ASTM D522 is a standard test method that provides a procedure for evaluating the flexibility and adhesion of adherent organic coatings subjected to bending stress. This test method involves bending a coated specimen around a fixed radius using a conical mandrel and observing the coating for any cracking, peeling or other damage.
This test can be used to evaluate the performance of coatings applied to a variety of substrates, including metals, plastics and composites, and is commonly used in the automotive, aerospace and marine industries to assess the durability of coatings to withstand bending stress during use and crack resistance.
ASTM D522 provides guidance on sample preparation, selection of appropriate mandrel size and radius, and procedures for conducting tests. The standard also includes requirements for conditioning samples prior to testing, as well as guidance for evaluating results.
During testing, the coated sample is wrapped around the cone and held in place. The samples were then visually inspected for any cracks, peeling or other damage to the coating. The diameter of the cone gradually decreases and the bending continues until the coating shows signs of failure or the cone reaches its minimum diameter.
Test results are usually reported as the smallest mandrel diameter at which no cracking or detachment of the coating is observed. The results can be used to assess the flexibility and adhesion of the coating and to compare the performance of different coating systems.
In conclusion, ASTM D522 provides a standardized procedure for mandrel bend testing with organic coatings attached and can be a valuable tool in evaluating the performance of coatings subjected to bending stress. By following the procedures outlined in the standard, users can obtain reliable and repeatable results that can be used to inform important decisions related to coating selection and quality control.
