OCT 1 1969

NATIONAL BUREAU OF STANDARDS REPORT

10 086

Progress Report

on TEST METHODS FOR EVALUATING THE STRESS

CORROSION BEHAVIOR OF ALUMINUM ALLOYS

To

Materials Division

Naval Air Systems Command

Department of the N avy

<NB^

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards was established by an act of Congress March 3. 1901. Today,

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NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT

3120410

OCT 1 1969

NBS REPORT

10 086

Progress Report

on TEST METHODS FOR EVALUATING THE STRESS

CORROSION BEHAVIOR OF ALUMINUM ALLOYS

By

W. F. Gerhold

Engineering Metallurgy Section

To

Materials Division

Naval Air Systems Command

Department of the N avy

IMPORTANT NOTICE NATIONAL BUREAU OF STA

for use within the Government. I and review. For this reason, the whole or in part, is not authori Bureau of Standards, Washingtoi

the Report has been specifically

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST)

on October 9, 2015.

; accounting documents intended

ubjected to additional evaluation

listing of this Report, either in Office of the Director, National

the Government agency for which

pies for its own use. <NBS>

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

Progress Report

on

Test Methods for Evaluating the Stress

Corrosion Behavior of Aluminum Alloys

W. F. Gerhold

Engineering Metallurgy Section

Results to date in an investigation comparing test

methods used for evaluating the s tress - corros ion behavior

of aluminum alloys (authorized under RRMA 2123) are

included herein.

Test methods studied in this investigation are the

constant strain method and the constant load method for

applying stress to the specimens.

The aluminum alloys used for test specimens in these

studies include the following:

2219-T352 aluminum alloy hand forging

(10 in . thick)

2219-T852 aluminum alloy hand forging

(10 in . thick)

2219-T62 aluminum alloy sheet (0.064

in . thick)

7079-T651 aluminum alloy rolled plate

(6 in . thick)

The tests are being conducted in the marine atmosphere

at Kure Beach, N. C. (80 ft. lot) and in the laboratory at

the National Bureau of Standards, Washington, D. C., and at

the Alcoa Research Laboratories, New Kensington, Pennsylvania.

Tables 1, 2, and 3 contain the results obtained to date from

tests conducted in these environments.

These tests are continuing.

USCOMM-NBS-DC

Table 1. Results obtained from stress - corros ion tests conducted in the marine atmosphere at Kure Beach, N.C. (80 ft. lot)

Constant Strain Method Constant Load Method

Exposure Stress, F/N Days to Percent Loss Remarks F/N Days to Percent Loss Percent of (a) Failure in Tensile (a) Failure in Tensile

Yield Strength (b) Strength (b) Strength

2219-T352 Aluminum Alloy Hand Forging (10 in . Thick), Short Transverse***1 *

75 2/3 42 , 58 _ (c) 3/3 9 , 9 , 9

- 50 3/3 58, 76, 113 - 3/3 13, 14 , 23 - 0 0/3 Rem 26, 135 25, 26 (c) 0/2 Rem 13, 23 9 , 13 2219-T852 Aluminum Alloy Hand Forging (10 in . Thick), Short Transverse***1 * 75 1/3 888 _ (d) 0/3 414(3) NF 13 , 14, 15

0 0/3 Rem 888 (i) (d) 0/3 Rem 414(3) 10 , 11 , 15 2219-T62 Aluminum Alloy Sheet (0.064 in. Thick), Transverse^^

Preform (f) 0/3 _ _ (e) No :Specimens Exposed

75 0/3 - - (e) 0/3 4 14 ( 3) NF 6 , 7, 8

0 0/3 - (e) 0/3 Rem 414(3) 7 , 8, 9

7079-T651 Aluminum Alloy Rolled Plate (6 in. Thick), Short Transverse*''1 *

25 3/3 259, 545, 1144 3/3 24 , 31 , 31 - 15 0/3 - - (e) 3/3 24 , 29 , 82 - 0 0/3 " - (e) 0/3 Rem 24 , 29 , 82 5 , 6, 22

7079-T651 Aluminum Alloy Rolled Plate (6 in. Thick), Long Transverse**'1 *

75 3/3 58(2) , 85 - 0/3 29 , 36 , 37 - 0 0/3 Rem 135, 267(2) 6, 7, 8 0/3 Rem 29 , 36, 37 3 , (g) , 4

(a) F-Number of specimens that failed.

N-Number of specimens exposed

(b) Rem - Unstressed specimens removed from test after exposure for number of days shown. NF - Stressed specimens had not failed after exposure for number of days shown.

Numbers in parentheses refer to number of specimens.

(c) One specimen still on exposure; Total exposure time to Sept. 1, 1969 - 1600 days.

(d) Two specimens still on exposure; Total exposure time to Sept. 1, 1969 - 1600 days.

(e) Three specimens still on exposure; Total exposure time to Sept. 1, 1969 - 1600 days.

(f) Preform - Specimen deformed to introduce residual stresses and then additionally stressed

by constant strain method.

(g) Specimen broke while removing it from test.

(h) Principal axis of the specimen with respect to the direction of working.

(i) Data not available.

Table 2. Results obtained from stress-corrosion tests conducted in an artificial laboratory

environment (aqueous solution containing 3.5% NaCl - intermittent immersion).

