ASTM G35-23

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: G35 − 98 (Reapproved 2015) G35 − 23
Standard Practice for
Determining the Susceptibility of Stainless Steels and
Related Nickel-Chromium-Iron Alloys to Stress-Corrosion
Cracking in Polythionic Acids
This standard is issued under the fixed designation G35; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This practice covers procedures for preparing and conducting the polythionic acid test at room temperature, 22 to 25°C (72
to 77°F),22 °C to 25 °C (72 °F to 77 °F), to determine the relative susceptibility of stainless steels or other related materials
(nickel-chromiumiron(nickel-chromium-iron alloys) to intergranular stress corrosion cracking.
1.2 This practice can be used to evaluate stainless steels or other materials in the “as received” condition or after being subjected
to high-temperature service, 482 to 815°C (900 to 1500°F),482 °C to 815 °C (900 °F to 1500 °F), for prolonged periods of time.
1.3 This practice can be applied to wrought products, castings, and weld metal of stainless steels or other related materials to be
used in environments containing sulfur or sulfides. Other materials capable of being sensitized can also be tested in accordance
with this test.
1.4 This practice may be used with a variety of stress corrosion test specimens, surface finishes, and methods of applying stress.
1.5 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for
information only and are not considered standard.
1.6 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 healthsafety, health, and environmental practices and determine
the applicability of regulatory limitations prior to use. For more specific precautionary statements, see Section 7.
1.7 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D1193 Specification for Reagent Water
G1 Practice for Preparing, Cleaning, and Evaluating Corrosion Test Specimens
This practice is under the jurisdiction of ASTM Committee G01 on Corrosion of Metals and is the direct responsibility of Subcommittee G01.06 on Environmentally
Assisted Cracking.
Current edition approved Nov. 1, 2015June 1, 2023. Published November 2015June 2023. Originally approved in 1988. Last previous edition approved in 20102015 as
G35–98(2010).G35 – 98 (2015). DOI: 10.1520/G0035-98R15.10.1520/G0035-23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
G35 − 23
G15G28 Terminology Relating to Corrosion and Corrosion TestingTest Methods for Detecting Susceptibility to Intergranular
Corrosion in Wrought, Nickel-Rich, Chromium-Bearing Alloys (Withdrawn 2010)
G30 Practice for Making and Using U-Bend Stress-Corrosion Test Specimens
G193 Terminology and Acronyms Relating to Corrosion
3. Summary of Practice
3.1 The stressedStressed test specimens are placed in the container along with a sensitized and stressed AISI Type 302 (UNS
S30200) or Type 304 (UNS S30400) stainless steel control specimen. A sufficient amount of the previously prepared polythionic
acid solution is added to the container to immerse the test specimens. A cover is placed on the container and the test exposure is
carried out at room temperature.temperature followed by inspection for cracks.
4. Significance and Use
4.1 This environment provides Polythionic acids are chemically described as H S O , where x is usually 3, 4, or 5 (1) though
2 x 6
can be more than 50 (2). These acid environments provide a way of evaluating the resistance of stainless steels and related alloys
to intergranular stress corrosion cracking. Failure is accelerated by the presence of increasing amounts of intergranular precipitate.
Results for the polythionic acid test have not been correlated exactly with those of intergranular corrosion tests. tests (Test Methods
G28). Also, this test may not be relevant to stress corrosion cracking in chlorides or caustic environments.
4.2 The polythionic acid environment may produce areas of shallow intergranular attack in addition to the more localized and
deeper cracking mode of attack. Examination of failed specimens is necessary to confirm that failure occurred by cracking rather
than mechanical failure of reduced sections.
5. Apparatus
5.1 Any suitable glass or other transparent, inert container can be used to contain the acid solution and stressed specimens during
the period of test at room temperature, 22 to 25°C (72 to 77°F).22 °C to 25 °C (72 °F to 77 °F). The container should be fitted with
a removable top to reduce evaporation and to allow access to the stressed specimen (or specimens) for the periodic inspection.
6. Reagents
6.1 Purity of Reagents—The polythionic acid solution shall be prepared using reagent grade sulfurous acid and technical grade
hydrogen sulfide; or, distilled water, commercial grade sulfur dioxide, and technical grade hydrogen sulfide.
6.2 Purity of Water—Reagent water Type IV (Specification D1193) shall be used to prepare the test solutions.
6.3 Wackenroder’s or Polythionic Acid Solution (13)—A slow current of hydrogen sulfide is passed for an hour through a fritted
glass tube into a flask containing chilled (0°C, 32°F)(0 °C, 32 °F) 6 % sulfurous acid, after which the liquid is kept in the stoppered
flask for 48 h at room temperature. This operation is repeated until the liquid no longer gives off the odor of sulfur dioxide after
standing at room temperature for a few hours. Note safety precautions in Section 7.
6.3.1 In an alternative method (24), the polythionic acid solution is prepared by passing a slow current of sulfur dioxide gas
through a fritted glass bubbler submerged in a container of distilled water. This is continued until the solution becomes saturated,
and then the hydrogen sulfide gas is slowly bubbled into the sulfurous acid solution.
6.3.2 The presence of polythionic acids in the solution prepared in accordance with 6.3 or 6.3.1 can be checked by either of the
following methods. Polarographya variety of methods. Previous versions of this standard suggested direct analysis through the use
of polarography (35) can be employed to identify the thionic acids, or the percent of acid present inwet techniques that employ
mercury chloride the(6). solution can be determined by wet techniquesThe peer-reviewed technical literature has demonstrated the
(successful4). The simplest use of high-p
...