What is the primary focus of Magnetic Particle Testing?

Magnetic Particle Testing (MPT) specializes in identifying surface and near-surface defects in ferromagnetic materials. This is achieved by applying a magnetic field to the test material and then using ferrous particles that will collect at any discontinuities, such as cracks or voids, on or just beneath the surface. The primary focus is on these types of defects because they are most critical for the integrity and safety of components subjected to mechanical stresses.

Surface and near-surface defects are crucial to detect because they can significantly impact the performance and reliability of a material or structure. For example, cracks can grow over time under cyclic loading, leading to catastrophic failures if not detected early. Hence, MPT is designed to be a highly effective method for locating such flaws, which are often invisible to the naked eye.

The other options, while related to various aspects of materials testing, do not specifically pertain to the main objective of Magnetic Particle Testing. Evaluating internal structures, assessing material hardness, and measuring thermal stability fall under different testing methodologies and are not the primary focus of MPT.