ASTM D522 Mandrel Bend Test of Attached Organic Coatings

Scope:

The ASTM D522 test contains two 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, sheet metal, or rubber-type materials. Two methods are 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 curing or drying, the coated panels are bent over a mandrel, and the coating’s elongation or resistance to cracking is evaluated. In ASTM D522, the coated panels are bent over a conical mandrel in Test Method A. In contrast, 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, it is 2. The substrate thickness for coating elongation rating is a cold-rolled steel strip of 0.8 mm (1/32 inches). For rating coated material, it is sheet metal of less than 0.8 mm (1/32 inches) thickness or rubber-type material of less than 13 mm thickness (1⁄2 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, used to determine the elongation or resistance to cracking of attached organic coatings on substrates.