Metals

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17 pages, 39445 KiB

Open AccessFeature PaperArticle

Rationally-Based Structural Design of Welded Plate Panels

by Ahmed Hammad, Yehia Abdel-Nasser, Cristina Churiaque and José María Sánchez-Amaya

Metals 2021, 11(9), 1381; https://doi.org/10.3390/met11091381 - 31 Aug 2021

Viewed by 2500

This study predicts the behavior of welded plate panels (unstiffened plates) with different geometrical properties (slenderness ratio and aspect ratio) in order to address a rational structural design procedure, as these parameters are of great importance from a structural design perspective. Nonlinear finite [...] Read more.

This study predicts the behavior of welded plate panels (unstiffened plates) with different geometrical properties (slenderness ratio and aspect ratio) in order to address a rational structural design procedure, as these parameters are of great importance from a structural design perspective. Nonlinear finite element analysis has been used to simulate the butt-welding process of plate panels, giving the three-dimensional distribution of distortion and residual stresses induced by welding through the design of a moving heat source. The numerical results are validated with published experimental measurements. The effect of geometrical properties such as slenderness ratio β and aspect ratio a/b on the creation of welding-induced imperfections (distortion and residual stresses) have been investigated in this work. These geometrical properties influence the creation of the welding-induced imperfections, which in turn affect the load-carrying capacity of the plate panels. Three different plate slenderness ratios with three different aspect ratios have been studied. It is concluded that increasing the plate aspect ratio can highly increase the out-of-plane distortion magnitude as well as the compressive residual stress. The plates with high slenderness ratio (thin thicknesses) are highly affected by increasing plate aspect ratio a/b. As the slenderness ratio β increases, the reduction in the ultimate strength due to the existence of welding-induced imperfections highly decreases. Slenderness ratio β can highly affected the ultimate strength of plates with smaller aspect ratio more than plates with higher aspect ratio. Full article

(This article belongs to the Special Issue Design of Welded Steel Structures)

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16 pages, 5838 KiB

Open AccessFeature PaperArticle

Increasing the Durability of Trimming Dies Used to Clean Anodes in the Aluminum Industry

by Delia Gârleanu, Claudia Borda, Gabriel Gârleanu, Cristina Modrogan, Marius Dumitraș, Dan Dobrotă, Sever-Gabriel Racz and Loredana Cristina Dascălu

Metals 2021, 11(8), 1157; https://doi.org/10.3390/met11081157 - 22 Jul 2021

Cited by 1 | Viewed by 2396

Abstract

Increasing the durability of trimming dies used to clean anodes is a very important goal in order to reduce the costs involved in obtaining aluminum. The research focused both on choosing an optimal material for the execution of trimming dies and on the [...] Read more.

Increasing the durability of trimming dies used to clean anodes is a very important goal in order to reduce the costs involved in obtaining aluminum. The research focused both on choosing an optimal material for the execution of trimming dies and on the application of technologies for plating active areas and, at the same time, on optimizing the geometric shape of the active area of the trimming die. In order to choose an optimal material from which to make the trimming dies, it was taken into account that they are usually made of X210Cr12 steel. In the stage of choosing an optimal material for the execution of the trimming dies, five steels were taken into account, namely: K105, K107, K110, K360, and K460. Analyses of the metallographic structure of the passage area were performed between the metal deposited by welding and the base material, demonstrating the fact that hot welding plating allows obtaining a more homogeneous metallographic structure compared to cold welding plating. The choice of new material was not a solution to increase the durability of the trimming die. Change in the trimming die geometry determined a reduction in deformations of about 13.8 times and of the equivalent stresses of about 7 times compared to those obtained in the case of the old trimming die. In addition, the durability of the trimming die with the new construction shape increases approximately three times compared to the trimming die with the old geometric shape. This demonstrates that the solution to increasing the durability of the trimming die is to adopt an optimal geometry of the active part at the expense of choosing an optimal material. Full article

(This article belongs to the Special Issue Design of Welded Steel Structures)

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19 pages, 3999 KiB

Open AccessArticle

Computational Fluid Dynamics (CFD) Simulation of Inclusion Motion under Interfacial Tension in a Flash Welding Process

by Md Irfanul Haque Siddiqui, Hassan Alshehri, Jamel Orfi, Masood Ashraf Ali and Dan Dobrotă

Metals 2021, 11(7), 1073; https://doi.org/10.3390/met11071073 - 3 Jul 2021

Cited by 7 | Viewed by 3023

Abstract

Non-metallic inclusions particles are detrimental to the mechanical properties of a material. It is very important to understand the motion behavior of inclusion particles in molten metal. The motion behavior of non-metallic inclusion particles during weld pool solidification and their distribution in joint [...] Read more.

