Joining of Unweldable Materials: Concepts, Techniques and Processes

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Guest Editor
Department of Mechanical Engineering, University of Coimbra, 3030-788 Coimbra, Portugal
Interests: friction stir welding; modelling; aluminum; mechanical characterization; digital image correlation; plasticity and microstructural characterization
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Guest Editor
1. ISEL, Department of Mechanical Engineering, Polytechnic Institute of Lisbon, Rua Conselheiro Emídio Navarro, 1959-007 Lisboa, Portugal
2. CEMMPRE, Department of Mechanical Engineering, University of Coimbra, Rua Luís Reis Santos, 3030-788 Coimbra, Portugal
Interests: solid-state welding; friction stir welding; explosion welding; dissimilar materials welding; solid-state processing
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Guest Editor
1. ESAD.CR, Polytechnic Institute of Leiria, Rua Isidoro Inácio Alves de Carvalho, 2500-321 Caldas da Rainha, Portugal
2. CEMMPRE, Department of Mechanical Engineering, University of Coimbra, Rua Luís Reis Santos, 3030-788 Coimbra, Portugal
Interests: welding technology; processing technology; microstructural and mechanical characterization; friction stir welding; explosion welding
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The use of new engineering materials developed for special purposes related to assembly has become a challenge for the general industry. In fact, beyond the development of these important cutting-edge materials, their capability to be joined is also a huge challenge. This is mostly due to the complete absence of knowledge on the permanent joining of these materials by well-known joining methods, plus the industrial interest in their combination with materials commonly used in engineering applications.

The objective of the present Special Issue is to illustrate recent developments on the joining of unweldable materials, focusing the main concepts, techniques, and processes. We intend to gather a significant number of multidisciplinary contributions addressing the following issues:

  • Joining of dissimilar materials;
  • Joining of new materials;
  • Joining of unweldable or hardly weldable materials;
  • Permanent joining processes;
  • Proof of concept;
  • New techniques for material joining;
  • New process approaches for material joining;
  • Conventional manufacturing processes applied on material joining;
  • Microstructural and mechanical analysis;
  • Numerical simulation.

Prof. Dr. Carlos Leitao
Prof. Dr. Ivan Galvão
Prof. Dr. Rui Manuel Leal
Guest Editors

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Published Papers (5 papers)

