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GB/T 223.11-2008Iron, steel and alloy -- Determination of chromium content -- Visual titration or potentiometric titration method (English PDF)

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Issued by

General Administration of Quality Supervision, Inspection and Quarantine

Level / Type

National · Recommended

Issue date

September 11, 2008

Implementation date

May 1, 2009

Scope

GB/T 223.11-2008 (Iron, steel and alloy -- Determination of chromium content -- Visual titration or potentiometric titration method) is available as an English-translated PDF.

GB/T 223.11-2008 — This Part of GB/T 223 specifies the determination of chromium content with visual titration or potentiometric titration method.

Method I of this Part is applicable to the determination of chromium content with mass fraction 0.10%~35.00% in pig iron, carbon steel, alloy steel, high-temperature alloy and precision alloy; method II of this Part is applicable to the determination of chromium content with mass fraction 0.25%~35.00% in iron and steel.

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Document preview — GB/T 223.11-2008

National Standard of the People's Republic of China

ICS: 77.080.01
Classification: H 11

Issued by: General Administration of Quality Supervision, Inspection and Quarantine

Foreword...3
1 Scope...5
2 Normative references...5
3 Method I -- Visual Titration Method...6
4 Method II -- Potentiometric Titration Method...15
5 Test report...21
Annex A (Informative) Method I -- Source Data of Common Precision Test...23

Foreword

This Part of GB/T 223 replaces GB/T 223.11 - 1991 "Methods for Chemical Analysis

of Iron, Steel and Alloy - The Ammonium Persulfate Oxidation Volumetric Method

for the Determination of Chromium Content".

In this revision, the name of this Part is changed to "Iron, Steel and

Alloy-Determination of Chromium Content-Visual Titration or Potentiometric

Titration Method", including two analysis methods. method I visual titration method

and method II potentiometric titration method.

Compared with GB/T 223.11 - 1991, method I of this Part has the following main

revisions.

- modified the content range of determination;

- added the content related to correct vanadium interference by theoretical

calculation method;

- modified the description content for reagents and water in the analysis is

added, and the expression method for solution concentration;

- modified the specimen quantity and its expression;

- added quantity units in result calculation formulae are revised, and calculation

formula for correcting vanadium interference by theoretical calculation

method;

- re-organized precision test.

Method II in this Part is modified in relation to ISO 4937. 1986 "Steel and iron --

Determination of chromium content -- Potentiometric or visual titration method".

Compared with ISO 4937. 1986, it has the following main revisions.

- only potentiometric titration method therein is adopted, and the technical

contents are consistent with it;

- a note is added respectively to "instrument" and "titration of specimen

containing vanadium".

Annex A, Annex B and Annex C in this Part are informative.

This Part was proposed by China Iron and Steel Association.

This Part shall be under the jurisdiction of National Technical Committee on Iron

and Steel of Standardization Administration of China.

The drafting organizations of this Part. Central Iron & Steel Research Institute,

Taiyuan Iron and Steel Company.

Main drafters of this Part. Wang Kejuan, Chang Xiaojun, Luo Qianhua, Dai

Xueqian.

Versions of standard substituted by this Standard are.

- GB/T 223-1963, GB/T 223.11-1982, GB/T 223.11-1991.

Iron, steel and alloy - Determination of chromium content -

Visual titration or potentiometric titration method

WARNING. the personal using this Part of GB/T 223 shall have the practical

experience of regular laboratory working. This Part does not point out all

possible safety problems. The users are under the obligation to adopt proper

safety and health measures and shall ensure meet the requirements specified

in national relevant regulations.

1 Scope

This Part of GB/T 223 specifies the determination of chromium content with visual

titration or potentiometric titration method.

Method I of this Part is applicable to the determination of chromium content with

mass fraction 0.10%~35.00% in pig iron, carbon steel, alloy steel, high-temperature

alloy and precision alloy; method II of this Part is applicable to the determination of

chromium content with mass fraction 0.25%~35.00% in iron and steel.

2 Normative references

The following standards contain provisions which, through reference in this Part of

GB/T 223, constitute provisions of this Part. For dated reference, subsequent

amendments to (excluding correction to), or revisions of, any of these publications

do not apply. However, the parties to agreements based on this standard are

encouraged to investigate the possibility of applying the most recent editions of the

standards. For undated references, the latest edition of the normative document

referred to applies.

