ASTM G58-85(1999)
(Practice)Standard Practice for Preparation of Stress-Corrosion Test Specimens for Weldments
Standard Practice for Preparation of Stress-Corrosion Test Specimens for Weldments
SCOPE
1.1 This practice covers procedures for the making and utilization of test specimens for the evaluation of weldments in stress-corrosion cracking (SCC) environments.
1.2 Test specimens are described in which (a) stresses are developed by the welding process only, (b) stresses are developed by an externally applied load in addition to the stresses due to welding, and (c) stresses are developed by an externally applied load only with residual welding stresses removed by annealing.
1.3 This practice is concerned only with the welded test specimen and not with the environmental aspects of stress-corrosion testing. Specific practices for the bending and loading of test specimens, as well as the stress considerations involved in preparation of C-rings, U-bend, bent beam, and tension specimens are discussed elsewhere in ASTM standards.
1.4 The actual stress in test specimens removed from weldments is not precisely known because it depends upon the level of residual stress from the welding operation combined with the applied stress. A method for determining the magnitude and direction of residual stress which may be applicable to weldment is described in Test Method E837. The reproducibility of test results is highly dependent on the preparation of the weldment, the type of test specimen tested, and the evaluation criteria used. Sufficient replication should be employed to determine the level of inherent variability in the specific test results that is consistent with the objectives of the test program.
1.5 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. (For more specific safety hazard information, see Section 8.)
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Designation:G58–85(Reapproved1999)
Standard Practice for
Preparation of Stress-Corrosion Test Specimens for
Weldments
ThisstandardisissuedunderthefixeddesignationG 58;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 This practice covers procedures for the making and 2.1 ASTM Standards:
utilization of test specimens for the evaluation of weldments in E 8 TestMethodsforTensionTestingofMetallicMaterials
stress-corrosion cracking (SCC) environments. E 399 Test Method of Plane-Strain Fracture Toughness of
1.2 Test specimens are described in which ( a) stresses are Metallic Materials
developed by the welding process only, ( b) stresses are E 837 Test Method for Determining Residual Stresses by
developed by an externally applied load in addition to the the Hole-Drilling Strain-Gage Method
stresses due to welding, and (c) stresses are developed by an G 1 Practice for Preparing, Cleaning, and Evaluating Cor-
externally applied load only with residual welding stresses rosion Test Specimens
removed by annealing. G 30 Practice for Making and Using U-Bend Stress-
1.3 This practice is concerned only with the welded test Corrosion Test Specimens
specimen and not with the environmental aspects of stress- G 35 Practice for Determining the Susceptibility of Stain-
corrosion testing. Specific practices for the bending and load- less Steels and Related Nickel-Chromium-Iron Alloys to
ing of test specimens, as well as the stress considerations Stress-Corrosion Cracking in Polythionic Acids
involved in preparation of C-rings, U-bend, bent beam, and G 36 Practice for Performing Stress-Corrosion Cracking
tensionspecimensarediscussedelsewhereinASTMstandards. Tests in a Boiling Magnesium Chloride Solution
1.4 The actual stress in test specimens removed from G 37 Practice for Use of Mattsson’s Solution of pH 7.2 to
weldments is not precisely known because it depends upon the Evaluate the Stress-Corrosion Cracking Susceptibility of
level of residual stress from the welding operation combined Copper-Zinc Alloys
with the applied stress. A method for determining the magni- G 38 Practice for Making and Using C-Ring Stress Corro-
tudeanddirectionofresidualstresswhichmaybeapplicableto sion Test Specimen
weldment is described in Test Method E 837. The reproduc- G 39 PracticeforPreparationandUseofBent-BeamStress-
ibility of test results is highly dependent on the preparation of Corrosion Test Specimens
the weldment, the type of test specimen tested, and the G 44 Practice for Evaluating Stress Corrosion Cracking
evaluation criteria used. Sufficient replication should be em- Resistance of Metals in 3.5 % Sodium Chloride Solution
ployed to determine the level of inherent variability in the G 49 Practice for Preparation and Use of Direct Tension
specific test results that is consistent with the objectives of the Stress Corrosion Test Specimens
test program.
3. Summary of Practice
1.5 This standard does not purport to address all of the
3.1 The following summarizes the test objectives that may
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- be evaluated:
3.1.1 Resistance to SCC of a total weldment (weld, heat-
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. (For more specific affected zone, and parent metal) as produced by a specific
welding process.
safety hazard information, see Section 7.)
3.1.2 Resistance to SCC of deposited weld metal.
3.1.3 Determination of a stress level or stress intensity that
will produce SCC in a weldment.
This practice is under the jurisdiction of ASTM Committee G-1 on Corrosion
of Metals, and is the direct responsibility of Subcommittee G01.06 on Stress-
Corrosion Cracking and Corrosion Fatigue. Annual Book of ASTM Standards, Vol 03.01.
Current edition approved June 28, 1985. Published November 1985. 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.
