GB/T 223.6-2025 Iron, steel and alloy—Determination of boron content—Neutralization titrimetric method and spectrophotometric method English, Anglais, Englisch, Inglés, えいご
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Contents
Foreword
1 Scope
2 Normative References
3 Terms and Definitions
4 Method 1: Visual Titrimetric Method
5 Method 2: Potentiometric Titration Method
6 Method 3: Spectrophotometric Method (Sodium Carbonate Separation-Diphenylcarbazide Spectrophotometry)
7 test method
Iron,steel and alloy—Determination of boron content—Neutralization titrimetric method and spectrophotometric method
Warning—Personnel using this document shall have practical laboratory experience. This document does not address all potential safety issues. Users are responsible for implementing appropriate safety and health measures and ensuring compliance with relevant national regulations.
1 Scope
This document describes methods for determining boron content in iron, steel, and alloys using:
Method 1 (Neutralization Titrimetric Method): Suitable for high-boron stainless steel with boron content of 0.50%–2.00%
Method 2 (Methanol Distillation-Curcumin Photometric Method): applicable to carbon steel, alloy steel, superalloys, and precision alloys with boron content of 0.0005%–0.20%
.
Method 3 (Direct Curcumin Photometric Method): for steel (0.0005%–0.012%) and non-alloy steel (0.0001%–0.0005%)
2 Normative References
The following referenced documents are indispensable for the application of this document. For dated references, only the cited version applies; for undated references, the latest version (including amendments) applies.
GB/T 6379.1: Accuracy (Trueness and Precision) of Measurement Methods—Part 1: General Principles and Definitions (IDT ISO 5725-1:1994).
GB/T 6379.2: Accuracy (Trueness and Precision) of Measurement Methods—Part 2: Basic Methods for Repeatability and Reproducibility of Standard Measurement Methods (IDT ISO 5725-2:1994).
GB/T 6682: Water for Analytical Laboratory Use—Specifications and Test Methods (MOD ISO 3696:1987).
GB/T 7729: General Rules for Spectrophotometric Methods in Chemical Analysis of Metallurgical Products.
GB/T 20066: Steel and Iron—Sampling and Preparation of Samples for Chemical Composition Determination (IDT ISO 14284:1996)
ISO 385-1 Laboratory glassware—Burettes— Part 1:General requirements
ISO648 Laboratory glassware—One-mark pipettes
ISO 1042 Laboratory glassware—One-mark volumetric flasks
ISO 3696 Water for analytical laboratory use—Specification and test methods
ISO 5725-1 Accuracy (trueness and precision)of measurement methods and results—Part 1:General principles and defini- tions
ISO 5725-2 Accuracy(trueness and precision)of measurement methods and results—Part 2: Basic method for the determination of repeatability and reproducibility of a standard measure- ment method
ISO 5725-3 Accuracy(trueness and precision)of measurement methods and results—Part 3:Intermedi- ate measures of the precision of a standard measurement method
ISO 14284 Steel and iron—Sampling and preparation of samples for the determination of chemical composition
3 Terms and Definitions
No terms or definitions require clarification in this document.
4 Method 1: Neutralization Titrimetric Method
4.1 Principle
The sample is dissolved in hydrochloric acid, oxidized with hydrogen peroxide, and separated from iron, chromium, nickel, and other elements using a strong alkali. The solution is acidified using p-nitrophenol as an indicator, boiled to remove carbon dioxide, and readjusted to pH 7. In the presence of mannitol, the solution is titrated with a sodium hydroxide standard solution using phenolphthalein as an indicator.
1 g of sample containing >15 mg of tungsten (W) or >15 mg of molybdenum (Mo) will interfere with the determination.
4.2 Reagents
Unless otherwise specified, only analytically pure reagents and Grade 2 water (as per GB/T 6682) shall be used.
4.2.1 Mannitol.
4.2.2 Hydrochloric acid (1+1).
Mix 1 part hydrochloric acid with 1 part water; prepare fresh before use.
4.2.3 Hydrochloric acid (1+10).
Mix 1 part hydrochloric acid with 10 parts water; prepare fresh before use.
4.2.4 Hydrogen peroxide solution (1+1).
Mix 1 part hydrogen peroxide with 1 part water; store in a plastic bottle.
4.2.5 Sodium hydroxide solution (200 g/L).
Dissolve 20 g sodium hydroxide in water, dilute to 100 mL, and store in a plastic bottle.
4.2.6 Sodium hydroxide solution (4 g/L).
Dissolve 0.4 g sodium hydroxide in water, dilute to 100 mL, and store in a plastic bottle.
4.2.7 Barium chloride solution (100 g/L).
4.2.8 Neutral water.
Boil distilled water to remove carbon dioxide, then cool under running water; prepare fresh before use.
4.2.9 p-Nitrophenol solution (10 g/L).
Dissolve 0.5 g p-nitrophenol in 40 mL ethanol, then dilute to 50 mL with water.
4.2.10 Phenolphthalein solution (5 g/L).
Dissolve 0.25 g phenolphthalein in 30 mL ethanol, then dilute to 50 mL with water.
4.2.11 Sodium hydroxide standard solution [c(NaOH) ≈ 0.1 mol/L].
4.2.11.1 Preparation:
Dissolve 4 g sodium hydroxide in 250 mL water, add 1 mL barium chloride solution (4.2.7), boil for 1–2 min, cool, and dilute to 1000 mL. Mix well, allow barium carbonate precipitate to settle, then transfer the clear supernatant to another plastic bottle via siphon.
4.2.11.2 Standardization:
