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Characterization of dissimilar Al-Cu BFSW welds; interfacial microstructure, flow mechanism and intermetallics formation

Tamadon A., Abdali M., Pons D. J., Clucas D.

Advances in Materials Science

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2020

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Vol. 20, nr 3(65)

52--78

EN

The purpose of this study is to elucidate the flow features of the dissimilar Al-Cu welded plates. The welding method used is Bobbin Friction Stir Welding (BFSW), and the joint is between two dissimilar materials, aluminium alloy (AA6082-T6) and pure copper. Weld samples were cut from along the weld line, and the cross-sections were polished and observed under an optical microscope (OM). Particular regions of interest were examined under a scanning electron microscope (SEM) and analysed with Energy Dispersive X-ray Spectroscopy (EDS) using the AZtec software from Oxford Instruments. The results and images attained were compared to other similar studies. The reason for fracture was mainly attributed to the welding parameters used; a higher rotational speed may be required to achieve a successful BFSW between these two materials. The impact of welding parameters on the Al-Cu flow bonding and evolution of the intermetallic compounds were identified by studying the interfacial microstructure at the location of the tool action. The work makes an original contribution to identifying the solid-phase hybrid bonding in Al-Cu joints to improve the understanding of the flow behaviours during the BFSW welding process. The microstructural evolution of the dissimilar weld has made it possible to develop a physical model proposed for the flow failure mechanism.

2

The effect of welding defects to the tensile behavior in corrosive environment of AISI 304L stainless steel joined with shielded metal electrode

Türkan M., Karakaş Ö.

Journal of Achievements in Materials and Manufacturing Engineering

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2017

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Vol. 85, nr 1

26--30

EN

Purpose: Determination of the tensile behavior of welded constructions made of austenitic stainless steel in corrosive environments is of great importance for the safer use of the construction. When austenitic stainless steels are welded together, welding defects can occur in some cases. And stainless steels are used in corrosive environments. Thus, we are aimed to investigate the effect of welding defects the tensile behavior in corrosive environment of AISI 304 L stainless steel joined with shielded metal electrode. Design/methodology/approach: Hardness measurements and micro-macro structures examination were made before the corrosion test to characterize the structure of the weld zone. Corrosion tests were carried out in accordance with EN ISO 9227 by exposing the welded tensile specimens to salt spray for 24-96-240-480-720-1000 hours. After the salt spray test, tensile tests were performed. The fractured surfaces were examined following the tensile tests by scanning electron microscope (SEM). Findings: A significant decrease in the tensile strength of the material was observed with the increase of the salt spraying period as a result of the tests. It is worth noting that corrosion products were occurred especially in the areas of welding defects. Research limitations/implications: This study was performed on materials containing welding defects. In addition, the corrosive environment was provided by salt spraying. It should not be forgotten that the materials may behave differently in different corrosive environments. Originality/value: While there are studies regarding effects of welding defects and corrosion individually, no study has been found in the literature which considers the effect of welding defects within corrosive environments on the material strength. Therefore, this study presents novel findings by considering both detrimental effects at the same time. The study shows significant decrease in strength of the material due to welding defects and corrosive environment.

3

Wpływ imperfekcji wykonawczych konstrukcji kolejowych mostów stalowych na ich nośność doraźną i zmęczeniową

Wysokowski A.

Budownictwo i Architektura

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2013

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Vol. 12, nr 2

71--78

PL

W ostatnich latach w naszym kraju modernizowanych i przebudowywanych jest wiele odcinków linii kolejowych w tym głównie magistralnych. Większa cześć z nich dostosowywana jest do kolei o zwiększonych prędkościach. Wiąże się to z przebudową lub budową obiektów mostowych w tym mostów stalowych. Przedmiotowy referat dotyczy imperfekcji wykonawczych przebadanych przez autora konstrukcji mostów stalowych, które w ostatnim okresie zrealizowane zostały w ciągu wspomnianych wcześniej modernizowanych magistralnych linii kolejowych. Opisane imperfekcje polegają m.in. na odchyłkach geometrycznych konstrukcji od założonego projektu. Dotyczy to również wad spoin o różnym charakterze, które wystąpiły w newralgicznych elementach konstrukcji mostu. Celem referatu jest wykazanie wpływu imperfekcji na nośność doraźną i zmęczeniową konstrukcji mostowych. Autor wykazał, że stwierdzone imperfekcje mają istotny wpływ na trwałość zmęczeniową – szczególnie dotyczy to wad spoin, natomiast dużo mniejsze jest ich znaczenie dla nośności doraźnej.Analizy te autor wykonał w oparciu o sposoby teoretyczne, opracowane we wcześniejszych swoich pracach. Przy analizie posłużono się nowymi normami do projektowania konstrukcji stalowych z grupy eurokodów.

EN

In recent years, in our country are modernized and rebuilt several sections of railway lines, mainly main lines. The greater part is adapted to increased speeds. However, such an adaptation involve the reconstruction or construction of new bridges including steel ones. The paper concerns the executive imperfections of constructions of steel bridges which in recent years have been built in the modernized main railway lines. These imperfections consist of, among others, the geometric imperfections from the assumed construction project. This also applies to defects in welds of various types that occur in critical elements of bridge structure. The aim of this paper is to demonstrate the influence of imperfections on the load carrying capacity and fatigue of these structures. Author showed that the observed imperfections have a significant impact on the fatigue life - especially for weld defects, in the case of load carrying capacity their importance is much smaller. These analyses are performed by using the theoretical methods developed in previous reports. In the analysis new standards for the design of steel structures from Eurocodes group were used.

4

O przyczynach pęknięcia dolnego węzła gałęzi wieży kratowej

Wuwer W., Kowolik B.

Inżynieria i Budownictwo

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2004

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R. 60, nr 4

184-187

PL

Wykonana z rur stalowa wieża kratowa wysokości 48,5 m uległa awarii. Wskutek niewłaściwego skonstruowania i niestarannego wykonania dolnych węzłów w jednym z nich nastąpiło pęknięcie gałęzi wzdłuż spoiny łączącej blachę węzłową z rurą. Przeanalizowano przyczyny uszkodzeń.

EN

The 48,5 m hight lattice tower constructed of steel pipes has locally broken down due to not adequate and careless construction of the bottom joints. In one joint the branch has burst along the weid joining of the gusset plate with the tube.

5

Wady złączy spawanych

Czuchryj J.

Dozór Techniczny

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2000

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z. 5

107--110

6

Zachowanie się spoin z pęknięciami w kratowym moście kolejowym

Wichtowski B.

Przegląd Spawalnictwa

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1999

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R. 71, nr 8

12-14

PL

Opis konstrukcji wiaduktu poddanego badaniom rentgenograficznym oraz tensometrycznym po 45 latach eksploatacji. Wyniki badań własnych wytrzymałości na zmęczenie spoin z wewnętrznymi pęknięciami i ich rozkład w przekrojach złączy czołowych węzłów.

EN

Description of the structure of an overbridge subjected to X-ray and extensometric examination after 45 years of service. Results of the author's own investigations of welds with internal cracks for fatigue strength and the cracks distribution in the cross-sections of butt joints.