ASTM D4145-10(2022) PDF

SIGNIFICANCE AND USE 4.1 Organic coatings on precoated sheet are subjected to stresses when fabricated into products by roll forming, brake bending, or other deformation processes. These stresses can exceed the flexibility or adhesive strength of the coating, resulting in fracture of the coating which exposes the substrate, or in the loss of adhesion of the coating to the substrate. This test is a means of evaluating the ability of a coating system to withstand the stresses of fabrication. 4.2 The bend direction, whether the axis of bend is transverse to or along the rolling direction of the metal, and the temperature of the specimen when it is bent can affect the results of this test and should be agreed upon between the supplier and the user. SCOPE 1.1 This test method describes a procedure for determining the flexibility and adhesion of organic coatings (paints) on metallic substrates that are deformed by bending when the sheet is fabricated into building panels or other products. 1.2 The metal substrate must be capable of passing this test without fracturing and with no excessive grain development. 1.3 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.