Skip to product information
1 of 4

PayPal, credit cards. Download editable-PDF and invoice in 1 second!

GB/T 21931.1-2008 English PDF (GBT21931.1-2008)

GB/T 21931.1-2008 English PDF (GBT21931.1-2008)

Regular price $140.00 USD
Regular price Sale price $140.00 USD
Sale Sold out
Shipping calculated at checkout.
Quotation: In 1-minute, 24-hr self-service. Click here GB/T 21931.1-2008 to get it for Purchase Approval, Bank TT...

GB/T 21931.1-2008: Nickel, ferronickel and nickel alloys -- Determination of carbon content -- Infrared absorption method after induction furnace combustion

GB/T 21931.1-2008
Nickel, ferronickel and nickel alloys - Determination of carbon content - Infrared absorption method after induction furnace combustion ICS 77.100
National Standards of People's Republic of China
GB/T 21931.1-2008/ISO 7524.1985
Determination of carbon content of nickel, nickel-iron and nickel alloys High frequency combustion infrared absorption method
(ISO 7524.1985, IDT)
2008-05-30 released
Implementation of.2008-12-01
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China Issued by China National Standardization Administration
This part of GB/T 21931 is equivalent to ISO 7524.1985 "Determination of carbon content of nickel, nickel-iron and nickel alloys. External Absorption Law.
The technical content of this part is exactly the same as ISO 7524.1985.For ease of use, this part has been modified as follows. a) The term "this International Standard" is changed to "this Part";
b) Use a decimal point "." to replace the comma "," as a decimal point; c) Delete the foreword of the international standard;
d) National standards are adopted for normative references;
e) The contents of the crucible cover in the international standard have been deleted. Appendix A, Appendix B and Appendix C of this section are informative appendices. This part was proposed by the China Iron and Steel Association.
This part is under the jurisdiction of the Metallurgical Industry Information Standards Institute. Drafting organization of this section. Shanxi Taigang Stainless Steel Co., Ltd. The main drafters of this section. Dai Xueqian, Zhang Ruilin, Zhang Jiansheng. GB/T 21931.1-2008/ISO 7524.1985
Determination of carbon content of nickel, nickel-iron and nickel alloys High frequency combustion infrared absorption method
Warning. The personnel using this section should have practical experience in formal laboratory work. This section does not point out all possible security issues. The user is responsible for taking appropriate safety and health measures and ensuring compliance with the conditions stipulated by relevant national laws and regulations. 1 scope
This part of GB/T 21931 specifies the determination of the carbon content in nickel, nickel-iron and nickel alloys by the infrared absorption method after high-frequency induction combustion. This section applies to the carbon content (mass fraction) in nickel and ferronickel for 0.001% to 2.0%, and the carbon content (mass fraction) in nickel alloys is 0.001% to 0.5% determination. Examples of the composition of nickel, nickel-iron and nickel alloys are shown in Appendix A. 2 Normative references
The clauses in the following documents have become clauses of this part by reference to this part of GB/T 21931.All dated quotations All subsequent amendments (excluding errata content) or revisions do not apply to this section, however, it is encouraged to reach The parties to the agreement study whether the latest versions of these documents can be used. For undated references, the latest version is applicable to this section.
GB/T 63779.1 Measurement methods and accuracy of results (accuracy and precision) Part 1.General principles and definitions (GB/T 6379.1-2004, ISO 5725-1..1994, IDT)
GB/T 63779.2 Accuracy of measurement methods and results (accuracy and precision) Part 2.Determine the repeatability of standard measurement methods The basic method of performance and reproducibility (GB/T 6379.2-2004, ISO 5725-2.1994, IDT) 3 Principle
Place the sample, flux, and accelerator in a high-frequency induction furnace and burn it at a high temperature under oxygen flow. The carbon dioxide produced is carried by oxygen to In the measuring chamber of the infrared detector, carbon dioxide absorbs infrared energy of a certain wavelength, and its absorption energy is proportional to the concentration of carbon. According to the detector The measured value can determine the carbon content.
4 Reagents and materials
4.1 Oxygen, the purity is greater than 99.5%.
4.2 Caustic soda asbestos (or soda lime), particle size 0.7mm ~ 1.2mm (14 mesh ~ 22 mesh). 4.3 Magnesium perchlorate, particle size 0.7mm~1.2mm (14 mesh ~ 22 mesh). 4.4 Glass wool.
