Method for detecting trace sulfur in bearing steel

Abstract

The invention relates to the technical field of physical and chemical detection, in particular to a method for detecting trace sulfur in bearing steel. The method comprises the following steps: (1) sample pretreatment: soaking a sample in an acetic acid solution for 1-2 minutes, taking out the sample, immediately washing the sample with running water, and immediately putting the sample into absolute ethyl alcohol for storage; (2) crucible pretreatment: putting a crucible into a muffle furnace at the temperature of 1100-1300 DEG C, preserving heat for 1-3 hours, and storing in a dryer; and (3) detection by an infrared carbon-sulfur analyzer: weighing the sample pretreated in the step (1), blow-drying the sample with hot air, putting the sample into the crucible pretreated in the step (2), uniformly covering the crucible with a fluxing agent, and analyzing the sample on the infrared carbon-sulfur analyzer. The detection method provided by the invention can effectively improve the conditions of large amount fluctuation, poor accuracy, poor precision and the like of trace sulfur in the bearing steel detected by a traditional method; the method is simple, convenient and rapid, the analysis result is stable and reliable, the labor intensity of post personnel is reduced, and the working efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the field of physical and chemical detection technology, and in particular to a method for detecting trace sulfur in bearing steel. Background Art

[0002] Bearing steel is steel used to produce balls, rollers and bearing rings. Bearings bear a lot of pressure and friction when working, so bearing steel needs to have high and balanced hardness standards and wear resistance, as well as high elastic limit. The requirements for the balance of chemical composition, content and distribution of non-metallic material inclusions of bearing steel are very strict, and it is one of the most stringent steel grades in any steel production.

[0003] At present, the conventional detection method for the sulfur content of bearing steel below 10ppm has large fluctuations in measurement values, poor accuracy, and poor precision. It is necessary to study a detection method for trace sulfur in bearing steel in order to optimize the detection parameters and provide faster and more accurate analysis results. Summary of the invention

[0004] The purpose of the present invention is to provide a method for detecting trace sulfur in bearing steel, so as to solve the problems of large fluctuations in the value of trace sulfur detected by traditional methods, poor accuracy, poor precision, etc., and to utilize the advantages of instrumental analysis to accurately and quickly complete the goal of analyzing trace sulfur in bearing steel.

[0005] In order to achieve the above object, the technical solution of the present invention is as follows:

[0006] The present invention provides a method for detecting trace sulfur in bearing steel, the method comprising the following steps:

[0007] (1) Sample pretreatment:

[0008] Immerse the sample in acetic acid solution for 1 to 2 minutes, rinse with running water immediately after taking it out, and then immediately store it in anhydrous ethanol;

[0009] (2) Crucible pretreatment:

[0010] Place the crucible in a muffle furnace at 1100-1300°C for 1-3 hours and store in a desiccator;

[0011] (3) Infrared carbon and sulfur analyzer detection:

[0012] Weigh the sample pretreated in step (1), blow dry it with hot air, put it into the crucible pretreated in step (2), evenly cover it with flux, and analyze it on an infrared carbon-sulfur analyzer.

[0013] In the above technical solution, further, in step (1), when the sample is a thin plate steel sample, a punching machine is used to punch out a sheet sample; when the sample is a thick plate steel sample, a cutting machine is used to cut a strip sample, and then a cutting machine is used to cut a block sample.

[0014] In the above technical solution, further, in step (2), the crucible is a ceramic crucible.

[0015] In the above technical solution, further, in step (3), the flux is tungsten particles.

[0016] In the above technical solution, further, in step (3), the sample weighing amount is 0.5 to 0.6 g.

[0017] In the above technical solution, further, in step (3), the working conditions of the infrared carbon-sulfur analyzer are: power of 2.2KW, carrier gas flow rate of 3L / min, carrier gas pressure of 35±10%psi, and power gas pressure of 40±10%psi.

[0018] In the above technical solution, further, in step (3), the analysis time is 40 to 60 seconds and the comparison level is 2.

