A method for correcting carbon potential using a three gas analyzer

Abstract

The application discloses a method for correcting carbon potential by using a three-gas analyzer, and is characterized by comprising a constant carbon coefficient calculation formula at different temperatures in a steel heating furnace, which is K=[8753÷(T+273)] 2 The step of the application is the step of π-20, wherein K is a specified carbon coefficient; T is an actual temperature in a heat treatment furnace; the percentage content of CO, CO2 and CH4 in the heating furnace during heat treatment is measured by using a three-gas analyzer, and the carbon potential value is calculated, wherein CP0% is a set carbon potential value on a carbon potential control table of the heat treatment furnace, K is a specified carbon coefficient, and if the actual carbon potential in the heating furnace deviates from the set carbon potential value by ±0.05% through calculation, the set carbon potential value on the carbon potential control table of the heat treatment furnace is adjusted to the actual carbon potential value, and the advantage is that the measurement of the carbon potential is fast and accurate.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for determining carbon potential, in particular to a method for correcting carbon potential by using a three-gas analyzer. BACKGROUND

[0002] Carbon potential is a parameter for characterizing the ability of a carbon-containing atmosphere to change the carbon content of the surface of a steel piece at a certain temperature. The so-called carbon potential refers to the carbon concentration when the steel is in the austenite state and reaches equilibrium with the furnace atmosphere composition under certain temperature and furnace atmosphere composition conditions. This value is a characteristic of the atmosphere and also a characteristic of the steel, and only has meaning when the system is in equilibrium. Carbon potential is the main parameter that needs to be controlled in processes such as gas carburizing and decarburizing. When the carbon potential of the furnace atmosphere is not effectively controlled, the carbon content of the surface of the steel component or the carbon concentration of the carburized layer often fails to meet the process requirements. At a certain carburizing temperature, the carbon potential of the furnace atmosphere mainly depends on the composition of the furnace atmosphere and the results of the reactions of the components with each other at high temperatures. The main components of the carburizing furnace atmosphere are CO, H2, N2 and small amounts of CO2, H2O, O2, CH4 and unsaturated hydrocarbons, etc. Among them, the main carburizing components for steel are CH4 and CO, and a small amount of CO2, H2O and O2 in the furnace atmosphere will have an oxidizing and decarburizing effect on the steel.

[0003] At present, the control of carbon potential is performed by a carbon controller. A required carbon potential is set in the carbon controller, and precise control is achieved near the set value by combination of the carbon controller and an oxygen probe. Whether the carbon potential controlled by the carbon controller is accurate needs to be determined by rigorous measurement according to the method for determining carbon potential of steel by a steel ball in JB / T10312-2011. The method for determining carbon potential of steel by a steel ball has the advantages of accuracy, but has the disadvantage of long time consumption, which needs 2-3 hours and requires many additional devices.

[0004] The three-gas analyzer is an electronic product applied in the heat treatment carburizing process, which can meet the requirement of furnace gas detection of the carburizing and quenching atmosphere furnace. The carbon potential is calculated by detecting the carbon monoxide, carbon dioxide and methane in the furnace atmosphere, so as to achieve the purpose of controlling the carbon potential in the furnace. The three-gas analyzer has the advantages of fast speed, which only needs 3-6 minutes and does not require additional devices. However, the three-gas analyzer can only measure the percentage content of CO, CO2 and CH4 in the furnace, and the carbon potential is calculated according to the fixed coefficient at normal temperature. Since the parameters such as material and temperature are constantly changing in the heat treatment, the deviation of the carbon potential calculated by the fixed coefficient of the three-gas analyzer is relatively large. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a method for quickly and accurately correcting carbon potential by using a three-gas analyzer.

[0006] The technical solution adopted by the present application to solve the above technical problem is as follows: a method for correcting carbon potential by using a three-gas analyzer, comprising the following steps:

[0007] (1) Determination of carbon coefficient

[0008] The actual temperature in the heating furnace is collected, and the carbon coefficient at the temperature is calculated, and the calculation formula is specifically: K = [8753 ÷ (T + 273)] 2 π-20, wherein K is the specified carbon coefficient, T is the actual temperature in the heat treatment furnace, π is the circular constant, and (2) Measurement of carbon potential The percentage contents of CO, CO2 and CH4 in the heating furnace during the heat treatment process are measured by a three-gas analyzer, and the carbon potential value is calculated according to the contents of the three gases, and the calculation formula is as follows:

[0009] CP = 0.003 × (0.429 × CO% - 0.25 × CO2% + 0.75 × CH4%) × (T + 273) × CP0%, wherein CP is the actual carbon potential in the heating furnace, CO% is the volume percentage content of CO measured by the three-gas analyzer, CO2% is the volume percentage content of CO2 measured by the three-gas analyzer, CH4% is the volume percentage content of CH4 measured by the three-gas analyzer, T is the actual temperature in the heat treatment furnace, CP0% is the set carbon potential value on the carbon potential control table of the heat treatment furnace, and K is the specified carbon coefficient.

