CN114082914B - Rapid evaluation method for molten steel inclusion in CSP production - Google Patents
Rapid evaluation method for molten steel inclusion in CSP production Download PDFInfo
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- CN114082914B CN114082914B CN202010854605.2A CN202010854605A CN114082914B CN 114082914 B CN114082914 B CN 114082914B CN 202010854605 A CN202010854605 A CN 202010854605A CN 114082914 B CN114082914 B CN 114082914B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/16—Controlling or regulating processes or operations
- B22D11/18—Controlling or regulating processes or operations for pouring
- B22D11/181—Controlling or regulating processes or operations for pouring responsive to molten metal level or slag level
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Abstract
The invention discloses a method for quickly evaluating inclusion in molten steel in CSP production, which comprises the following steps: measuring a first content of Si element in molten steel after converter steelmaking as an evaluation basic value; measuring the second content of the Si element and the first variable quantity thereof after tapping of the converter, judging whether the first variable quantity is larger than a first limited threshold value, if so, changing a tapping hole if the slag quantity is too large during tapping of the converter; determining the third content and the second variable quantity of the refined Si element, and judging whether the second variable quantity is greater than a second limited threshold value, if so, the metallurgical auxiliary material has a problem; and (4) measuring the fourth content and the third variable quantity of the Si element after the continuous casting of the tundish, judging whether the third variable quantity is larger than a third limited threshold value, and if so, causing a problem in the covering agent. The invention can judge the compliance of the working procedures according to the inclusion content of molten steel in each working procedure in the CSP continuous cast steel production process, thereby evaluating the quality of refined and continuously cast slabs.
Description
Technical Field
The invention relates to a CSP (Compact strip production) continuous casting production process, in particular to a method for quickly evaluating inclusion in molten steel in CSP production.
Background
In the continuous casting production process, inclusions in molten steel need to be evaluated, and accurate and efficient evaluation of molten steel purity is of great significance to improvement of technology and improvement of molten steel purity. The vertical No. 0 section with the length of 2.5m is generally arranged in a traditional continuous casting machine, so that impurities can float upwards in a certain time and space, but the vertical No. 0 section is not arranged in the CSP crystallizer, and molten steel is rapidly cooled in the CSP crystallizer, so that the impurities do not float upwards in a sufficient time and space, and therefore, the method can track and evaluate the compliance of the working procedure in time according to the components of the molten steel in the continuous casting process, and has an extremely important effect on stabilizing CSP production.
In the prior art, the method for evaluating the purity of molten steel inclusions, namely molten steel, in the CSP continuous casting process mostly takes flaw detection as a technical means, has low efficiency and hysteresis, and cannot be used immediately in a production line; especially in the current context of mass production, it is not possible to track each furnace and perform such inefficient evaluation work.
For example: the Chinese patent application CN201510677846.3 discloses a device and a method for detecting large-particle inclusions in steel, wherein high-frequency ultrasonic waves emitted by a high-frequency ultrasonic probe are coupled by water and enter a detected sample to detect the detected steel, and the detection mode of ultrasonic flaw detection is low in efficiency. The Chinese patent application CN03802443.8 discloses an evaluation method for large-size inclusions in bearing steel and a rolling bearing, the evaluation method is to arrange a round rod made of the evaluated bearing steel and an ultrasonic probe in an ultrasonic transmission medium, measure the size and the number of the large-size inclusions in a flaw detection volume, remove the probability of the existence of the large-size inclusions in the evaluated bearing steel, only can be used for evaluating the large-size inclusions in the steel, and has poor precision and large use limitation.
Disclosure of Invention
The invention aims to provide a method for rapidly evaluating molten steel inclusion in CSP production, which can judge the compliance of working procedures according to the content of the molten steel inclusion in each working procedure in the CSP continuous casting production process so as to evaluate the quality of refined and continuously cast slabs.
