NDT ( MT ) Level II

A: Principle: MT responds to flux leakage driven by stress and microstructural change. In service returns, the fillet sees peak bending stress and heat input during grinding. That aligns with burn-induced cracking localized to the radius. Distractor B traps people who know residual fields exist, but it doesn't explain why only high-stress fillets show linear repeatable indications.

A: Principle: Adequate magnetizing force scales with section size, not particle sensitivity alone. For circular fields, current per diameter gives the order of magnitude. 50 mm times 20–30 A/mm lands near 1–1.5 kA. Distractor B catches those importing yoke logic into head shots.

A: Principle: Field adequacy must be proven before interpretation. Lifting force and field direction establish that cracks can leak flux. Surface prep follows, then inspection. Distractor C traps people who know bath control matters but misplace it ahead of magnetic field verification.

A: Principle: Drawings can specify method but not defect limits unless stated. ISO 9934 covers technique, not product acceptance. You still need a product spec. Distractor B catches engineers assuming a default method where the standard allows multiple techniques.