[0019] The beneficial effects of the present invention are:

[0020] The detection method of the present invention can effectively improve the traditional method of detecting trace sulfur in bearing steel, which has large fluctuations in the value, poor accuracy, poor precision, etc. The method of the present invention is simple and fast, and the analysis results are stable and reliable, which reduces the labor intensity of post personnel and improves work efficiency.

[0021] The result of the method of the present invention is highly accurate and precise, and solves the problem of poor precision in analyzing the sulfur content of bearing steel below 10 ppm. DETAILED DESCRIPTION

[0022] The following examples may enable those skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.

[0023] The present invention provides a method for detecting trace sulfur in bearing steel, comprising the following steps:

[0024] (1) Sample pretreatment:

[0025] The traditional sample preparation method is to grind the sample surface with a grinding wheel and then drill out steel scraps with a vertical bench drill. This method is prone to secondary pollution. The present invention improves the sample preparation method. When the sample is a thin plate steel sample, a sheet sample is punched out with a sample puncher. When the sample is a thick plate steel sample, a strip sample is cut out with a cutting machine, and then a block sample is cut out with a sample cutter. The obtained sample is immersed in an acetic acid solution for 1 to 2 minutes, and immediately rinsed with running water after being taken out, and then immediately stored in anhydrous ethanol.

[0026] (2) Crucible pretreatment:

[0027] The detection of trace sulfur requires a very low blank value, and the untreated ceramic crucible absorbs moisture and gas in the air due to pollution, resulting in a high blank value and is very unstable. Therefore, the crucible for analysis must be pretreated before use. The present invention uses a ceramic crucible, and the pretreatment method is: placing the ceramic crucible in a muffle furnace at 1100-1300°C for 1-3h, and storing it in a desiccator for no more than 24 hours. This treatment can effectively avoid secondary pollution, and the blank value is low and relatively stable.

[0028] (3) Infrared carbon and sulfur analyzer detection:

[0029] Weigh the sample pretreated in step (1) and blow dry it with hot air, put it into the ceramic crucible pretreated in step (2), evenly cover it with 1.2-1.5 g of flux, and analyze it on a CS-600 infrared carbon and sulfur analyzer;

[0030] The working conditions of the infrared carbon and sulfur analyzer are shown in Table 1:

[0031] Table 1 CS-600 infrared carbon and sulfur analyzer working conditions

[0032] parameter Reference range Power / KW 2.2 Carrier gas flow rate / (L / min) 3 Carrier gas pressure (psi) 35±10％ Power air pressure (psi) 40±10％ Detection limit (ppm) 0.001

[0033] The role of flux in sulfur analysis is to lower the melting point of the sample, increase the combustion temperature, and prevent the sample from splashing. Commonly used fluxes for steel samples include tungsten particles, tin particles, and a mixture of tungsten particles and tin particles. These fluxes were used to test the standard sample BGY97-2 with a sulfur content of 0.0007%.

[0034] The test process is as follows: take 0.6g of sample, put it into a ceramic crucible that has been kept in a muffle furnace at 1200℃ for 2 hours, add different fluxes, set the analysis time to 50s, the comparison level to 2, and analyze it in a CS-600 infrared carbon and sulfur analyzer.

[0035] The test results are shown in Table 2:

[0036] Table 2 Effect of flux on test results

[0037]

[0038] It can be seen from Table 2 that the measured values ​​using tin particles or tungsten-tin mixed flux are high, the stability is poor, and there is a lot of dust during the measurement, so tungsten particles are used as flux.

[0039] The sample weight has a certain influence on the accuracy of the analysis results. The main reason is that if the sample weight is too low, the representativeness of the sample will be low, while if the sample weight is too high, the analysis result will be low due to the poor melting property of the sample. The standard sample BGY97-2 with a sulfur content of 0.0007% is used to balance the sample weight for the test;

[0040] The test process is as follows: weigh samples of different masses, put them into a ceramic crucible that has been kept in a muffle furnace at 1200°C for 2 hours, add 1.2g of tungsten particles as a flux, set the analysis time to 50s, the comparison level to 2, and analyze them in a CS-600 infrared carbon and sulfur analyzer.