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Research

15 pages, 7616 KiB  
Article
Production of Aluminium-Polymer Joints by Friction Stir Spot Welding
by Miguel A. R. Pereira, Ivan Galvão, José D. M. Costa, Ana M. Amaro and Rui M. Leal
J. Manuf. Mater. Process. 2024, 8(4), 179; https://doi.org/10.3390/jmmp8040179 - 17 Aug 2024
Viewed by 695
Abstract
The joining of AA6082-T6 and polyamide 6 using pinless friction stir spot welding was investigated in this study. The influence of the clamping frame geometry was studied and the welds produced were characterized based on their morphology and mechanical performance. The morphological analysis [...] Read more.
The joining of AA6082-T6 and polyamide 6 using pinless friction stir spot welding was investigated in this study. The influence of the clamping frame geometry was studied and the welds produced were characterized based on their morphology and mechanical performance. The morphological analysis was evaluated based on the comparison of the different joining areas and on the presence of defects in the resolidified layer of the polymer. In turn, the mechanical performance of the joints was evaluated by tensile-shear testing. Additionally, the influence of plunge depth parameter was studied for the clamping frame geometry providing the best mechanical performance. While the clamping frame geometry had a greater impact on the size of the joining areas, therefore influencing the micro-mechanical interlocking mechanisms, the plunge depth mainly affected the plunging of the aluminium into the polymeric material, therefore affecting the macro-mechanical interlocking mechanism. The strongest joints, which failed for a load of about 2700 N, were produced with the clamping frame geometry that restricted the welding zone the least, and used the highest plunge depth. Full article
(This article belongs to the Special Issue Joining of Unweldable Materials: Concepts, Techniques and Processes)
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17 pages, 4514 KiB  
Article
Effect of Liquid Miscibility Gap on Defects in Inconel 625–GRCop42 Joints through Analysis of Gradient Composition Microstructure
by Jakub Preis, Donghua Xu, Brian K. Paul, Peter A. Eschbach and Somayeh Pasebani
J. Manuf. Mater. Process. 2024, 8(1), 42; https://doi.org/10.3390/jmmp8010042 - 14 Feb 2024
Cited by 4 | Viewed by 2041
Abstract
Joining of Cu-based dispersion-strengthened alloys to Ni-based superalloys has garnered increased attention for liquid rocket engine applications due to the high thermal conductivity of Cu-based alloys and high temperature tensile strength of Ni-based superalloys. However, such joints can suffer from cracking when joined [...] Read more.
Joining of Cu-based dispersion-strengthened alloys to Ni-based superalloys has garnered increased attention for liquid rocket engine applications due to the high thermal conductivity of Cu-based alloys and high temperature tensile strength of Ni-based superalloys. However, such joints can suffer from cracking when joined via liquid state processes, leading to part failure. In this work, compositions of 15–95 wt.% GRCop42 are alloyed with Inconel 625 and characterized to better understand the root cause of cracking. Results indicate a lack of miscibility between Cu-deprived and Cu-rich liquids in compositions corresponding to 30–95 wt.% GRCop42. Two distinct morphologies are observed and explained by use of CALPHAD; Cu-deprived dendrites with Cu-rich interdendritic zones at 30–50 wt.% GRCop42 and Cu-deprived spheres surrounded by a Cu-rich matrix at 60–95 wt.% GRCop42. Phase analysis reveals brittle intermetallic phases precipitate in the 60–95 wt.% GRCop42 Cu-deprived region. Three cracking mechanisms are proposed herein that provide guidance on the avoidance of defects Ni-based superalloy to Cu-based dispersion strengthened alloy joints. Full article
(This article belongs to the Special Issue Joining of Unweldable Materials: Concepts, Techniques and Processes)
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10 pages, 12584 KiB  
Article
Joining Strength of Self-Piercing Riveted Vibration-Damping Steel and Dissimilar Materials
by Keong Hwan Cho, Jin Hyeok Joo, Min Gyu Kim, Dong Hyuck Kam and Jedo Kim
J. Manuf. Mater. Process. 2023, 7(2), 65; https://doi.org/10.3390/jmmp7020065 - 13 Mar 2023
Viewed by 2075
Abstract
A vibration-damping steel panel is used for lightweight vehicles to block any noise subjected to the passenger cabin replacing heavy fiber-based insulators. Conventional weld joining methods often encounter problems due to the presence of viscoelastic compounds reducing the joint quality and making the [...] Read more.
A vibration-damping steel panel is used for lightweight vehicles to block any noise subjected to the passenger cabin replacing heavy fiber-based insulators. Conventional weld joining methods often encounter problems due to the presence of viscoelastic compounds reducing the joint quality and making the joining process unproductive. In this work, we present experimental results that show the self-piercing riveting (SPR) process can be used to produce high-quality joints between vibration-damping steel and (i) commonly used steel alloy (SPFC590DP), (ii) carbon-fiber-reinforced-plastic (CFRP) panels. Various die shapes are used to investigate the resulting interlock width and bottom thickness of the joints and tensile shear load tests were performed to evaluate the joining strength. The results show that high-quality joints between vibration-damping steel and the steel alloy are possible for all the dye types and panel configurations, used in this study, producing up to 6.2 kN of tensile shear load. High-quality joints were also possible with CFRP producing up to 4.0 kN, however, acceptable joints were formed only when the CFRP panels were on top during the riveting process due to severe cracking. Full article
(This article belongs to the Special Issue Joining of Unweldable Materials: Concepts, Techniques and Processes)
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12 pages, 4350 KiB  
Article
Tube Joining by a Sheet Flange Connection
by Rafael M. Afonso and Luís M. Alves
J. Manuf. Mater. Process. 2023, 7(1), 12; https://doi.org/10.3390/jmmp7010012 - 29 Dec 2022
Cited by 1 | Viewed by 2170
Abstract
Joining of tubes to tubes by means of plastic deformation at ambient temperature allows one to solve the main limitations produced by the necessity of joining thin-walled tubes of low-to-medium diameter size made from materials that are not suitable to be welded and/or [...] Read more.
Joining of tubes to tubes by means of plastic deformation at ambient temperature allows one to solve the main limitations produced by the necessity of joining thin-walled tubes of low-to-medium diameter size made from materials that are not suitable to be welded and/or have reduced contact interfaces. The new joining solution allows one to obtain permanent mechanical joints of tubes or pipes by means of an accessory lightweight sheet metal flange subjected to annular indentation and subsequent injection of its material towards the tube walls to produce a mechanical interlock between the different elements. The sheet-flange connection can then be utilized to affix the joined tube assembly to walls or other different structures and equipment, by means of fasteners or other joining accessories attached to the sheet flange. Similar or dissimilar material combinations can be easily and safely produced while guaranteeing levels of leak-tightness within the maximum internal operating pressure of the individual tubes. A combined numerical–experimental approach is employed to identify the operative parameters as well as to explain the deformation conditions. Pull-out loads and internal fluid pressure are applied to the manufactured joint to evaluate its behavior under typical operating conditions that it may be subjected to during its service life depending on the application. Full article
(This article belongs to the Special Issue Joining of Unweldable Materials: Concepts, Techniques and Processes)
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18 pages, 11495 KiB  
Article
Friction Stir Weldability at High Welding Speed of Two Structural High Pressure Die Casting Aluminum Alloys
by Javier Vivas, Ana Isabel Fernández-Calvo, Egoitz Aldanondo, Uxue Irastorza and Pedro Álvarez
J. Manuf. Mater. Process. 2022, 6(6), 160; https://doi.org/10.3390/jmmp6060160 - 12 Dec 2022
Cited by 5 | Viewed by 2308
Abstract
In this work, the friction stir weldability of two structural high-pressure die casting aluminum alloys designed to manufacture thin-walled automotive components is investigated and compared. AlSi10MnMg and AlMg4Fe2 alloys were friction stir welded at a high welding speed (from 500 to 2000 mm/min) [...] Read more.
In this work, the friction stir weldability of two structural high-pressure die casting aluminum alloys designed to manufacture thin-walled automotive components is investigated and compared. AlSi10MnMg and AlMg4Fe2 alloys were friction stir welded at a high welding speed (from 500 to 2000 mm/min) for a fixed rotation speed of 1500 RPM. The investigation was performed by studying the material flow influence on defect formation and microstructure, the mechanical properties of the welds and the forces that act during the friction stir welding process. The AlSi10MnMg alloy shows a lower incidence of defects than the AlMg4Fe2 alloy at all welding speeds investigated. Both materials present a great friction stir welding performance at 500 mm/min with a high joint efficiency in terms of ultimate tensile strength: 92% in AlSi10MnMg alloy and 99% in AlMg4Fe2 alloy. Full article
(This article belongs to the Special Issue Joining of Unweldable Materials: Concepts, Techniques and Processes)
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