Non-metallic inclusions particles are detrimental to the mechanical properties of a material. It is very important to understand the motion behavior of inclusion particles in molten metal. The motion behavior of non-metallic inclusion particles during weld pool solidification and their distribution in joint areas is dependent on various factors. In the alternative current (AC) flash welding process, inclusions motions are dependent on welding plate movement, interfacial tensions, etc. Apart from this, the temperature of the molten metal in the welding zone and the size of inclusion particles also play an important role. Secondly, the Marangoni forces are developed due to interfacial tension which affects the movement of inclusion particles at the solid-liquid interface in a solidifying welding pool. The interfacial tension varies with the change in surfactant concentration and other factors. In this work, the effect of upsetting rate and interfacial tension on alumina inclusions has been studied. The interfacial tension controls the pushing and engulfment of non-metallic inclusions at the solid-liquid interface. A two-dimensional multiphase mathematical model has been developed to study the inclusion motion behavior at the solid–liquid interface in a solidifying weld pool. The numerical model has been developed by adding the volume of fluid method (VOF), a dynamic mesh model and discrete phase model for a realistic approach. The predicted results show that the upsetting setting parameters have a substantial effect on the overall non-metallic inclusion motion. The inclusions were seen moving away from the welded joint due to the high up-setting rate. The results also reveal that the inclusions were engulfed by the solidification front under the effect of the strong interfacial tension between the non-metallic inclusions and the molten steel. Full article

(This article belongs to the Special Issue Design of Welded Steel Structures)

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22 pages, 12582 KiB

Open AccessArticle

Research Regarding the Increase of Durability of Flexible Die Made from 50CrMo4 Used in the Typographic Industry

by Gabriela Valeria Neamțu (Folea), Cristina Mohora, Dorel Florea Anania and Dan Dobrotă

Metals 2021, 11(6), 996; https://doi.org/10.3390/met11060996 - 21 Jun 2021

Cited by 3 | Viewed by 3563

Abstract

A large amount of packaging used mainly in the food industry is obtained by technologies that involve the use of machines such as those that cut with flexible die. The durability of the flexible die is a very important aspect and in this [...] Read more.

A large amount of packaging used mainly in the food industry is obtained by technologies that involve the use of machines such as those that cut with flexible die. The durability of the flexible die is a very important aspect and in this regard the purpose of the research was to identify technologies for its development. Thus, the research considered the analysis of the durability of the knives made of 50CrMo4 steel considering hard chrome-plating treatment, as well as laser hardening of the knives. For the analysis of the durability of the tools, two technological parameters were considered, namely the moment of the tightening force, which had values in the range of 50 Nm–110 Nm, and the die cutting speed, which was adjusted to values in the range of 50–60 m/min. For the analysis of the durability of the flexible die, the wear of the tools was taken into account, as well as the maximum length of the die cut material. Full article

(This article belongs to the Special Issue Design of Welded Steel Structures)

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29 pages, 7609 KiB

Open AccessArticle

Experimental Research on the Behaviour of Metal Active Gas Tailor Welded Blanks during Single Point Incremental Forming Process

by Valentin Oleksik, Dan Dobrota, Sever-Gabriel Racz, Gabriela Petruta Rusu, Mihai Octavian Popp and Eugen Avrigean

Metals 2021, 11(2), 198; https://doi.org/10.3390/met11020198 - 22 Jan 2021

Cited by 3 | Viewed by 2327

Abstract

The present paper aims to study the behaviour of Metal Active Gas (MAG) tailor welded blanks during the single point incremental forming process (SPIF) from an experimental point of view. The single point incremental forming process was chosen for manufacturing truncated cone and [...] Read more.

The present paper aims to study the behaviour of Metal Active Gas (MAG) tailor welded blanks during the single point incremental forming process (SPIF) from an experimental point of view. The single point incremental forming process was chosen for manufacturing truncated cone and truncated pyramid shaped parts. The same material (S355) and the same thickness (0.9 mm) were selected for the joining of blank sheets because the main goal of the paper was to study the influence of the MAG welding process throughout the SPIF process. A Kuka robot, equipped with a force transducer and an optical measurement system were used for manufacturing and evaluating the parts by SPIF. The selected output data were major and minor strain, thickness reduction, forces and springback at the SPIF process. Another line test was performed to evaluate the formability in SPIF. The main conclusion of the paper is that during the SPIF process, fractures occur in one side welded blanks even at moderate wall angles, while in the case of double side welded blanks there is a decrease of formability but parts can still be produced at moderate angles (55 degrees) without any problems. Full article

(This article belongs to the Special Issue Design of Welded Steel Structures)

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22 pages, 3335 KiB

Open AccessArticle

Optimizing the Shape of Welded Constructions Made through the Technique “Temper Bead Welding”

by Dan Dobrotă

Metals 2020, 10(12), 1655; https://doi.org/10.3390/met10121655 - 9 Dec 2020

Cited by 4 | Viewed by 2552

Abstract

Welded constructions are subject to high stresses during operation. One solution for improving the behavior in exploitation of welded constructions in various cases is to use the welding technique “temper bead welding” (TBW). In the paper, the optimization of the geometry of the [...] Read more.

