ASTM G103-97

Standard Practice for Evaluating Stress-Corrosion Cracking Resistance of Low Copper 7XXX Series Al-Zn-Mg-Cu Alloys in Boiling 6% Sodium Chloride Solution

SCOPE
1.1 This stress corrosion practice is intended for statically loaded smooth non-welded or welded specimen tests of 7XXX series Al-Zn-Mg alloys containing less than 0.26% copper.
1.2 This practice is concerned primarily with the test medium which may be used with a variety of test specimens and methods for applying stress. Exposure times, criteria of failure, and so on, are variable and not specified.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. See Section 8 for additional precautions.

General Information

• Status: Historical
• Publication Date: 09-Dec-1997
• ICS: 77.120.10 - Aluminium and aluminium alloys
• Technical Committee: G01 - Corrosion of Metals
• Drafting Committee: G01.06 - Environmentally Assisted Cracking

Relations

• Replaced By: ASTM G103-97(2005) - Standard Practice for Evaluating Stress-Corrosion Cracking Resistance of Low Copper 7XXX Series Al-Zn-Mg-Cu Alloys in Boiling 6% Sodium Chloride Solution
• Effective Date: 01-Oct-2005
• Referred By: ASTM G30-22 - Standard Practice for Making and Using U-Bend Stress-Corrosion Test Specimens
• Effective Date: 10-Dec-1997

