ASTM D2794
Standard Test Method for Resistance of Organic Coatings to the Effects of Rapid Deformation (Impact)
Evaluates cracking or loss of adhesion when an organic coating and metal panel are rapidly deformed by a falling-weight impact.
What ASTM D2794 specifies
ASTM D2794 evaluates an organic coating on a metal panel using a falling weight, punch, and die. The panel is struck either on the coated face for direct impact or on the reverse face for reverse impact. Drop height or mass is varied to determine the largest impact energy at which the coating shows no specified cracking or adhesion failure. Results are commonly reported in inch-pounds or joules, but are specific to the instrument geometry, panel material and thickness, film thickness, cure, and failure-detection method. A product specification must supply the required energy and acceptance criterion.
ASTM D2794 types and classes
Every designation the document defines, with the thickness it requires and the tests it imposes.
| Designation | Meaning | Requirement / test |
|---|---|---|
Direct impact | Impactor strikes the coated face of the test panel | Maximum passing impact energy and agreed failure examination |
Reverse impact | Impactor strikes the reverse side and places the coating over the deformed area in tension | Maximum passing impact energy and agreed failure examination |
Tests and the drawing call-out
Tests the document imposes
- Direct impact
- Reverse impact
- Visual or agreed crack-detection examination
How to cite it
Drawing call-out
IMPACT RESISTANCE PER ASTM D2794, <DIRECT|REVERSE>, MINIMUM <ENERGY>Angle brackets mark the choices the drawing must make; every finish page shows a completed example.
ASTM D2794 — frequently asked
What is the difference between direct and reverse impact?
Direct impact strikes the coated face. Reverse impact strikes the back of the panel and stretches the coating over the deformation.
Does ASTM D2794 set a passing impact value?
No. The product or coating specification sets the required energy and failure criterion.
Can impact values from different panels be compared?
Only with care. Panel alloy, thickness, film thickness, cure, and instrument geometry materially affect the result.
ASTM D2794 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 ↗