Structure–performance correlation under hydrogen-assisted fatigue

Establish quantitative correlations between post-Laser Shock Peening residual-stress profiles, dislocation densities, and nanostructuring and fatigue-crack-growth parameters measured in hydrogen-containing environments, in order to determine whether the protective effects of Laser Shock Peening persist under long-term cyclic loading.

Background

Laser Shock Peening is reported to reduce hydrogen transport and delay crack initiation through deep compressive residual stresses and near-surface microstructural modification. However, most existing studies rely on permeation measurements or slow strain-rate tensile tests, which do not reproduce cumulative fatigue damage or the time-dependent evolution of stress and defect fields during service.

The review identifies a specific unresolved issue: very few studies directly connect the residual-stress state and LSP-induced defect architecture to fatigue-crack-growth curves, such as ΔK–da/dN relationships, under hydrogen exposure. Resolving this problem is necessary to assess the durability of LSP-treated hydrogen-infrastructure components under realistic cyclic loading.

References

As a result, the literature contains very few studies that quantitatively correlate residual stress state, dislocation density, and the degree of LSP-induced nanostructuring with fatigue crack growth parameters, such as Δ𝐾–𝑑𝑎/𝑑𝑁 curves measured directly in hydrogen-containing environments. The absence of such studies prevents a clear assessment of whether LSP’s protective effects persist under long-term cyclic loading.

— Laser Shock Peening in Hydrogen Environments: Coupled Stress Transport Trapping Mechanisms and Application Gaps  (2609.08469 - Gadalinska et al., 8 Sep 2026) in Section 3.4, Gap 1: Lack of quantitative structure–performance correlation under hydrogen (SSRT/fatigue)

Applying Cryo-APT to LSP-modified surface layers could provide definitive evidence as to whether compressive stresses and defect architectures truly block hydrogen migration at the nanometre scale, one of the central unresolved questions in this field.

— Laser Shock Peening in Hydrogen Environments: Coupled Stress Transport Trapping Mechanisms and Application Gaps  (2609.08469 - Gadalinska et al., 8 Sep 2026) in Section 4, Conclusions and future research directions

Important implementation questions remain, including the thermal stability of LSP-induced states.

— Laser Shock Peening in Hydrogen Environments: Coupled Stress Transport Trapping Mechanisms and Application Gaps  (2609.08469 - Gadalinska et al., 8 Sep 2026) in Section 4, Conclusions and future research directions