Prakt. Met. Sonderband 38 (2006) 251 
ito these Texture. Texture formation in the FZ was 
elements 105] examined using EBSD. Due to the coarse 
-Al solid N po -m—CMT grain size in the FZ, the scanned region by 
"ga Ne EBSD was extended up to 1x3mm?. The 
xchanical 85 EBSD analyses reveal two distinct grain 
imilar for 80 morphologies (Fig.9, CMT). From the 
rease of A kt edges with the parent material, elongated 
Ty Wr. . 
> AIMg3- 65 ; grains grow toward the weld pool, whereas 
on zone. & 60] in the weld centre the grains become more 
detected AA | equiaxed. Fig.8 is a so-called Inverse 
hardness 8 6 4 2 0 2 4 6 8 PoleFigure (IPF)-map along TD 
sumably Distance to the weld center [mm] (perpendicular to the weld line), i.e. the 
;tion of Fig.8: Microhardness profile across the welds color levels represent the crystallographic 
orientations of grains with respect to the stereographic 
standard triangle along the TD-specimen direction. From the 
IPF-map along TD it is also apparent, that a certain 
crystallographic texture exists in the FZ but it is in general not 
very sharp. Fig.10 shows the pole figures obtained for the 
entire FZ (Fig.10a) and for the elongated grains at the weld 
boundaries (Fig.10b). In both cases the (100) lattice plane is 
the texture pole, which appears tilted around the welding 
direction (WD) (a ~ 80°) and rotated around ND (8 ~ 10°). The 
(a) maximum texture strength for [010] TD 
199 19 the entire FZ amounts to 2.9. sum 
© Bol However, if the elongated 
/ @ of Bete grains at the weld boundaries 
hases PP WV are considered separately, the 
int i de texture strength increases up — 
iki to a maximum of 3.4 (Fig.10b). Fig.9: IPF-map of CMT 
183 i This kind of crystallographic ~~ weld in the transversal 
Era texture reflects the effect of the direction 
WV te — vectorial heat flow during the 
N m solidification process on the orientation of grain growth 
(b) 100 110 within the weld pool. Thus, the (100) lattice planes with the 
SP , oc lowest surface energy in case of fcc-metals will grow 
an AS Sm preferentially along the heat flow direction [8,9]. The heat 
Co © 
J 
0» 
© 3 cr 
Fig.11: Scheme of the heat flow within the fusion zone 
Fig.10: Pole figures 
obtained for the CMT weld 
flow, on the other hand, presumably occurs toward the 
three main specimen directions WD, TD and ND (fig.11) due to the low depth-to-width 
aspect ratio of the investigated welds (maximum 1.5). Thus, the true spatial arrangement 
of the vector of heat flow (hy) is defined by the magnitudes of heat flow occurring along 
WD, TD and ND. Therefore, the <100> crystal direction coincides with h; in the FZ.