Research

13 pages, 2859 KiB

Open AccessArticle

Composition of Organosilicate Coatings High-Temperature Breakdown Products and Their Distribution in the Weld

by Leonid Zhabrev, Dmitry Kurushkin, Igor Mushnikov, Aleksey Shamshurin, Svetlana Chuppina and Oleg Panchenko

Materials 2022, 15(3), 699; https://doi.org/10.3390/ma15030699 - 18 Jan 2022

Viewed by 1229

Abstract

The construction assembly and the repair of steel constructions painted with protective coatings are often carried out using arc welding. During the welding process, the coating in the weld zone is degrading. The protective coatings breakdown products are involved in the pore and [...] Read more.

The construction assembly and the repair of steel constructions painted with protective coatings are often carried out using arc welding. During the welding process, the coating in the weld zone is degrading. The protective coatings breakdown products are involved in the pore and non-metallic inclusion formation in the weld, the composition and distribution study of which makes it possible to analyze the reactions occurring during the welding. In this study, welding beads were deposited on the coated sheet surface by MAG welding. The distribution of inclusions (the average diameter and the relative content) along with the porosity in different bead zones were investigated by optical and scanning electron microscopy and digital image processing, and the chemical composition of inclusions was determined using energy-dispersive X-ray spectroscopy. The amount of diffusible hydrogen in the deposited metal was estimated with the vacuum method. In this work, four organosilicate coatings grades, differing in their purpose and heat resistance, were used, and their effect on the weld was studied. Full article

(This article belongs to the Special Issue Advances in Sustainable Manufacturing by Welding and Additive Manufacturing)

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23 pages, 8826 KiB

Open AccessArticle

The Influence of Tool Wear on the Mechanical Performance of AA6061-T6 Refill Friction Stir Spot Welds

by Willian S. de Carvalho, Maura C. Vioreanu, Maxime R. A. Lutz, Gonçalo P. Cipriano and Sergio T. Amancio-Filho

Materials 2021, 14(23), 7252; https://doi.org/10.3390/ma14237252 - 27 Nov 2021

Cited by 11 | Viewed by 2150

Abstract

The Refill Friction Stir Spot Welding (RFSSW) process—an alternative solid-state joining technology—has gained momentum in the last decade for the welding of aluminum and magnesium alloys. Previous studies have addressed the influence of the RFSSW process on the microstructural and mechanical properties of [...] Read more.

The Refill Friction Stir Spot Welding (RFSSW) process—an alternative solid-state joining technology—has gained momentum in the last decade for the welding of aluminum and magnesium alloys. Previous studies have addressed the influence of the RFSSW process on the microstructural and mechanical properties of the AA6061-T6 alloy. However, there is a lack of knowledge on how the tool wear influences the welding mechanical behavior for this alloy. The present work intended to evaluate and understand the influence of RFSSW tool wear on the mechanical performance of AA6061-T6 welds. Firstly, the welding parameters were optimized through the Designing of Experiments (DoE), to maximize the obtained ultimate lap shear force (ULSF) response. Following the statistical analysis, an optimized condition was found that reached a ULSF of 8.45 ± 0.08 kN. Secondly, the optimized set of welding parameters were applied to evaluate the wear undergone by the tool. The loss of worn-out material was systematically investigated by digital microscopy and the assessment of tool weight loss. Tool-wear-related microstructural and local mechanical property changes were assessed and compared with the yielded ULSF, and showed a correlation. Further investigations demonstrated the influence of tool wear on the height of the hook, which was located at the interface between the welded plates and, consequently, its effects on the observed fracture mechanisms and ULSF. These results support the understanding of tool wear mechanisms and helped to evaluate the tool lifespan for the selected commercial RFSSW tool which is used for aluminum alloys. Full article

(This article belongs to the Special Issue Advances in Sustainable Manufacturing by Welding and Additive Manufacturing)

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14 pages, 7639 KiB

Open AccessArticle

Effect of Different Tool Probe Profiles on Material Flow of Al–Mg–Cu Alloy Joined by Friction Stir Welding

by Anton Naumov, Evgenii Rylkov, Pavel Polyakov, Fedor Isupov, Andrey Rudskoy, Jong-Ning Aoh, Anatoly Popovich and Oleg Panchenko

Materials 2021, 14(21), 6296; https://doi.org/10.3390/ma14216296 - 22 Oct 2021

Cited by 5 | Viewed by 1376

Abstract

Friction Stir Welding (FSW) was utilized to butt−join 2024–T4 aluminum alloy plates of 1.9 mm thickness, using tools with conical and tapered hexagonal probe profiles. The characteristic effects of FSW using tools with tapered hexagonal probe profiles include an increase in the heat [...] Read more.