G58
3.1.4 Evaluation of SCC failure in the specific zones of a the demands of welding practice being evaluated. It is appli-
weld (weld metal, partially melted zone, weld interface, cable to any welding procedure and can involve single- or
heat-affected zone, and base metal). multiple-pass welds.
Procedure:
(a) Specimen size—as required.
(b) Note grain direction and weld longitudinally or across grain.
(c) For multiple-pass welds, grind between passes. Use back gouging from
opposite side to attain 100 % weld penetration.
(d) Discard weld ends.
(e) Remove test sections as required. Sections may be taken across the weld or
longitudinally with the weld.
FIG. 1 Flat Weldment
3.1.5 Evaluation of the effect of notches and stress raisers in 5.1.2 Circular Bead Weldment (Fig. 2)—This weldment (2,
weldments. 3, 4, 5) measures the tendency for SCC in the base metal,
heat-affected zone, and deposited weld metal. The circular
4. Significance and Use
weld develops residual stresses. It is applicable to any material
4.1 The intent of this practice is to indicate standard welded form (plate, bar, castings) that can be machined to the
specimens and welding procedures for evaluating the SCC
recommended size. The welding procedure involves one cir-
characteristics of weldments in corrosive environments. The cular stringer bead deposit of weld metal.
practice does not recommend the specific corrosive media that
5.1.3 Bead-on-Bar Weldment (Fig. 3)—This weldment, (2)
may be selected by the user depending upon the intent of his
measures the tendency for SCC of the base metal. The
investigation. Specific corrosive media are included in Prac-
longitudinal fusion welds develop residual stresses on the bar.
tices G 35, G 36, G 37, and G 44. Other environments can be
It is applicable to materials that can be machined to approxi-
used as required.
mately a 25-mm or 1-in. round.
5.1.4 Direct Tension Weldments (Fig. 4)—These weldments
5. Types of Specimens and Specific Applications
(3, 4, 5) measure the cracking tendency in weld metal, base
5.1 This practice covers the following procedures for the
metal, or heat-affected zone. The applied stress is developed in
preparation of test weldments. The form of the material to be
uniaxially loaded tension specimens. Notches may be intro-
evaluated (plate, bar, tubing, casting, or forging) may deter-
duced into the weld metal, base metal, or heat-affected zone.
mine whether its usage is applicable in a given test. Residual
The tension specimens are machined from welded plate or cast
welding stresses may be left intact or they may be fully or
sections (Fig. 1) and may be made exclusively from weld
partially removed by an appropriate heat treatment.
metal.
5.1.1 Flat Welding (Fig. 1)—This weldment (1) is appli-
5.1.5 U-Bend Weldment (Fig. 5)—This weldment (5, 6)
cable for all tension and bend specimens. The size of the
measures crack tendency in the weld, base metal, and
weldment may be varied according to the needs of the user or
heataffected zone. The bending operation after welding creates
highlevelsofelasticandplasticstrainresultinginawiderange
of stresses in a single specimen. The presence of residual
The boldface numbers in parentheses refer to the list of references at the end of
welding stresses make this a most severe test procedure. It is
this practice.
Procedure:
1 1
(a) Specimen size: 100 by 100 by 3 to 12 mm (4 by 4 by ⁄8 to ⁄2 in.)
(b) Clamp or tack weld the edges of the test specimen to a base plate to obtain
restraint.
(c) Weld a 50-mm or 2-in. diameter circular bead using the selected weld process
(Table 1).
(d) Examine both sides of specimen after exposure.
FIG. 2 Circular Bead Weldment
G58
Procedure:
(a) Specimen size: 25-mm (1 in.) diameter by 150 mm (6 in.) long.
(b) Fusion weld (GTAW) entire length on opposite sides.
1 3
(c) Discard 6 mm or ⁄4 in. from ends and remove 20-mm or ⁄4-in. test specimens.
(d) Examine cross section for radial cracking.
FIG. 3 Bead-on-Bar Weldment
Procedure:
(a) Direct tension specimens to be machined directly from flat plate weldment (Fig. 1).
(b) See Practice G 49 and Test Methods E 8 for recommended dimensions.
FIG. 4 Direct Tension Weldments
Procedure:
(a) U-bend specimens to be machined directly from flat plate weldment (Fig. 1)
(b) See Practice G 30 for bending method.
NOTE 1—The welds may be oriented 90° to the direction shown.
