Special Issue "Recent Developments in Non-conventional Welding of Materials"

A special issue of Materials (ISSN 1996-1944).

Deadline for manuscript submissions: 15 December 2020.

Special Issue Editors

Prof. Dr. Rui Manuel Leal
Website
Guest Editor
ESAD.CR, Polytechnic Institute of Leiria, Rua Isidoro Inácio Alves de Carvalho, 2500-321 Caldas da Rainha, Portugal
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.
Prof. Dr. Ivan Galvão
Website
Guest Editor
1. ISEL, Department of Mechanical Engineering, Polytechnic Institute of Lisbon, Rua Conselheiro Emídio Navarro, 1959-007 Lisboa, Portugal
2. University of Coimbra, CEMMPRE, Department of Mechanical Engineering, Rua Luís Reis Santos, 3030-788 Coimbra, Portugal
Interests: solid-state welding; friction stir welding; explosion welding; dissimilar materials welding; solid-state processing
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

Welding is one of the technological fields with the greatest impact in many industries, such as automotive, aerospace, energy production, electronics, the health sector, etc. Welding technologies are currently used to join the most diverse materials, from metallic alloys to polymers, composites, or even biological tissues. Despite the relevance and wide application of traditional welding technologies, these processes do not meet the demanding requirements of some industries. This has driven strong research efforts in non-conventional welding processes, such as laser welding, ultrasonic welding, impact welding, friction stir welding, diffusion welding, and many other welding technologies. Important studies have been recently developed all over the world on the application of these processes to the joining of cutting-edge materials and material combinations, enabling the production of joints with improved properties. Thus, this Special Issue will present the most recent developments in the non-conventional welding of materials. Experimental and numerical modelling/simulation research on all aspects related to this multidisciplinary subject are welcome. Original research and review papers addressing innovative developments in non-conventional welding processes and process applications are valuable scientific contributions.

We look forward to receiving your contributions to this issue.

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

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 papers will be 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. Materials is an international peer-reviewed open access semimonthly 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 2000 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

  • Non-conventional welding
  • Laser welding
  • Ultrasonic welding
  • Impact welding
  • Friction stir welding
  • Diffusion welding
  • Experimental
  • Numerical modelling/simulation
  • Materials
  • Properties

Published Papers (10 papers)