4.5 Crucible.
4.5.1 The size of the ceramic crucible should be accurate, so that the sample can fit in the induction coil of the furnace (see 9.1). 4.5.2 When the carbon content (mass fraction) is less than 0.01%, the crucible is burned in air or oxygen for no less than 1h in a furnace at 1,100°C. Store in a desiccator or sealed container afterwards. A resistance furnace with a combustion tube can be used, with oxygen passing through the combustion tube. 4.6 Flux. low-carbon tin, copper plus tin or copper (see 9.2).
4.7 Accelerator. low-carbon copper, pure iron, tungsten or nickel (see 9.2). 4.8 Steel standard samples. carbon content (mass fraction) 0.01% to 2.5%. GB/T 21931.1-2008/ISO 7524.1985
5 Instruments
High-frequency induction burner and infrared absorption carbon meter can be purchased from the manufacturer. The operation of the instrument is in accordance with the manufacturer's instructions. According to the system Factory technical specifications require a pressure regulator to control the pressure of oxygen entering the furnace (usually 28kN/m2). See the characteristics of commodity instruments Appendix B.
6 Take samples
6.1 The collection and preparation of laboratory samples shall be carried out in accordance with the agreed procedures or in accordance with relevant national standards. 6.2 Laboratory samples are generally granular, drill chips or milling chips, and no further processing is required. 6.3 If the laboratory sample is contaminated by grease during grinding or drilling, it should be cleaned with analytical pure acetone and dried in air. 6.4 If the laboratory sample has a large difference in particle size, the sample size should be obtained after reduction. 7 Analysis steps
Warning. The danger of this experiment is mainly the burning (burn) that easily occurs during the pre-firing and melting stages of the crucible. So it should be used from start to finish Clamp the crucible and place the used crucible in a suitable container. The use of oxygen cylinders should comply with its usual safety measures. Local enrichment of oxygen can cause Fire, so oxygen must be effectively discharged from the equipment during the combustion process. 7.1 The amount of sample
Weigh 1.0g sample to the nearest 0.0001g.
7.2 Blank test
According to the sample analysis method, add quantitative flux and accelerator. Perform at least three blank tests. 7.3 Preparation for analysis
7.3.1 Before calibrating and measuring the sample, the instrument must be checked and adjusted to ensure that the instrument is in a normal and stable working state, and determine the best analysis condition.
7.3.2 After completing the blank calibration, the instrument automatically deducts the blank in the subsequent sample measurement. 7.4 Calibration
Use the standard sample in 4.8 to calibrate. Within the measurement range, select a standard sample with appropriate content to measure at least three times to perform system linearity adjust. Then measure a series of standard samples, check the linear relationship after calibration, and if necessary, further calibrate the working curve. 7.5 Sample analysis
Place the weighed sample (7.1) in the crucible (4.5), and cover the appropriate amount of flux and accelerator (variety and amount of flux and accelerator) It depends on the characteristics of the equipment and the type of sample. Typical ones include adding 2g copper, or 2g~3g tungsten, or 1g copper plus 1g Pure iron). Use the same conditions, procedures, and operations as the standard samples for measurement. 8 Results presentation
8.1 Result calculation
According to the relationship between absorption energy and carbon concentration, the carbon content is obtained from the calibration curve. The analysis result of the element to be measured should be in the calibration curve Use a series of standard samples within the content range.
8.2 Precision
The methods specified in this section are compared and verified by 8 laboratories in 5 countries. Take 5 samples at different times according to the test procedure Perform parallel sample analysis operations.
Repeatability and reproducibility are calculated in accordance with GB/T 6379, and the results are given in Table 1. GB/T 21931.1-2008/ISO 7524.1985
Table 1 Analysis and statistics results
Average carbon content
(Mass score)/%
Standards in the laboratory
Deviation (狊W)
Inter-laboratory standards
Deviation (sb)
A22 0.0014 0.0006 0.0006 0.0017 0.0024
B31 0.061 0.0016 0.0001 0.0045 0.0046
A28 1.84 0.012 0.068 0.033 0.19
Nickel S65 0.0225 0.0006 0.0003 0.00018 0.00020
02(A) 0.0010 0.0007 0.0012 0.0021 0.0041
