Report v1 · Case #1

# Failure Investigation Report — hhhuukk
**Status:** DRAFT | **Generated:** 2026-06-20 13:31 UTC | **Case #1** | **Run #1**
**Knowledge pack:** mtis_met_tax_cards v0.1.0 — approval status: **ai_generated_draft**

> **DRAFT — engineering decision-support output.** This report was produced with AI assistance and a knowledge pack whose approval status is shown above. It is not an expert opinion and must be reviewed by a qualified engineer before any reliance. Confidence ratings indicate strength of supporting evidence, not probability.

> **Liability declaration (DRAFT — not yet legally checked).** This report is a draft, AI-assisted decision-support output of the MTIS Failure Investigator. It is **not professional engineering advice and not an expert opinion**, and must be reviewed and verified by a suitably qualified engineer before any reliance or action. Findings are based solely on the information entered and on a knowledge base still under expert review. Confidence ratings indicate strength of supporting evidence, **not probability or certainty**. [MTIS legal entity] accepts no liability for any decision taken on the basis of this output.

## Case details
- Component: sdfsdf
- Material: not stated
- Mode: standard
- Description: The dam thing broke when it was loaded for the first time, probably because it was designed by claude code.

## Methodology
Structured claim-based investigation. Claims were admitted per the evidence status model; the deterministic diagnostic engine matched claims to pack indicators; confidence per the documented model (S, K, C, M, B dimensions). At Diagnose, adaptive questioning selected the next most-discriminating indicator until a mode reached high confidence or candidates were exhausted.

## Evidence claims used in this run
- [C1] (Description / narrative — EV-DESC, user_entered, status: user_entered_fact) The dam thing broke when it was loaded for the first time, probably because it was designed by claude code.
- [C2] (Service history — EV-SERVICE, ai_extracted, status: approved) The component broke when it was loaded for the first time.
- [C3] (Design data — EV-DESIGN, ai_extracted, status: approved) The failure is attributed to it being designed by claude code.
- [C4] (Material specification — EV-MATSPEC, user_entered, status: user_entered_fact) Material specification and certification status? — Answer: steel
- [C5] (Design data — EV-DESIGN, user_entered, status: user_entered_fact) Design loads and duty cycle vs actual service loads? — Answer: 140% of the design load
- [C6] (Manufacturing records — EV-MFGREC, user_entered, status: user_entered_fact) Manufacturing route incl. welding, plating, heat treatment records? — Answer: Rolling
- [C7] (Loading & stress — EV-LOAD, user_entered, status: user_entered_fact) Loading character: steady/cyclic/impact; known vibration? — Answer: Dropped
- [C8] (Maintenance & lubrication — EV-MAINT, user_entered, status: user_entered_fact) Maintenance and inspection history incl. lubrication? — Answer: None it was new
- [C9] (Macro / visual examination — EV-MACRO, user_entered, status: user_entered_fact) Macro fracture description: deformation, zones, origin location? — Answer: One large crack running the entire length with no evidnce of plastic deformation
- [C10] (Fracture-surface examination (fractography) — EV-FRACTO, user_entered, status: user_entered_fact) Fracture surface features: beach marks, chevrons, dimples, facets? — Answer: smooth sharp fracture surfaces
- [C11] (Corrosion products / deposits — EV-CORRPROD, user_entered, status: user_entered_fact) Corrosion: pits, products, thinning measurements? — Answer: no
- [C12] (Dimensional measurements — EV-DIM, user_entered, status: user_entered_fact) Wear: scoring, debris, dimensional loss at contacts? — Answer: no
- [C13] (Microscopy / metallography — EV-MICRO, user_entered, status: user_entered_fact) Secondary cracking present? Branched? — Answer: no
- [C14] (Chemical composition — EV-CHEM, user_entered, status: user_entered_fact) Lab results: chemistry, hardness, microstructure vs spec? — Answer: steel contained Mn and S

## Candidate failure modes
*Confidence is evidence support for this mode — NOT a probability.*
### Thermal-mechanical fatigue — Confidence 80.0/100 (High)
**Supporting evidence present:**
- Network or surface cracks (claims: C10)
- crack orientation related to thermal stress (claims: C9, C13)
- service temperature cycles (claims: C5)
**Evidence missing:**
- oxide-filled cracks (would come from Corrosion products / deposits)
**Suggested test / examination to raise certainty:**
- Corrosion-product / deposit analysis (EDS / XRD)

### Fretting fatigue cracking — Confidence 80.0/100 (High)
**Supporting evidence present:**
- Dark fretting debris (claims: C12)
- contact scar (claims: C12)
- crack at contact edge (claims: C9, C12, C13)
**Evidence missing:**
- multiple shallow origins (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component

### Bending fatigue — Confidence 75.0/100 (High)
**Supporting evidence present:**
- Semi-elliptical surface origin (claims: C9, C10)
- crack front marks (claims: C9, C10, C13)
**Evidence missing:**
- final overload opposite origin (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component

### Ammonia SCC — Confidence 75.0/100 (High)
**Supporting evidence present:**
- Intergranular/transgranular cracking (claims: C13)
- blue/green corrosion products possible (claims: C11)
**Evidence missing:**
- residual stress source (would come from Service environment)
**Suggested test / examination to raise certainty:**
- Service-environment chemistry review or sampling