[0010] (3) If the actual carbon potential in the heating furnace deviates from the set carbon potential value by ±0.05%, the set carbon potential value on the carbon potential control table of the heat treatment furnace is adjusted to the actual carbon potential value.

[0011] Compared with the prior art, the method for correcting carbon potential by using a three-gas analyzer has the advantages that the method is not only fast, but also very accurate, and the accurate and rapid measurement of carbon potential is realized. DETAILED DESCRIPTION

[0012] The application will be further described in detail below in combination with embodiments. DETAILED EMBODIMENTS

[0014] 1. A method for correcting carbon potential by using a three-gas analyzer, comprising the following steps:

[0015] (1) Determination of carbon coefficient

[0016] The actual temperature in the heating furnace is collected, and the carbon coefficient at the temperature is calculated, and the calculation formula is specifically: K = [8753 ÷ (T + 273)] 2 π-20, wherein K is the specified carbon coefficient, T is the actual temperature in the heat treatment furnace, π is the circular constant, and (2) Measurement of carbon potential The percentage contents of CO, CO2 and CH4 in the heating furnace during the heat treatment process are measured by a three-gas analyzer, and the carbon potential value is calculated according to the contents of the three gases, and the calculation formula is as follows:

[0017] Table 1 Carbon coefficient table K

[0018] Temperature °C 820 830 840 850 860 870 880 Carbon fixation coefficient 181.47 181.1 177.83 174.30 167.50 164.23 161.05 Temperature °C 890 900 910 920 930 940 950 Carbon fixation coefficient 157.95 154.93 151.98 149.11 146.31 143.58 140.92 ;

[0019] (2) Measurement of carbon potential

[0020] The percentage content of CO, CO2, CH4 in the heating furnace during heat treatment is measured by a three-gas analyzer, and the carbon potential value is calculated according to the content of the three gases, and the calculation formula is as follows:

[0021] CP = 0.003 x (0.429 x CO% - 0.25 x CO2% + 0.75 x CH4%) x (T + 273) x CP0% x, CP: carbon potential calculated by the three-gas analyzer;

[0022] CO%: refers to the volume percentage content of CO measured by the three-gas analyzer;

[0023] CO2%: refers to the volume percentage content of CO2 measured by the three-gas analyzer;

[0024] CH4%: refers to the volume percentage content of CH4 measured by the three-gas analyzer;

[0025] T: refers to the actual temperature in the heat treatment furnace, ℃;

[0026] CP0%: refers to the set carbon potential value on the carbon potential control table of the heat treatment furnace;

[0027] K: refers to the carbon coefficient;

[0028] (3) If the actual carbon potential in the heating furnace deviates from the set carbon potential value by ±0.05%, the set carbon potential value on the carbon potential control table of the heat treatment furnace is adjusted to the actual carbon potential value.

[0029] Example 1

[0030] The heat treatment temperature T is 870℃, the set carbon potential value CP0% on the carbon potential control table is 0.33%, and the volume percentage content of the three gases measured by the three-gas analyzer is: CO% is 28.11, CO2% is 1.42, and CH4% is 1.17.

[0031] First, according to the temperature T of 870℃, the carbon coefficient can be calculated as 164.23 according to formula (1), or the carbon coefficient can be found from Table 1 as 164.23, then the content of the three gases, the carbon coefficient, and the carbon potential set value are calculated according to formula (2) to calculate the carbon potential: CP = 0.003 x (0.429 x 28.11 - 0.25 x 1.42 + 0.75 x 1.17) x (870 + 273) x 0.33% x

[0032] = 0.331%. Under this condition, if the carbon potential is determined by the national standard JB / T 10312-2011 steel boat determination carbon potential method, the carbon potential is 0.331%. The actual carbon potential value exceeds the carbon potential setting value by 0.3%, and the carbon potential setting value is adjusted to 0.331%.

[0033] Example 2

[0034] The heat treatment temperature T is 820°C, the carbon potential control table sets the carbon potential value CP0% to 0.60%, and the volume percentage content of the three gases measured by the three gas analyzer is: CO% is 28.56, CO2% is 1.58, and CH4% is 0.87.

