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Rectilinear blocks of the very high-strength aerospace aluminum alloy 7449 were solution treated and cold water quenched. They were then stress relieved immediately by cold compression. The amount of cold compression was systematically varied from 0 to 0.3 %. The amount of plastic strain was limited to well below the industrial standard of ~2 %. The blocks then received a stabilizing aging treatment. The residual stress distribution remaining in the blocks was characterized using neutron diffraction, with the aim of tracking how the through thickness 3-D residual strains and stresses change as cold compression progresses. Stress relief was of the order of 30–50 %, but there was no discernible systematic increase in stress relief as the plastic deformation magnitude was increased. It is suggested that this is mainly due to the differences between the samples being less than the experimental uncertainty of the neutron diffraction strain measurement technique.

A deep rolling process was applied on 4140H steel specimens with a self-built loading frame and investigated in situ with neutron radiation using the SALSA instrument at the Institut Laue-Langevin (ILL). A neutron diffraction stress imaging approach was developed and used to determine material changes from the surface up to several millimeters inside the material by single expositions. The strains could be evaluated as deviations of the diffraction signal along the height of an area detector, and the theoretical maximum depth resolution was given by geometrical magnification together with the detector pixel size. The results of these experiments together with complementary post-process investigations could be used to link the internal load during the process with resulting material modifications such as the generated residual strains.

A round robin benchmark weldment, denoted TG6, from the European Network on Neutron Techniques Standardization for Structural Integrity (NeT), offers the ability to test the technique of residual stress determination using neutron diffraction to an extreme. This test component comprises a 200 mm by 150 mm by 12 mm rectangular base plate made from Inconel 600 with three passes of Alloy 82 weld metal deposited in a slot of length 76 mm. This not only has large grain issues in the weld region but a large interplanar spacing variation caused by high strain gradients and a change in material composition. Because of the high absorption of neutrons in the Inconel 600 within the gauge volume, there is a large difference between the instrumental gauge volume IGV (which is the volume of space defined by the neutron beam paths through the defining apertures, taking into account properties of the beam) compared with the sampled gauge volume SGV (which is the intersection of the IGV with the sample that takes into account the absorption of the neutrons). The relative shift in position of the center of gravity of measurement (when the gauge volume is fully immersed in the sample) has been observed to be significant, for example, ∼0.3 mm, using 1 by 1 by 5 mm3 defining optics (where 5 mm is the gauge volume height) and increases approximately proportionally with larger gauge volumes dimensions in the horizontal plane. The magnitude of this shift depends upon many parameters. Measuring the sample and rotating 180° and measuring again, taking the average is another way one can eliminate this absorption effect. This novel approach is compared with three neutrons instruments on the same sample.

Low transformation temperature (LTT) weld filler materials offer an attractive alternative to cost intensive postweld treatments as they can mitigate detrimental welding residual stresses during the welding process. Compared to conventional weld filler materials, LTT alloys are characterized by a delayed martensite transformation at low temperatures, which can result in compressive residual stresses in the weld. The high strength of these filler materials makes them potentially applicable to high-strength steels as well as for a large amount of requested repair works in steel structures. The focus of the study is on the confirmation of the LTT idea with regard to the residual stress state for multipass weld lines processed by metal active gas welding. It is demonstrated that the contour method is a well-suited technique for measuring the residual stress in the weld joint as it gives an entire two-dimensional map of the residual stress state in the weld line, heat affected zone (HAZ), and base material. The technique was applied at different LTT alloys with varying chemical compositions. Additionally, the results are compared to residual stress maps that were determined by neutron diffraction using the Strain Analyzer for Large Scale Engineering Applications, an instrument referred to as SALSA, at the Institut Laue-Langevin in Grenoble. For all investigated specimens, compressive residual stress distributions were determined in the area of the weld joint and the HAZ. They are balanced by tensile residual stresses in the surrounding base material. However, it is shown that the size of the region exhibiting compressive residual stresses and the absolute values of the compressive residual stresses depend on the chemical composition of the weld filler material.