[0041] The test results are shown in Table 3:

[0042] Table 3 The influence of samples on the test results

[0043]

[0044]

[0045] As can be seen from Figure 3, by comparing the average value and the relative standard deviation, the sample weight is selected to be 0.5-0.6 g, and the preferred sample weight is 0.6 g.

[0046] The analysis time of the sample is determined by the analysis time and the comparison level in the analysis method. In actual testing, the integral curve on the computer screen should be observed. If tailing occurs, the comparison level should be appropriately increased to avoid the analysis result being affected by excessive blank. When the analysis time is 20s, 30s, 40s, 50s, and 60s, the comparison level is tested with the standard sample BGY97-2 with a sulfur content of 0.0007%; the test results are shown in Table 4:

[0047] Table 4 Effects of analysis time and comparison level on test results

[0048]

[0049]

[0050] As can be seen from Table 4, the analysis time is selected to be 40 to 60 s, preferably 50 s, and the comparison level is 2.

[0051] Example 1

[0052] The accuracy tests were carried out on standard samples BGY97-1, YSBS20123-2002, BGY97-2, and GBW01148. The accuracy test results are shown in Table 5.

[0053] Table 5 Accuracy experimental results

[0054]

[0055] It can be seen from Table 5 that the method of the present invention has good accuracy.

[0056] Example 2

[0057] For bearing steel samples 1#, 2#, and 3#, strip samples were cut by a cutting machine, and small pieces of samples were cut by a sample cutter. The samples were immersed in acetic acid solution for 1 minute, rinsed with running water immediately after being taken out, and then immediately placed in anhydrous ethanol. They were blown dry with hot air during analysis. 0.6g of sample was weighed and placed in a ceramic crucible that had been kept warm in a muffle furnace at 1200℃ for 2 hours. 1.2g of tungsten particles were added as flux, the analysis time was set to 50s, the comparison level was set to 2, and the analysis was carried out in a CS-600 infrared carbon and sulfur analyzer. The working conditions shown in Table 1 were adopted, and the experimental results are shown in Table 6.

[0058] Table 6 Production sample test results

[0059]

[0060]

[0061] It can be seen from Table 6 that the sample analysis results are good and the precision is good.

[0062] The above embodiments are only preferred embodiments of the present invention and are not intended to limit the implementation methods. The protection scope of the present invention shall be subject to the scope defined in the claims. Other different forms of changes or modifications may be made based on the above description. Obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A method for detecting trace sulfur in bearing steel, characterized in that: The method comprises the following steps: (1) Sample pretreatment: Immerse the sample in acetic acid solution for 1 to 2 minutes, rinse with running water immediately after taking it out, and then immediately store it in anhydrous ethanol; (2) Crucible pretreatment: Place the crucible in a muffle furnace at 1100-1300°C for 1-3 hours and store in a desiccator; (3) Infrared carbon and sulfur analyzer detection: Weigh the sample pretreated in step (1), blow dry it with hot air, put it into the crucible pretreated in step (2), evenly cover it with flux, and analyze it on an infrared carbon-sulfur analyzer.

2. The detection method according to claim 1, characterized in that: In step (1), when the sample is a thin plate steel sample, a punching machine is used to punch out a sheet sample; when the sample is a thick plate steel sample, a cutting machine is used to cut out a strip sample, and then a cutting machine is used to cut out a block sample.

3. The detection method according to claim 1, characterized in that: In step (2), the crucible is a ceramic crucible.

4. The detection method according to claim 1, characterized in that: In step (3), the flux is tungsten particles.

5. The detection method according to claim 1, characterized in that: In step (3), the sample weight is 0.5 to 0.6 g.

6. The detection method according to claim 1, characterized in that: In step (3), the working conditions of the infrared carbon-sulfur analyzer are: power of 2.2KW, carrier gas flow rate of 3L / min, carrier gas pressure of 35±10%psi, and power gas pressure of 40±10%psi.

7. The detection method according to claim 1, characterized in that: In step (3), the analysis time is 40 to 60 seconds and the comparison level is 2.

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