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This standard is drafted according to rules given in GB/T 1.1-2009.
This standard supersedes "Standard Test Method for Spark Discharge Atomic Emission Spectrometric Analysis of Carbon and Low-alloy Steel (Routine Method)" (GB/T 4336-2002); compared with the latter, the main technical changes in this standard are as follows:
- The standard name is changed to "Carbon and Low-alloy Steel - Determination of Multi-element Contents - Spark Discharge Atomic Emission Spectrometric Method (Routine Method)";
- The determination scope of each element in Table 1 is modified;
- Documents referred in "Normative References" (Chapter 2) are added;
- The principle description specified in "Principle" (Chapter 3) is modified;
- The description of excitation light source in 4.1 is modified;
- The description of spark chamber in 4.2 is modified;
- The argon purity requirements in 4.3 are modified, and the position of instrument with constant argon pressure and flow is specified;
- The description of electrode in 4.4 is modified;
- The focal length and wave length range in 4.5 are modified;
- The description of photometric system in 4.6 is modified;
- Chapter 6 is changed to "Standard Sample, Standardization Sample and Control Sample" from "Standard Sample and Recalibration Sample", and the description is also modified accordingly;
- "Calibration" (Chapter 8) and its description are added;
- The former Chapter 8 "Analysis Conditions and Analysis Procedures" is changed to Chapter 9, and the description is also modified;
- The former Chapter 10 "Precision" is changed to Chapter 11; the repeatability limit and reproducibility limit formulas of each element are worked out again according to the precision test result;
- "Acceptability of Measuring Result and Determination of Final Report Result" (Chapter 12) is added;
- "Accuracy Judgment for Measuring Result in Laboratory" (Chapter 13) is added;
- "Test Report" (Chapter 14) is added;
- Appendix A and Appendix B (both are informative) are added.
This standard is proposed by China Iron and Steel Association.
This standard is under the jurisdiction of the National Technical Committee on Iron and Steel of Standardization Administration of China (SAC/TC 183).
Drafting organizations of this standard: Central Iron & Steel Research Institute, Baosteel Group Co., Ltd., Wuhan Iron and Steel (Group) Corporation, Angang Steel Company Limited, Shanxi Taigang Stainless Steel Co., Ltd., Hengyang Valin Steel Tube Co. Ltd., Jiugang Steel (group) Co., Ltd., Institute of Metal Research, Chinese Academy of Sciences, National Center For Quality Supervision & Test of Steel Material Products, NCS Testing Technology Co., Ltd., Shimadzu Enterprise Management (China) Co., Ltd., Oxford Instruments (Shanghai) Co., Ltd., Yantai Dongfang Analytical Instruments Co., Ltd. and Focused Photonics (Hangzhou), Inc.
Chief drafting staff of this standard: Cheng Haiming, Jia Yunhai, Luo Qianhua, Shen Ke, Zhang Ye, Yu Yuanjun, Dai Xueqian, Sun Jianjun, Zhao Bin, Ma Hongbo, Guo Dongsheng and Gan Zhengbin.
The previous editions of the standard superseded by this standard are as follows:
- GB/T 4336-1984 and GB/T 4336-2002.
Carbon and Low-alloy Steel - Determination of Multi-element Contents - Spark Discharge Atomic Emission Spectrometric Method (Routine Method)
碳素钢和中低合金钢 多元素含量的测定
火花放电原子发射光谱法(常规法)
1 Scope
This standard specifies the method for determining the contents of carbon, silicon, manganese, phosphorus, sulphur, chromium, nickel, tungsten, molybdenum, vanadium, aluminum, titanium, copper, niobium, cobalt, boron, zirconium, arsenic and tin in carbon and low-alloy steel with the spark discharge atomic emission spectrometric method (routine method).
This standard is applicable to the analysis of as-cast or forged carbon and low-alloy steel samples such as electric furnace, induction furnace, electroslag furnace and converter. See Table 1 for the application scope and determination scope of each element.
Table 1 Application Scope and Determination Scope of Each Element
Element Application scope (mass fraction)/% Determination scope (mass fraction)/%
C 0.001~1.3 0.03~1.3
Si 0.006~1.2 0.17~1.2
Mn 0.006~2.2 0.07~2.2
P 0.003~0.07 0.01~0.07
S 0.002~0.05 0.008~0.05
Cr 0.005~3.0 0.1~3.0
Ni 0.001~4.2 0.009~4.2
W 0.06~1.7 0.06~1.7
Mo 0.0009~1.2 0.03~1.2
V 0.0007~0.6 0.1~0.6
Al 0.001~0.16 0.03~0.16
Ti 0.0007~0.5 0.015~0.5
Cu 0.005~1.0 0.02~1.0
Nb 0.0008~0.12 0.02~0.12
Co 0.0015~0.3 0.004~0.3
B 0.0001~0.011 0.0008~0.011
Zr 0.001~0.07 0.006~0.07
As 0.0007~0.014 0.004~0.014
Sn 0.0015~0.02 0.006~0.02
Note: The low-content range in the “Application scope” column has not been verified by precision tests, and the laboratory shall select appropriate instruments, conditions and standard samples and operate with caution under strictly control during test of the low-content samples.