The invention is realized by the following steps:
a method for rapidly evaluating inclusion in molten steel in CSP production comprises the following steps:
step 1: measuring a first content Si1 of Si element in molten steel after converter steelmaking, and taking the first content Si1 as an evaluation basic value;
step 2: measuring a second content Si2 of the Si element in the molten steel after tapping of the converter, and calculating a first variation quantity delta Si1 of the Si element in the molten steel after tapping of the converter;
and 3, step 3: judging whether a first variation quantity delta Si1 of Si element in molten steel after converter tapping is larger than a first limited threshold value, if so, judging that the slag discharge quantity is too large during converter tapping, replacing a tapping hole, and if not, executing a step 4;
and 4, step 4: measuring a third content Si3 of the Si element in the refined molten steel, and calculating a second variation quantity delta Si2 of the Si element in the refined molten steel;
and 5: judging whether a second variation quantity delta Si2 of the Si element in the molten steel after refining treatment is larger than a second limited threshold value, if so, judging that the raw material source of the metallurgical auxiliary material added in the refining treatment has a problem, replacing the metallurgical auxiliary material, and if not, executing the step 6;
and 6: measuring the fourth content Si4 of the Si element in the molten steel after the continuous casting of the tundish, and calculating the third variation delta Si3 of the Si element in the molten steel after the continuous casting of the tundish;
and 7: and judging whether a third variation quantity delta Si3 of Si element in the molten steel after the continuous casting of the tundish is larger than a third limited threshold, if so, judging that the tundish covering agent has a problem, replacing the covering agent, and if not, entering the molten steel into a CSP crystallizer for continuous production.
The first defined threshold value is 6.5-7.7 x 10 -4 %。
The second defined threshold value is 2.80-3.88 x 10 -4 %。
The third defined threshold value is 2.80-3.88 x 10 -4 %。
The rapid evaluation method is applied to CSP production of aluminum deoxidized steel.
Compared with the prior art, the invention has the following beneficial effects:
1. the method determines the purity of the molten steel in an online sampling mode in each production process of CSP continuous cast steel, and can quickly find out whether the processes restricting the product quality are in compliance or not by taking the data of inclusions in the molten steel as an evaluation basis, thereby improving the detection and evaluation efficiency and ensuring the production of the CSP continuous cast steel.
2. The method can quickly judge the specific flow which does not meet the production or management requirements in each process according to the content and the variable quantity of the Si element, and feeds the specific flow back to the related processes of the steelmaking process in time, thereby guiding the adjustment of equipment and the improvement of the process, being beneficial to reducing the inclusion of molten steel, stabilizing continuous casting and effectively improving the production quality and efficiency.
The method can perform online tracking measurement on the content of Si element which is inclusion in the molten steel in the CSP continuous casting production process, and judge the compliance of the process according to the content of Si element in the molten steel in each process and the variable quantity thereof, thereby evaluating the quality of the refined and continuously cast slab and having important guiding significance for the CSP production.
Drawings
FIG. 1 is a flow chart of the method for rapidly evaluating inclusions in molten steel in CSP production according to the present invention.
Detailed Description
The invention is further described with reference to the following figures and specific examples.
Referring to the attached figure 1, in the CSP continuous casting production process, molten steel is mainly subjected to converter steelmaking, refining treatment, tundish continuous casting, crystallization and other processes, and the processes from the molten steel to a casting blank are completed.
After the converter steelmaking is finished, deoxidation is needed during the converter tapping, the deoxidation generally takes metallic aluminum as the main component, the converter steel slag is inevitably brought out during the tapping, and the converter steel slag contains a stronger oxide-SiO 2 And reacting with metal aluminum, wherein the reaction formula is as follows: siO 2 2 +[Al]=Al 2 O 3 +[Si]The content of Si element in the molten steel is greatly improved when the converter taps.
