Stress Corrosion Susceptibility Of Welded Aluminum Alloys

Item

Title
Stress Corrosion Susceptibility Of Welded Aluminum Alloys
Description
Adequate knowledge of the stress corrosion thresholds of welded aluminum alloys is required by designers to utilize mechanical properties fully. This program determined threshold stress levels for 2014-T6, X2021-T8E31, 2024-T81, 2219-T87, X7002-T6, 7039-T64, and 7106-T6. Variables were sheet and plate, long transverse grain direction, welded and post-weld heat treated, notched and unnotched. Tests were conducted using step load and constant load 500 hours alternate immersion in synthetic sea water at sus­tained stress levels up to 75-percent yield strength. All basic, unwelded alloys, sheet and plate, had thresholds above 75-percent yield strength. Thresholds for unnotched sheet alloys were below 75-percent yield strength for 2014-T6, as welded (W), weld + age (A) and weld + solution heat treat + age (S), X2021-T8E31 (W), 2024-T81 (W), 2219-T87 (S), 7039-T64 (S) and 7106-T6 (A) (S). The most susceptible to stress corrosion cracking was X2021-T8E31 (W). A fatigue crack at the edge of the weld bead caused in­creased susceptibility to stress corrosion for several of the sheet alloy-weld­-tempers. For unnotched plate product, stress corrosion cracking was in­curred for only 2014-T6 (S) and 7039-T64 (S) below 75-percent yield strength; this was at higher stress levels than the (W) and (A) tempers tested. A fatigue crack at the edge of the weld bead caused severe susceptibility to stress corrosion cracking for plate alloys, X2021-T8E31 (S), 7039-T64 (S) and 2014-T6 (S). An Engineering Data Materials Matrix is presented. 5tress corrosion cracking typically initiated at the edge of the weld bead and prog­ressed along the fusion line, branching into the weld bead and heat affected zone. Progression was characterized by a series of jumps exhibiting both corrosion and stress corrosion stages. Additional work is recommended in spectrum loading and natural environment stress corrosion testing, electron beam welding and basic studies of microstructural effects.
Date
1967
Index Abstract
Contrails and DTIC
Photo Quality
Complete
Report Number
AFML TR 67-291
Creator
Turley, Richard F.
Avery, Charles H.
Dash, Edward
Corporate Author
Douglas Aircraft Company
Laboratory
Air Force Materials Laboratory
Extent
180
Identifier
AD0824852
AD0824852
Access Rights
Export Control
Distribution Classification
1
Contract
AF 33(615)-5419
DoD Project
7381
DoD Task
738107
DTIC Record Exists
Yes
Distribution Change Authority Correspondence
AFSC USAF LTR
Report Availability
Full text available
Date Issued
1967-08
Abstract
Adequate knowledge of the stress corrosion thresholds of welded aluminum alloys is required by designers to utilize mechanical properties fully. This program determined threshold stress levels for 2014-T6, X2021-T8E31, 2024-T81, 2219-T87, X7002-T6, 7039-T64, and 7106-T6. Variables were sheet and plate, long transverse grain direction, welded and post-weld heat treated, notched and unnotched. Tests were conducted using step load and constant load 500 hours alternate immersion in synthetic sea water at sus­tained stress levels up to 75-percent yield strength. All basic, unwelded alloys, sheet and plate, had thresholds above 75-percent yield strength. Thresholds for unnotched sheet alloys were below 75-percent yield strength for 2014-T6, as welded (W), weld + age (A) and weld + solution heat treat + age (S), X2021-T8E31 (W), 2024-T81 (W), 2219-T87 (S), 7039-T64 (S) and 7106-T6 (A) (S). The most susceptible to stress corrosion cracking was X2021-T8E31 (W). A fatigue crack at the edge of the weld bead caused in­creased susceptibility to stress corrosion for several of the sheet alloy-weld­-tempers. For unnotched plate product, stress corrosion cracking was in­curred for only 2014-T6 (S) and 7039-T64 (S) below 75-percent yield strength; this was at higher stress levels than the (W) and (A) tempers tested. A fatigue crack at the edge of the weld bead caused severe susceptibility to stress corrosion cracking for plate alloys, X2021-T8E31 (S), 7039-T64 (S) and 2014-T6 (S). An Engineering Data Materials Matrix is presented. 5tress corrosion cracking typically initiated at the edge of the weld bead and prog­ressed along the fusion line, branching into the weld bead and heat affected zone. Progression was characterized by a series of jumps exhibiting both corrosion and stress corrosion stages. Additional work is recommended in spectrum loading and natural environment stress corrosion testing, electron beam welding and basic studies of microstructural effects.
Type
report
Provenance
Lockheed Martin Missiles & Fire Control
Subject
Stress Corrosion
Aluminum Alloys
Welds
Cracks
Sheets
Metal Plates
Sea Water
Liquid Immersion Tests
Heat Treatment
Fracture (Mechanics)
Publisher
Wright-Patterson Air Force Base, OH : Air Force Materials Laboratory, Research and Technology Division, Air Force Systems Command
Format
1 online resource (xiv, 164 pages) : ill.
NTRL Accession Number
AD824852
Date Modified
Scanned by request 4/14/2021 submitted by National Aeronautics and Space Administration (Government Agency - Domestic)
Scanned by request 4/14/2021 submitted by MG Aerospace (Aerospace Industry - International)