### Polythionic acid SCC — Confidence 75.0/100 (High)
**Supporting evidence present:**
- Intergranular cracking in sensitised HAZ/base metal (claims: C13)
- refinery shutdown history (claims: C8)
**Evidence missing:**
- sulphide/acid conditions (would come from Corrosion products / deposits)
**Suggested test / examination to raise certainty:**
- Corrosion-product / deposit analysis (EDS / XRD)

### Scuffing / scoring — Confidence 75.0/100 (High)
**Supporting evidence present:**
- Longitudinal score marks (claims: C10)
- smeared/overheated surfaces (claims: C10)
**Evidence missing:**
- rapid damage onset (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component

### Galling — Confidence 73.3/100 (High)
**Supporting evidence present:**
- Severe torn surfaces (claims: C10)
- seizure marks (claims: C10)
- high friction history (claims: C8)
**Evidence missing:**
- transfer lumps (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component

### VHCF — Confidence 66.7/100 (Moderate)
**Supporting evidence present:**
- Internal fish-eye origin (claims: C9)
- little surface initiation (claims: C10)
**Evidence missing:**
- fine granular area (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component

### Creep crack initiation/growth — Confidence 66.7/100 (Moderate)
**Supporting evidence present:**
- Intergranular cracking (claims: C13)
- time-dependent crack extension (claims: C9, C13)
**Evidence missing:**
- creep cavities ahead of crack (would come from Microscopy / metallography)
**Suggested test / examination to raise certainty:**
- Metallographic sectioning and microscopy

### LME — Confidence 66.7/100 (Moderate)
**Supporting evidence present:**
- Intergranular or brittle crack path (claims: C9, C13)
- rapid cracking during contact (claims: C12, C13)
**Evidence missing:**
- liquid metal residue (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component

### Low-cycle fatigue — Confidence 65.0/100 (Moderate)
**Supporting evidence present:**
- Multiple crack origins (claims: C9, C13)
- plastic strain marks (claims: C10)
- transgranular cracking (claims: C13)
- rapid crack growth after cyclic plasticity (claims: C9, C13)
**Contradicting evidence:**
- Very high cycle count with elastic stress only (claims: C5)

### Wear (adhesive/abrasive) — Confidence 65.0/100 (Moderate)
**Supporting evidence present:**
- Surface material loss, scoring, grooves, galling or polishing at contact surfaces (claims: C12)
- Wear debris in lubricant or assembly (claims: C12)
- Lubrication deficiency (starvation, degradation, wrong lubricant, dry running) (claims: C8)
**Evidence missing:**
- Dimensional loss at contact surfaces beyond tolerance (would come from Dimensional measurements)
- Abrasive contamination present (sand, dust, grit) (would come from Service environment)
**Suggested test / examination to raise certainty:**
- Dimensional / wall-thickness survey
- Service-environment chemistry review or sampling
- Surface examination
- Dimensional survey
- Lubricant/debris analysis
- Hardness

### Fretting wear — Confidence 60.0/100 (Moderate)
**Supporting evidence present:**
- Dark oxide debris (claims: C12)
- polished/rough contact scar (claims: C12)
**Evidence missing:**
- shallow pits (would come from Macro / visual examination)
- stick-slip boundary (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component

### Plating-induced hydrogen embrittlement — Confidence 60.0/100 (Moderate)
**Supporting evidence present:**
- Delayed brittle fracture after plating (claims: C9, C10)
- intergranular/quasi-cleavage features (claims: C10)
- high hardness (claims: C14)
- plating history (claims: C6, C8)
**Evidence missing:**
- Delayed brittle fracture after plating (would come from Coating / protection records)
**Suggested test / examination to raise certainty:**
- Coating / protection system review

### Torsional shear fracture — Confidence 53.3/100 (Moderate)
**Supporting evidence present:**
- Spiral fracture (claims: C9, C10)
- dimpled shear features (claims: C10)
**Evidence missing:**
- shear lips (would come from Macro / visual examination)
- plastic twisting (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component

### High-temperature hydrogen attack — Confidence 53.3/100 (Moderate)
**Supporting evidence present:**
- Decarburised zones (claims: C9)
- intergranular cracking/blisters (claims: C13)
**Evidence missing:**
- methane fissures (would come from Macro / visual examination)
- loss of strength (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component

### Alpha-prime embrittlement — Confidence 48.0/100 (Moderate)
**Supporting evidence present:**
- Hardness/toughness change (claims: C14)
- brittle fracture (claims: C9, C10)
- thermal exposure record (claims: C6)
**Evidence missing:**
- Hardness/toughness change (would come from Hardness)
- phase decomposition evidence (would come from Microscopy / metallography)
**Suggested test / examination to raise certainty:**
- Hardness survey across the section
- Metallographic sectioning and microscopy

### Weld-toe fatigue — Confidence 45.0/100 (Moderate)
**Supporting evidence present:**
- Crack at weld toe/root (claims: C9, C13)
- beach marks (claims: C10)
**Evidence missing:**
- Crack at weld toe/root (would come from Welding records)
- lack-of-fusion or undercut as initiator (would come from Welding records)
**Suggested test / examination to raise certainty:**
- Welding record review

### Coating cracking — Confidence 45.0/100 (Moderate)
**Supporting evidence present:**
- Crack network in coating (claims: C9, C13)
- substrate corrosion at cracks (claims: C11)
**Evidence missing:**
- Crack network in coating (would come from Coating / protection records)
- thermal mismatch pattern (would come from Operating conditions)
**Suggested test / examination to raise certainty:**
- Coating / protection system review
- Operating-condition data review

