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Materialien/Werkstoffe Poster: Do., 13:00–15:30 D-P402
Characterization of friction stir welded aluminium matrix joints using synchrotron
radiation
Alicja Skrzypinska 1 , Walter Reimers 1
1 TU Berlin, Sekr. BH18, Institut für Werkstoffwissenschaften und -technologien, Metallische
Werkstoffe, Ernst-Reuter-Platz 1, 10587 Berlin
Fig. 1: 2D stress
distribution
image for aluminium
phase in
dissimilar joint
of Al-MMC
Friction Stir Welding is a solid state joining process, in which a cylindrical
shouldered tool with a profiled pin is inserted into the joint line
between two pieces of material. Frictional heat is created between the
wear resistant pin and two work pieces, which are butted together
and clamped onto a backing bar. The heat causes the materials to
soften, without reaching melting point, and allows the rotating pin
to traverse along the joint.
In the study here presented the following friction stir weldings were
investigated: Al reinforced by SiC (similar joints) and Al-SiC welded
with Al (dissimilar joints). These materials are difficult to weld because
of the irregular distribution of silicon carbide particles in the
weld. These heterogeneity may also cause complicated residual stress
distributions in cross-sections of the weld, so the study aims at the
determination of the particle distributions and stress fields in these
weldings.
In addition to conventional synchrotron x-ray diffraction measurements using point
collimators, measurements with the capillary detector set up were performed at the
diffractometer G3, HASYLAB [1]. Here with an area of 5mm x14mm can be investigated
at one time with resolution of 13µm. As result a 2D image (Fig.1) with the
near-surface stress distribution is obtained.
Simultaneously the 2D-image shows the particle distribution. The differences in the
particle distribution in dissimilar weldings with MMC on advancing and retreating side
are presented and explained. Maximum tensile stresses of 220 MPa are formed in the
weld zone.
[1] Th. Wroblewski et. al., Nucl. Inst. Met. Phys Res., A 428 (1999) 570
The authors would like to acknowledge S. Dallkilic and G. Biallas of Deutsches Zentrum
für Luft- und Raumfahrt e.V. (DLR) in der Helmholtzgemeinschaft for sample
preperation.