Ding Testing & Inspection

Read：18+ Date：2025-04-30 16:01:37 Author: DTI

Intergranular Corrosion Test

I. Definition

The Intergranular Corrosion Test is an accelerated metal corrosion test method used to inspect the intergranular corrosion sensitivity of metal materials under specific medium conditions. Its primary purpose is to understand whether the material's chemical composition, heat treatment, and processing techniques are appropriate.

Intergranular corrosion refers to the corrosion that extends inward along the grain boundaries of a metal. This type of corrosion can disrupt the bonding between grains and significantly reduce the mechanical strength of the metal.

II. Purpose of Testing

Assessing Intergranular Corrosion Sensitivity: To determine the tendency of materials to undergo intergranular corrosion in specific corrosive media.
Inspecting Metallurgical Quality: To evaluate whether the heat treatment and welding processes of the materials are appropriate through intergranular corrosion testing.
Selecting Suitable Materials: To choose more corrosion - resistant materials by comparing the intergranular corrosion performance of different materials.
Predicting Service Life: To predict the service life of materials based on the results of intergranular corrosion testing and actual operating conditions.

III. Testing Standards

International Standards:
- ASTM A262: Used for detecting the intergranular corrosion sensitivity of austenitic stainless steel.
- ISO 3651: Applicable for intergranular corrosion testing of austenitic, ferritic, and duplex stainless steels.
Chinese Standards:
- GB/T 4334 - 2020: Corrosion of metals and alloys - Method for intergranular corrosion testing of austenitic and duplex (austenitic - ferritic) stainless steels.
- GB/T 31935 - 2015: Corrosion of metals and alloys - Method for intergranular corrosion testing of low - chromium ferritic stainless steel.
- GB/T 32571 - 2016: Corrosion of metals and alloys - Method for intergranular corrosion testing of high - chromium ferritic stainless steel.

IV. Testing Methods

Sulfuric Acid - Copper Sulfate - Copper Chip Method: Suitable for inspecting intergranular corrosion caused by carbon and nitride precipitation in almost all types of stainless steel and certain nickel - based alloys.
Nitric Acid Corrosion Test: Samples are boiled continuously five times in boiling 65% nitric acid solution for 48 hours each time, and then the weight loss rate is measured.
Oxalic Acid Immersion Test: A rapid screening test that involves immersing samples in oxalic acid solution to observe whether intergranular erosion occurs, thereby judging the intergranular corrosion sensitivity of the material.
EPR Test: Using electrochemical methods to measure the sensitivity of materials to intergranular corrosion. The passivation behavior and intergranular corrosion tendency of the material are analyzed by recording the relationship curve of current with potential changes.

V. Testing Procedure

Sample Preparation:
- The surface area of the sample is 10cm² - 30cm². If there is scale on the sample, it should be removed by cutting or grinding.
- Weigh the sample.
Test Solution Preparation:
- For example, prepare a sulfuric acid solution with a concentration of 5.0% ± 0.1% and a density of 1.03103g/mL - 1.03237g/mL.
Testing Process:
- Place the sample on a glass rack in the middle of the solution, and the boiling time is 6 hours continuously.
- Put the sample into the boiling solution after it has boiled, and start timing after it boils again.
Post - Testing Treatment:
- Remove the sample, clean it thoroughly, dry it, and then weigh the sample.
Result Evaluation:
- The corrosion rate is calculated using a formula.

VI. Precautions

Strictly Control Testing Conditions: Including solution concentration, temperature, time, etc.
Accurately Evaluate Test Results: Avoid misjudgment and omission.
Enhance Safety and Environmental Protection Measures: Ensure the safety of operators and the environment.

VII. Application Fields

Intergranular corrosion testing is widely used in aerospace, automotive, petrochemical, and other fields. It plays an important role in ensuring the quality and safety of products.

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One-Stop Metal Material Testing Service

The Intergranular Corrosion Test

Intergranular Corrosion Test

I. Definition

II. Purpose of Testing

III. Testing Standards

IV. Testing Methods

V. Testing Procedure

VI. Precautions

VII. Application Fields

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One-Stop Metal Material Testing Service

The Intergranular Corrosion Test

Intergranular Corrosion Test

I. Definition

II. Purpose of Testing

III. Testing Standards

IV. Testing Methods

V. Testing Procedure

VI. Precautions

VII. Application Fields

Get Your Free Testing Plans and Quotation

Ask professional engineers for on-line service, and receive testing proposals within 2 hours.

Six Reasons to choose DTI

Only Four Steps to Get Your Reports

Test Enquiry

Sample Delivery

Lab Testing

Reports Issuance

After-Testing Service

Issues You May Care About

What is the difference between DTI and other third-party services?

How long will it take for DTI to issue a report?

Are the reports authoritative? Can they be used for export abroad?

What testing standards are used for the assessment?

What should I do if I have doubts about the test report provided?

What would I do if I’m not sure what items to be tested?

One-Stop Solutions Recommended

Automotive Material Product Testing Solutions

Shipbuilding Industry Solutions

Wind Power Industry Product Testing Solutions

Railway Industry Product Testing Solutions

Aerospace Industry Product Testing Solutions

Bridges and Steel Structures Product Testing Solutions

Laboratory and Research Institution Product Testing Solutions

Construction Industry Product Testing Solutions

Special Equipment Product Testing Solutions

LEARN ABOUT DING TESTING & INSPECTION

To be an influential, authoritative, third-party testing organization in China.

Contact Us

Ask professional engineers for on-line service, and receive testing proposals within 2 hours.

Legal Notices

Disclaimer

Disclaimer：

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Minors and Children Under 18

How We Use Your Information

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Choices About How We Use and Disclose Your Information

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