Case study #1 (Tool: AustCoat v3a, Mar 2026): FeCrAl Laser-Clad Coating on 316L

The tool’s forward and inverse optimization converge independently on the same design region: 520 μm, Al 6.5 wt%, dilution ≤20%. This self-consistency confirms the model’s trend surface is stable. At this thickness the oxidation-limited lifetime scales with the available Al reservoir while remaining within a mechanically interrogable regime, allowing stress effects to be experimentally resolved rather than assumed negligible. The associated nominal lifetime of ~32,000 h at 600 °C in oxygen-controlled LBE is the model’s prior-only upper estimate, not a calibrated prediction; the operative planning range is the prior 95% CI of 15,000–33,000 h, derived from UQ sampling over physically reasonable parameter distributions. The experimental campaign is the calibration step that converts this range into a validated posterior. The 6.5 wt% Al anchor is set conservatively below the α’ embrittlement regime for future irradiated service compatibility.

Two physical mechanisms are the priority experimental targets. First, dilution control at the interface: the tool predicts Al_eff remains above the 4–5 wt% α-Al₂O₃ stability threshold, as established for FeCrAl alloys in the literature, across the full 5–20% dilution range at the anchor composition. Confirmation requires post-exposure cross-sectioning and interfacial composition profiling, and samples should explicitly span the GO/NO-GO boundary rather than target only the nominal design point. Second, oxygen potential stability: the process window map confirms steadystate chemistry compliance across the swept O₂ × dilution space. Subject to loop instrumentation capability, coupon exposure should include monitored oxygen activity excursions to test repassivation capacity under transient conditions; if transient control is unavailable, steady-state compliance confirmation remains the fallback objective.

The dominant unresolved uncertainty is spallation risk, where the prior 95% CI spans 5.5% to 74.5%. Until the spallation term is calibrated, lifetime outputs are scenario projections, not engineering forecasts, and this uncertainty cannot be narrowed computationally. Stress validation requires FEM with actual geometry; the analytical approximation flags a residual stress concern at 520 μm. A single coupon at the anchor specification, intended to establish the reference adhesion and residual stress point, with oxide adhesion measurement and residual stress characterization by XRD sin²ψ taken both as-deposited and post-exposure, constitutes the minimum dataset needed to calibrate this term and enable a posterior rerun. Lifetime sensitivity to kinetic parameters will become resolvable at that stage; in prior-only mode variance is dominated by the spallation term. The experimental intent is not to fully characterize adhesion statistics in this phase, but to collapse the prior spallation probability interval through measured stress–adhesion coupling, thereby reducing posterior lifetime variance by directly constraining the dominant uncertainty term.

The governing experimental question is not whether 520 μm is thick enough. It is whether interfacial Al concentration is reliably maintained above the alumina-forming threshold under the specified deposition and service conditions, and whether the oxide layer formed remains adherent across thermal cycles.

What’s needed: agreement of coupon deposition specification and as-deposited characterisation requirements including XRD sin²ψ; agreement of LBE exposure conditions spanning the GO/NO-GO dilution boundary; agreement of post-exposure characterisation protocol covering cross-section, EDX interfacial composition profiling, and oxide adhesion measurement; provisional scoping of data ingestion into the tool calibration routine and posterior UQ rerun pending experimental outcomes. The tool’s priors being tested against experimental conditions would be the first step toward a calibrated model. Dedicated coupon exposure, if pursued, constitutes the validation campaign.

Cornacchia, G. (2026). FeCrAl laser cladding on austenitic steel in lead-cooled fast reactor service: a physics-first screening framework. Zenodo. https://doi.org/10.5281/zenodo.19249816