ASTM D522
Standard Test Methods for Mandrel Bend Test of Attached Organic Coatings
Evaluates flexibility and resistance to cracking of attached organic coatings when a coated panel is bent over cylindrical or conical mandrels.
What ASTM D522 specifies
ASTM D522 evaluates the elongation and flexibility of an attached organic coating on a bendable substrate. Method A uses cylindrical mandrels of selected diameter and reports the smallest diameter passed without the specified cracking or delamination. Method B uses a conical mandrel, producing a continuous range of strain along one bend; the crack endpoint can be measured or converted to elongation using the prescribed geometry. Results depend on substrate thickness and temper, film thickness, cure, bend speed, temperature, and inspection method. The governing coating requirement must define the method, mandrel criterion, and allowable cracking.
ASTM D522 types and classes
Every designation the document defines, with the thickness it requires and the tests it imposes.
| Designation | Meaning | Requirement / test |
|---|---|---|
Method A | Coated panel is bent over a selected cylindrical mandrel | Smallest passing mandrel diameter or pass/fail at specified diameter |
Method B | Coated panel is bent over a conical mandrel to create a strain gradient | Crack endpoint, elongation, or pass/fail criterion |
Tests and the drawing call-out
Tests the document imposes
- Method A cylindrical mandrel
- Method B conical mandrel
- Visual cracking and delamination examination
How to cite it
Drawing call-out
FLEXIBILITY PER ASTM D522, METHOD <A|B>, <MANDREL OR ACCEPTANCE CRITERION>Angle brackets mark the choices the drawing must make; every finish page shows a completed example.
ASTM D522 — frequently asked
What is ASTM D522 Method A?
Method A bends a coated panel over cylindrical mandrels and identifies a passing diameter or pass/fail result at a specified diameter.
What is ASTM D522 Method B?
Method B uses a conical mandrel, creating a range of strain in one bend so the coating crack endpoint can be evaluated.
Does a smaller mandrel indicate better flexibility?
For otherwise identical panels and procedures, passing a smaller diameter generally indicates greater coating flexibility.
ASTM D522 is copyrighted by ASTM International. This page explains the document so a drawing can be read; it does not reproduce the standard. Purchase the current edition from the publisher. Official source ↗