GB/T 223.13, Methods for chemical analysis of iron, steel and alloy - The

ammonium ferrous sulfate titration method for the determination of vanadium

content

GB/T 223.14, Methods for chemical analysis of iron, steel and alloy - The

N-benzoy-N-phenylhydroxylamine extraction photometric method for the

determination of vanadium content

GB/T 223.76, Methods for chemical analysis of iron, steel and alloy - The flame

atomic absorption spectrometric method for the determination of vanadium

content

GB/T 6379.1, Accuracy (trueness and precision) of measurement methods and

results - Part 1. General principles and definitions (GB/T 6379.1-2004, ISO

5725-1. 1 994, IDT)

GB/T 6379.2, Accuracy (trueness and precision) of measurement methods and

results - Part 2. Basic method for the determination of repeatability and

reproducibility of a STANDARD measurement method (GB/T 6379.2-2004, ISO

5725-2. 1994, IDT)

GB 12805, Laboratory glassware - Burettes

GB 12806, Laboratory glassware-one-mark volumetric flasks GB 12808

Laboratory glassware - One-mark pipettes

GB/T 20066, Steel and iron - Sampling and preparation of samples for the

determination of chemical composition (GB/T 20066-2006, ISO 14284. 1996,

IDT)

GB/T 20125, Low-alloy steel - Determination of multi-element contents -

Inductively coupled plasma atomic emission spectrometric method

3 Method I -- Visual Titration Method

3.1 Principle

After the specimen is dissolved by acid, chromium is oxidized to chromium (VI) by

ammonium persulfate using silver nitrate as the catalyst in the medium of sulfuric

acid and phosphoric acid, and titrated by ferrous ammonium sulfate standard

solution.

The specimen containing vanadium, using ferrous-phenanthroline solution as the

indicator, is added with excess ferrous ammonium sulfate standard titration solution,

and back titrated with potassium permanganate solution; or is determined by proper

national vanadium standards and corrected for interference of vanadium with

theoretical calculation method.

There is below 2 mg of cerium noninterference determination in the test solution.

3.2 Reagents

Unless otherwise specified, during the analysis, only confirmed analytical reagent

and distilled water, deionized water or equivalent purity water are used.

3.2.1 Anhydrous sodium acetate.

3.2.2 Hydrochloric acid, rho is about 1.19 g/mL.

3.2.3 Hydrochloric acid, rho is about 1.19 g/mL, diluted to 1+3.

3.2.4 Nitric acid, rho is about 1.42 g/mL.

3.2.5 Phosphoric acid, rho is about 1.69 g/mL.

3.2.6 Sulfuric acid, rho is about 1.84 g/mL, diluted to 1+1.

3.2.7 Sulfuric acid, rho is about 1.84 g/mL, diluted to 5+95.

3.2.8 Hydrofluoric acid, rho is about 1.15 g/mL.

3.2.9 Sulfuric acid - phosphoric acid mixture. add 320mL of sulfuric acid (3.2.6)

and 80mL of phosphoric acid (3.2.5) in 600mL of water, and blend.

3.2.10 Silver nitrate solution, 10g/L. weigh out 1.0g of silver nitrate, dissolve in

100mL of water, dropwise add several drops of nitric acid (3.2.4), and store in a

brown bottle.

3.2.11 Ammonium persulfate solution, 300 g/L, prepare before use.

3.2.12 Sodium chloride solution, 50 g/L.

3.2.13 Manganese sulfate solution, 40 g/L.

3.2.14 Phenyl anthranilic acid solution, 2 g/L. weigh out 0.2 g of reagent, place in a

300mL beaker, add 0.2 g of anhydrous sodium carbonate, add 20 mL of water, heat

and dissolve, dilute with water to 100 mL, and blend.

3.2.15 Ferrous-phenanthroline solution. weigh out 1.49 g of phenanthroline and

0.98 g of ferrous ammonium sulfate, place in a 300 mL beaker, add 50 mL of water,

heat, dissolve, cool, dilute with water to 100 mL, and blend.

3.2.16 Chromium standard solution

3.2.16.1 Chromium stock solution, 2.000 g/L.

weigh out 5.6578 g of potassium bichromate (reference) baked at 150°C for 1h and

cooled in a dryer to the room temperature, place it in a beaker, add water for

dissolving it, shift it in a 1000 mL volumetric flask, dilute with water to the scale, and

blend.

1 mL of this solution contains 2.000 mg of chromium.

3.2.16.2 Chromium standard solution A, 1.000 g/L.

Take and shift 50.00 mL of chromium stock solution (3.2.16.1) and place in 100-mL

volumetric flask, dilute it with water to the scale, and blend.

1 mL of this solution contains 1.000 mg of chromium.

3.2.16.3 Chromium standard solution B, 0.500 g/L.

Take and shift 25.00 mL of chromium stock solution (3.2.16.1), place in a 100-mL

volumetric flask, dilute it with water to the scale, and blend.

1 mL of this solution contains 0.500 mg of chromium.

3.2.17 Ferrous ammonium sulfate standard titration solution

3.2.17.1 Preparation

Weigh out 6 g, 12 g and 24...

......

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This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 23 pages — is available in the English PDF.

Referenced standards

Normative references

GB/T 223 · GB/T 6379.1 · GB/T 6379.1-2004 · GB/T 6379.2 · GB/T 6379.2-2004 · GB 12805 · GB 12806 · GB 12808 · ISO 14284

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