GB/T 4334.2-2000 – Method of Ferric Sulfate-Sulfuric Acid Test for Stainless Steels

GB/T 4334.2-2000

Method of Ferric Sulfate-Sulfuric Acid Test for Stainless Steels

ICS 77.040.99 | H 25

Issued: 2000-10-25 | Effective: 2001-09-01

Published by: State Bureau of Quality and Technical Supervision

Preface

This standard is non-equivalent to the Japanese Industrial Standard JIS G 0572-1984 “Method of Ferric Sulfate-Sulfuric Acid Test for Stainless Steels”. The standard is basically the same as the Japanese standard in terms of test solution, test apparatus and equipment, test conditions and procedures, and test results evaluation. It adds provisions for sample preparation, specimen dimensions, weld sample sampling diagrams, and sensitization treatment of welded specimens.

This revision modifies the following provisions:

  • Added Chapter 2: Referenced Standards; Chapter 8: Test Report
  • Added Section 3.1.3: Provisions for sampling of welded pipes
  • Added Section 3.1.5: Provisions for test surfaces and weld joints
  • Added requirements for specimen dimensions and preparation of welded pipes in Table 1
  • Changed “finish” to “roughness” in the original Section 1.1.7 (now 3.1.7)
  • Cancelled original Section 1.2.3
  • Added Figures 1, 2, 5, and 6

GB/T 4334 includes the following parts:

  • GB/T 4334.1 – Stainless Steel – 10% Oxalic Acid Etch Test Method
  • GB/T 4334.2 – Stainless Steel – Ferric Sulfate-Sulfuric Acid Corrosion Test Method
  • GB/T 4334.3 – Stainless Steel – 65% Nitric Acid Corrosion Test Method
  • GB/T 4334.4 – Stainless Steel – Nitric-Hydrofluoric Acid Corrosion Test Method
  • GB/T 4334.5 – Stainless Steel – Ferric Sulfate-Copper Sulfate Corrosion Test Method

This standard supersedes GB/T 4334.2-1984 from the date of implementation.

Proposed by: National Metallurgical Industry Bureau

Under the jurisdiction of: National Steel Standardization Technical Committee

Drafting organizations: Central Iron and Steel Research Institute, Hefei General Machinery Research Institute, Shanghai No.5 Steel Special Group Co., Ltd., Metallurgical Information and Standards Institute

Primary drafters: Wang Zaizhuan, Zuo Weimin, Hu Xiaobo

First published: April 1984

1. Scope

This standard specifies the specimen preparation, test solution, test apparatus, test conditions and procedures, test result evaluation, and test report for the ferric sulfate-sulfuric acid corrosion test method for stainless steels.

This standard applies to the test method for evaluating the intergranular corrosion susceptibility of austenitic stainless steels by boiling tests in ferric sulfate-sulfuric acid solution, using corrosion rate as the evaluation criterion.

2. Referenced Standards

The following standards contain provisions that, through reference in this standard, constitute provisions of this standard. All standards are subject to revision. Parties using this standard should explore the possibility of using the latest versions of the following standards:

  • GB/T 625-1989 – Chemical Reagents – Sulfuric Acid
  • GB/T 2100-1980 – Technical Conditions for Steel Castings
  • GB/T 8170-1987 – Rules of Rounding for Numerical Values

3. Sampling and Preparation

3.1 Sampling and Preparation

3.1.1 Specimens for pressure-worked steel materials shall be sampled from the same heat number, same heat treatment batch, and same specification of steel materials.

3.1.2 Cast specimens shall be sampled from test blocks cast from the same heat number of steel water according to GB/T 2100. For steel grades containing stabilizing elements (titanium or niobium), samples shall be taken from the last cast test block of the heat.

3.1.3 Welded pipe specimens shall be taken from welded pipes of the same heat number, same heat treatment batch, and same specification.

