E. I. du Pont de Nemours and Company, Inc., Experimental Station, Wilmington, Del.
Pages: 82 Published: Jan 1978
The first evaluation methods for stainless steels, the 65 percent nitric acid and the copper sulfate-sulfuric acid tests, were originally simulated service tests. Later, when the results obtained with these tests were used to prevent failures by intergranular attack in other media, they were transformed into methods of general applicability for detecting susceptibility to intergranular attack. Since the 1949 ASTM symposium on this subject, several new methods have been introduced to accomplish this goal more rapidly and effectively. This has led to a large variety of ASTM test methods which also include the nickel-rich, chromium-bearing alloys.
In an overview of all current ASTM test practices for detecting susceptibility to intergranular attack, opportunities for improvements and simplifications are discussed. New data are presented on the properties of the various copper sulfate-sulfuric acid tests and on the performance of the new iron-chromium-molybdenum ferritic stainless steels in evaluation test solutions. The need for assessment criteria for determining the occurrence of intergranular attack in all test practices is emphasized with proposals for such criteria. A plan for a greatly reduced number of improved tests is proposed. The introduction of new melting, refining, and casting methods and of new iron-chromium-molybdenum stainless steels has increased the importance of evaluation test methods and the need for improvements in ASTM test practices.
stainless steels, intergranular corrosion, ferritic stainless steels, austenitic stainless steels, nickel alloys, nitric acid, oxalic acid, etching, copper sulfates, stress corrosion, pitting, corrosion, evaluation, condensers, heat treatments, sigma phase, chromium carbides, nitrides
Paper ID: STP34842S