AS 2136-1977 pdf download.Method for detecting the susceptibility of copper and its alloys to stress corrosion cracking using the mercurous nitrate test.
I SCOPE. This standard describes a procedure for detecting the susceptibility of copper and copper base alloy products to stress Corrosion cracking by immersion of test pieces in an acidified solution of mercurous nitrate.
2 DEFINITIONS. For the purpose of this standard, the following definitions apply
2.1 Stress corrosion cracking-spontaneous cracking of metals by simultaneous action of stress (residual and/or applied)and certain specific corrosive media.
MOTE: Cracking occurs with little or no deformation of the adjacent metal.
2.2 Applied stress-stress applied from without and including stresses resulting from assembly operations.
2.3 Residual stress-internal stress in the metal resulting usually from cold working.
5 TEST PROCEDURE. Test pieces prepared in accordance with the requirements ot Clause 3 shall he tested in the following manner:
(a) Pickle to remove all carbonaceous and oxide films by treatmen for 30 s maximum in either of the following solution:
(I) An aqueous solution of 15 percent V/V sulphuric acid.
(ii) An aqueous solution of 40 percent V/V nitric acid.
(b) Wash in running water.
(c) Drain off excess water and totally immerse the test piece in the test solution. The volume of test solution shall be not less than 1.5 mlil(X) mm2 of test piece surface exposed.
(d) After 30 mm remove the test piece from the test solution and wash well in running water.
(e) Wipe off any excess mercury from the surface of the test piece.
(1) Examine the test surface for the presence of cracks using a low power microscope or other suitable magnifying equipment at a magnification of 10 x to 20 x.AS 2136-1977 pdf download.