established by a layer composed of a mixture of α-Ti and Ti2(Ag, Cu). The highest shear strength (152 ± 4 MPa) was obtained for brazing at 980 °C and fracture of joints occurred partially across the interface, throughout the hardest layers formed close to ZrO2, and partially across the ceramic sample. Full article
(This article belongs to the Special Issue Mechanical Characteristics of Brazed Joints in Metallic Materials)
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16 pages, 7325 KiB  
Article
Development of Rapidly-Quenched Al-Ge-Si Filler Alloys for the Joining of Stainless Steel AISI 304 and Aluminum Alloy AA6082
by Alexander Ivannikov, Vasilii Fedorov, Anton Abramov, Milena Penyaz, Diana Bachurina, Thomas Uhlig, Alexey Suchkov, Guntram Wagner, Pavel Morokhov and Oleg Sevryukov
Metals 2021, 11(12), 1926; https://doi.org/10.3390/met11121926 - 29 Nov 2021
Cited by 3 | Viewed by 1856
Abstract
Aluminum alloys based on the Al-Ge-Si system with a germanium content of up to 40 wt.%, promising for the brazing of aluminum alloy AA6082 with the stainless steel AISI 304, were studied. The temperature characteristics and microstructural and mechanical properties of the filler [...] Read more.
Aluminum alloys based on the Al-Ge-Si system with a germanium content of up to 40 wt.%, promising for the brazing of aluminum alloy AA6082 with the stainless steel AISI 304, were studied. The temperature characteristics and microstructural and mechanical properties of the filler alloys were systematically investigated. Differential scanning calorimetry showed that with an increase in the germanium content from 28.0 to 40.0 wt.%, the liquidus temperature of the filler alloys decreased from 514.8 to 474.3 °C. X-ray diffraction analysis and electron microscopy data showed that the foil of the filler alloys reveals a homogeneous structure. The ingots of the alloys contain two eutectics, the first of which consists of a solid solution of (Al, Ge) with a solid solution of (Ge, Si), and the second consists of a solid solution of (Al, Ge) with a solid solution based on (Ge). When the content of germanium increases from 28.0 to 40.0 wt.%, a separation of the faceted solid solution particles (Ge, Si) and an increase in their number could be observed. Nanohardness measurements showed that the (Ge, Si) and (Ge) solid solutions had similar nanohardness, with values of 11.6 and 10.2 GPa, respectively. Simultaneously, the Al solid solution and the intermetallic Al7Ge2Fe phase exhibited significantly lower nanohardness values of 0.7 and 6.7 GPa, respectively. Brinell hardness measurements showed that the ingots of the filler alloys were sufficiently ductile and had a hardness comparable to that of AA6082, which is used for brazing with AISI 304 stainless steel. The obtained results for the studied ingots and the rapidly quenched foils can be used to predict the forming structure of the seam after brazing and adjusted for diffusion processes occurring between the brazed materials and the studied filler alloys. Full article
(This article belongs to the Special Issue Mechanical Characteristics of Brazed Joints in Metallic Materials)
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10 pages, 3033 KiB  
Article
Effect of Intermetallic Compound Bridging on the Cracking Resistance of Sn2.3Ag Microbumps with Different UBM Structures under Thermal Cycling
by Chun-Chieh Mo, Dinh-Phuc Tran, Jing-Ye Juang and Chih Chen
Metals 2021, 11(7), 1065; https://doi.org/10.3390/met11071065 - 01 Jul 2021
Cited by 14 | Viewed by 3225
Abstract
In this study, the effect of intermetallic compound (IMC) bridging on the cracking resistance of microbumps with two different under bump metallization (UBM) systems, Cu/solder/Cu and Cu/solder/Ni, under a thermal cycling test (TCT) is investigated. The height of the Sn2.3Ag solders was ~10 [...] Read more.