In the production steps from refining to continuous casting, A covering agent, which is generally CaO-MgO-A, needs to be added L2 O 3 The ternary phase is mainly, and the covering agent may also contain SiO 2 Impurities, if SiO in the covering agent 2 The content of impurities is relatively large (e.g. more than 3%, for example, 1000kg of covering agent, siO 2 The content of impurities should be controlled within 30 kg), and the above reaction with metallic aluminum also occurs, resulting in a great increase in the content of Si element in molten steel in refining treatment and continuous casting tundish production processes. Therefore, it is necessary to track the content of Si element in molten steel in each step.
A rapid evaluation method for molten steel inclusion in CSP production is applied to CSP production of aluminum deoxidized steel, and comprises the following steps:
step 1: a first content Si1 of an Si element in molten steel after converter steelmaking is measured, and the first content Si1 is used as a base value for evaluation. The Si content in the molten steel in the following steps can be measured on line by adopting the measuring method without influencing the production by sampling the molten steel in the step and measuring the Si content in the molten steel.
Step 2: and measuring a second content Si2 of the Si element in the molten steel after converter tapping, and calculating a first variation quantity delta Si1 of the Si element in the molten steel after converter tapping, wherein the delta Si1= Si2-Si1. The first variation quantity delta Si1 is mainly caused by that a part of converter steel slag is brought out in the steel tapping process and reacts with the metallic aluminum for deoxidation, so that the slag discharging quantity in the converter can be calculated according to the first variation quantity delta Si1, and when the slag discharging quantity exceeds a certain limit, the steel tapping hole needs to be replaced so as to ensure the purity of the molten steel in the subsequent process.
And step 3: and (4) judging whether a first variation quantity delta Si1 of an Si element in the molten steel after the steel is tapped by the converter is larger than a first limited threshold value, if so, judging that the slag amount is too large when the steel is tapped by the converter, replacing a steel tapping hole, and if not, executing the step 4.
According to the calculation of 300 tons of molten steel loaded in a 300 ton steel ladle, the upper limit threshold of the slag quantity of 300 tons of molten steel is 100kg, and SiO in slag 2 The content is generally about 10%, wherein, half of SiO is contained 2 Can participate in the reaction of oxidizing metallic Al, i.e. 100 x 10% x 0.5=5kg, the 5kg SiO 2 The Si content is 5 + 28/(28 + 32) =2.33Kg, and the Si content in 300 ton molten steel is 2.33/300/1000 + 100% =7.7 x 10 -4 %, i.e. the upper limit of the first defined threshold value, is 7.7 × 10 -4 % of the total weight of the composition. Preferably, the first defined threshold may be set to 6.5-7.7 × 10 -4 %。
And 4, step 4: and measuring a third content Si3 of the Si element in the molten steel after the refining treatment, and calculating a second variation quantity delta Si2 of the Si element in the molten steel after the refining treatment, wherein delta Si2= Si3-Si2.
And 5: and (6) judging whether a second variation quantity delta Si2 of the Si element in the molten steel after the refining treatment is larger than a second limited threshold value, if so, judging that the source of the raw material of the metallurgical auxiliary material added in the refining treatment is in a problem, and if not, executing the step 6. The metallurgical auxiliary materials added to the steel melt during refining are generally included in the steel meltAdsorbing the deoxidation product Al 2 O 3 The basic oxide CaO and the aluminum slag for removing FeO in the slag are added, and impurities in the metallurgical auxiliary materials are generally SiO with higher oxidability 2 Mainly, if the source of the metallurgical auxiliary materials is judged to be in problem, the raw materials are reported and replaced in time, and the influence on the production is avoided.
Other auxiliary materials are required to be added into the molten steel in the refining process, if SiO in the auxiliary materials 2 Oxidizing molten steel containing excessive impurities, charging 50kg of molten steel containing 10% SiO in 300 tons of molten steel 2 Calculated as impurities and auxiliary materials, the SiO content of the product is half of that of the product 2 That is, 2.5kg of Si in 300 tons of molten steel can participate in the oxidation of molten steel, and the Si content is 3.88X 10 -4 %, i.e. the second defined threshold value, is 3.88X 10 -4 % of the total weight of the composition. Preferably, the second defined threshold may be set to 2.80-3.88 × 10 -4 %。
Step 6: and measuring a fourth content Si4 of the Si element in the molten steel after the continuous casting of the tundish, and calculating a third variation quantity delta Si3 of the Si element in the molten steel after the continuous casting of the tundish, wherein the delta Si3= Si4-Si3.