FIG. 5 U-Bend Weldment
applicable to any material that can be formed into a U-shape crack initiation or propagation in various areas of a weldment.
without mechanical cracking or localized bending in the Notches or cracks may be introduced into the weld metal, base
heataffected zone. metal, or heat-affected zone. The specimen will contain re-
5.1.6 Bent-Beam Weldment (Fig. 6)—This weldment (4, 5, sidual welding stresses and applied stresses. Weldments may
6) measures cracking tendency in the weld bead, the weldbase be prepared in accordance with Fig. 1 or by means of the
metal interface, and heat-affected zone due to stress concen- K-preparation for multiple-pass welds (Fig. 11 and Ref (7)).
tration. The specimen will contain residual welding stresses 5.1.8 TuningForkWeldment (Fig. 8)—This weldment (5, 8)
and stresses due to elastic strain produced by bending. This measures cracking tendency in the base metal, heat-affected
specimen is particularly applicable to materials that cannot be zone, or weld-base metal interface if the weld reinforcement is
bent into a U-shape. not removed. When the reinforcement is removed, cracking
5.1.7 PrecrackedCantileverBeamWeldment (Fig. 7)—This may also occur in the weld metal, depending on the suscepti-
weldment (5) measures the level of stress intensity to produce bility of the three zones of the weldment and the coincidence
G58
Procedure:
(a) Bent-beam specimens to be machined directly from flat plate weldment. (Fig. 1).
Fulcrum should be notched so as not to contact weld bead.
(b) Dimensions: as required.
(c) See Practice G 39 for stress calculations.
NOTE 1—The welds may be oriented 90° to the direction shown.
FIG. 6 Bent-Beam Weldment
Procedure:
(a) Specimens may be machined from flat plate weldment (Fig. 1) or K-weld
preparation (Fig. 11).
(b) See Test Method E 399 and Ref (13).
FIG. 7 Precracked Cantilever Beam Weldment
Procedure:
(a) Specimens are machined from parent metal and machined to shape.
(b) Weld bead is applied across the test specimen at the base of one tine.
(c) Either style specimen is appropriate for this test.
FIG. 8 Tuning Fork Weldment
Procedure:
(a) The dimensions of the plate sections may be varied to suit the needs of the
material under study.
(b) To obtain maximum and uniform weld restraint it is essential to grind all mating
surfaces flat. The ground area should be extended to cover the test weld area.
(c) Weld in sequence shown. The number of passes may be varied to suit the
needs of the test.
(d) Remove and discard 6.4 mm ( ⁄2 in.) on both ends and section tests specimens
as required.
FIG. 9 Cruciform Weldment
of maximum stress with the base metal, heat-affected zone, or 5.1.9 CruciformWeldment (Fig. 9)—This weldment (9) will
weldmetal.Stressesareappliedbyclosingthetinesofthefork, develop the highest degree of weld restraint and residual weld
and the toe of the weld acts as a metallurgical notch. Tuning- stresses. It has been used for evaluating the susceptibility of
fork specimens may also be machined exclusively from weld high-strength steel and armor plate to underbead cracking in
metal. the heat-affected zone of the weld. The welding sequence will
G58
Procedure:
(a) Use plate, bar, tube, or pipe of suitable size from which C-ring specimens can be machined.
(b) Weld one side for the entire length before cutting slot. The weld bead may be applied in a 60° groove to obtain 100 % weld penetration or it may be applied
on the surface only. Cut slot after machining plate or bar to form tube.
(c) Discard 6.4 mm ( ⁄4 in.) on both ends and remove 25-mm (1-in.) long test specimens.
(d) For slit tubing test, machine a thin slit in the side opposite weld. Stress may be applied by forcing a wedge or block in the slit.
(e) For C-ring dimension and loading see Practice G 38.
FIG. 10 Slit Tubing and C-Ring Weldments
Procedure:
(a) Double bevel groove butt-weld preparation.
(b) Vertical face buttered with filler metal.
(c) Weld joint completed with multiple passes of filler metal.
(d) Joint machined and notched as required.
(e) See Ref (7).
FIG. 11 K-Weld Preparation
NOTE 1—Calculated stresses developed in beam specimens, C-rings,
produce an increasing degree of restraint with each successive
etc. with weld beads intact will not accurately represent stresses generated
weld pass. The number of passes may be varied. Sections are
in fillets at the edge of the weld beads and in relatively thick beads, and
taken from the weldment and if not already cracked may be
strain gages will be needed if precise values of the applied stress are
exposed to SCC environments.
required. The effective stress of course will be the algebraic sum of the
5.1.10 C-Ring and Slit Tubing Weldments (Fig. 10)—These
applied stress and residual welding stresses.
weldments (2, 4, 5)measurethecrackingtendencyintheweld,
NOTE 2—Calculated stresses also may be erroneous for bead-off
base metal, and heat-affected zone. In the C-ring test (Practice
specimens of weldments of dissimilar alloys or in the case of relatively
G 38), the stress is applied externally. In the slit tubing test, the
soft heat-affected zones.
stress is applied by a wedge that is forced into the slit section.
While any material form can be machined into a ring section,
6. Welding Considerations
this test is specifically designed for tubing.
6.1 The choice of a welding method and the application of
5.1.11 K-Weld Preparation (Fig. 11)—This weldment (7)
proper welding techniques are major factors influencing the
was specifically designed to test the stress-corrosion cracking
overall corrosion resistance of a weldment. Each welding
tendency in various zones of a multiple-pass weld. Notches are
method as described in Refs (10, 11) has its own inherent
made in the weld metal, weld interface, heat-affected zone, or
characteristics which will govern the overall quality of the
parent metal
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