13(G) 0.223 0.0014 0.0043 0.0041 0.0012
49(C) 0.0093 0.0007 0.0010 0.0018 0.0033
9 Analysis process and instrument description
9.1 Crucible
A ceramic crucible must be used to hold the sample and necessary additives for the subsequent melting process. The crucible must be exactly matched in size with the support so that The sample in the crucible is just inside the induction heating coil.
Typical dimensions of combustion crucible.
25mm high
Outer diameter 25mm
Inner diameter 20mm
Wall thickness 2.5mm
Bottom thickness 8mm
The crucible is pre-fired in oxygen at 1100°C to remove carbon.
9.2 Flux and accelerator
9.2.1 The addition of flux can bond the small particles of the sample together, make the induction in the furnace more effective, and produce a melt with good fluidity. body. Tin, a mixture of copper and tin, copper and tungsten can meet the requirements. 9.2.2 Copper, pure iron, tungsten and nickel are commonly used accelerators. The accelerant is added for the following reasons. a) For unsatisfactory samples processed by other methods, such as finely divided or complex materials, it can provide a good coupling induction medium; b) Play the role of chemical fuel and increase the combustion temperature; c) When the sample volume is small, it is used to increase the total content of the crucible without increasing the sample volume. The fluxes and accelerators used should have low carbon content and should be used in the calibration procedure. Various factors (oxygen, refractories, flux and promotion Agent) constitute the blank value of carbon, and the sum of all blank values cannot exceed 0.001% (mass fraction). Note. Some materials are both fluxes and accelerators.
9.3 Characteristics and operation of high frequency induction furnace
9.3.1 See Appendix B for the performance characteristics of commercial high-frequency furnaces. 9.3.2 Allow oxygen to flow through the reagent tube containing alkali asbestos agent (4.2) and magnesium perchlorate (4.3) for purification. During the standby period, still need to maintain The flow rate is about 0.5L/min.
9.3.3 A glass wool filter is installed between the furnace combustion chamber and the analyzer. Replace if necessary. Furnace room, bracket and filter should be regular Clean up to remove oxide residues.
9.3.4 The manufacturer may recommend setting up a pre-burning program before oxygen injection. During the burn-in period, the sample is in a red hot state. Enter, the temperature will increase greatly.
9.3.5 The temperature reached by combustion depends on the type and amount of metal in the furnace and crucible. After the sample is melted, keep high temperature to make carbon dioxide GB/T 21931.1-2008/ISO 7524.1985
It can be completely transferred from the furnace to the infrared analysis cell. 9.3.6 The flow rate of oxygen in the combustion phase is not exactly the same between the instrument and the instrument, and it is usually about 2.0L/min. 9.3.7 When the instrument has been shut down for several hours or after cleaning the furnace chamber or filter, stabilize the instrument as described in 7.1. 10 Test report
The test report should include the following.
a) Identification of samples, laboratory and date of analysis, etc.;
b) The degree of compliance with the provisions of this section;
c) Analysis results and their representation;
d) Abnormal phenomena observed in the measurement;
e) Operations not included in this section that may have an impact on the analysis results, or optional operations. GB/T 21931.1-2008/ISO 7524.1985
Appendix A
(Informative appendix)
Examples of chemical composition of nickel, nickel-iron and nickel alloys Table A. 1.Table A. 2.Table A. The component examples in 3 cannot be interpreted as technical conditions for chemical components. Table A. 1 Example of the composition of nickel% (mass fraction)
99.95 0.1 0.015 0.005 0.002 0.0025
99.9 0.5 0.03 0.03 0.03 0.03
99.0 1.5 0.15 0.2 0.4 0.01
Table A. 2 Examples of nickel-iron composition% (mass fraction)
Brand Ni C
LC 15 0.005 0.10 0.20 margin 0.03 0.20
60 0.03
MC 15 0.03 0.5 0.20 Margin 0.10 1.0
60 1.0
HC 15 1.0 2.0 0.20 Margin 0.40 4.0
60 2.5
Note. Co. 1/40~1/20 of Ni content.
Table A. 3 Examples of nickel alloy composition% 1) (mass fraction)
Alloy 2) AlB C Co3) Cr Cu Fe Mn Mo Ni PS Si Ti Others
2.5 2.0-63.44)-0.025 0.5--
0.5 6.0
1.0-72.04)-0.015 0.5--
C 0.4
0.5 5.0
1.0-70.04)-0.015 0.5 2.2
D 0.2
0.006 0.08-7.0
0.3 Margin 0.4 2.8
0.0150.015 0.4 0.6
E 0.15
0.7 Margin 1.5-30.0
-0.015 1.0 0.15
0.5 5.0 1.0-margin 4)-0.020 1.0 0.2
0.020 0.13 5.0 18.0
0.2 1.5 1.0-Margin-0.015 1.0 2.0
GB/T 21931.1-2008/ISO 7524.1985
Table A. 3 (continued)% 1) (quality score)
Alloy 2) AlB C Co3) Cr Cu Fe Mn Mo Ni PS Si Ti Others
