ASTM B530 Standard test Method for Magnetic Measurement of Coating Thickness: Electrodeposited Nickel Coatings on Magnetic and non-magnetic Substrates includes non-destructive measurement of the thickness of electrodeposited nickel coatings on magnetic or non-magnetic substrates using a magnetic instrument.
Meaning and use

5.1 The thickness of the coating is generally important to its performance. This magnetic method is suitable for non-destructive measurement of thickness and specification acceptance of certain nickel coatings.

5.2 The method requires that the magnetic properties of the coating and its substrate be the same as those of the reference standard used for instrument calibration adjustment.

5.3 The method should not be used to determine the thickness of self-catalyzed deposited nickel-phosphorus alloys containing more than 8% P in steel. As long as the measurements are made prior to any heat treatment, those coatings are sufficiently non-magnetic for test method B499 to be suitable for the determination.

B530-2014 “Standard test method for Measuring Coating thickness by magnetic method: Electrodeposited nickel Coatings on magnetic and non-magnetic substrates”

Step 1: Scope

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

1.2 These instruments measure the magnetic attraction between the magnet and the coating – substrate combination (classified as “magnetic pull-off”), or the change in magnetic flux density within the probe (classified as “electron”).

1.3 For this test method, two types of coating-substrate combinations can be encountered: Type A, nickel coatings on magnetic substrates, and Type B nickel coatings on non-magnetic substrates.

1.4 The effective measurement range of instruments using the magnetic attraction principle is up to 50μm (2 mils) for type A coatings and up to 25μm (1 mil) for type B coatings. For gauges based on the principle of flux density variation, the effective range is much larger and measurements up to 1 mm (40 mils) or higher can be made on both types of coatings.

1.5 Measurements made in accordance with this test method shall comply with the requirements of ISO Standard 2361, printed in 1982.

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

1.7 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.