Step 7 · Questions

Structured questions

These questions are ordered to narrow down the candidate failure modes — general background first, then targeted confirmation questions for the modes currently ranking highest. Answers feed the engine; leave any blank to skip.

Currently leading from your evidence so far: Wear (adhesive/abrasive) Moderate · Corrosion (general/pitting/crevice) Low · Fatigue Low. The confirmation questions below target these first.

Background

Material specification and certification status? answered Material specification

Design loads and duty cycle vs actual service loads? answered Design data

Manufacturing route incl. welding, plating, heat treatment records? answered Manufacturing records

Full service history: duration, duty, excursions, incidents? Service history

Loading character: steady/cyclic/impact; known vibration? answered Loading & stress

Environment chemistry: chlorides, H2S, caustic, temperature, wet/dry cycles? Service environment

Maintenance and inspection history incl. lubrication? answered Maintenance & lubrication

Fleet/comparator experience with similar components? Fleet / comparator data

Observation

Macro fracture description: deformation, zones, origin location? answered Macro / visual examination

Fracture surface features: beach marks, chevrons, dimples, facets? answered Fracture-surface examination (fractography)

Corrosion: pits, products, thinning measurements? answered Corrosion products / deposits

Wear: scoring, debris, dimensional loss at contacts? answered Dimensional measurements

Secondary cracking present? Branched? answered Microscopy / metallography

Lab results: chemistry, hardness, microstructure vs spec? answered Chemical composition

Anything at the origin: inclusion, porosity, weld defect, pit? Fracture-surface examination (fractography)

Confirm: Wear targets Wear (adhesive/abrasive) · Moderate

Is there surface loss, scoring, grooves, galling or polishing at contact surfaces? Macro / visual examination

Is there wear debris or dimensional loss beyond tolerance at contacts? Dimensional measurements

Lubrication deficiency or abrasive contamination present? Maintenance & lubrication

Confirm: Corrosion targets Corrosion (general/pitting/crevice) · Low

Is there general wall thinning / measurable metal loss, or pitting/crevice attack? Dimensional measurements

Are corrosion products/deposits present (rust, scale, oxide)? Corrosion products / deposits

Was the environment corrosive (chlorides, acids, moisture, seawater); coating/CP breakdown? Service environment

Confirm: Fatigue targets Fatigue · Low

Are beach marks / crack-arrest lines or SEM striations present? Fracture-surface examination (fractography)

Did the crack initiate at a stress concentration; are ratchet marks present? Macro / visual examination

Was the service loading cyclic/vibratory/rotating over many cycles? Loading & stress

Confirm: Ductile overload targets Ductile overload · Low

Is there gross plastic deformation (necking/bending/bulging) next to the fracture? Macro / visual examination

Under SEM, is the fracture dimpled (microvoid coalescence / cup-and-cone)? Inclusions at dimple bases? Microscopy / metallography

Is a single overload / impact / pressure-surge event documented? Loading & stress

Confirm: Hydrogen embrittlement targets Hydrogen embrittlement · Low

Is the material a high-strength/high-hardness susceptible grade? Material specification

Is there a hydrogen source (plating, pickling, CP, H2S/sour)? Was a relief bake done? Service environment

Intergranular/quasi-cleavage morphology, or delayed failure under static load? Fracture-surface examination (fractography)

Confirm: Stress corrosion cracking targets Stress corrosion cracking · Low

Does metallography show branched and/or inter/transgranular cracking with little deformation? Microscopy / metallography

Is there a susceptible alloy-environment combination present? Service environment

Is there a sustained static tensile/residual stress; multiple secondary cracks? Loading & stress

Confirm: Brittle fracture targets Brittle fracture · Low

Is the fracture flat with little/no plastic deformation, normal to the stress? Macro / visual examination

Is the surface bright granular/crystalline or cleavage; chevrons pointing to origin? Fracture-surface examination (fractography)

Low temperature, impact loading, or high hardness/low toughness at failure? Operating conditions

Confirm: Manufacturing / material defect targets Manufacturing/material defect · Low

Is there a discrete defect at the fracture origin (inclusion, porosity, lap, seam, void)? Fracture-surface examination (fractography)

Is chemical composition, hardness or microstructure outside specification? Chemical composition

Early-life failure, or pre-service NDT indications / concessions on record? Inspection records

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