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Research

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Open AccessArticle
Influence of Impact Velocity on the Residual Stress, Tensile Strength, and Structural Properties of an Explosively Welded Composite Plate
Materials 2020, 13(12), 2686; https://doi.org/10.3390/ma13122686 - 12 Jun 2020
Cited by 1
Abstract
This study aimed to analyze the effect of the impact velocity of a Zr 700 flyer plate explosively welded to a Ti Gr. 1/P265GH bimetallic composite on the residual stress formation, structural properties, and tensile strength. The residual stresses were determined by the [...] Read more.
This study aimed to analyze the effect of the impact velocity of a Zr 700 flyer plate explosively welded to a Ti Gr. 1/P265GH bimetallic composite on the residual stress formation, structural properties, and tensile strength. The residual stresses were determined by the orbital hole-drilling strain-gauge method in a surface layer of Zr 700 in as-received and as-welded conditions. The analysis of the tensile test results based on a force parallel to interfaces was used to propose a model for predicting the yield force of composite plates. Compressive residual stresses found in the initial state of the Zr 700 plate were transformed to tensile stresses on the surface layer of the welded Zr 700 plate. A higher impact velocity resulted in higher tensile stresses in the Zr 700 surface layer. To increase the resistance of the composite plate to stress-based corrosion cracking, a lower value of impact velocity is recommended in the welding process. Full article
(This article belongs to the Special Issue Recent Developments in Non-conventional Welding of Materials)
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Open AccessArticle
Nugget Formation and Mechanical Behaviour of Friction Stir Welds of Three Dissimilar Aluminum Alloys
Materials 2020, 13(11), 2664; https://doi.org/10.3390/ma13112664 - 11 Jun 2020
Abstract
The aim of this research was to investigate the influence of the properties of the base materials and welding speed on the morphology and mechanical behavior of the friction stir welds of three dissimilar aluminum alloys in a T-joint configuration. The base materials [...] Read more.
The aim of this research was to investigate the influence of the properties of the base materials and welding speed on the morphology and mechanical behavior of the friction stir welds of three dissimilar aluminum alloys in a T-joint configuration. The base materials were the AA2017-T4, AA5083-H111, and AA6082-T6 alloys in 3 mm-thick sheets. The AA6082-T6 alloy was the stringer, and the other alloys were located either on the advancing or retreating sides of the skin. All the T-joint welds were produced with a constant tool rotation speed but with different welding speeds. The microstructures of the welds were analyzed using optical microscopy, scanning electron microscopy with energy dispersive spectroscopy, and the electron backscatter diffraction technique. The mechanical properties were assessed according to micro-hardness, tensile, and fatigue testing. Good quality welds of the three dissimilar aluminum alloys could be achieved with friction stir welding, but a high ratio between the tool’s rotational and traverse speeds was required. The welding speed influenced the weld morphology and fatigue strength. The positioning of the skin materials influenced the nugget morphology and the mechanical behavior of the joints. The joints in which the AA2017 alloy was positioned on the advancing side presented the best tensile properties and fatigue strength. Full article
(This article belongs to the Special Issue Recent Developments in Non-conventional Welding of Materials)
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Open AccessArticle
Effect of FSW Traverse Speed on Mechanical Properties of Copper Plate Joints
Materials 2020, 13(8), 1937; https://doi.org/10.3390/ma13081937 - 20 Apr 2020
Cited by 2
Abstract
The paper describes the influence of the friction stir welding travel speed on the mechanical properties of the butt joints of copper plates. The results of static and fatigue tests of the base material (Cu-ETP R220) and welded specimens produced at various travel [...] Read more.
The paper describes the influence of the friction stir welding travel speed on the mechanical properties of the butt joints of copper plates. The results of static and fatigue tests of the base material (Cu-ETP R220) and welded specimens produced at various travel speeds were compared, considering a loading applied both parallel and perpendicularly to the rolling direction of the plates. The mechanical properties of the FSW joints were evaluated with respect to parameters of plates’ material in the delivery state and after recrystallisation annealing. The strength parameters of friction stir welding joints were compared with the data on tungsten inert gas welded joints of copper plates available in the literature. The results of microhardness tests and fractographic analysis of tested joints are also presented. Based on the above test results, it was shown that although in the whole range of considered traverse speeds (from 40 to 80 mm/min), comparable properties were obtained for FSW copper joints in terms of their visual and microstructural evaluation, their static and especially fatigue parameters were different, most apparent in the nine-fold greater observed average fatigue life. The fatigue tests turned out to be more sensitive criteria for evaluation of the FSW joints’ qualities. Full article
(This article belongs to the Special Issue Recent Developments in Non-conventional Welding of Materials)
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Open AccessArticle
The Effect of Post-Weld Hot-Rolling on the Properties of Explosively Welded Mg/Al/Ti Multilayer Composite
Materials 2020, 13(8), 1930; https://doi.org/10.3390/ma13081930 - 19 Apr 2020
Cited by 6
Abstract
The paper describes an investigation of an explosively welded Mg/Al/Ti multilayer composite. Following the welding, the composite was subjected to hot-rolling in three different temperatures: 300 °C, 350 °C and 400 °C, with a total relative strain of 30%. The rolling speed was [...] Read more.