In this study, the effect of intermetallic compound (IMC) bridging on the cracking resistance of microbumps with two different under bump metallization (UBM) systems, Cu/solder/Cu and Cu/solder/Ni, under a thermal cycling test (TCT) is investigated. The height of the Sn2.3Ag solders was ~10 µm, which resembles that of the most commonly used microbumps. We adjusted the reflow time to control the IMC bridging level. The samples with different bridging levels were tested under a TCT (−55–125 °C). After 1000 and 2000 TCT cycles (30 min/cycle), the samples were then polished and characterized using a scanning electron microscope (SEM). Before IMC bridging, various cracks in both systems were observed at the IMC/solder interfaces after the 1000-cycle tests. The cracks propagated as cyclic shapes from the sides to the center and became more severe as the thermal cycle was increased. With IMC bridging, we could not observe any further failure in all the samples even when the thermal cycle was up to 2000. We discovered that IMC bridging effectively suppressed crack formation in microbumps under TCTs. Full article
(This article belongs to the Special Issue Mechanical Characteristics of Brazed Joints in Metallic Materials)
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23 pages, 11046 KiB  
Article
Microstructure, Residual Stresses, and Strain-Rate-Dependent Deformation and Fracture Behavior of AISI 304L Joints Brazed with NiCrSiB Filler Metals
by Johannes L. Otto, Milena Penyaz, Kerstin Möhring, Lars Gerdes, Thorge Schaum, Alexander Ivannikov, Anke Schmiedt-Kalenborn, Boris Kalin and Frank Walther
Metals 2021, 11(4), 593; https://doi.org/10.3390/met11040593 - 05 Apr 2021
Cited by 5 | Viewed by 2584
Abstract
The knowledge of alloy–process–structure–property relationships is of particular interest for several safety-critical brazed components and requires a detailed characterization. Thus, three different nickel-based brazing filler metals were produced with varying chromium and molybdenum content and were used to braze butt joints of the [...] Read more.
The knowledge of alloy–process–structure–property relationships is of particular interest for several safety-critical brazed components and requires a detailed characterization. Thus, three different nickel-based brazing filler metals were produced with varying chromium and molybdenum content and were used to braze butt joints of the austenitic stainless steel AISI 304L under vacuum. Two holding times were used to evaluate diffusion-related differences, resulting in six specimen variations. Significant microstructural changes due to the formation and location of borides and silicides were demonstrated. Using X-ray diffraction, alloy-dependent residual stress gradients from the brazing seam to the base material were determined and the thermal-induced residual stresses were shown through simulations. For mechanical characterization, impact tests were carried out to determine the impact toughness, as well as tensile tests at low and high strain rates to evaluate the strain-rate-dependent tensile strength of the brazed joints. Further thermal, electrical, and magnetic measurements enabled an understanding of the deformation mechanisms. The negative influence of brittle phases in the seam center could be quantified and showed the most significant effects under impact loading. Fractographic investigations subsequently enabled an enhanced understanding of the fracture mechanisms. Full article
(This article belongs to the Special Issue Mechanical Characteristics of Brazed Joints in Metallic Materials)
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8 pages, 23702 KiB  
Article
Influence of the Thickness of the Reaction Zone in Aluminum/Stainless Steel Brazed Joints on the Mechanical Properties
by Vasilii Fedorov, Thomas Uhlig and Guntram Wagner
Metals 2021, 11(2), 217; https://doi.org/10.3390/met11020217 - 26 Jan 2021
Cited by 5 | Viewed by 2202
Abstract
The study deals with the characterization of the relationship between the microstructure of the reaction zone and the mechanical properties in the brazed joints of aluminum alloy 3003 and stainless steel AISI 304 in order to determine the influence of the intermetallic layers [...] Read more.