### Ratcheting — Confidence 44.4/100 (Moderate)
**Supporting evidence present:**
- Incremental dimensional growth (claims: C12)
- local thinning (claims: C11)
**Evidence missing:**
- ovalisation (would come from Macro / visual examination)
- bulging (would come from Macro / visual examination)
- fatigue may follow (would come from Loading & stress)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component
- Loading / stress review or analysis

### Plastic collapse — Confidence 41.7/100 (Moderate)
**Supporting evidence present:**
- Gross deformation before rupture (claims: C9)
**Evidence missing:**
- hinge lines (would come from Macro / visual examination)
- collapse shape consistent with limit load (would come from Loading & stress)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component
- Loading / stress review or analysis

### Intergranular brittle fracture — Confidence 41.7/100 (Moderate)
**Supporting evidence present:**
- Faceted grain-boundary surface (claims: C10)
**Evidence missing:**
- rock-candy morphology (would come from Macro / visual examination)
- grain-boundary precipitates or cavities (would come from Microscopy / metallography)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component
- Metallographic sectioning and microscopy

### Torsional fatigue — Confidence 41.7/100 (Moderate)
**Supporting evidence present:**
- Helical or 45-degree crack path (claims: C9, C13)
**Evidence missing:**
- shear-mode initiation (would come from Macro / visual examination)
- final torsional overload zone (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component

### Chloride SCC — Confidence 41.7/100 (Moderate)
**Supporting evidence present:**
- Branched transgranular cracks in austenitic stainless steels (claims: C13)
**Evidence missing:**
- chloride deposits (would come from Corrosion products / deposits)
- heat-transfer concentration sites (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Corrosion-product / deposit analysis (EDS / XRD)
- Macro / visual examination of the fracture and component

### Droplet impingement erosion — Confidence 41.7/100 (Moderate)
**Supporting evidence present:**
- Impact pits (claims: C7)
**Evidence missing:**
- leading-edge roughening (would come from Macro / visual examination)
- directional erosion pattern (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component

### Tribocorrosion — Confidence 41.7/100 (Moderate)
**Supporting evidence present:**
- Wear scar with corrosion products (claims: C11)
**Evidence missing:**
- repassivation damage (would come from Macro / visual examination)
- accelerated loss versus wear/corrosion alone (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component

### Type II hot corrosion — Confidence 41.7/100 (Moderate)
**Supporting evidence present:**
- Pitting-like hot corrosion (claims: C11)
**Evidence missing:**
- sulphate deposits (would come from Corrosion products / deposits)
- attack at temperature/deposit-prone zones (would come from Corrosion products / deposits)
**Suggested test / examination to raise certainty:**
- Corrosion-product / deposit analysis (EDS / XRD)

### Nitridation / chlorination — Confidence 41.7/100 (Moderate)
**Supporting evidence present:**
- Nitride/halide products (claims: C11)
**Evidence missing:**
- internal attack (would come from Macro / visual examination)
- embrittlement or accelerated wastage (would come from Dimensional measurements)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component
- Dimensional / wall-thickness survey

### Corrosion (general/pitting/crevice) — Confidence 34.4/100 (Low)
**Supporting evidence present:**
- General wall thinning or measurable metal loss (claims: C11)
- Pitting or crevice attack on surfaces (claims: C11)
**Evidence missing:**
- Corrosive service environment (chlorides, acids, moisture, seawater) (would come from Service environment)
- Corrosion products/deposits present (rust, scale, oxide) (would come from Corrosion products / deposits)
- Protective coating or cathodic protection breakdown (would come from Coating / protection records)
**Suggested test / examination to raise certainty:**
- Service-environment chemistry review or sampling
- Corrosion-product / deposit analysis (EDS / XRD)
- Coating / protection system review
- Corrosion product analysis
- Dimensional/thickness survey
- Environment chemistry

### Slurry erosion — Confidence 30.0/100 (Low)
**Supporting evidence present:**
- Thinning/grooving at flow changes (claims: C11)
- particle impact features (claims: C7, C10)
- corrosion products if synergistic (claims: C11)
**Contradicting evidence:**
- Stagnant corrosion under deposit without erosive flow (claims: C11)

### Hot tearing — Confidence 30.0/100 (Low)
**Supporting evidence present:**
- Interdendritic crack surfaces (claims: C9, C10, C13)
- oxidised crack surfaces (claims: C9, C10, C13)
- location at constrained sections (claims: C9)
**Contradicting evidence:**
- Service fatigue crack with beach marks (claims: C5, C10)

### Necking — Confidence 29.2/100 (Low)
**Supporting evidence present:**
- cup-and-cone fracture association (claims: C9, C10)
- dimples if fractured (claims: C10)
**Evidence missing:**
- Local area reduction (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component

### Resonance-induced fatigue — Confidence 29.2/100 (Low)
**Supporting evidence present:**
- fatigue beach marks (claims: C10)
- service vibration history (claims: C5, C7, C8)
**Evidence missing:**
- Multiple origins at high-stress points (would come from Loading & stress)
**Suggested test / examination to raise certainty:**
- Loading / stress review or analysis

### Stress-oriented HIC — Confidence 29.2/100 (Low)
**Supporting evidence present:**
- crack orientation stress-related (claims: C9, C13)
- sour-service history (claims: C8)
**Evidence missing:**
- Array of small cracks linking through wall (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component

