ISO/TC 156/WG 5 - Intergranular corrosion

ISO 3651-3:2017 specifies the determination of the intergranular corrosion susceptibility of low-Cr [less than 16 % Cr, less than 0,3 % Ni, less than 0,3 % Ti and less than 0,3 % Nb, less than 0,3 % (Ti + Atomic weight ratio Nb)] ferritic stainless steels in the 0,5 % sulfuric acid/copper sulfate test. It also specifies the purposes which may be assigned to the test. The method is applicable to stainless steels supplied in the form of rolled sheets and welded tubes and intended for use in a mildly oxidizing acid medium. It is important to note that the result of the corrosion test is only strictly valid for the corrosive medium used in the test. It constitutes a basis for estimating the resistance to intergranular corrosion but cannot be used to check resistance to other forms of corrosion (general corrosion, pitting, stress corrosion, etc.). It is important for the user to adapt the specified corrosion test where steels are used. This test is, in no case, considered as an absolute criterion of the quality of the metal.

ISO 21610:2009 specifies accelerated methods for the determination of the intergranular corrosion susceptibility of austenitic stainless steels. The methods specified by the standard provide results identical to those obtained when using ISO 3651‑1 and ISO 3651‑2, but the test period for the accelerated corrosion test is shorter. The standard is applicable to the testing of various kinds of metal production, including two-layer rolled metal, welded joints, deposited metal and weld seam metal. Two test methods are specified: method A: corrosion test in a solution of copper sulfate and concentrated sulfuric acid in the presence of metallic copper; method B: corrosion test in a solution of copper sulfate, sulfuric acid and copper fluoride in the presence of metallic copper.

ISO 15329:2006 specifies an electrochemical method to determine susceptibility to intergranular corrosion of solution-heat-treatable aluminium alloys, that is 2XXX, 6XXX, 7XXX and 8XXX alloys, without protective coatings and in various ageing conditions. ISO 15329:2006 is applicable to cast and wrought heat-treatable aluminium alloys in the form of castings, forgings, plates, sheets, extrusions, and semi-finished or finished parts, in order to carry out a comparative assessment of alloys of different grades and thickness depending on their chemical composition and other factors, and also to check the thermal processing quality of the tested materials. The test results provide information to help to determine the intergranular corrosion resistance and thermal processing quality of the tested materials (see Clauses 8 and 9).

Specifies the methods of intergranular corrosion testing for solution heat-treatable aluminium alloys without protective coatings. Applies to cast and wrought heat-treatable aluminium alloys in the form of castings, forgings, plates, sheets, extrusions and semi-finished or finished parts. Anables comparative assessments of alloys of different grades and thickness depending on their chemical composition and other factors.

Includes four methods: iron(III) sulfate - sulfuric acid test, copper - copper-sulfate - sulfuric acid test, hydrochloric acid test and nitric acid test. ISO 9400 defines the term nickel-based alloy. Specifies apparatus, test specimens, procedure and evaluation.