ASTM A923-25 PDF

Full title and description

ASTM A923-25 — Standard Test Methods for Detecting Detrimental Intermetallic Phase in Duplex Austenitic/Ferritic Stainless Steels. This standard defines three complementary test methods (sodium hydroxide etch, Charpy impact, and ferric chloride corrosion) used to detect the presence of intermetallic phases in duplex stainless steels when those phases significantly affect toughness or corrosion resistance.

Abstract

These test methods permit detection of detrimental intermetallic phases in certain duplex (austenitic‑ferritic) stainless steels to the extent that toughness and/or corrosion resistance are significantly affected. The standard specifies Test Method A (sodium hydroxide etch), Test Method B (Charpy impact classification), and Test Method C (ferric chloride corrosion) and explains applicability, sampling orientation, and acceptance criteria for listed duplex grades. The tests indicate presence or absence of detrimental intermetallic phases rather than identifying their precise chemistry.

General information

• Status: Active.
• Publication date: Latest revision 2025 (standard shown as A923‑25; last updated Sep 17, 2025).
• Publisher: ASTM International (ASTM).
• ICS / categories: 77.040.99 — Other methods of testing of metals / testing of ferrous materials.
• Edition / version: ASTM A923‑25 (designation shown as A0923‑25 in ASTM catalog).
• Number of pages: 10 pages.

Scope

The standard is intended to detect the presence of intermetallic compounds in certain duplex stainless steels (listed in the standard's tables) that can form during exposures roughly between 320 °C and 955 °C (≈600 °F to 1750 °F). It establishes procedures and acceptance criteria for the three classification tests, clarifies sampling requirements (regions most likely to have slowest cooling), and notes that correct heat treatment/rapid cooling can eliminate these phases. The methods are diagnostic of intermetallic precipitation as it affects toughness and corrosion resistance, but they do not determine the precise chemical identity of the precipitates.

Key topics and requirements

• Three test methods: A — Sodium hydroxide etch (etch‑structure classification), B — Charpy impact classification test, C — Ferric chloride corrosion classification test.
• Applicability and acceptance criteria are given by grade and condition (base metal, HAZ, weld metal) with specified temperatures and minimum/maximum acceptance limits for each test method.
• Sampling guidance: test specimens must be taken from locations and orientations most likely to show intermetallic precipitation (typically the most slowly cooled regions).
• These methods detect whether intermetallic phases are present to a degree that degrades toughness/corrosion resistance; they do not identify the exact phase chemistry.
• Referenced procedural distinctions: the methods differ from other duplex test methods (for example, Test Method A1084) and are not substitutes for general corrosion or pitting‑resistance tests (see distinctions with Test Methods G48 where applicable).

Key technical details and acceptance tables are specified in the full standard document.

Typical use and users

Used by metallurgical laboratories, quality control/assurance teams, fabricators, manufacturers and purchasers of duplex stainless steel products, welding and inspection specialists, and materials engineers to screen material or welds for deleterious intermetallic precipitation that could impair service toughness or corrosion resistance. It is often specified in product acceptance criteria or QA procedures for duplex stainless steel components.

Related standards

Referenced or related documents commonly cited with A923 include Test Method A1084 (similar‑purpose tests for other duplex steels) and Test Methods in the G48 family (pitting/corrosion procedures, noted as distinct from the A923 ferric chloride classification). Historical and earlier A923 editions (A923‑23, A923‑22, A923‑14, etc.) provide revision history and context. The standard is maintained by ASTM Committee A01 (Ferrous Metals) and appears in Book of Standards volume 01.03.

Keywords

duplex stainless steel; intermetallic; sigma phase; chi phase; sodium hydroxide etch; Charpy impact; ferric chloride corrosion; precipitation; toughness; corrosion resistance; A923‑25.

FAQ

Q: What is this standard?

A: ASTM A923‑25 is a set of test methods for detecting detrimental intermetallic phases in duplex (austenitic‑ferritic) stainless steels, focused on effects to toughness and corrosion resistance.

Q: What does it cover?

A: It covers three classification tests — sodium hydroxide etch, Charpy impact classification, and ferric chloride corrosion — plus applicability tables, sampling guidance, and acceptance criteria for listed duplex grades. The methods indicate presence/absence of detrimental intermetallic phases rather than identifying their exact chemistry.

Q: Who typically uses it?

A: Materials and corrosion engineers, metallurgists, fabrication and welding inspectors, quality/control laboratories, and purchasers or specifiers of duplex stainless steel components use A923 for acceptance screening and failure‑prevention activities.

Q: Is it current or superseded?

A: As published in ASTM's catalog the current active designation is A923‑25; the listing shows the standard as active with its latest revision in 2025 (last updated Sep 17, 2025). Users should confirm the active status before relying on the text for procurement or compliance.

Q: Is it part of a series?

A: It is a standalone test methods standard maintained under ASTM Committee A01 (ferrous metals) and appears alongside previous editions (A923‑23, A923‑22, etc.). It cross‑references related ASTM test methods such as A1084 and corrosion test families (G48) where appropriate.

Q: What are the key keywords?

A: Duplex, intermetallic, etch test, Charpy, ferric chloride, precipitation, toughness, corrosion resistance, duplex stainless steel, A923‑25.