Material mechanisms of the nanostructured metallic multilayer post-weld treatment for fatigue strength increase

While traditional post weld treatments intend to reduce the fatigue failure potential by changing the weld seam geometry, introduction of compressive residual stresses and shielding off environmental impacts, the novel nanostructured metallic multilayer (NMM) post-weld treatment covers all three mechanisms simultaneously. NMM offer combined high strength and ductility and a significantly enhanced fatigue resistance. In a recent study a strong enhancement in fatigue resistance was detected. Utilizing energy-dispersive X-Ray diffraction techniques at the P61A-beamline at the German Synchrotron (DESY), it was found that residual stresses generated during the deposition process play a crucial role in this enhancement. Specifically, tensile stresses within the nanolaminate induce beneficial compressive stresses in the underlying substrate, effectively inhibiting fatigue crack initiation and resulting in an unprecedented increase in fatigue strength. NMM treatment of the double-V weld increases the fatigue strength from FAT class 80 to 225. This paper investigates which process parameters optimize the compressive stress profile in the steel base material, paving the way for the NMM post-weld treatment to reliably and economically contribute to longevity of cyclically loaded metal infrastructure.

Subjects

fatigue

lifetime extension

electrodeposition

NMM

XRD

thin film

multilayer

DDC Class

620.11: Engineering Materials

Lizenz

https://creativecommons.org/licenses/by-nc-nd/4.0/

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publishedVersion

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1-s2.0-S2452321625005682-main-1.pdf

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Material mechanisms of the nanostructured metallic multilayer post-weld treatment for fatigue strength increase