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)