Friction Stir Welding (FSW) was utilized to butt−join 2024–T4 aluminum alloy plates of 1.9 mm thickness, using tools with conical and tapered hexagonal probe profiles. The characteristic effects of FSW using tools with tapered hexagonal probe profiles include an increase in the heat input and a significant modification of material flow, which have a positive effect on the metallurgical characteristics and mechanical performance of the weld. The differences in mechanical properties were interpreted through macrostructural changes and mechanical properties of the welded joints, which were supported by numerical simulation results on temperature distribution and material flow. The material flow resulting from the tapered hexagonal probe was more complicated than that of the conical probe. If in the first case, the dynamic viscosity and strain rate are homogeneously distributed around the probe, but in the case of the tapered hexagonal probe tool, the zones with maximum values of strain rates and minimum values of dynamic viscosity are located along the six tapered edges of the probe. Full article

(This article belongs to the Special Issue Advances in Sustainable Manufacturing by Welding and Additive Manufacturing)

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11 pages, 2006 KiB

Open AccessArticle

Mechanical Properties and Microstructural Characterization of Laser Welded S32520 Duplex Stainless Steel

by Hany S. Abdo and Asiful H. Seikh

Materials 2021, 14(19), 5532; https://doi.org/10.3390/ma14195532 - 24 Sep 2021

Cited by 7 | Viewed by 1351

Abstract

This paper investigates an experimental design of laser butt welding of S32520 duplex stainless steel, which has been passed out with the help of a pulsed Nd: YAG laser supply. The intention of the present research is to learn the impact of beam [...] Read more.

This paper investigates an experimental design of laser butt welding of S32520 duplex stainless steel, which has been passed out with the help of a pulsed Nd: YAG laser supply. The intention of the present research is to learn the impact of beam diameter, welding speed, and laser power on the superiority of the butt weld. The individuality of butt joints has been characterized in terms of tensile properties, fractography, and hardness. It was noticed that unbalanced particle orientations indirectly produce a comparatively fragile quality in the laser welded joint. The outcome of varying process parameters and interaction effect of process parameters on ultimate tensile strength and micro hardness were studied through analysis of experimental data. With different process parameters, the heat energy delivered to the material was changed, which was reflected in tensile strength measurement for different welded samples. From this present research, it was shown that, up to a certain level, an increase in process parameters amplified the tensile strength, but after that, certain level tensile strength decreased with the increase in process parameters. When process parameters exceeded that certain level, the required amount of heat energy was not delivered to the material, resulting in low bead width and less penetration, thus producing less strength in the welded joint. Less strength leads to more ductile weld joints. Microhardness was higher in the weld zone than in the base region of welded samples. However, the heat affected zone had a high microhardness range. Full article

(This article belongs to the Special Issue Advances in Sustainable Manufacturing by Welding and Additive Manufacturing)

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12 pages, 5113 KiB

Open AccessArticle

Features of Filler Wire Melting and Transferring in Wire-Arc Additive Manufacturing of Metal Workpieces

by Artem Voropaev, Rudolf Korsmik and Igor Tsibulskiy

Materials 2021, 14(17), 5077; https://doi.org/10.3390/ma14175077 - 05 Sep 2021

Cited by 3 | Viewed by 2058

Abstract

In this paper, we present the results of a study on droplet transferring with arc space short circuits during wire-arc additive manufacturing (WAAM GMAW). Experiments were conducted on cladding of single beads with variable welding current and voltage parameters. The obtained oscillograms and [...] Read more.

