Stress Corrosion Tests for Aluminum Alloys
FRANKFORD ARSENAL PHILADELPHIA PA
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Two techniques have been studied for the purpose of developing improved stress corrosion tests for 5083 and 7039 alloys. These are 1 chemical and electrochemical pretreatments of specimens using a sodium chloride solution prior to alternate immersion AI and 2 the use of a salt spray test as a more rapid stress corrosion test method. In addition, AI stress corrosion data have been obtained on 5083-H115 forged material. The results of tests using the chemical and the electrochemical pretreatments indicate that the time to failure of 5083 and 7039 alloys in AI are unaffected. Electrochemical pretreatments in nitric acid solution appear to be nondiscriminatory in achieving significant reductions in failure times on 5083 alloy. The use of salt spray on 5083-H131 has no effect on reducing the median time to failure. However, significant reductions in failure time are achieved with the use of salt spray on 7039-T6 alloy when the results are compared with those obtained from AI. Forged 5083-H115 plate shows no susceptibility to stress corrosion after 12 to 15 months exposure to AI. The use of thermal stabilization treatments on this alloy significantly increases susceptibility to stress corrosion.
- Properties of Metals and Alloys