Crystal orientation in nugget zone of friction stir welded 5083 aluminum alloy plates

The cold rolled 5083 aluminum alloy plates were welded by friction stir welding(FSW). The characteristics of grains orientation evolution in FSW nugget zone(NZ) was researched by electron backscatter diffraction(EBSD) and orientation imaging microscopy(OIM) with analyzing grain characterization, misorientation distribution, textures distribution and orientation distribution function(ODF). The results show that the dynamic recrystallization occurred in NZ due to the effect of heat and deformation which caused a severe plastic flow. Crystal in nugget zone appears to be equiaxed grain with average size 15.8μm, and fraction of high angle grain boundaries(HAGB) appreciably increased. In the base metal, there were strong Brass texture 011 <211> and S texture 123 <634> that total fractions were above 30.6% and 13.6%, respectively. Conversely, after FSW, B and S textures in the NZ were obviously weakened as total fraction of only 4% and 1.8%, respectively. Furthermore, although the fraction of R texture 124 <211> caused by in-situ recrystallization is up to 7.7%, other common textures in face centered cubic(FCC) metal were weak in the NZ, and every fractions was also below 8%, which means that strong orientation turned into weak orientation in nugget zone.