Meaning
Material characterization tests measure the ability of a substance to support the formation of a magnetic field within itself. Magnetic permeability testing is used to verify that stainless steels or other non-magnetic alloys have not developed magnetic phases during manufacturing or service. This measurement is required for equipment destined for sensitive electronic environments or specific chemical processing plants.
Phase Measurement
Ferrite content in austenitic steel is identified by its magnetic response. Phase measurement through magnetic permeability testing provides a non-destructive way to estimate the volume fraction of magnetic inclusions in a non-magnetic matrix.
Alloy Integrity
Fabrication processes like welding or cold working can induce a phase transformation that alters the properties of the metal. Magnetic permeability testing detects these changes before they lead to reduced corrosion resistance or mechanical failure. A high reading often suggests that the heat treatment was insufficient or that the cooling rate was too slow.
Instrument Calibration
Precise sensors require a stable environment and a certified reference block to provide accurate data. Because magnetic permeability testing is sensitive to the probe angle and surface roughness, the technician must maintain consistent pressure during the check. Frequent verification against a zero point ensures that the readings remain within the project specifications.