The study deals with the characterization of the relationship between the microstructure of the reaction zone and the mechanical properties in the brazed joints of aluminum alloy 3003 and stainless steel AISI 304 in order to determine the influence of the intermetallic layers on the tensile shear strength of the joints. The joints were produced by induction brazing using an AlSi10 filler in an argon atmosphere at a temperature of 600 °C. Due to the local heat input into the liquid brazing filler during a short brazing time, a thin reaction zone is formed in the brazed joints (~1 µm), which ensures good mechanical properties of the joints. In order to observe the growth kinetics of the reaction zone in the brazed joints and to investigate the influence of the thickness of the reaction zone on the mechanical properties of the brazed joints, the joints were aged at temperatures of 200 °C and 500 °C for 6, 48 and 120 h. The results have shown that the thickness of this layer increases to a maximum of 2 µm depending on the duration of the thermal aging at a temperature of 200 °C. The results of the tensile shear strength tests have shown that the brazed joints with this thin layer ensure a high strength. The thermal aging at a temperature of 500 °C influences the growth of the reaction zone in the brazed joints significantly. The total thickness of the reaction zone increases to a maximum of 12 µm during the thermal aging. The results of the tensile shear tests of these joints have shown that the thermal aging at a higher temperature leads to a decrease of the tensile shear strength of the brazed joints to 67% due to the growth of the existing intermetallic layer and the formation of a new intermetallic layer in the reaction zone. Full article
(This article belongs to the Special Issue Mechanical Characteristics of Brazed Joints in Metallic Materials)
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8 pages, 2739 KiB  
Article
Microstructural and Mechanical Characterization of W-CuCrZr Joints Brazed with Cu-Ti Filler Alloy
by Javier de Prado, María Sánchez, David Swan and Alejandro Ureña
Metals 2021, 11(2), 202; https://doi.org/10.3390/met11020202 - 22 Jan 2021
Cited by 2 | Viewed by 1699
Abstract
The determination of the mechanical properties of a brazed joint is an important factor to reach the metallurgical level of a joint development. This paper evaluates the mechanical properties, and its correlation with the joint microstructure, of a W-CuCrZr joint brazed in a [...] Read more.
The determination of the mechanical properties of a brazed joint is an important factor to reach the metallurgical level of a joint development. This paper evaluates the mechanical properties, and its correlation with the joint microstructure, of a W-CuCrZr joint brazed in a high vacuum furnace using 80Cu-20Ti flexible filler material in tape form. This joint is meant to be implemented in the divertor application in future fusion power plants. Main experimental parameters were a brazing temperature of 960 °C and a dwell time of 10 min. The microstructure of the joint was constituted by Cu solid solution and Cu4Ti phases. This last phase was distributed in the W-braze interface. Mechanical properties were evaluated by means of Vickers microhardness and mechanical tests by applying pure shear loads. The microhardness profile of the brazed joint indicated that W remained with the as-received hardness but CuCrZr base material was softened after the brazing procedure. Shear strength of 96 ± 15 MPa was obtained for the brazed joint and fracture propagated at the W-braze interface. Full article
(This article belongs to the Special Issue Mechanical Characteristics of Brazed Joints in Metallic Materials)
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Review

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11 pages, 1790 KiB  
Review
Overview of the Mechanical Properties of Tungsten/Steel Brazed Joints for the DEMO Fusion Reactor
by Diana Bachurina, Vladimir Vorkel, Alexey Suchkov, Julia Gurova, Alexander Ivannikov, Milena Penyaz, Ivan Fedotov, Oleg Sevryukov and Boris Kalin
Metals 2021, 11(2), 209; https://doi.org/10.3390/met11020209 - 24 Jan 2021
Cited by 17 | Viewed by 2484
Abstract
A Demonstration (DEMO) thermonuclear reactor is the next step after the International Thermonuclear Experimental Reactor (ITER). Designs for a DEMO divertor and the First Wall require the joining of tungsten to steel; this is a difficult task, however, because of the metals’ physical [...] Read more.
A Demonstration (DEMO) thermonuclear reactor is the next step after the International Thermonuclear Experimental Reactor (ITER). Designs for a DEMO divertor and the First Wall require the joining of tungsten to steel; this is a difficult task, however, because of the metals’ physical properties and necessary operating conditions. Brazing is a prospective technology that could be used to solve this problem. This work examines a state-of-the-art solution to the problem of joining tungsten to steel by brazing, in order to summarize best practices, identify shortcomings, and clarify mechanical property requirements. Here, we outline the ways in which brazing technology can be developed to join tungsten to steel for use in a DEMO application. Full article
(This article belongs to the Special Issue Mechanical Characteristics of Brazed Joints in Metallic Materials)
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