ISO 4212:2023 PDF

Name: ISO 4212:2023 — Corrosion of metals and alloys — Method of oxalic acid etching test for intergranular corrosion of austenitic stainless steel
SKU: ISO 4212:2023
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Corrosion of metals and alloys — Method of oxalic acid etching test for intergranular corrosion of austenitic stainless steel

Название (английский):

ISO 4212:2023

Corrosion of metals and alloys — Method of oxalic acid etching test for intergranular corrosion of austenitic stainless steel

Статус документа:: Действующий
Формат:: Электронный (PDF)
Количество страниц:: 6
Дата публикации:: 8 февраля 2023 г.
Издание:: ISO IS 4212 edition 1 version 1
ICS:: 77.060

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Описание (английский):

This document specifies a method to test for intergranular corrosion (IGC) in austenitic stainless steels using an oxalic acid etch. This method can evaluate non-sensitization of austenitic stainless steels by observing the structure of the etched surface with a microscope after performing electrolytic etching (hereinafter called “etching”) on austenitic stainless steel in an oxalic acid solution.

Abstract

Похожие стандарты

Стандарты, упомянутые в описании

Overview

ISO 4212:2023 specifies an oxalic acid etching test for detecting intergranular corrosion (IGC) characteristics in austenitic stainless steels. The standard defines an electrolytic etching procedure and microscopic evaluation to determine whether a stainless steel specimen is non‑sensitized or suspected of sensitization. This method is a rapid, simple screening technique that complements ISO IGC tests (ISO 3651-1, ISO 3651-2, ISO 12732) and established practices such as ASTM A262-15 and JIS G0571.

Key Topics and Requirements

Purpose: Screen for non‑sensitization or suspicion of sensitization by observing etched surface structure (does not by itself quantify sensitization).

Test solution: Dissolve 100 g oxalic acid crystals in 900 ml deionized/distilled water (ISO 3696 Grade 3). For some Mo‑containing steels, ammonium peroxodisulfate (100 g/900 ml) may be used.

Apparatus: DC power supply (example: 15 V, 20 A), variable resistor, ammeter, cathode (stainless beaker or plate), inert test vessel, holder and thermometer (±1 °C).

Specimen preparation: Fine polishing (buffing with diamond suspension), isolation of non‑tested areas with insulating material; welded sections should include base metal, HAZ and weld metal where applicable.

Etching conditions: Oxalic acid solution at 20–50 °C; etch as an anode for 90 s at 1 A/cm². For ammonium peroxodisulfate: 5–10 min at 1 A/cm².

Microscopy: Examine entire etched surface; typical magnification 200×–500× for rolled, forged, cast products or weld zones.

Etch classification:

A (Step structure): orientation‑dependent step features.
B (Dual structure): grooves at grain boundaries but no fully surrounded grains.
C (Groove structure): one or more grains completely surrounded by grooves.

Evaluation: A or B indicate no further ferric sulfate/65% HNO3/CuSO4/EPR testing required; C (grooved) indicates suspicion of sensitization and requires follow‑up testing (ISO 3651-1, ISO 3651-2, ISO 12732).

Test report: Must reference ISO 4212:2023 and record steel grade, specimen details, sensitization heat treatment (if applied), solution and times, etching structure, solution temperature, deviations and anomalies, and test date.

Applications

Rapid screening in corrosion laboratories and metal production QA/QC for austenitic stainless steel components.

Weld and fabrication inspection to identify areas that may require further IGC testing.

Material acceptance testing for manufacturers, fabricators, shipbuilding, chemical and power industry components where IGC risk is a concern.

Metallurgists and corrosion engineers use it as a cost‑effective triage method before undertaking detailed IGC or electrochemical reactivation (EPR) tests.

Related Standards

ISO 3651-1, ISO 3651-2 (detailed IGC corrosion tests)

ISO 12732 (EPR double loop method)

ASTM A262-15 Practice A (oxalic acid etch)

JIS G0571:2003 (basis for ISO 4212)

Keywords: ISO 4212:2023, oxalic acid etching test, intergranular corrosion, austenitic stainless steel, sensitization, electrolytic etching, IGC screening, metallurgical inspection.

ISO 4212:2023 PDF

Abstract

Похожие стандарты

Overview

Key Topics and Requirements

Applications

Related Standards

Технические детали

SIST EN ISO 3651-1:2000

Determination of resistance to intergranular corrosion of stainless steels - Part 1: Austenitic and ferritic-…

SIST EN ISO 3651-2:2000

Determination of resistance to intergranular corrosion of stainless steels - Part 2: Ferritic, austenitic and…

SIST EN ISO 12732:2008

Corrosion of metals and alloys - Electrochemical potentiokinetic reactivation measurement using the double lo…

SIST EN ISO 3696:1998

Water for analytical laboratory use - Specification and test methods (ISO 3696:1987)