Constant Strain Method* Constant Load Method

Exposure Stress, f7n Days to Percent Loss Remarks F/N Days to Percent Loss Percent of (a) Failure in Tensile (a) Failure in Tensile

Yield Strength (b) Strength (b) Strength

2219-T352 Aluminum Alloy Forging (10 in. Thick) ,

f cl Short Transverse^ J 75 3/3 1(3) 3/3 1, 1, 3

- 50 3/3 2 , 2 , 82 - 3/3 5, 24, 27 - 0 0/3 Rem 84(3) 2 7

f e) 0/3 Rem 5 , 24 , 27 6, 28, 24

2219 T852 Aluminum Alloy Forging (10 in

Thick) , Short Trans verse

* c '

75 0/3 183(3) NF 16(e) 1/3 33, 60(2) NF 31, 32

0 0/3 Rem 183(3) 32(e) 0/3 Rem 33, 60(2) 30, 34, (f)

2219-T62 Aluminum Alloy Sheet (0.064 in. Thick) , fcl Transverse^

Preform(d) 0/3 183(3) NF _ No !Specimens Exposed

37 75 ( e ^ 0/3 183(3) NF 46 ( e ) 0/3 60(3) NF

0 0/3 Rem 183(3) 44(e) 0/3 Rem 60(3) 38(e)

7079-T651 Aluminum Alloy Rolled Plate (6 in. Thick), Short Transverse

25 0/3 183(3) NF 42(e) 3/3 4(3) - IS 0/3 183(3) NF 13(e) 0/3 61(3) NF 14(e)

0 0/3 Rem 183(3) 12 ( e ) 0/3 Rem 61(3) 2g(e)

7079-T651 Aluminum Alloy Rolled Plate (6

('c') in. Thick), Long Transverse 1 ’

75 3/3 3, 6, 6

- 3/3 6 , 12 , 15 -

0 0/3 Rem 183(3) 5(e) 0/3 Rem 6 , 12, 15 2, 6, 3

* Tests performed by Alcoa (data reported by Alcoa)

(a) F-Number of specimens that failed

N-Number of specimens exposed.

(b) Rem - Unstressed specimens removed from test after exposure for number of days shown. NF - Stressed specimens had not failed after exposure for number of days shown.

Numbers in parentheses refer to number of specimens.

(c) Principal axis of the specimen with respect to the direction of working.

(d) Preform - Specimen deformed to introduce residual stresses and then additionally stressed

by constant strain method.

(e) Average value for number of specimens exposed.

(fl Specimen broke while removing it from test.

Table 3. Results obtained from stress -corrosion tests conducted in an artifical laboratory

environment (IN NaCl solution with 10 ml 30°. H

? 0? /1 of solution - intermittent

immersion) . L L

Constant Strain Method Constant Load Method

Exposure Stress,

Percent of

Yield Strength

F/N

(a) Days to Failure

(b)

Percent Loss Remarks

in Tensile

Strength

F/N

(a) Days to Failure

(b)

Percent Loss

in Tensile

Strength

2219-T3S2 Aluminum Alloy Hand Forging (10 in. Thick), Short Transverse* 0 *

75 3/3 2, 2, 8

_ 3/3 1,1,2 - SO 3/3 1, 1, 8

- 3/3 2, 3, 3

- 0 0/3 Rem 2 , 2

,

8 (f) 0/3 Rem 2 , 3 , 3 28, 29, 28

2219-T852 Aluminum Alloy Hand Forging (10 in. Thick), Short Transverse* 1-"*

75 0/3 60(3) NF (f) 3/3 19, 24, 41 - 0 0/3 Rem 60(3) (f) 0/3 Rem 19 , 24 , 41 37, 39, 57

2219-T62 Aluminum Alloy :Sheet (0.064 in. Thick), Transverse* 1- * Preform(d) 0/3 65(3) NF No :Specimens Exposed

75 0/2 65(2) NF 51(e) 1/3 48, 65(2) NF 41 , 46

0 0/2 Rem 65(3) 46(e) 0/3 Rem 48, 65(2) 34, 44, 51

7079-T651 Aluminum Alloy Rolled Plate (6 (c) in. Thick), Short Transverse 1 J

25 2/3 8 , 21 , 60 NF (f) 3/3 2, 7, 7

- 15 0/3 60(3) NF (£) 0/3 61(3) NF 47(e)

0 0/3 Rem 60(3) (f) 0/3 Rem 61(3) 4 7 e

7079-T651 Aluminum Alloy Rolled Plate (6 in. Thick), Long Transverse* 0 *

75 3/3 2(3) - 3/3 13, 18, 18 -

0 0/3 Rem 2(3) 3(e) 0/3 Rem 13, 18, 18 0,2,5

(a) F-Number of specimens that failed.

N-Number of specimens exposed.

(b) Rem - Unstressed specimens removed from test after exposure for number of days shown. NF - Stressed specimens had not failed after exposure for number of days shown. Number in parentheses refer to number of specimens.

(c) Principal axis of the specimen with respect to the direction of working.

(d) Preform - Specimen deformed to introduce residual stresses and then additionally stressed

by constant strain method.

(e) Average value for number of specimens exposed.

(f) Data not available.


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