Title
Istraživanje uticaja parametara zavarivanja trenjem sa mešanjem na dinamičku izdržljivost zavarenog spoja legure aluminijuma 2024 T351
Creator
Milčić, Miodrag D. 1987-
Copyright date
2020
Object Links
Select license
Autorstvo-Nekomercijalno-Bez prerade 3.0 Srbija (CC BY-NC-ND 3.0)
License description
Dozvoljavate samo preuzimanje i distribuciju dela, ako/dok se pravilno naznačava ime autora, bez ikakvih promena dela i bez prava komercijalnog korišćenja dela. Ova licenca je najstroža CC licenca. Osnovni opis Licence: http://creativecommons.org/licenses/by-nc-nd/3.0/rs/deed.sr_LATN. Sadržaj ugovora u celini: http://creativecommons.org/licenses/by-nc-nd/3.0/rs/legalcode.sr-Latn
Language
Serbian
Cobiss-ID
Theses Type
Doktorska disertacija
description
Datum odbrane: 31.08.2020.
Other responsibilities
mentor
Anđelković, Boban 1957-
član komisije
Kramberger, Janez 1953-
član komisije
Grabulov, Vencislav 1978-
član komisije
Banić, Milan 1979-
član komisije
Mijajlović, Miroslav
Academic Expertise
Tehničko-tehnološke nauke
University
Univerzitet u Nišu
Faculty
Mašinski fakultet
Group
Katedra za mašinske konstrukcije, razvoj i inženjering
Alternative title
A research on influence of the friction stir welding's parameters on welded joint's fatigue strength at AA 2024 T351
Publisher
[M. D. Milčić]
Format
VII, 220 listova
description
Biografija autora: list 220;
Bibliografija: listovi 189-200.
description
Mechanical elements and constructions, welding
Abstract (en)
In order to ensure a quality welded joint, and thus safe operation and high reliability of the
welded part or structure achieved by friction stir welding, it is necessary to select the
optimal welding parameters. The parameters of friction stir welding significantly affect the
structure of the welded joint, and thus the mechanical properties of the welded joint.
Investigation of the influence of friction welding parameters was performed on 6 mm thick
plates of aluminum alloy AA 2024 T351. The quality of the welded joint is predominantly
influenced by the number of tool revolutions speed n and the welding speed v. In this
research, it was adopted that the number of tool revolutions be constant n=750 rpm, and the
welding speed changed (v=73, 116 and 150 mm / min). Imperfections of the face and roots
of the welded specimens were not determined on all welded work pieces by the visual
method. Not a single welded sample, examined by radiographic examination, have not been
founded welding defects.
Experimental investigations of the macro and micro-structure of welded joints achieved by
different welding parameters were performed, followed by tests of mechanical properties of
welded joints: tensile testing, bending testing, Charpy impact testing, fracture mechanics
parameters testing, fatigue crack growth rate and fatigue testing of welded joints.
The efficiency of welded joints for welding parameter B-750/116 is almost 100%, that is
the tensile strength of the welded joint is approximately equal to the tensile strength of the
base metal. Welded joints are not suitable for bending stresses according to the results of
bending tests under static and dynamic loading conditions. By Charpy impact testing of
welded joints using an instrumented pendulum, fairly low values of impact energy were
obtained for all welded joints with generated notch in different positions of the welded joint
structure.
By examining the parameters of fracture mechanics, for welded joints achieved by different
welding parameters, the fracture toughness KIc is the highest on the retreating side of the
welded joint, and the lowest in the middle of the joint. The highest fracture toughness was
obtained for welding parameters B-750/116.
Fatigue tests of welded joints were performed on a servo-hydraulic pulsator and on electrodynamic
shaker. The best properties of fatigue strength were shown by welded joints
achieved by welding parameters B-750/116.
Based on extensive experimental research, in general, the best structural, and thus
mechanical properties of butt welded joints of aluminum alloy AA 2024 T351 were
achieved by welding parameters B-750/116, that is with the ratio of welding parameters
n/v=6.47.
Authors Key words
Zavarivanje trenjem sa mešanjem, Legura aluminijuma 2024 T351, Parametri
zavarivanja, Mehanička svojstva zavarenih spojeva, Visokociklični zamor,
Elasto-plastična mehanika loma, Zamorna prslina
Authors Key words
Friction stir welding, Aluminum alloy 2024 T351, Welding parameters,
Mechanical properties of welded joints, High-cycle fatigue, Elastic-plastic
fracture mechanics, Fatigue crack
Classification
621.791.1::[620.178.3:669.71.055(043.3)
Subject
T130; T210; T450
Type
Tekst
Abstract (en)
In order to ensure a quality welded joint, and thus safe operation and high reliability of the
welded part or structure achieved by friction stir welding, it is necessary to select the
optimal welding parameters. The parameters of friction stir welding significantly affect the
structure of the welded joint, and thus the mechanical properties of the welded joint.
Investigation of the influence of friction welding parameters was performed on 6 mm thick
plates of aluminum alloy AA 2024 T351. The quality of the welded joint is predominantly
influenced by the number of tool revolutions speed n and the welding speed v. In this
research, it was adopted that the number of tool revolutions be constant n=750 rpm, and the
welding speed changed (v=73, 116 and 150 mm / min). Imperfections of the face and roots
of the welded specimens were not determined on all welded work pieces by the visual
method. Not a single welded sample, examined by radiographic examination, have not been
founded welding defects.
Experimental investigations of the macro and micro-structure of welded joints achieved by
different welding parameters were performed, followed by tests of mechanical properties of
welded joints: tensile testing, bending testing, Charpy impact testing, fracture mechanics
parameters testing, fatigue crack growth rate and fatigue testing of welded joints.
The efficiency of welded joints for welding parameter B-750/116 is almost 100%, that is
the tensile strength of the welded joint is approximately equal to the tensile strength of the
base metal. Welded joints are not suitable for bending stresses according to the results of
bending tests under static and dynamic loading conditions. By Charpy impact testing of
welded joints using an instrumented pendulum, fairly low values of impact energy were
obtained for all welded joints with generated notch in different positions of the welded joint
structure.
By examining the parameters of fracture mechanics, for welded joints achieved by different
welding parameters, the fracture toughness KIc is the highest on the retreating side of the
welded joint, and the lowest in the middle of the joint. The highest fracture toughness was
obtained for welding parameters B-750/116.
Fatigue tests of welded joints were performed on a servo-hydraulic pulsator and on electrodynamic
shaker. The best properties of fatigue strength were shown by welded joints
achieved by welding parameters B-750/116.
Based on extensive experimental research, in general, the best structural, and thus
mechanical properties of butt welded joints of aluminum alloy AA 2024 T351 were
achieved by welding parameters B-750/116, that is with the ratio of welding parameters
n/v=6.47.
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