ASTM D522 Mandrel Bend Test of Attached Organic Coatings

Scope:

ASTM D522 test contains two test methods that determine the elongation or resistance to cracking of attached organic coatings on substrates. The substrate can be a cold-rolled steel strip, sheet metal, or rubber-type material.

Test Procedure:

For the ASTM D522 test, the coating material is applied at a constant thickness to panels of steel strip or sheet metal, or rubber-type materials. There are two methods included: Method A and Method B. These test methods are applicable for rating attached coatings for their capacity to withstand cracking when elongated and are also useful in determining the flexibility of coatings on flexible substrates. 

After the process of curing or drying, the coated panels are bent over a mandrel and the elongation or resistance to cracking of the coating is evaluated. In ASTM D522, the coated panels are bent over a conical mandrel in Test Method A whereas the coated panels are bent over cylindrical mandrels of various diameters in Test Method B. 

Sample size:

For ASTM D522, the number of samples per product in test method A is 3 and in test method B is 2. The substrate thickness for coating elongation rating is a cold-rolled steel strip of 0.8 mm (1/32 inches) thickness and for rating coated material is a sheet metal of less than 0.8 mm (1/32 inches) thickness or rubber-type material of less than 13 mm thickness (½ inches). The dimensions of the samples are 46 inches.

Data:

The following data is calculated in ASTM D522:

Mean and range of coating elongation or resistance
Mean and range of coating film thickness
Total elongation formula

Conclusion:

ASTM D522 is a set of two test methods A and B that are used to determine the elongation or resistance to cracking of attached organic coatings on substrates.