The paper describes an investigation of an explosively welded Mg/Al/Ti multilayer composite. Following the welding, the composite was subjected to hot-rolling in three different temperatures: 300 °C, 350 °C and 400 °C, with a total relative strain of 30%. The rolling speed was 0.2 m/s. The investigation of the composite properties involves microhardness analysis and mini-specimen tensile tests of the joints. The composite Mg/Al and Al/Ti bonds in the as-welded state and after rolling in 400 °C were subjected to microstructure analysis using scanning electron (SEM) and transmission electron microscopy (TEM). In the Al/Ti interface, the presence of melted zones with localized intermetallic precipitates has been reported in the as-welded state, and it has been stated that hot-rolling results in precipitation of intermetallic particles from the melted zone. The application of the hot-rolling process causes the formation of a continuous layer in the Mg/Al joint, consisting of two intermetallic phases, Mg2Al3 (β) and Mg17Al12 (γ). Full article
(This article belongs to the Special Issue Recent Developments in Non-conventional Welding of Materials)
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Open AccessArticle
Effect of Tilt Angle and Pin Depth on Dissimilar Friction Stir Lap Welded Joints of Aluminum and Steel Alloys
Materials 2019, 12(23), 3901; https://doi.org/10.3390/ma12233901 - 26 Nov 2019
Cited by 3
Abstract
Automobile, aerospace, and shipbuilding industries are looking for lightweight materials for cost effective manufacturing which demands the welding of dissimilar alloy materials. In this study, the effect of tool rotational speed, welding speed, tilt angle, and pin depth on the weld joint were [...] Read more.
Automobile, aerospace, and shipbuilding industries are looking for lightweight materials for cost effective manufacturing which demands the welding of dissimilar alloy materials. In this study, the effect of tool rotational speed, welding speed, tilt angle, and pin depth on the weld joint were investigated. Aluminum 5052 and 304 stainless-steel alloys were joined by friction stir welding in a lap configuration. The design of the experiments was based on Taguchi’s orthogonal array for conducting the experiments with four factors and three levels for each factor. The microstructural analysis showed tunnel defects, micro voids, and cracks which formed with 0° and 1.5° tilt angles. The defects were eliminated when the tilt angle increased to 2.5° and a mixed stir zone was formed with intermetallic compounds. The presence of the intermetallic compounds increased with the increase in tilt angle and pin depth which further resulted in obtaining a defect-free weld. Hooks were formed on either side of the weld zone creating a mechanical link for the joint. A Vickers hardness value of HV 635.46 was achieved in the mixed stir zone with 1000 rpm, 20 mm/min, and 4.2 mm pin depth with a tilt angle of 2.5°, which increased by three times compared to the hardness of SS 304 steel. The maximum shear strength achieved with 800 rpm, 40 mm/min, and a 4.3 mm pin depth with a tilt angle of 2.5° was 3.18 kN. Full article
(This article belongs to the Special Issue Recent Developments in Non-conventional Welding of Materials)
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Open AccessArticle
Texture Evolution in AA6082-T6 BFSW Welds: Optical Microscopy and EBSD Characterisation
Materials 2019, 12(19), 3215; https://doi.org/10.3390/ma12193215 - 01 Oct 2019
Cited by 5
Abstract
One of the difficulties with bobbin friction stir welding (BFSW) has been the visualisation of microstructure, particularly grain boundaries, and this is especially problematic for materials with fine grain structure, such as AA6082-T6 aluminium as here. Welds of this material were examined using [...] Read more.
One of the difficulties with bobbin friction stir welding (BFSW) has been the visualisation of microstructure, particularly grain boundaries, and this is especially problematic for materials with fine grain structure, such as AA6082-T6 aluminium as here. Welds of this material were examined using optical microscopy (OM) and electron backscatter diffraction (EBSD). Results show that the grain structures that form depend on a complex set of factors. The motion of the pin and shoulder features transports material around the weld, which induces shear. The shear deformation around the pin is non-uniform with a thermal and strain gradient across the weld, and hence the dynamic recrystallisation (DRX) processes are also variable, giving a range of observed polycrystalline and grain boundary structures. Partial DRX was observed at both hourglass boundaries, and full DRX at mid-stirring zone. The grain boundary mapping showed the formation of low-angle grain boundaries (LAGBs) at regions of high shear as a consequence of thermomechanical nature of the process. Full article
(This article belongs to the Special Issue Recent Developments in Non-conventional Welding of Materials)
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Open AccessArticle
Investigation on Effect of Strain Rate and Heat Generation on Traverse Force in FSW of Dissimilar Aerospace Grade Aluminium Alloys
Materials 2019, 12(10), 1641; https://doi.org/10.3390/ma12101641 - 20 May 2019
Cited by 3
Abstract
The emergence of the aerospace sector requires efficient joining of aerospace grade aluminium alloys. For large-scale industrial practices, achievement of optimum friction stir welding (FSW) parameters is chiefly aimed at obtaining maximum strain rate in deforming material with least application of traverse force [...] Read more.
The emergence of the aerospace sector requires efficient joining of aerospace grade aluminium alloys. For large-scale industrial practices, achievement of optimum friction stir welding (FSW) parameters is chiefly aimed at obtaining maximum strain rate in deforming material with least application of traverse force on the tool pin. Exact computation of strain rate is not possible due to complex and unexposed material flow kinematics. Estimation using micro-structural evolution serves as one of the very few methods applicable to analyze the yet unmapped interdependence of strain rate and traverse force. Therefore, the present work assessed strain rate in the stir zone using Zener Holloman parameter. The maximum and minimum strain rates of 6.95 and 0.31 s−1 were obtained for highest and least traverse force, respectively. Full article
(This article belongs to the Special Issue Recent Developments in Non-conventional Welding of Materials)
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Review