### Strain-age embrittlement — Confidence 29.2/100 (Low)
**Supporting evidence present:**
- brittle fracture tendency (claims: C9, C10)
- strain-age thermal history (claims: C8)
**Evidence missing:**
- Increased yield/ductility loss (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component

### Fatigue — Confidence 27.8/100 (Low)
**Supporting evidence present:**
- Beach marks (crack arrest lines) on fracture surface (claims: C10)
- Cyclic/vibratory/rotating service loading (claims: C7)
**Evidence missing:**
- Fatigue striations visible under SEM (would come from Fracture-surface examination (fractography))
- Ratchet marks indicating multiple initiation sites (would come from Fracture-surface examination (fractography))
- Initiation at stress concentration (fillet, keyway, thread, hole, weld toe, notch) (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- SEM fractography of the fracture surface
- Macro / visual examination of the fracture and component
- SEM fractography
- Macro examination of origin
- Stress analysis
- Hardness

### Uniform corrosion — Confidence 23.3/100 (Low)
**Supporting evidence present:**
- corrosion products (claims: C11)
- predictable corrosion allowance consumption (claims: C11)
**Evidence missing:**
- Relatively even wall loss (would come from Dimensional measurements)
- thickness reduction (would come from Dimensional measurements)
**Suggested test / examination to raise certainty:**
- Dimensional / wall-thickness survey

### Two-body abrasive wear — Confidence 23.3/100 (Low)
**Supporting evidence present:**
- cutting/ploughing marks (claims: C10)
- wear debris (claims: C12)
**Evidence missing:**
- Parallel grooves (would come from Macro / visual examination)
- directionality (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component

### Quench cracking — Confidence 22.0/100 (Low)
**Supporting evidence present:**
- Cracks at sharp corners/section changes (claims: C10)
- high hardness (claims: C14)
- no service crack-growth marks (claims: C5, C10)
**Contradicting evidence:**
- Fatigue striations from service cycles (claims: C5)
**Evidence missing:**
- brittle appearance (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component

### Corrosion-fatigue cracking — Confidence 21.7/100 (Low)
**Supporting evidence present:**
- Fatigue features with corrosion products (claims: C10, C11)
**Contradicting evidence:**
- Dry inert service (claims: C5)
**Evidence missing:**
- multiple origins at pits (would come from Macro / visual examination)
- reduced life versus air (would come from Macro / visual examination)
- branching may occur (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component

### Dynamic overload fracture — Confidence 20.0/100 (Low)
**Supporting evidence present:**
- Deformation pattern aligned with impact (claims: C9)
- sudden overload features (claims: C10)
**Contradicting evidence:**
- Service crack-growth evidence predating the impact (claims: C5)
**Evidence missing:**
- local denting (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component

### Temper embrittlement — Confidence 20.0/100 (Low)
**Supporting evidence present:**
- Intergranular brittle fracture (claims: C9, C10)
- service heat-treatment history (claims: C5, C8)
**Contradicting evidence:**
- Ductile fracture (claims: C9, C10)
- no embrittling thermal history (claims: C8)
**Evidence missing:**
- upward shift in transition temperature (would come from Operating conditions)
**Suggested test / examination to raise certainty:**
- Operating-condition data review

### Coating delamination — Confidence 20.0/100 (Low)
**Supporting evidence present:**
- interfacial fracture (claims: C9, C10)
- corrosion products under coating (claims: C11)
- poor surface profile/contamination (claims: C10)
**Evidence missing:**
- Lifted coating (would come from Coating / protection records)
**Suggested test / examination to raise certainty:**
- Coating / protection system review

### Grinding burn — Confidence 19.4/100 (Low)
**Supporting evidence present:**
- hardness gradient (claims: C14)
- surface cracks (claims: C10)
**Evidence missing:**
- Temper colour (would come from Macro / visual examination)
- retempered/rehardened layer (would come from Hardness)
- residual stress (would come from Loading & stress)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component
- Hardness survey across the section
- Loading / stress review or analysis

### Solidification cracking — Confidence 18.0/100 (Low)
**Supporting evidence present:**
- Centreline/interdendritic weld crack (claims: C9, C13)
- oxidised/segregated surfaces (claims: C10)
- no service striations (claims: C5)
**Contradicting evidence:**
- Hydrogen cold crack in HAZ after cooling (claims: C9, C13)
**Evidence missing:**
- Centreline/interdendritic weld crack (would come from Welding records)
**Suggested test / examination to raise certainty:**
- Welding record review

### Thermal bowing — Confidence 17.5/100 (Low)
**Supporting evidence present:**
- distortion without cracking (claims: C13)
- thermal gradients in service history (claims: C5)
**Evidence missing:**
- Repeatable bowing with temperature (would come from Operating conditions)
**Suggested test / examination to raise certainty:**
- Operating-condition data review

### Ductile overload — Confidence 17.5/100 (Low)
**Supporting evidence present:**
- Dimpled (microvoid coalescence) fracture surface under SEM; cup-and-cone profile (claims: C10)
- Documented single overload, impact or pressure surge event (claims: C7)
**Contradicting evidence:**
- Beach marks or fatigue striations present (claims: C10)
**Evidence missing:**
- Gross plastic deformation, necking, bending or bulging adjacent to fracture (would come from Macro / visual examination)
- Shear lips at fracture edges; fracture at ~45 degrees to load (would come from Fracture-surface examination (fractography))
- Inclusions or second-phase particles at the bases of dimples (microvoid nucleation sites) under SEM (would come from Microscopy / metallography)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component
- SEM fractography of the fracture surface
- Metallographic sectioning and microscopy
- Visual/macro
- SEM fractography
- Tensile test

