Stress Corrosion Crack Initiation Testing of High Strength Aluminum Alloys Using Tuning Fork Type Specimens

摘要

The applicability of various corrosive environments for stress corrosion crack initiation testing was investigated. Specimens underwent standard constant load, constant total strain, and constant strain rate tests. Atmospheric exposure effects, immersion in 3.5% NaCl solution at 61% relative humidity, and testing in salt chromate solutions were studied. Results show that salt-chromate solutions inhibit general corrosion effectively, but do not result in cracking or, at a low pH value, lead to unrealistic ranking of materials as to stress corrosion cracking. Material behavior experienced under atmospheric conditions is reflected very well by alternate immersion testing in a salt solution. Pickling pretreatment causes a different degree of attack in different alloys and results in substantially shorter lifetimes for alternate immersion testing.