Q1: Inspection of surface and sub-surface cracks in non-magnetic alloys is done by __________ testing method.

ANS:C - dye penetrant

Inspection of surface and sub-surface cracks in non-magnetic alloys is typically done by dye penetrant testing method. Here's a brief explanation of each method and why dye penetrant testing is suitable for non-magnetic alloys:

1. X-ray Testing: X-ray testing involves passing X-rays through the material being inspected and detecting any changes in the X-ray pattern caused by defects such as cracks or voids. However, X-ray testing is more suitable for materials with higher densities or atomic numbers, such as metals, and may not be as effective for non-magnetic alloys, especially those with low density or atomic number.
2. Magnetic Particle Testing: Magnetic particle testing is based on the principle of magnetic induction. It involves magnetizing the material being inspected and applying ferromagnetic particles (typically iron filings or magnetic powders) on the surface. These particles will be attracted to and accumulate around any magnetic discontinuities, such as cracks or defects. However, magnetic particle testing is not suitable for non-magnetic alloys because they do not exhibit magnetic properties.
3. Dye Penetrant Testing: Dye penetrant testing, also known as liquid penetrant testing or dye penetrant inspection, is a widely used method for detecting surface-breaking and near-surface defects in non-magnetic alloys. It involves applying a liquid dye penetrant to the surface of the material and allowing it to seep into any surface cracks or defects through capillary action. After excess penetrant is removed, a developer is applied to draw out the penetrant from the defects, making them visible under ultraviolet (UV) light or visible light. Dye penetrant testing is highly sensitive and can detect very fine surface cracks and defects in non-magnetic materials.
4. Ultrasonic Testing: Ultrasonic testing involves sending high-frequency sound waves (ultrasonic waves) into the material being inspected and analyzing the reflected waves to detect internal defects such as cracks, voids, or inclusions. While ultrasonic testing is effective for inspecting both magnetic and non-magnetic materials, it is primarily used for detecting internal defects rather than surface cracks.