The ASCOR test: a simple automated method for stress corrosion testing of aluminium alloys

Abstract

Alternate immersion stress corrosion testing according to ASTM specification G44 has proven to be representative for aluminium alloys in natural environments resembling the actual environmental conditions for aircraft. A simple automated stress corrosion testing method called the ASCOR (Automated Stress COrrosion Ring) test was developed to test aluminium alloys according to this specification. The method involves testing cylindrical or sheet specimens in a loading ring provided with strain gauges to measure the load. Initiation of a stress corrosion crack results in a small load decrease. During the test the load is measured periodically and stored in a Data Acquisition system controlled by a Personal Computer. A specific load decrease is used as the criterion for stress corrosion crack initiation. The main advantages of the method are that a large number of specimens can be tested simultaneously in a climate chamber, and that SCC initiation lives can be determined according to a clearly defined criterion without time-consuming and subjective inspections, and without disturbing the test procedure.