In this paper, we present the results of a study on droplet transferring with arc space short circuits during wire-arc additive manufacturing (WAAM GMAW). Experiments were conducted on cladding of single beads with variable welding current and voltage parameters. The obtained oscillograms and video recordings were analyzed in order to compare the time parameters of short circuit and arc burning, the average process peak current, as well as the droplets size. Following the experiments conducted, 2.5D objects were built-up to determine the influence of electrode stickout and welding torch travel speed to identify the droplet transferring and formation features. Moreover, the current–voltage characteristics of the arc were investigated with varying WAAM parameters. Process parameters have been determined that make it possible to increase the stability of the formation of the built-up walls, without the use of specialized equipment for forced droplet transfer. In the course of the research, the following conclusions were established: the most stable drop transfer occurs at an arc length of 1.1–1.2 mm, reverse polarity provides the best drop formation result, the stickout of the electrode wire affects the drop transfer process and the quality of the deposited layers. The dependence of the formation of beads on the number of short circuits per unit length is noted. Full article

(This article belongs to the Special Issue Advances in Sustainable Manufacturing by Welding and Additive Manufacturing)

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17 pages, 42246 KiB

Open AccessArticle

Fatigue Performance of Metal–Composite Friction Spot Joints

by Seyed Mohammad Goushegir, Jorge F. dos Santos and Sergio T. Amancio-Filho

Materials 2021, 14(16), 4516; https://doi.org/10.3390/ma14164516 - 11 Aug 2021

Cited by 5 | Viewed by 1607

Abstract

Friction spot joining is an alternative technique for joining metals with polymers and composites. This study investigated the fatigue performance of aluminum alloy 2024/carbon-fiber-reinforced poly(phenylene sulfide) joints that were produced with friction spot joining. The surface of the aluminum was pre-treated using various [...] Read more.

Friction spot joining is an alternative technique for joining metals with polymers and composites. This study investigated the fatigue performance of aluminum alloy 2024/carbon-fiber-reinforced poly(phenylene sulfide) joints that were produced with friction spot joining. The surface of the aluminum was pre-treated using various surface treatment methods. The joined specimens were tested under dynamic loading using a load ratio of R = 0.1 and a frequency of 5 Hz. The tests were performed at different percentages of the lap shear strength of the joint. Three models—exponential, power law, and wear-out—were used to statistically analyze the fatigue life of the joints and to draw the stress–life (S–N) curves. The joints showed an infinite life of 25–35% of their quasi-static strength at 10⁶ cycles. The joints surpassing 10⁶ cycles were subsequently tested under quasi-static loading, showing no considerable reduction compared to their initial lap shear strength. Full article

(This article belongs to the Special Issue Advances in Sustainable Manufacturing by Welding and Additive Manufacturing)

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14 pages, 33386 KiB

Open AccessArticle

Shoulder Related Temperature Thresholds in FSSW of Aluminium Alloys

by David G. Andrade, Sree Sabari, Carlos Leitão and Dulce M. Rodrigues

Materials 2021, 14(16), 4375; https://doi.org/10.3390/ma14164375 - 05 Aug 2021

Cited by 5 | Viewed by 2084

Abstract

Friction Stir Spot Welding (FSSW) is assumed as an environment-friendly technique, suitable for the spot welding of several materials. Nevertheless, it is consensual that the temperature control during the process is not feasible, since the exact heat generation mechanisms are still unknown. In [...] Read more.

Friction Stir Spot Welding (FSSW) is assumed as an environment-friendly technique, suitable for the spot welding of several materials. Nevertheless, it is consensual that the temperature control during the process is not feasible, since the exact heat generation mechanisms are still unknown. In current work, the heat generation in FSSW of aluminium alloys, was assessed by producing bead-on-plate spot welds using pinless tools. Coated and uncoated tools, with varied diameters and rotational speeds, were tested. Heat treatable (AA2017, AA6082 and AA7075) and non-heat treatable (AA5083) aluminium alloys were welded to assess any possible influence of the base material properties on heat generation. A parametric analysis enabled to establish a relationship between the process parameters and the heat generation. It was found that for rotational speeds higher than 600 rpm, the main process parameter governing the heat generation is the tool diameter. For each tool diameter, a threshold in the welding temperature was identified, which is independent of the rotational speed and of the aluminium alloy being welded. It is demonstrated that, for aluminium alloys, the temperature in FSSW may be controlled using a suitable combination of rotational speed and tool dimensions. The temperature evolution with process parameters was modelled and the model predictions were found to fit satisfactorily the experimental results. Full article

