ASTM G28-24 PDF

Full title and description

ASTM G28-24 — Standard Test Methods for Detecting Susceptibility to Intergranular Corrosion in Wrought, Nickel‑Rich, Chromium‑Bearing Alloys. This document provides two standardized test procedures (Method A and Method B) for evaluating susceptibility of certain wrought nickel‑rich, chromium‑bearing alloys and weldments to intergranular corrosion under defined boiling acid or mixed‑acid/oxidizing salt conditions.

Abstract

ASTM G28-24 specifies two laboratory test methods used to detect susceptibility to intergranular corrosion in selected wrought nickel‑rich, chromium‑bearing alloys. Method A is a boiling ferric sulfate – 50% sulfuric acid test; Method B is a boiling mixed acid/oxidizing salt test (23% sulfuric + 1.2% hydrochloric + 1% ferric chloride + 1% cupric chloride). The tests are intended to reveal processing or composition changes that produce grain‑boundary precipitation and associated step increases in corrosion rate; results guide materials selection, heat treatment evaluation, and quality control.

General information

• Status: Active
• Publication date: November 1, 2024 (ASTM record shows a last-update entry on December 3, 2024).
• Publisher: ASTM International
• ICS / categories: 77.120.40 (Nickel, chromium and their alloys); Corrosion of metals (metallurgy / corrosion testing).
• Edition / version: G28-24 (2024 edition)
• Number of pages: 7

Scope

These test methods cover two specific laboratory procedures for detecting susceptibility to intergranular corrosion in wrought, nickel‑rich, chromium‑bearing alloys. Method A (boiling ferric sulfate in 50% sulfuric acid) measures uniform and intergranular corrosion components for selected alloys. Method B (boiling mixed acid/oxidizing salt) is designed to produce a step‑function increase in corrosion rate where high levels of grain boundary precipitation exist. The standard is applicable to wrought products and weldments; it is not intended for cast products. SI units are the default; select corrosion‑rate units in the test may be expressed in conventional inch‑pound units where noted.

Key topics and requirements

• Two distinct test procedures: Method A (ferric sulfate / sulfuric acid) and Method B (mixed acid + oxidizing salts).
• Specified test solutions, boiling conditions, sample geometry, and exposure times tailored to particular nickel alloys.
• Alloy applicability table and recommended test durations for common nickel alloys (e.g., N06007, N06022, N06030, N06059, N06455, N10276, etc.).
• Measurement and interpretation of corrosion rate and step‑function increases to determine susceptibility.
• Requirements for specimen preparation, cleaning, and reporting of results.
• Safety, handling, and environmental warning notes for the aggressive chemicals used in testing.
• Guidance on using results to evaluate effects of processing, heat treatment, and welds on intergranular corrosion susceptibility.

Typical use and users

ASTM G28-24 is used by corrosion testing laboratories, materials and metallurgical engineers, quality control and assurance teams, alloy producers, fabricators, and design engineers in industries that employ nickel‑rich alloys (aerospace, chemical processing, oil & gas, power generation, and specialty manufacturing). Typical applications include pre‑production alloy qualification, heat‑treatment verification, weldment assessment, failure analysis, and contract test work where intergranular corrosion susceptibility must be documented.

Related standards

ASTM G28-24 is commonly used alongside related ASTM practices and test methods for corrosion and metallography, including (but not limited to) A262 (practices for detecting intergranular attack in stainless steels), G1 (preparation, cleaning, and evaluation of corrosion test specimens), G31 (immersion corrosion testing), G193 (terminology / related corrosion definitions), and other G‑series corrosion standards. ASTM G28-24 replaces or updates the prior edition (ASTM G28-22).

Keywords

intergranular corrosion; ferric sulfate; sulfuric acid; mixed acid; oxidizing salt; nickel‑rich alloys; chromium‑bearing alloys; corrosion susceptibility; corrosion testing; test methods; ASTM G28-24.

FAQ

Q: What is this standard?

A: ASTM G28-24 is a set of standard laboratory test methods for detecting susceptibility to intergranular corrosion in wrought, nickel‑rich, chromium‑bearing alloys. It defines two specific boiling‑acid/oxidizing procedures (Method A and Method B) and reporting requirements.

Q: What does it cover?

A: It covers the ferric sulfate–50% sulfuric acid boiling test (Method A) and a boiling mixed acid/oxidizing salt test (Method B: 23% sulfuric + 1.2% hydrochloric + 1% ferric chloride + 1% cupric chloride), specimen preparation, exposure times for listed alloys, measurement of corrosion rate, interpretation criteria for susceptibility, and safety considerations.

Q: Who typically uses it?

A: Corrosion testing laboratories, materials engineers, alloy suppliers, fabricators, quality assurance teams, and designers in industries that use nickel alloys (e.g., aerospace, chemical processing, oil & gas, power generation) use this standard to evaluate material and process susceptibility to intergranular attack.

Q: Is it current or superseded?

A: As of February 22, 2026, ASTM G28-24 is the current active edition. It was published as the 2024 edition (G28-24) with an ASTM site update record in early December 2024 and replaces the earlier G28-22 edition.

Q: Is it part of a series?

A: Yes. G28 is part of ASTM's corrosion test methods (Book of Standards volume covering Corrosion of Metals; Committee G01). It is commonly referenced alongside other G‑series corrosion practices and test methods such as A262, G1, G31 and related terminology documents.

Q: What are the key keywords?

A: Key keywords include intergranular corrosion, ferric sulfate, sulfuric acid, mixed acid, oxidizing salt, nickel‑rich, chromium‑bearing, corrosion test, susceptibility, ASTM G28-24.