Characterization of Friction Stir Welded Tubes by Means of Tube Bulge Test

Journal Article · Wed May 04 00:00:00 EDT 2011 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.3589689· OSTI ID:21516709

D'Urso, G; Longo, M; Giardini, C ^[1]

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1. University of Bergamo-Dept. of Design and Technologies-Italy-Viale Marconi 5, 24044 Dalmine (Italy)

Mechanical properties of friction stir welded joints are generally evaluated by means of conventional tensile test. This testing method might provide insufficient information because maximum strain obtained in tensile test before necking is small; moreover, the application of tensile test is limited when the joint path is not linear or even when the welds are executed on curved surfaces. Therefore, in some cases, it would be preferable to obtain the joints properties from other testing methods. Tube bulge test can be a valid solution for testing circumferential or longitudinal welds executed on tubular workpieces. The present work investigates the mechanical properties and the formability of friction stir welded tubes by means of tube bulge tests. The experimental campaign was performed on tubular specimens having a thickness of 3 mm and an external diameter of 40 mm, obtained starting from two semi-tubes longitudinally friction stir welded. The first step, regarding the fabrication of tubes, was performed combining a conventional forming process and friction stir welding. Sheets in Al-Mg-Si-Cu alloy AA6060 T6 were adopted for this purpose. Plates having a dimension of 225x60 mm were bent (with a bending axis parallel to the main dimension) in order to obtain semi-tubes. A particular care was devoted to the fabrication of forming devices (punch and die) in order to minimize the springback effects. Semi-tubes were then friction stir welded by means of a CNC machine tool. Some preliminary tests were carried out by varying the welding parameters, namely feed rate and rotational speed. A very simple tool having flat shoulder and cylindrical pin was used. The second step of the research was based on testing the welded tubes by means of tube bulge test. A specific equipment having axial actuators with a conical shape was adopted for this study. Some analyses were carried out on the tubes bulged up to a certain pressure level. In particular, the burst pressure and the wall thickness were measured for each tested tube.

• OSTI ID: 21516709
• Journal Information: AIP Conference Proceedings, Vol. 1353, Issue 1; Conference: ESAFORM 2011: 14. international ESAFORM conference on material forming, Belfast, Northern Ireland (United Kingdom), 27-29 Apr 2011; Other Information: DOI: 10.1063/1.3589689; (c) 2011 American Institute of Physics; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALUMINIUM ALLOYS
ALUMINIUM COMPOUNDS
COPPER COMPOUNDS
CYLINDRICAL CONFIGURATION
FRICTION
MACHINE TOOLS
MAGNESIUM COMPOUNDS
MECHANICAL PROPERTIES
QUATERNARY ALLOY SYSTEMS
SILICON COMPOUNDS
SOLID SOLUTIONS
STRAINS
SURFACES
TESTING
THICKNESS
TUBES
VELOCITY
WELDED JOINTS
WELDING
ALKALINE EARTH METAL COMPOUNDS
ALLOY SYSTEMS
ALLOYS
CONFIGURATION
DIMENSIONS
DISPERSIONS
EQUIPMENT
FABRICATION
HOMOGENEOUS MIXTURES
JOINING
JOINTS
MIXTURES
SOLUTIONS
TOOLS
TRANSITION ELEMENT COMPOUNDS