🔍 Key Concepts

• Surface vs. subsurface defects and which methods can see below the surface • How dye penetrant and magnetic particle testing actually work • Basic principle of ultrasonic testing and where it’s commonly used on shafts and welds

💭 Think About

• For each method, ask yourself: does this method mainly reveal open-to-the-surface cracks or can it detect defects inside the metal? • Consider which methods require the defect to be at or near the surface for the test medium (dye or magnetic particles) to enter or collect. • Think about which method sends energy into the material and reads reflections from internal flaws, commonly used for shaft and plate inspections.

✅ Before You Answer

• Confirm which methods are primarily limited to surface-breaking or very near-surface cracks. • Identify which method is routinely used for internal flaw detection in shafts, plates, and welds. • Before choosing “All of the above,” verify that every single method in the list can reliably detect a subsurface defect, not just surface defects.