Measurement of the residual stress field in MIG-welded Al-2024 and Al-7150 aluminium alloy compact tension specimens

Neutron diffraction has been used to measure the residual-stress field in MIG-welded Al-2024 and Al-7150 aluminium alloy compact-tension (CT) specimens. The measurements were made on the POLDI time-of-flight diffractometer, which uses a multiple frame overlap method. Strains in the three principal directions of each specimen were determined from the measured lattice plane spacing as a function of position through the weld relative to stress-free reference lattice plane spacings obtained from a comb-like reference sample. The resultant calculated residual stresses are compared to those existing in the original welded plate from which the specimens were machined.