ASTM G28-22 PDF

SIGNIFICANCE AND USE 3.1 The boiling ferric sulfate-sulfuric acid test may be applied to the following alloys in the wrought condition: Alloy Testing Time, h N06007 120 N06022 24 N06030 120 N06059 24 N06200 24 N06455 24 N06600 24 N06625 120 N06686 24 N06985 120 N08020 120 N08367 24 Alloy Testing Time, h N08800 120 N08825A 120 N10276 24(A) While the ferric sulfate-sulfuric acid test does detect susceptibility to inter- granular corrosion in Alloy N08825, the boiling 65 % nitric acid test, Practices A262, Practice C, for detecting susceptibility to intergranular corrosion in stainless steels is more sensitive and should be used if the intended service is nitric acid. 3.2 This test method may be used to evaluate as-received material and to evaluate the effects of subsequent heat treatments. In the case of nickel-rich, chromium-bearing alloys, the test method may be applied to wrought and weldments of products. The test method is not applicable to cast products. SCOPE 1.1 These test methods cover two tests as follows: 1.1.1 Method A, Ferric Sulfate-Sulfuric Acid Test (Sections 3 – 10, inclusive)—This test method describes the procedure for conducting the boiling ferric sulfate—50 % sulfuric acid test which measures the susceptibility of certain nickel-rich, chromium-bearing alloys to intergranular corrosion (see Terminology G193), which may be encountered in certain service environments. The uniform corrosion rate obtained by this test method, which is a function of minor variations in alloy composition, may easily mask the intergranular corrosion components of the overall corrosion rate on alloys N10276, N06022, N06059, and N06455. 1.1.2 Method B, Mixed Acid-Oxidizing Salt Test (Sections 11 – 18, inclusive)—This test method describes the procedure for conducting a boiling 23 % sulfuric + 1.2 % hydrochloric + 1 % ferric chloride + 1 % cupric chloride test which measures the susceptibility of certain nickel-rich, chromium-bearing alloys to display a step function increase in corrosion rate when there are high levels of grain boundary precipitation. 1.2 The purpose of these two test methods is to detect susceptibility to intergranular corrosion as influenced by variations in processing or composition, or both. Materials shown to be susceptible may or may not be intergranularly corroded in other environments. This must be established independently by specific tests or by service experience. 1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.3.1 Exception—Some desired corrosion rate units in 8.1.1 are given in inch-pound units. 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. Warning statements are given in 5.1.1, 5.1.3, 5.1.9, 13.1.1, and 13.1.11. 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.