### Seam / lamination — Confidence 17.5/100 (Low)
**Supporting evidence present:**
- orientation parallel to rolling direction (claims: C6)
- inclusion-lined surfaces (claims: C10)
**Evidence missing:**
- Planar internal indication (would come from Non-destructive testing)
**Suggested test / examination to raise certainty:**
- Non-destructive testing (UT / RT / MPI / PT)

### Quench/heat-treatment distortion — Confidence 16.7/100 (Low)
**Supporting evidence present:**
- out-of-tolerance dimension (claims: C12)
- hardness/microstructure gradients (claims: C14)
**Evidence missing:**
- Warping (would come from Macro / visual examination)
- bowing (would come from Macro / visual examination)
- twist (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component

### Axial fatigue — Confidence 16.7/100 (Low)
**Supporting evidence present:**
- beach marks (claims: C10)
**Evidence missing:**
- Planar crack growth normal to axial stress (would come from Loading & stress)
- final overload (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Loading / stress review or analysis
- Macro / visual examination of the fracture and component

### Primary creep / secondary creep deformation — Confidence 16.7/100 (Low)
**Supporting evidence present:**
- creep strain record (claims: C6)
**Evidence missing:**
- Permanent elongation/sagging/bulging (would come from Macro / visual examination)
- grain-boundary cavities may begin (would come from Microscopy / metallography)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component
- Metallographic sectioning and microscopy

### Crevice corrosion — Confidence 16.7/100 (Low)
**Supporting evidence present:**
- sharp boundary between exposed (claims: C10)
**Evidence missing:**
- Attack under gasket/deposit/lap joint (would come from Corrosion products / deposits)
- crevice area (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Corrosion-product / deposit analysis (EDS / XRD)
- Macro / visual examination of the fracture and component

### Chromium carbide sensitisation — Confidence 16.7/100 (Low)
**Supporting evidence present:**
- intergranular corrosion/SCC (claims: C11)
**Evidence missing:**
- Grain-boundary carbide/depleted zones (would come from Microscopy / metallography)
- HAZ association (would come from Welding records)
**Suggested test / examination to raise certainty:**
- Metallographic sectioning and microscopy
- Welding record review

### Subsurface rolling-contact fatigue — Confidence 16.0/100 (Low)
**Supporting evidence present:**
- Subsurface origin (claims: C9)
- inclusion-associated crack (claims: C9, C13)
**Contradicting evidence:**
- Surface corrosion/wear origin only (claims: C10, C11)
**Evidence missing:**
- spall (would come from Fracture-surface examination (fractography))
- butterfly morphology (would come from Fracture-surface examination (fractography))
**Suggested test / examination to raise certainty:**
- SEM fractography of the fracture surface

### Sigma phase formation — Confidence 16.0/100 (Low)
**Supporting evidence present:**
- Brittle fracture (claims: C9, C10)
- hardness changes (claims: C14)
**Contradicting evidence:**
- No sigma phase in microstructure (claims: C14)
- ductile fracture (claims: C9, C10)
**Evidence missing:**
- reduced toughness (would come from Macro / visual examination)
- metallographic sigma phase (would come from Microscopy / metallography)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component
- Metallographic sectioning and microscopy

### Sulfide stress cracking — Confidence 15.2/100 (Low)
**Supporting evidence present:**
- high hardness/strength (claims: C14)
- often little corrosion loss (claims: C11)
**Contradicting evidence:**
- low-strength qualified material (claims: C4)
**Evidence missing:**
- Brittle cracks (would come from Macro / visual examination)
- H2S/sour-service exposure (would come from Service environment)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component
- Service-environment chemistry review or sampling

### Hydrogen embrittlement — Confidence 14.3/100 (Low)
**Supporting evidence present:**
- Hydrogen source: plating, pickling, cathodic protection, H2S/sour service (claims: C6)
**Evidence missing:**
- Hydrogen source: plating, pickling, cathodic protection, H2S/sour service (would come from Service environment)
- High-strength/high-hardness steel (susceptible grade) (would come from Material specification)
- Intergranular or quasi-cleavage fracture morphology (would come from Fracture-surface examination (fractography))
- Delayed failure under static load (hours–weeks after installation) (would come from Service history)
**Suggested test / examination to raise certainty:**
- Service-environment chemistry review or sampling
- Material specification & certification review
- SEM fractography of the fracture surface
- Service-history record review
- Fractography (intergranular)
- Hardness

### Surface-initiated rolling-contact fatigue — Confidence 13.3/100 (Low)
**Supporting evidence present:**
- surface cracks (claims: C10)
**Evidence missing:**
- Micropitting (would come from Macro / visual examination)
- grey staining (would come from Macro / visual examination)
- shallow spalls (would come from Fracture-surface examination (fractography))
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component
- SEM fractography of the fracture surface

### Bimetallic corrosion — Confidence 12.5/100 (Low)
**Supporting evidence present:**
- location tied to couple (claims: C9)
**Evidence missing:**
- Preferential attack of one metal near joint/contact (would come from Loading & stress)
- noble metal protected (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Loading / stress review or analysis
- Macro / visual examination of the fracture and component