2 Normative References
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the normative document (including any amendments) applies.
GB/T 6379.1 Accuracy (Trueness and Precision) of Measurement Methods and Results - Part 1: General Principles and Definitions
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 20066 Steel and Iron - Sampling and Preparation of Samples for the Determination of Chemical Composition
3 Principle
Make the well-prepared block sample discharge with the counter electrode under the action of spark light source to generate plasma in inert atmosphere at high temperature. Where the measured element is excitated, the electron will transit in the atom between different energy levels; the characteristic spectral line will be generated when transiting from high energy level to low energy level; then measure the spectral intensity of characteristic spectral line of the selected analytical element and the internal standard element. Calculate the content of the measured element through calibration curve according to the relation between the spectral line intensity (or intensity ratio) and the concentration of the measured element in sample.
4 Instruments
The spark discharge atomic emission spectrometer is mainly composed of the following units.
4.1 Excitation light source
The excitation light source shall be a stable spark excitation light source.
4.2 Spark chamber
The spark chamber is specially designed for argon, and is directly installed on the spectrometer. It is equipped with an argon flushed spark stand to arrange planar sample and rod counter electrode. The argon gas circuit in spark chamber shall be able to displace the air in the light path between analytical gap and collecting lens, and shall provide argon atmosphere for the analytical gap.
4.3 Argon system
The argon system mainly includes the argon container, two-stage pressure regulator, gas flowmeter and the sequential control part which is able to automatically change the argon flow according to analysis conditions.
The purity and flow of argon have a significant impact on the analysis of measured value; it shall be ensured that the purity of argon shall not be less than 99.995%, otherwise, the argon purification device shall be used, and the pressure and flow of argon in spark chamber shall be maintained constant.
4.4 Counter electrode
Different counter electrodes shall be used for different equipment. Generally, the conical tungsten bar with diameter of 4~8mm and with top processed into 30°~120° or other electrode material is used, and the purity shall be greater than 99%. The flat tip tungsten electrode with diameter of 1mm may also be used. The time for replacing the counter electrode shall be determined by each laboratory according to specific conditions.
4.5 Spectrometer
Generally, the reciprocal of dispersion of first-order spectral line of spectrometer shall be less than 0.6nm/mm, the focal length is within 0.35~1.0m, and the wave length range is 165.0~410.0nm. The vacuum degree of spectrometer shall work blow 3Pa or be filled with high-purity inert gas (such gas does not absorb the spectral line with wave length less than 200nm, and its purity is not lower than 99.999%).
4.6 Photometric system
The photometric system shall include the photoelectric conversion detector receiving signal, the integrating capacitor capable of storing each output electric signal, the measuring unit used for directly or indirectly recording the voltage or frequency on the capacitor, and the necessary circuit switching device provided for the required time sequence.
5 Sampling and Sample Preparation
5.1 Sampling
Sampling and sample preparation shall be in accordance with the requirements of GB/T 20066. During sampling, the analysis sample shall be uniform, and free from shrinkage and crack. During the sampling of as-cast sample, the molten steel shall be injected into the specified mould, the content of deoxidizing agent shall not exceed 0.35% if aluminum deoxidation is adopted; the representative position shall be selected in steel sampling.
5.2 Sample preparation
As for the sample taken out from mould, the sample is generally cut out at the lower 1/3 point in height direction. For the uncut samples, the surface thickness shall be reduced by 1mm. The cutting machine equipped with resin cutting disc and metal-cutting machine tool etc. shall be adopted as the cutting equipment.
The analysis sample shall be sufficient to cover the excitated hole diameter of spark stand, generally, the diameter is required to be greater than 16mm and the thickness be greater than 2mm; the sample surface shall be flat and clean. Grinder, abrasive paper grinding disc or abrasive band grinding machine may be adopted, the miller may also be adopted for processing. Aluminum oxide, zirconium oxide and silicon carbide etc. are adopted as the grinding material. Generally, the particle size of grinding material is 0.25~0.124mm.
The standard sample and analysis sample shall be grinded under the same condition and shall not be overheated.
Note: the selection of different grinding materials may affect the detection of relevant trace elements.
6 Standard Sample, Standardization Sample and Control Sample
6.1 Standard sample
Standard sample is used for plotting calibration curve, of which chemical property and texture structure are similar with those of analysis sample, the content range of analytical element shall be covered and proper gradient shall be maintained, the content of analytical element is valued with accurate and reliable method.