[0035] First, according to the temperature T of 820°C, the fixed carbon coefficient is calculated to be 181.47 according to formula (1), or the fixed carbon coefficient is 181.47 which can be found from table 1, then the content of the three gases, the fixed carbon coefficient, and the carbon potential setting value are calculated according to formula (2), and the carbon potential is calculated as follows: CP = 0.003 × (0.429 × 28.56 - 0.25 × 1.58 + 0.75 × 0.87) × (820 + 273) × 0.60% ×

[0036] = 0.601%. Under this condition, if the carbon potential is determined by the national standard JB / T 10312-2011 steel boat determination carbon potential method, the carbon potential is 0.601%. The actual carbon potential value exceeds the carbon potential setting value by 0.17%, and the carbon potential setting value is adjusted to 0.601%.

[0037] Example 3

[0038] The heat treatment temperature T is 900°C, the carbon potential control table sets the carbon potential value CP0% to 0.28%, and the volume percentage content of the three gases measured by the three gas analyzer is: CO% is 29.40, CO2% is 1.17, and CH4% is 0.42.

[0039] First, according to the temperature T of 900°C, the fixed carbon coefficient is calculated to be 154.93 according to formula (1), or the fixed carbon coefficient is 154.93 which can be found from table 1, then the content of the three gases, the fixed carbon coefficient, and the carbon potential setting value are calculated according to formula (2), and the carbon potential is calculated as follows: CP = 0.003 × (0.429 × 29.40 - 0.25 × 1.17 + 0.75 × 0.42) × (900 + 273) × 0.28% ×

[0040] = 0.281%. Under this condition, if the carbon potential is determined by the national standard JB / T 10312-2011 steel boat determination carbon potential method, the carbon potential is also 0.281%. The actual carbon potential value exceeds the carbon potential setting value by 0.36%, and the carbon potential setting value is adjusted to 0.281%.

[0041] Example 4

[0042] The heat treatment temperature T is 950 DEG C, the carbon potential control table sets the carbon potential value CP0% to 1.20%, and the three gas analyzer measures the volume percentage content of the three gases as follows: CO% is 30.54, CO2% is 1.87, and CH4% is 0.35.

[0043] First, according to the temperature T of 950 DEG C, the fixed carbon coefficient is calculated as 140.92 according to the formula (1), and the fixed carbon coefficient is also 140.92 which can be found from Table 1. Then, the content of the three gases, the fixed carbon coefficient, and the carbon potential setting value are calculated according to the formula (2) to calculate the carbon potential: CP=0.003×(0.429×30.54-0.25×1.87+0.75×0.35)×(950+273)×1.20%×

[0044] =1.22%. Under the above conditions, if the carbon potential is measured according to the national standard JB / T 10312-2011 steel pipe determination carbon potential method, the carbon potential is also 1.22%. The actual carbon potential value exceeds the carbon potential setting value by 1.7%, and the carbon potential setting value is adjusted to 1.22%.

[0045] From the above specific examples, it can be known that the method for correcting the carbon potential by using the three gas analyzer is accurate and reliable.

[0046] In practical application, the formula (1) and (2) are programmed into the three gas analyzer, and only the mouse needs to click the button "carbon potential calculation button" to immediately display the carbon potential value.

[0047] The above description is not a limitation of the present application, and the present application is not limited to the above examples. Changes, modifications, additions or replacements made by ordinary skilled in the art within the essential scope of the present application should also belong to the protection scope of the present application.

Claims

1. A method of correcting carbon potential with a three gas analyzer, characterized by The method comprises the following steps: (1) carbon coefficient determination The actual temperature in the heating furnace is collected, and the fixed carbon coefficient at the temperature is calculated, and the calculation formula is specifically: K = [8753 ÷ (T + 273)] 2 π-20, wherein K is a specified carbon coefficient, T is an actual temperature in the heat treatment furnace, π is a circular constant, and the unit of T is ℃. (2) carbon potential measurement The percentage content of CO, CO2 and CH4 in the heating furnace during the heat treatment process is measured by a three-gas analyzer, and the carbon potential value is calculated according to the content of the three gases, and the calculation formula is as follows: where CP is the actual carbon potential in the furnace; CO% is the volume percent CO as measured by the three gas analyzer; CO2% is the volume percent CO2 as measured by the three gas analyzer; CH4% is the volume percent CH4 as measured by the three gas analyzer; T is the actual temperature in the furnace in °C; CP0% is the set carbon potential value on the carbon potential control chart for the furnace; and K is the carbon coefficient. (3) if the actual carbon potential in the heating furnace deviates from the set carbon potential value by ±0.05%, the set carbon potential value on the heat treatment furnace carbon potential control table is adjusted to the actual carbon potential value.

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