### Cavitation erosion — Confidence 12.5/100 (Low)
**Supporting evidence present:**
- little corrosion product initially (claims: C11)
**Evidence missing:**
- Honeycomb/pitted roughness (would come from Macro / visual examination)
- damage at low-pressure/high turbulence zones (would come from Loading & stress)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component
- Loading / stress review or analysis

### Metal dusting corrosion — Confidence 12.5/100 (Low)
**Supporting evidence present:**
- carburised zones (claims: C9)
**Evidence missing:**
- Pits/grooves filled with carbonaceous dust (would come from Macro / visual examination)
- rapid local wastage (would come from Dimensional measurements)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component
- Dimensional / wall-thickness survey

### Scale/coating spallation — Confidence 12.5/100 (Low)
**Supporting evidence present:**
- exposed substrate hot corrosion/oxidation (claims: C11)
**Evidence missing:**
- Spalled scale patches (would come from Fracture-surface examination (fractography))
- repeated scale layers (would come from Corrosion products / deposits)
**Suggested test / examination to raise certainty:**
- SEM fractography of the fracture surface
- Corrosion-product / deposit analysis (EDS / XRD)

### Stress rupture — Confidence 11.1/100 (Low)
**Supporting evidence present:**
- intergranular cracking (claims: C13)
**Evidence missing:**
- Creep cavities (would come from Microscopy / metallography)
- necking or bulging (would come from Macro / visual examination)
- oxide-filled cracks (would come from Corrosion products / deposits)
**Suggested test / examination to raise certainty:**
- Metallographic sectioning and microscopy
- Macro / visual examination of the fracture and component
- Corrosion-product / deposit analysis (EDS / XRD)

### Pressure burst — Confidence 10.0/100 (Low)
**Supporting evidence present:**
- wall thinning if corrosion-assisted (claims: C11)
**Evidence missing:**
- Fish-mouth opening (would come from Macro / visual examination)
- ductile tearing (would come from Macro / visual examination)
- hoop-stress orientation (would come from Loading & stress)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component
- Loading / stress review or analysis

### Creep-fatigue interaction — Confidence 10.0/100 (Low)
**Supporting evidence present:**
- cavities plus fatigue features (claims: C10)
**Evidence missing:**
- Mixed transgranular/intergranular cracking (would come from Fracture-surface examination (fractography))
- oxide-filled cracks (would come from Corrosion products / deposits)
- dwell sensitivity (would come from Service history)
**Suggested test / examination to raise certainty:**
- SEM fractography of the fracture surface
- Corrosion-product / deposit analysis (EDS / XRD)
- Service-history record review

### Relaxation failure — Confidence 10.0/100 (Low)
**Supporting evidence present:**
- little visible cracking (claims: C13)
**Evidence missing:**
- Loss of bolt preload (would come from Loading & stress)
- gasket leakage (would come from Macro / visual examination)
- relaxed spring force (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Loading / stress review or analysis
- Macro / visual examination of the fracture and component

### Under-deposit corrosion — Confidence 10.0/100 (Low)
**Supporting evidence present:**
- chemistry gradient evidence (claims: C14)
**Evidence missing:**
- Attack under scale/sludge/deposit (would come from Corrosion products / deposits)
- tubercles (would come from Corrosion products / deposits)
- pit clusters (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Corrosion-product / deposit analysis (EDS / XRD)
- Macro / visual examination of the fracture and component

### High-temperature sulfidation — Confidence 10.0/100 (Low)
**Supporting evidence present:**
- sulphur-rich corrosion products (claims: C11)
**Evidence missing:**
- Sulphide scale (would come from Corrosion products / deposits)
- metal loss (would come from Dimensional measurements)
- carburisation/sulfidation interactions possible (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Corrosion-product / deposit analysis (EDS / XRD)
- Dimensional / wall-thickness survey
- Macro / visual examination of the fracture and component

### Graphitisation of carbon steel — Confidence 10.0/100 (Low)
**Supporting evidence present:**
- service temperature history (claims: C5, C8)
**Evidence missing:**
- Graphite nodules/planes (would come from Microscopy / metallography)
- reduced strength (would come from Macro / visual examination)
- intergranular/planar weakness (would come from Fracture-surface examination (fractography))
**Suggested test / examination to raise certainty:**
- Metallographic sectioning and microscopy
- Macro / visual examination of the fracture and component
- SEM fractography of the fracture surface

### Coating blistering — Confidence 10.0/100 (Low)
**Supporting evidence present:**
- fluid/corrosion products beneath (claims: C11)
**Evidence missing:**
- Dome-shaped blisters (would come from Coating / protection records)
- loss of adhesion (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Coating / protection system review
- Macro / visual examination of the fracture and component

### Stress corrosion cracking — Confidence 9.8/100 (Low)
**Supporting evidence present:**
- Branched cracking in metallographic section (claims: C13)
**Contradicting evidence:**
- Fully ductile dimpled fracture (claims: C10)
**Evidence missing:**
- Susceptible alloy–environment combination present (would come from Service environment)
- Sustained static tensile stress incl. residual stress (welding, forming) (would come from Loading & stress)
- Inter- or transgranular cracking with little plastic deformation (would come from Microscopy / metallography)
**Suggested test / examination to raise certainty:**
- Service-environment chemistry review or sampling
- Loading / stress review or analysis
- Metallographic sectioning and microscopy
- Metallography (branching)
- SEM
- Environment chemistry