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Open AccessReview
Manufacturing Parameters, Materials, and Welds Properties of Butt Friction Stir Welded Joints–Overview
Materials 2020, 13(21), 4940; https://doi.org/10.3390/ma13214940 - 03 Nov 2020
Abstract
The modern and eco-friendly friction stir welding (FSW) method allows the combination of even such materials that are considered to be non-weldable. The development of FSW technology in recent years has allowed a rapid increase in the understanding of the mechanism of this [...] Read more.
The modern and eco-friendly friction stir welding (FSW) method allows the combination of even such materials that are considered to be non-weldable. The development of FSW technology in recent years has allowed a rapid increase in the understanding of the mechanism of this process and made it possible to perform the first welding trials of modern polymeric and composite materials, the joining of which was previously a challenge. The following review work focuses on presenting the current state of the art on applying this method to particular groups of materials. The paper has been divided into subchapters focusing on the most frequently used construction materials, with particular emphasis on their properties, applications, and usage of the FSW method for these materials. Mechanisms of joint creation are discussed, and the microstructure of joints and the influence of material characteristics on the welding process are described. The biggest problems observed during FSW of these materials and potential causes of their occurrence are quoted. The influence of particular parameters on the properties of manufactured joints for each group of materials is discussed on the basis of a wide literature review. Full article
(This article belongs to the Special Issue Recent Developments in Non-conventional Welding of Materials)
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Open AccessReview
Welding Joints in High Entropy Alloys: A Short-Review on Recent Trends
Materials 2020, 13(6), 1411; https://doi.org/10.3390/ma13061411 - 20 Mar 2020
Cited by 1
Abstract
High entropy alloys (HEAs) emerged in the beginning of XXI century as novel materials to “keep-an-eye-on”. In fact, nowadays, 16 years after they were first mentioned, a lot of research has been done regarding the properties, microstructure, and production techniques for the HEAs. [...] Read more.
High entropy alloys (HEAs) emerged in the beginning of XXI century as novel materials to “keep-an-eye-on”. In fact, nowadays, 16 years after they were first mentioned, a lot of research has been done regarding the properties, microstructure, and production techniques for the HEAs. Moreover, outstanding properties and possibilities have been reported for such alloys. However, a way of jointing these materials should be considered in order to make such materials suitable for engineering applications. Welding is one of the most common ways of jointing materials for engineering applications. Nevertheless, few studies concerns on efforts of welding HEAs. Therefore, it is mandatory to increase the investigation regarding the weldability of HEAs. This work aims to present a short review about what have been done in recent years, and what are the most common welding techniques that are used for HEAs. It also explores what are the measured properties of welded HEAs as well as what are the main challenges that researchers have been facing. Finally, it gives a future perspective for this research field. Full article
(This article belongs to the Special Issue Recent Developments in Non-conventional Welding of Materials)
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Open AccessFeature PaperReview
Manufacture and Performance of Welds in Creep Strength Enhanced Ferritic Steels
Materials 2019, 12(14), 2257; https://doi.org/10.3390/ma12142257 - 13 Jul 2019
Cited by 1
Abstract
Welding is a vital process required in the fabrication of ‘fracture critical’ components which operate under creep conditions. However, often the procedures used are based on ‘least initial cost’. Thus, it is not surprising that in many high energy applications, welds are the [...] Read more.
Welding is a vital process required in the fabrication of ‘fracture critical’ components which operate under creep conditions. However, often the procedures used are based on ‘least initial cost’. Thus, it is not surprising that in many high energy applications, welds are the weakest link, i.e., damage is first found at welds. In the worst case, weld cracks reported have had catastrophic consequences. Comprehensive Electric Power Research Institute (EPRI) research has identified and quantified the factors affecting the high temperature performance of advanced steels working under creep conditions. This knowledge has then been used to underpin recommendations for improved fabrication and control of creep strength enhanced ferritic steel components. This review paper reports background from this work. The main body of the review summarizes the evidence used to establish a ‘well engineered’ practice for the manufacture of welds in tempered martensitic steels. Many of these alternative methods can be applied in repair applications without the need for post-weld heat treatment. This seminal work thus offers major benefits to all stakeholders in the global energy sector. Full article
(This article belongs to the Special Issue Recent Developments in Non-conventional Welding of Materials)
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Planned Papers

The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.

1. Title: The effect of post-weld hot-rolling on the microstructure of explosively welded Mg/Al/Ti multilayer composite

Authors: Marcin Wachowski 1,*, Robert Kosturek 1, Lucjan Śnieżek 1, Sebastian Mróz 2

Affiliation:

1   Military University of Technology, Faculty of Mechanical Engineering, 2 gen. W. Urbanowicza str., 00-908 Warsaw, Poland

2   Czestochowa University of Technology, Faculty of Production Engineering and Materials Technology, 19

Abstract: The paper describes an investigation of explosively welded Mg/Al/Ti multilayer composite. Following the welding, composite was hot-rolled at temperature 400°C with a total relative strain of 30%. The strain rate was 1.0 [1/s]. The composite Mg/Al and Al/Ti bonds were subjected to microstructure analysis using scanning electron (SEM) and transmission electron microscopy (TEM). It has been found that no formation of intermetallic phases was observed in as-welded joints. Applying of hot-rolling process results in formation of a continuous layer in Mg/Al joint consisting of two intermetallic phases Mg2Al3 (ꞵ) and Mg17Al12 (γ). In Al/Ti joint applying of hot-rolling results in formation of a continuous melted layer with locally identified precipitations of the intermetallic phase TiAl3.

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