In response to the development of new materials and the application of materials and components in advanced technologies, non-destructive measurement methods of textures and residual stresses have gained worldwide significance in recent years. The materials science neutron diffractometer STRESS-SPEC at FRM II (Garching, Germany) is designed to be applied equally to texture and residual stress analyses by virtue of its very flexible configuration. Due to the high penetration capabilities of neutrons and the high neutron flux of STRESS-SPEC it allows a combined analysis of global texture, local texture, strain pole figure and FWHM pole figure in a wide varity of materials including metals, alloys, composites, ceramics and geological materials. Especially, the analysis of texture gradients in bulk materials using neutron diffraction has advantages over laboratory X-rays and EBSD for many scientific cases. Moreover, neutron diffraction is favourable for coarse grained materials, where bulk information averaged over texture inhomogeneities is needed, and also stands out due to easy sample preparation. In future, the newly developed robot system for STRESS-SPEC will allow much more flexibility than an Eulerian cradle as on standard instruments. Five recent measurements are shown to demonstrate the wide range of possible texture applications at STRESS-SPEC diffractometer.
Weld filler alloys that exploit transformation plasticity through low austenite to martensite transformation temperatures offer an effective method of reducing residual stresses in strong steel welds. However, in multipass welds, the heat input from later weld passes may be insufficient to retransform prior welding passes, leading to the accumulation of thermally induced strains and elevated residual stresses. In this work, the residual stress distributions produced around arc welds fabricated with a martensitic weld filler alloy that transforms at a low temperature have been studied as a function of the number of passes deposited and the interpass temperature. It is found that when the interpass temperature is above the transformation temperature of the weld metal, the entire multipass weld transforms as a single entity, thus permitting the optimum exploitation of the transformation plasticity. In contrast, the deposition of new metal with a relatively low interpass temperature leads to increased residual stresses in the underlying layers, reducing or eliminating the beneficial stress states previously created.
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