Residual stress determination in a thick ferritic steel weld plate using neutron diffraction

Abstract

The distribution of residual stresses was determined through the thickness of a 50-mm thick ferritic steel weld plate using (110) and/or (211) diffraction peaks. We proposed a two-peak combined methodology, which uses (110) and (211) peaks designed to have neutron wavelengths of 2.39 and 1.55 Å , respectively, in order to locate the neutron cross-section at each local minimum. The result shows that the available penetration path length can be maximized by (110) diffraction for the transmission geometry and (211) diffraction for the reflection geometry of the plate specimen. Furthermore, the stress components by the two peaks were similar to the results of the conventional one-peak measurement due to the same diffraction elastic constants between the (110) and (211) peaks in the bcc ferritic steel. Such appropriately combined twopeak method can significantly enhance the deep penetration capability for the determination of residual stresses in an extra thick steel plate specimen.

A utilização da difração de neutrões na determinação do perfil de tensões residuais em revestimentos por soldadura

“…A Figura 8 mostra que na zona de interface entre a austenite e a ferrite há alguma discrepância entre as tensões obtidas de um e outro lado da interface, a qual pode ser atribuída em parte ao microestruturas de estruturas aí presentes. Embora já existam algumas publicações sobre a determinação de tensões residuais em soldaduras com recurso à técnica de difração de neutrões [19,20], a utilização desta técnica em revestimentos por soldadura está ainda pouco documentada. Contudo, encontrou-se um artigo recente [21], sobre um aço inoxidável austenítico revestido por soldadura com aço ferrítico, o que representa a situação inversa da aqui estudada, onde se observou que as tensões residuais medidas na interface apresentavam discrepâncias similares.…”

Revealing the residual stress distribution in laser welded Eurofer97 steel by neutron diffraction and Bragg edge imaging

“…The lattice spacings corresponding to crystal planes {211} was used to calculate the residual stress, as such crystal plane is recommended to represent the residual stress on the macro-scale for body centred cubic structures [47,48]. The {110} crystal plane that has the highest intenstity over the peaks is also analysed to cross-validate the results from the neutron diffraction and NBEI.…”

A novel approach for nondestructive depth-resolved analysis of residual stress and grain interaction in the near-surface zone applied to an austenitic stainless steel sample subjected to mechanical polishing

“…The stresses in polycrystalline materials are usually inhomogeneous, therefore experimental methods allowing for the determination of their spatial distribution are particularly desirable. Experimental techniques based on neutron diffraction enable the measurements of the stress variation in large elements by scanning across the sample over distances of tens of mm with a resolution down to about one millimeter or even less (resolution is equal to the size of the gauge defined by the slip systems and/or collimators forming the incident and diffracted beam [13,29,30]). This can be done due to low absorption of neutron radiation in many materials, including metals.…”