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:G103–97
Standard Practice for
Evaluating Stress-Corrosion Cracking Resistance of Low
Copper 7XXX Series Al-Zn-Mg-Cu Alloys in Boiling 6%
Sodium Chloride Solution
This standard is issued under the fixed designation G 103; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Continuous immersion in boiling 6 % sodium chloride solution historically was considered to be an
effectiveacceleratedSCCtestingmediumforallAl-Zn-Mg-Cualloys(1, 2), butinmorerecentyears,
alternate immersion in 3.5 % sodium chloride solution (Practice G 44) has become the favored test
medium for the high copper (1.2 to 2.6 % Cu) 7XXX series alloys (3, 4). Evidence to date shows,
however, that the boiling 6 % sodium chloride medium correlates better with outdoor atmospheric
exposure than Practice G 44 for the 7XXX series alloys containing little or no copper (5, 6, 7, 8).
1. Scope G 30 Practice for Making and Using U-Bend Stress-
Corrosion Test Specimens
1.1 This stress corrosion testing practice is intended for
G 38 Practice for Making and Using C-Ring StressCorro-
statically loaded smooth non-welded or welded specimens of
sion Test Specimens
7XXX seriesAl-Zn-Mg-Cu alloys containing less than 0.26 %
G 39 PracticeforPreparationandUseofBent-BeamStress-
copper.
Corrosion Test Specimens
1.2 This practice is concerned primarily with the test me-
G 44 Practice for Evaluating Stress Corrosion Cracking
dium which may be used with a variety of test specimens and
ResistanceofMetalsandAlloysbyAlternateImmersionin
methods of applying stress. Exposure times, criteria of failure,
3.5 % Sodium Chloride Solution
and so on, are variable and not specified.
G 49 Practice for Preparation and Use of Direct Tension
1.3 This standard may involve hazardous materials, opera-
Stress Corrosion Test Specimens
tions, and equipment. This standard does not purport to
G 58 Practice for Preparation of Stress-Corrosion Test
address all of the safety concerns, if any, associated with its
Specimens for Weldments
use. It is the responsibility of the user of this standard to
establish appropriate safety and health practices and deter-
3. Summary of Practice
mine the applicability of regulatory limitations prior to use.
3.1 Stressed specimens are totally and continuously im-
See Section 8 for additional precautions.
mersed in boiling 6 % sodium chloride solution for up to 168
2. Referenced Documents h. Various types of smooth test specimens and methods of
stressing may be used. Performance is based on time to visual
2.1 ASTM Standards:
cracking.
B 580 Specification for Anodic Oxide Coatings on Alumi-
num
4. Significance and Use
D 1193 Specifications for Reagent Water
4.1 This practice is normally used for stress corrosion
screening for the development ofAl-Zn-Mg-Cu alloys contain-
This test method is under the jurisdiction of ASTM Committee G01 on ing less than 0.26 % copper. Effects on stress corrosion
Corrosion of Metals and is the direct responsibility of Subcommittee G01.06 on
resistance due to variables such as composition, thermo-
Stress Corrosion Cracking and Corrosion Fatigue.
mechanical processing, other fabrication variables and magni-
Current edition approved Dec. 10, 1997. Published February 1998. Originally
e1
tude of applied stress may be compared.
published as G 103 – 89. Last previous edition G 103 – 89 .
The boldface numbers in parentheses refer to the list of references at the end of
this standard.
Annual Book of ASTM Standards, Vol 02.05.
4 5
Annual Book of ASTM Standards, Vol 11.01. Annual Book of ASTM Standards, Vol 03.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
G103
4.2 For a given mechanical method of stressing, the relative 5.2.3 Metallic materials of construction should be limited to
stress corrosion resistance of the low copper Al-Zn-Mg-Cu copper free aluminum alloys, which may be anodized to
alloys in atmospheric exposure correlates better with perfor-
provide electrical contact resistance.
mance in boiling 6 % sodium chloride solution than with other
5.3 Specimen Holders—The specimen holders should be
accelerated testing media (7-9). In addition, this practice is
designed to electrically insulate the specimens from each other
relatively rapid.
and from other bare metal. An anodized aluminum holder has
4.3 This practice is not applicable to 2XXX (Al-Cu), 5XXX
been found to be appropriate. (Satisfactory anodic coating may
(Al-Mg), 6XXX (Al-Mg-Si), and the 7XXX (Al-Zn-Mg-Cu)
be TypeAor B, Specification B 580.) Periodic ohmeter checks
series alloys containing more than 1.2 % copper.
may be made to confirm electrical isolation of specimen and
4.3.1 For 7XXX series alloys containing between 0.26 %
anodized holder.
and 1.2 % copper, there is no general agreement as to whether
5.4 Heater for Solution:
this practice or Practice G 44 correlates better with stress
5.4.1 Heaters must be of sufficient capacity that boiling
corrosion resistance in service (5-8,10).
temperature can be maintained and solution can be brought
back up to a boil within 10 min after the introduction of test
5. Apparatus
specimens.
5.1 Fig. 1 illustrates one type of apparatus that has been
5.4.1.1 Quartz immersion heaters may be used.
used.
5.4.1.2 Hot plate resistance heaters may be used.
5.2 Materials of Construction:
5.2.1 Materialsofconstructionthatcomeincontactwiththe
6. Reagents and Solution Conditions
boiling salt solution shall be such that they are not affected by
the corrodent to an extent that they can cause contamination of 6.1 Reagent grade sodium chloride (NaCl) shall be used. It
the solution and change its corrosiveness. shall conform to the specifications of the Committee on
5.2.2 Useofglassoraluminumcontainersandcondensersis Analytical Reagents of theAmerican Chemical Society, where
recommended. such specifications are applicable.
U bend specimens (Practice G 39) stressed in an anodized aluminum fixture (right photo) are placed in a pyrex battery jar (left photo), which is placed over a mag-
netic stirrer. The 6 % salt solution is heated to boiling by means of two quartz immersion heaters. A powerstat controls the heat output of the quartz heaters. A cold
water circulating aluminum condenser tube is placed just below the aluminum cover to prevent evaporation losses. Stressed specimens are placed in the jar after
the solution comes to a boil. Specimens are examined in place for visual evidence of cracking.
FIG. 1 Boiling 6% NaCl—Stress Corrosion Testing Practice
G103
6.2 The 6 % NaCl solution shall be prepared using distilled 8. Safety Precautions
or deionized water conforming to the purity requirements of
8.1 Care should be taken in order to avoid burns from hot
Specification
...