Magnetic Particle Testing （MT） is a nondestructive testing （NDT） method used to find surface and near-surface defects in ferromagnetic materials like iron and steel. It works by magnetizing the material and then applying fine magnetic particles, either dry or in a liquid suspension, to the surface. If there are cracks or defects, they disrupt the magnetic field, causing the particles to gather and form visible indications of the flaws. This method is quick, reliable, and widely used in industries like construction, automotive, and aerospace to check for cracks, weld flaws, or fatigue in critical parts.