Welded constructions are subject to high stresses during operation. One solution for improving the behavior in exploitation of welded constructions in various cases is to use the welding technique “temper bead welding” (TBW). In the paper, the optimization of the geometry of the welded joints by the TBW technique was performed. Thus, corner welded joints made of S355 steel were analyzed. To make the welded joints, three layers of welding seams were deposited, and the intermediate layers were processed through cutting with various radii. To analyze the influence of the size of these rays on the behavior of welded constructions, a research program based on factorial experiences was designed. The samples were tested in terms of fatigue behavior by applying loads between ±8 kN and ±12 kN. The research also focused on determining the hardness of the materials in the joints welded and on determining the microstructure of the materials in the heat affected zone (HAZ). Research has shown that it is possible to improve the characteristics of joints made by the TBW technique in the sense that it can be achieved an improvement in fatigue stress, a decrease in the hardness of the HAZ material and an improvement in the metallographic structure of the HAZ material, meaning that it has a structure made of ferrite and fine pearlite. Full article

(This article belongs to the Special Issue Design of Welded Steel Structures)

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20 pages, 8213 KiB

Open AccessArticle

Welded Construction Design of Transition Fittings from Metal Pipes to Plastic Pipes

by Dan Dobrotă, Ionela Rotaru and Ioan Bondrea

Metals 2020, 10(9), 1231; https://doi.org/10.3390/met10091231 - 13 Sep 2020

Cited by 1 | Viewed by 5725

Abstract

Transition type fittings are components often used in facilities where fluids are transported that allow the passage from a high density polyethylene (HDPE) pipe to a steel pipe. In the presented studies, four types of transition fittings were analyzed in the first stage. [...] Read more.

Transition type fittings are components often used in facilities where fluids are transported that allow the passage from a high density polyethylene (HDPE) pipe to a steel pipe. In the presented studies, four types of transition fittings were analyzed in the first stage. The four types of transition fittings are distinguished by the shape of their welded steel construction. The performed analyses took into account testing the behavior upon exposure to fatigue, measuring the HDPE hardness and applying the finite element method (FEM). As a result of these studies it was demonstrated that the form of the welded steel construction has a very great influence on the operating behavior of the transition fitting. Thus, a new transition fitting with a welded steel construction was designed. In this new type of transition fitting, an approximately 50% increase in resistance to fatigue stress, an approximately 90% reduction in stress in the part material and a reduction in the hardness of the material in HDPE pipes was obtained. The studies allow not only an improvement of the characteristics for these types of parts, but also the optimization of other types of steel-plastic joints. Full article

(This article belongs to the Special Issue Design of Welded Steel Structures)

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18 pages, 8383 KiB

Open AccessArticle

Applicability of Hybrid Built-Up Wide Flange Steel Beams

by Hyunjin Ju, Se-Jung Lee, Sung-Mo Choi, Jong R. Kim and Deuckhang Lee

Metals 2020, 10(5), 567; https://doi.org/10.3390/met10050567 - 27 Apr 2020

Cited by 3 | Viewed by 6113

Abstract

To accommodate growing demands on either heavy steel structures or unique buildings with irregular configurations, built-up wide-flange steel (BWS) beams are being popularly used in modern steel construction. In current fabrication practices of BWS members, high-performance steels produced in steelmaking factories under the [...] Read more.

To accommodate growing demands on either heavy steel structures or unique buildings with irregular configurations, built-up wide-flange steel (BWS) beams are being popularly used in modern steel construction. In current fabrication practices of BWS members, high-performance steels produced in steelmaking factories under the thermo-mechanical control process (TMCP) are typically utilized to achieve proper welding performances. However, since its basic unit price is quite higher than typical hot-rolled steel materials, this study introduced a hybrid BWS section for cost saving with no performance degradation, where high-performance TMCP steel was used in flanges, and conventional hot-rolled steel was adopted in web plate. To verify the tensile performances of a hybrid BWS section with non-uniform properties, split T tension and Charpy impact tests were conducted, and flexural tests were also carried out on hybrid and homogeneous BWS beam members. On this basis, it was confirmed that the structural performance of the hybrid BWS member is comparable with that of the conventional one with a uniform section property. Full article

(This article belongs to the Special Issue Design of Welded Steel Structures)

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