Meaning and use

5.1 The thickness of the coating is generally important to its performance. For most non-ferrous coatings on steel, the magnetic method is reliable for non-destructively measuring coating thickness and is suitable for specification acceptance testing and SPC/SQC applications.

5.2 This test method should not be used to determine the thickness of electrodeposited nickel coatings on steel. Test method B530 is suitable for this determination.

ASTM B499-2014 Standard Test Method for Magnetic Measurement of Coating Thickness: Non-magnetic Coatings on Magnetic Metals

Step 1: Scope

1.1 This test method includes the non-destructive measurement of the thickness of a non-magnetic coating on a black or other magnetic base metal using a magnetic instrument. It is intended to complement the manufacturer’s instructions on the operation of the instrument, not to replace them.

Note 1 – Nickel-Phosphorus alloys with self-catalytic deposition containing more than 8% phosphorus measured by this test method are sufficiently non-magnetic as long as they are measured prior to any heat treatment.

1.2 These instruments measure the magnetic attraction between the magnet and the base metal, which is affected by the presence of a coating (classified as “magnetic pull off”) or by changes in the magnetic flux density within the probe (classified as “electron”). These instruments cannot distinguish the thickness of individual layers. They can only measure the cumulative thickness of all layers below the probe, down to the base metal.

1.3 Measurements made in accordance with this test method shall comply with the requirements of ISO International Standard 2178, printed in 1982.

1.4 Values expressed in SI units shall be considered standard. The values given in parentheses are for reference only.

1.5 This standard is not intended to address all safety concerns (if any) associated with its use. It is the responsibility of users of this standard to establish appropriate safety and health practices and to determine the applicability of regulatory restrictions prior to use.