### Brittle fracture — Confidence 9.5/100 (Low)
**Supporting evidence present:**
- Chevron (herringbone) marks pointing back to origin (claims: C10)
- Impact or high strain-rate loading (claims: C7)
**Contradicting evidence:**
- Dimpled ductile fracture surface (claims: C10)
**Evidence missing:**
- Little or no plastic deformation; flat fracture normal to stress (would come from Macro / visual examination)
- Bright granular/crystalline or cleavage fracture surface (would come from Fracture-surface examination (fractography))
- Low service/ambient temperature at failure (would come from Operating conditions)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component
- SEM fractography of the fracture surface
- Operating-condition data review
- Charpy impact
- SEM fractography
- Hardness

### Solid-particle erosion — Confidence 8.7/100 (Low)
**Supporting evidence present:**
- impact craters/cutting lips (claims: C7)
- thinning at elbows/nozzles (claims: C11)
**Contradicting evidence:**
- Electrochemical corrosion without particle impact pattern (claims: C11)
**Evidence missing:**
- Directional wastage (would come from Dimensional measurements)
**Suggested test / examination to raise certainty:**
- Dimensional / wall-thickness survey

### Carbide spheroidisation — Confidence 8.7/100 (Low)
**Supporting evidence present:**
- reduced hardness/strength (claims: C14)
- creep deformation association (claims: C9)
**Contradicting evidence:**
- As-manufactured microstructure (claims: C14)
- hardness within specification (claims: C4, C14)
**Evidence missing:**
- Spheroidised carbides (would come from Microscopy / metallography)
**Suggested test / examination to raise certainty:**
- Metallographic sectioning and microscopy

### Caustic SCC — Confidence 8.1/100 (Low)
**Supporting evidence present:**
- boiler/alkali service history (claims: C5)
**Contradicting evidence:**
- fatigue-only crack growth (claims: C9, C13)
**Evidence missing:**
- Intergranular or branched cracks near caustic concentration areas (would come from Fracture-surface examination (fractography))
- deposits (would come from Corrosion products / deposits)
**Suggested test / examination to raise certainty:**
- SEM fractography of the fracture surface
- Corrosion-product / deposit analysis (EDS / XRD)

### Incomplete penetration — Confidence 7.5/100 (Low)
**Supporting evidence present:**
- fatigue/fracture origin at root (claims: C9, C10)
**Evidence missing:**
- Root planar indication (would come from Non-destructive testing)
- notch-like root defect (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Non-destructive testing (UT / RT / MPI / PT)
- Macro / visual examination of the fracture and component

### Carburisation attack — Confidence 7.0/100 (Low)
**Supporting evidence present:**
- increased hardness (claims: C14)
- dimensional/microstructural changes (claims: C12)
**Contradicting evidence:**
- Surface decarburisation or general oxidation only (claims: C10)
**Evidence missing:**
- Carbide networks (would come from Microscopy / metallography)
- reduced ductility (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Metallographic sectioning and microscopy
- Macro / visual examination of the fracture and component

### Rolling-contact fatigue — Confidence 6.5/100 (Low)
**Supporting evidence present:**
- subsurface or surface-initiated crack networks (claims: C9, C13)
**Contradicting evidence:**
- corrosion pits alone (claims: C11)
**Evidence missing:**
- Pitting (would come from Macro / visual examination)
- spalling (would come from Fracture-surface examination (fractography))
- butterfly cracks (would come from Fracture-surface examination (fractography))
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component
- SEM fractography of the fracture surface

### Hydrogen blistering — Confidence 6.0/100 (Low)
**Supporting evidence present:**
- hydrogen/sour/corrosion history (claims: C8, C11)
**Evidence missing:**
- Raised blisters (would come from Coating / protection records)
- internal laminations (would come from Macro / visual examination)
- step cracks (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Coating / protection system review
- Macro / visual examination of the fracture and component

### Elastic buckling — Confidence 5.4/100 (Low)
**Supporting evidence present:**
- often little fracture at initiation (claims: C9, C10)
**Contradicting evidence:**
- tensile fracture as primary event (claims: C9, C10)
**Evidence missing:**
- Global or local out-of-plane deformation (would come from Macro / visual examination)
- wrinkles (would come from Macro / visual examination)
- lobes (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component

### General yielding — Confidence 4.6/100 (Low)
**Supporting evidence present:**
- no progressive beach marks (claims: C10)
**Contradicting evidence:**
- No permanent dimensional change (claims: C12)
**Evidence missing:**
- Permanent bend (would come from Macro / visual examination)
- necking (would come from Macro / visual examination)
- local plastic flow (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component

### Lap / fold — Confidence 3.8/100 (Low)
**Supporting evidence present:**
- fatigue crack from lap (claims: C9, C13)
**Contradicting evidence:**
- Open service crack with no oxide/fold interface (claims: C5)
**Evidence missing:**
- Folded oxide-containing seam (would come from Corrosion products / deposits)
- surface-breaking linear indication (would come from Non-destructive testing)
**Suggested test / examination to raise certainty:**
- Corrosion-product / deposit analysis (EDS / XRD)
- Non-destructive testing (UT / RT / MPI / PT)