H 4.5
0.2 1.0 1.0 4.5
Margin-0.015 1.0 0.9
I 0.3
0.005 0.04
0.2 0.7 0.6 5.6
Margin-0.007 0.4 1.9
J--0.02 19.0
1.0-2.0 1.0 26.0
Margin 4) 0.0400.035 0.1--
K 1.2
0.1 2.0 1.0 3.5
Margin 0.0150.015 0.1 2.8
L--0.02 2.5 14.5
1.0 15.0
Margin 0.0400.035 0.08-V0.35
1) Except for nickel, where a single value is the lowest limit, the other single values are the highest limit. 2) Before the establishment of recognized ISO grades, letters were used to indicate alloy types instead of trade names. 3) Where the limit value is not given, the maximum value of cobalt is 1.5% (mass fraction). 4) In some alloys, the amount of cobalt is calculated based on the amount of nickel. GB/T 21931.1-2008/ISO 7524.1985
Appendix B
(Informative appendix)
Characteristics of infrared carbon analyzer for commercial high frequency induction furnace B. 1 Burner
B. 1.1 The combustion furnace is composed of an induction coil and a high-frequency power supply. The combustion chamber is a quartz tube wound by an induction coil. The top and bottom of the tube are installed There are metal sheets and О-ring seals. There are gas inlet and outlet respectively on the metal sheet. B. 1.2 The apparent power of the high-frequency power supply is generally 1.5kVA~2.5kVA, but the frequencies produced by different manufacturers can be different. Used The frequencies used are 2MHz~6MHz, 15MHz and 20MHz. The high-frequency power supply inputs current to the induction coil wound on the quartz tube. The ring is usually forced to cool with air.
B. 1.3 The crucible containing the sample, flux and accelerator is placed on the support. The support should be accurately controlled. When it is lifted, the metal in the crucible can be It is precisely inside the induction coil and can produce effective induction when power is applied. B. 1.4 The diameter of the induction coil, the number of turns, the geometry of the combustion chamber in the furnace and the power of the power supply determine the quality of the coupling induction effect. These parameters are determined by the instrument manufacturer.
B. 1.5 The temperature reached by combustion depends in part on B. 1.4 factors, but also related to the characteristics of the metal in the crucible, the shape and material of the sample The quantity of materials is related. Some of these factors may differ to some extent for different operators. B. 2 Infrared gas analyzer
B. 2.1 In most instruments, gaseous combustion products are transferred to the analyzer system along with the oxygen flow. The gas passes through the infrared cell and the measurement is The absorption value of carbon to infrared radiation is integrated according to a predetermined time, and the signal is amplified and converted into a digital display of the percentage of carbon. B. 2.2 The combustion products in some analyzers are collected in a certain volume of oxygen, the volume of oxygen is controlled by pressure, and then the mixture is analyzed. The carbon dioxide content in the compound.
B. 2.3 The zero adjustment of the instrument, blank compensation, slope adjustment of the standard curve and correction of non-linear response are usually realized by electronic instruments. Minute The analyzer generally has the function of inputting the quality of the standard sample or sample amount and the correction of the reading. The instrument can also be equipped with an automatic weighing balance for weighing. Measure the crucible, weigh the sample and transfer the mass to the analyzer. GB/T 21931.1-2008/ISO 7524.1985
Book GB/T 21931.1-2008/ISO 7524.1985
Appendix C
(Informative appendix)
Optional non-aqueous titration analysis to determine carbon content
C. 1 The combustion products pass through the organic solvent absorption liquid to absorb carbon dioxide. C. 2 The absorbed carbon dioxide is continuously titrated with an organic solution, and the end of the titration is measured with an indicator color or a potentiometer. C. 3 The absorption solution is composed of 33 mL ethanolamine and 12 mL phenolphthalein, while phenolphthalein is prepared by dissolving 0.1 g phenolphthalein in 100 mL methanol. Add dimethylformamide to 1L, fill the burette with 20mL of this solution, and add a few drops of 4-n-butylammonium hydroxide to make the solution light blue Color, carbon dioxide fades the solution. As the combustion progresses, add the titrant to keep the initial blue color, which is calculated from the volume of titrant required The content of carbon in the sample.
Two laboratories verified this method with the samples described in 8.2, and the results are shown in Table C. 1. Table C. 1 Titration result...

View full details