![Sample our Physical Sciences journals, sign in here to start your FREE access for 14 days]({"type":"image" , "src" : "/sda/110819/TOC-Subject-Sample-2021-Physical-Sciences.jpg"})
Abstract
Neutron and synchrotron radiation have been employed to create 2D maps of the variation of strains and the unstrained lattice spacing d 0 in longitudinal and transverse direction over a cross-section of a friction stir weld (FSW) of an aluminium alloy AA-2024. Strains have been measured directly in the FSW using neutrons. The variation of the unstrained lattice parameter has been measured with synchrotrons on specially prepared stress-relaxed 'combs' of the original weld. The variation of d 0 across the weld varies on the same scale as the strains on a magnitude of ∼1000 μ;epsilon; thus influencing greatly the magnitude of inferred residual stresses in the sample. Both the d 0 variation and strain map show detailed features reflecting the characteristic microstructure generated during the welding process. In particular, they are asymmetric about the weld centre-line. The dominant longitudinal residual stress field is tensile beneath the edge of the tool and compressive in the weld centre-line. Transverse stresses are smaller by a factor of 3 and tend to be compressive. Stresses measured by diffraction agree well with results from conventional holedrilling performed in the same sample.