The deviation for analysis result will be generated if improper standard sample series are selected, therefore, adequate attention shall be paid for the selection of standard sample. During the plotting of calibration curve, several standard samples with different analytical element contents are generally adopted as one series, of which composition and smelting processes are better to be similar with those of analysis sample.
6.2 Standardization sample
Variation of instrument conditions will result in deviation of the determination result. In order to directly use the original calibration curve and obtain accurate results, 1~2 samples are used for standardizing the instrument, and such sample is referred to as standardization sample. The standardization sample shall be quite uniform and provided with proper content as required, it may be selected from standard samples and may also be specially smelted. Where two-point standardization is adopted, the contents near the upper limit and lower limit of the calibration curve of each element are respectively taken as its content.
Standardization sample is intended to correct the deviation of calibration curve caused by the measured value of instrument due to various causes, the standardization sample shall be uniform and stable spectral line intensity shall be obtained.
6.3 Control sample
Control sample is used for calibrating the determination results of analysis samples and may also be used for the correction of type standardization, which is provided with similar metallurgy processing, texture structure and chemical composition with the analysis sample.
Control sample may be made of molten metal with casting mould or made of metal finished. During the smelting of control sample, the content of each element shall be properly specified to realize approximate equivalence of the matrix component of each sample. Attention shall be paid to the error of fixed standard value as well as the traceability of data and method during the value assignment of control sample.
7 Instrument Preparation
7.1 Instrument storage
The spectrometer shall be placed in the shock-proof and clean laboratory in accordance with the requirements recommended by the instrument manufacturer, generally, the indoor temperature is 15~30℃ and the relative humidity shall be less than 80%. The variation of indoor temperature shall not exceed 5℃ in the same standardization cycle.
7.2 Power supply
In order to ensure the stability of instrument, the variation of power supply voltage shall be less than ±10% and the frequency variation be less than ±2% to ensure that the AC power supply is sine wave. The instrument is equipped with special ground wire according to service requirements.
7.3 Excitation light source
To enable the electric appliance part of excitation light source is stable in operation, proper power-on time shall be provided prior to operation.
The voltage regulator or pressure stabilizer equipment is adopted to adjust the power supply voltage to the value as required.
7.4 Counter electrode
The counter electrode shall be cleaned and replaced periodically, and the distance of its analytical gap shall be adjusted with an electrode spacing gauge to maintain the normal operation condition.
7.5 Optical system
The collecting lens shall be cleaned and traced periodically to calibrate the position of entrance slit.
7.6 Photometric system
Restart it after shutdown, generally, sufficient power-on time shall be ensured to make the photometric system operate stably.
Proper pre-burning time of analytical element is selected by making pre-burning curve. The integrating time is determined by experiment based on analysis precision.
Foreword I
1 Scope
2 Normative References
3 Principle
4 Instruments
5 Sampling and Sample Preparation
6 Standard Sample, Standardization Sample and Control Sample
7 Instrument Preparation
8 Calibration
9 Analysis Conditions and Analysis Procedures
10 Calculation of Analysis Result
11 Precision
12 Acceptability of Measuring Result and Determination of Final Report Result
13 Accuracy Judgment for Measuring Result in Laboratory
14 Test Report
Appendix A (Informative) Additional Information on Precision Experiment
Appendix B (Informative) Precision Data
GB/T 4336—2016《碳素钢和中低合金钢 多元素含量的测定 火花放电原子发射光谱法（常规法）》
国家标准第1号修改单
将表1增加一列“适用范围（质量分数）/%”，原“测定范围（质量分数）/%”改为“定量范围（质量分数）/%”，并增加表注。修改后的表1如下。
表1 各元素的适用范围和定量范围
元素 适用范围（质量分数）/% 定量范围（质量分数）/%
C 0.001~1.3 0.03~1.3
Si 0.006~1.2 0.17~1.2
Mn 0.006~2.2 0.07~2.2
P 0.003~0.07 0.01~0.07
S 0.002~0.05 0.008~0.05
Cr 0.005~3.0 0.1~3.0
Ni 0.001~4.2 0.009~4.2
W 0.06~1.7 0.06~1.7
Mo 0.0009~1.2 0.03~1.2
V 0.0007~0.6 0.1~0.6
Al 0.001~0.16 0.03~0.16
Ti 0.0007~0.5 0.015~0.5
Cu 0.005~1.0 0.02~1.0
Nb 0.0008~0.12 0.02~0.12
Co 0.0015~0.3 0.004~0.3
B 0.0001~0.011 0.0008~0.011
Zr 0.001~0.07 0.006~0.07
As 0.0007~0.014 0.004~0.014
Sn 0.0015~0.02 0.006~0.02
注：“适用范围”中低含量段未经精密度试验验证，实验室在测定低含量样品时注意选择合适仪器条件、标准样品等，严格控制，谨慎操作。
