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<p>Despite its relevance to engineering design, fatigue life assessment of additively manufactured materials subjected to variable-amplitude loading remains insufficiently understood. This paper investigates the fatigue response of L-PBF-processed maraging steel subjected to strain-controlled variable-amplitude loading. The loading sequences consisted of three increasing levels followed by three decreasing levels, repeated up to failure. Strain amplitudes varying from 0.175 to 1.0%, covering a representative spectrum of cyclic deformation levels, were investigated. The cyclic stress-strain response under variable-amplitude loading was modelled with an elasto-plastic constitutive model. A numerical framework combining well-known fatigue damage parameters along with classical and modified cumulative damage laws was developed to estimate the fatigue lifetime. In addition, EBSD and SEM observations were carried to investigate the effect of strain level on failure mechanisms and grain misorientation. Regarding the proposed methodology for fatigue life assessment, Miner’s law combined with the SWT model effectively predicted the fatigue lifetime, contributing to the safe and optimised design of additively manufactured components and structures. In addition, local deformation patterns and dislocation density tend to intensify with increasing strain amplitudes, while the fracture mode changes from ductile to mixed-mode characteristics as the strain level decreases.</p>

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Fatigue behaviour and life prediction of L-PBF-processed maraging steel under variable-amplitude loading

  • 期刊论文

  • 发表日期：

    2026年1月8日

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  • R. Branco,
  • Z. Marciniak,
  • P. Prates,
  • B. Das,
  • R. F. Martins,
  • C. Malça

摘要

Despite its relevance to engineering design, fatigue life assessment of additively manufactured materials subjected to variable-amplitude loading remains insufficiently understood. This paper investigates the fatigue response of L-PBF-processed maraging steel subjected to strain-controlled variable-amplitude loading. The loading sequences consisted of three increasing levels followed by three decreasing levels, repeated up to failure. Strain amplitudes varying from 0.175 to 1.0%, covering a representative spectrum of cyclic deformation levels, were investigated. The cyclic stress-strain response under variable-amplitude loading was modelled with an elasto-plastic constitutive model. A numerical framework combining well-known fatigue damage parameters along with classical and modified cumulative damage laws was developed to estimate the fatigue lifetime. In addition, EBSD and SEM observations were carried to investigate the effect of strain level on failure mechanisms and grain misorientation. Regarding the proposed methodology for fatigue life assessment, Miner’s law combined with the SWT model effectively predicted the fatigue lifetime, contributing to the safe and optimised design of additively manufactured components and structures. In addition, local deformation patterns and dislocation density tend to intensify with increasing strain amplitudes, while the fracture mode changes from ductile to mixed-mode characteristics as the strain level decreases.