(This article belongs to the Special Issue Advances in Sustainable Manufacturing by Welding and Additive Manufacturing)

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13 pages, 5328 KiB

Open AccessArticle

Wire Arc Additive Manufacturing of Al-Mg Alloy with the Addition of Scandium and Zirconium

by Taisiya Ponomareva, Mikhail Ponomarev, Arseniy Kisarev and Maxim Ivanov

Materials 2021, 14(13), 3665; https://doi.org/10.3390/ma14133665 - 30 Jun 2021

Cited by 11 | Viewed by 2525

Abstract

The proposed paper considers the opportunity of expanding the application area of wire arc additive manufacturing (WAAM) method by means of increasing the strength properties of deposited material, due to the implementation of aluminum wire with the addition of scandium and zirconium. For [...] Read more.

The proposed paper considers the opportunity of expanding the application area of wire arc additive manufacturing (WAAM) method by means of increasing the strength properties of deposited material, due to the implementation of aluminum wire with the addition of scandium and zirconium. For the experimental research, the welding wire 1575 of the Al-Mg-Sc-Zr system containing 0.23% Sc and 0.19% Zr was selected. The optimal welding parameters, ensuring the defect-free formation of deposited material with low heat input, were used. Porosity level was estimated. The thermal state was estimated by finite element simulation. Simulated thermal state was verified by comparison with thermocouples data. Post-heat treatment parameters that lead to maximum strength with good plasticity were determined. The maximum yield strength (YS) of 268 MPa and ultimate strength (UTS) of 403 MPa were obtained, while the plasticity was determined at least 16.0% in all WAAM specimens. Full article

(This article belongs to the Special Issue Advances in Sustainable Manufacturing by Welding and Additive Manufacturing)

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12 pages, 5720 KiB

Open AccessArticle

Gas Metal Arc Welding Modes in Wire Arc Additive Manufacturing of Ti-6Al-4V

by Oleg Panchenko, Dmitry Kurushkin, Fedor Isupov, Anton Naumov, Ivan Kladov and Margarita Surenkova

Materials 2021, 14(9), 2457; https://doi.org/10.3390/ma14092457 - 10 May 2021

Cited by 10 | Viewed by 3424

Abstract

In wire arc additive manufacturing of Ti-alloy parts (Ti-WAAM) gas metal arc welding (GMAW) can be applied for complex parts printing. However, due to the specific properties of Ti, GMAW of Ti-alloys is complicated. In this work, three different types of metal transfer [...] Read more.

In wire arc additive manufacturing of Ti-alloy parts (Ti-WAAM) gas metal arc welding (GMAW) can be applied for complex parts printing. However, due to the specific properties of Ti, GMAW of Ti-alloys is complicated. In this work, three different types of metal transfer modes during Ti-WAAM were investigated: Cold Metal Transfer, controlled short circuiting metal transfer, and self-regulated metal transfer at a direct current with a negative electrode. Metal transfer modes were studied using captured waveform and high-speed video analysis. Using these modes, three walls were manufactured; the geometry preservation stability was estimated and compared using effective wall width calculation, the microstructure was analyzed using optical microscopy. Transfer process data showed that arc wandering depends not only on cathode spot instabilities, but also on anode processing properties. Microstructure analysis showed that each produced wall consists of phases and structures inherent for Ti-WAAM. α-basketweave in the center of and α-colony on the grain boundary of epitaxially grown β-grains were found with heat affected zone bands along the height of the walls, so that the microstructure did not depend on metal transfer dramatically. However, the geometry preservation stability was higher in the wall, produced with controlled short circuiting metal transfer. Full article

(This article belongs to the Special Issue Advances in Sustainable Manufacturing by Welding and Additive Manufacturing)

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