3.1.4 Welded specimens shall be taken from test blocks that are made of the same steel material as the product and use the same welding procedure.

3.1.5 The surface to be tested shall be the service surface. For weld joint specimens, it shall include the base metal, heat-affected zone, and weld metal surfaces. Specimen dimensions and preparation requirements are shown in Table 1.

3.1.6 The sampling method shall原则上 be by sawing. If shearing is used, the affected portion shall be removed by cutting or grinding.

3.1.7 If scale is present on the specimen surface, it shall be removed by cutting or grinding.

3.1.8 During specimen surface grinding, overheating of the surface shall be prevented. The surface roughness Ra value of the finished specimen shall not exceed 0.8 μm. For specimens that cannot be ground, other methods may be used by agreement between both parties. Surface scale shall be removed before polishing.

3.2 Specimen Sensitization Treatment

3.2.1 Before sensitization and testing, specimens shall be degreased with an appropriate solvent or detergent (non-chlorinated) and dried.

3.2.2 Sensitization treatment shall be performed before grinding. For ultra-low carbon steels (carbon content ≤ 0.03%) or stabilized steel grades (with added titanium or niobium), heating at 650°C for 2 hours for pressure-worked specimens or 1 hour for cast specimens, followed by air cooling. Other sensitization treatment schedules may also be used.

3.2.3 Welded specimens shall be tested directly in the as-welded condition. For welded components that undergo hot working above 350°C after welding, the specimens shall undergo sensitization treatment after welding. The sensitization treatment schedule shall be specified by agreement.

4. Test Solution

Prepare (50.0 ± 0.3)% sulfuric acid solution (by mass) using high-purity sulfuric acid conforming to GB/T 625 and distilled or deionized water. To 600 mL of this solution, add 25 g of ferric sulfate Fe₂(SO₄)₃ (ferric ion concentration 21.0%~23.0%).

5. Test Apparatus and Equipment

5.1 A boiling flask with a ground-glass joint reflux condenser.

5.2 A heating device capable of maintaining the test solution at a gentle boil.

5.3 Vernier calipers for measuring specimen surface area.

6. Test Conditions and Procedures

6.1 Measure specimen dimensions and calculate the surface area (to three significant figures).

6.2 Weigh the specimen before testing (accurate to 1 mg).

6.3 The amount of test solution shall be not less than 20 mL/cm² of specimen surface area. For each test, a fresh solution shall be prepared.

6.4 Place the specimen in the test solution, supported by a glass holder to maintain it in the middle of the solution. Boil continuously for 120 hours. Only one specimen shall be placed in each container.

6.5 After testing, remove the specimen, brush off the corrosion products with a soft brush under running water, wash, dry, and weigh.

7. Test Result Evaluation

Test results are evaluated by corrosion rate, expressed in g/(m²·h), calculated as:

Corrosion Rate = (W₀ – W₁) / (S × T)

Where:

  • W₀ = Specimen mass before testing, g
  • W₁ = Specimen mass after testing, g
  • S = Specimen surface area, m²
  • T = Test duration, h

Calculation results shall be rounded according to GB/T 8170, to two decimal places.

8. Test Report

The test report shall include the following:

  • a) Specimen designation
  • b) Sensitization treatment schedule (if sensitized)
  • c) Test solution preparation and conditions
  • d) Specimen mass before and after testing
  • e) Specimen corrosion rate [g/(m²·h)]

Published by China Standards Press
No. 16 Sanlihe North Road, Fuxingmenwai, Beijing
Postal Code: 100045
Phone: 68522112

880 × 1230 1/16 | 3/4 print sheet | 12,000 words
First Edition: March 2001 | First Printing: March 2001
Print Run: 1-1,500
ISBN 1-55066 · 1-17460

Original Standard Document (PDF)

Download the original Chinese standard PDF:

GB/T 4334.2-2000 – 不锈钢硫酸-硫酸铁腐蚀试验方法 (Original PDF)

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