### Irradiation embrittlement / swelling — Confidence 2.5/100 (Low)
**Supporting evidence present:**
- service dose record (claims: C5, C6)
**Contradicting evidence:**
- No radiation service or dose record (claims: C5, C6)
**Evidence missing:**
- Toughness shift (would come from Macro / visual examination)
- hardening (would come from Hardness)
- swelling (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component
- Hardness survey across the section

### Hydrogen-assisted cold cracking — Confidence 2.0/100 (Low)
**Supporting evidence present:**
- high hardness (claims: C14)
**Contradicting evidence:**
- Solidification crack morphology during hot stage (claims: C9, C13)
- no hardness/hydrogen risk (claims: C14)
**Evidence missing:**
- HAZ or weld toe/root cracks (would come from Welding records)
- delayed occurrence (would come from Service history)
- hydrogen source (would come from Service environment)
**Suggested test / examination to raise certainty:**
- Welding record review
- Service-history record review
- Service-environment chemistry review or sampling

### Brinelling — Confidence 0.0/100 (Low)
**Contradicting evidence:**
- Fretting marks without plastic indentation (claims: C10)
**Evidence missing:**
- Indentations matching rolling elements or contact asperities (would come from Loading & stress)
- spacing related to geometry (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Loading / stress review or analysis
- Macro / visual examination of the fracture and component

### Stable ductile tearing — Confidence 0.0/100 (Low)
**Contradicting evidence:**
- No pre-existing crack (claims: C9, C13)
- all fracture surface instantaneous (claims: C9, C10)
**Evidence missing:**
- Stretched zone (would come from Macro / visual examination)
- stable tearing region (would come from Macro / visual examination)
- final overload zone (would come from Macro / visual examination)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component

### Atmospheric rusting/corrosion — Confidence 0.0/100 (Low)
**Contradicting evidence:**
- Submerged-only corrosion or high-temperature dry oxidation only (claims: C11)
**Evidence missing:**
- Rust/oxide scale (would come from Corrosion products / deposits)
- preferential attack at water traps (would come from Macro / visual examination)
- chloride/sulphur deposits (would come from Corrosion products / deposits)
**Suggested test / examination to raise certainty:**
- Corrosion-product / deposit analysis (EDS / XRD)
- Macro / visual examination of the fracture and component

### Hydrogen-induced cracking — Confidence 0.0/100 (Low)
**Contradicting evidence:**
- no internal cracking (claims: C13)
**Evidence missing:**
- Stepwise internal cracks parallel to surface/rolling plane (would come from Macro / visual examination)
- blister association (would come from Coating / protection records)
- sulphide exposure (would come from Corrosion products / deposits)
**Suggested test / examination to raise certainty:**
- Macro / visual examination of the fracture and component
- Coating / protection system review
- Corrosion-product / deposit analysis (EDS / XRD)

### Lack of fusion — Confidence 0.0/100 (Low)
**Contradicting evidence:**
- Service crack through fully fused material (claims: C5)
**Evidence missing:**
- Planar weld indication (would come from Non-destructive testing)
- unfused interface (would come from Macro / visual examination)
- crack/fatigue origin at weld sidewall or between passes (would come from Welding records)
**Suggested test / examination to raise certainty:**
- Non-destructive testing (UT / RT / MPI / PT)
- Macro / visual examination of the fracture and component
- Welding record review

## Candidate root causes
- **Design issue** — Confidence 64.0/100 (Moderate), via MECH-FM-MET-FAT-006. Typical for fatigue and cyclic cracking
- **Design issue** — Confidence 64.0/100 (Moderate), via MECH-FM-MET-FAT-010. Typical for fatigue and cyclic cracking
- **Design issue** — Confidence 60.0/100 (Moderate), via MECH-FM-MET-FAT-003. Typical for fatigue and cyclic cracking
- **Material selection issue** — Confidence 60.0/100 (Moderate), via MECH-FM-MET-EAC-004. Typical for environmentally assisted cracking and hydrogen damage
- **Material selection issue** — Confidence 60.0/100 (Moderate), via MECH-FM-MET-EAC-005. Typical for environmentally assisted cracking and hydrogen damage
- **Maintenance/inspection issue** — Confidence 60.0/100 (Moderate), via MECH-FM-MET-WEAR-005. Typical for tribology / wear / erosion
- **Maintenance/inspection issue** — Confidence 58.6/100 (Moderate), via MECH-FM-MET-WEAR-004. Typical for tribology / wear / erosion
- **Design issue** — Confidence 53.4/100 (Moderate), via MECH-FM-MET-FAT-013. Typical for fatigue and cyclic cracking

## Limitations
- Knowledge pack status is 'ai_generated_draft'; conclusions inherit that status.
- Scores reflect only admitted claims; unreviewed or rejected material is excluded.
- Keyword/tag matching may miss or mis-map evidence; review the evidence table above.
- Confidence is evidence support for a mode, not a probability or a finding of fact.

## Liability declaration (DRAFT)
This output is provided for decision support only and is **not professional engineering advice**. The MTIS Failure Investigator, its knowledge packs and AI extraction are drafts under expert review. The user is responsible for verifying all outputs against physical evidence and recognised standards and for exercising independent professional judgement. *This declaration is itself a DRAFT and must be reviewed by a suitably qualified lawyer before reliance (see project liability declaration).*

## Audit
Run #1 executed 2026-06-20 13:29:43.170194 with claims snapshot as listed; full trail available in the application audit log.