And 7: and judging whether a third variation quantity delta Si3 of Si element in the molten steel after the tundish is continuously cast is larger than a third limited threshold, if so, judging that the tundish covering agent has a problem, needing a production unit to timely contact with a covering agent supplier to ensure the product quality of supply, replacing the covering agent to avoid influencing the production, and if not, entering the molten steel into a CSP crystallizer to continue the production process.
In the continuous casting step, a covering agent is added to molten steel, 6-furnace molten steel can be used by charging 1000kg of the covering agent, and SiO in the covering agent 2 The content of impurities should not exceed 3%, then the SiO in molten steel in each furnace 2 The amount should not exceed 3% 1000/6=5kg, wherein 5kg SiO of molten steel per furnace 2 Half of the total, i.e. 2.5kg, take part in the chemical reaction, 2.5kg of SiO 2 The Si content in the steel is 2.5 x 28/(28 + 32) =2.33Kg, and the Si content in 300 ton steel is 3.88 multiplied by 10 -4 %, i.e. the third defined threshold value, is 3.88X 10 -4 % of the total weight of the composition. Preferably, the third defined threshold may be set to 2.80-3.88 × 10 -4 %。
Example 1:
in a steel plant, aluminum deoxidized steel is produced in a month, the Si element content of molten steel in each process is measured on line in the production process, and the measurement results are shown in Table 1:
TABLE 1 Si content in molten steel in respective steps
| Procedure (ii) | Content of Si element | Amount of change of Si element |
| Converter steelmaking | Si1=0.0040% | |
| Tapping from converter | Si2=0.0046% | △Si1=6×10 -4 % |
| Refining treatment | Si3=0.0076% | △Si2=30×10 -4 % |
| Continuous casting tundish | Si4=0.0078% | △Si3=2×10 -4 % |
As can be seen from Table 1:
1. the first content Si1 of Si element in the molten steel after converter steelmaking is 0.0040%, which is taken as the follow-up procedure complianceAccording to the method. In the present embodiment, the first defined threshold takes 7.7 × 10 -4 % and the second threshold is 3.8X 10 -4 % and the third limiting threshold is 3.88 × 10 -4 %。
2. Before converter tapping and refining treatment, the second content Si2 of Si element in the molten steel is 0.0046%, and the first variation Delta Si1 of Si element is calculated to be 6 x 10 -4 % less than a first defined threshold of 7.7X 10 -4 Percent, converter procedure compliance.
3. After the refining treatment, the third content Si3 of the Si element in the molten steel was 0.0076%, and the second change amount Δ Si2 of the Si element was calculated to be 30 × 10 -4 % greater than a second defined threshold of 3.8X 10 -4 Percent, the impurity content of the metallurgical auxiliary materials added in the refining procedure exceeds the standard, and related departments need to be contacted to replace the raw materials of the metallurgical auxiliary materials in time.
4. After the tundish continuous casting, the fourth content Si4 of the Si element in the molten steel is 0.0078%, and the third variation Delta Si3 of the Si element is calculated to be 2 multiplied by 10 -4 % of the total weight of the composition is less than a third defined threshold of 3.88X 10 -4 % and the continuous casting process is in compliance.
In the production process of this example, the evaluation results of the compliance of each process were: the production procedures are compliant.
The present invention is not limited to the above embodiments, and any modifications, equivalent replacements, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (4)
1. A method for quickly evaluating inclusion in molten steel in CSP production is characterized by comprising the following steps: the rapid evaluation method is applied to CSP production of aluminum deoxidized steel, and comprises the following steps:
step 1: measuring a first content Si1 of Si element in molten steel after converter steelmaking, and taking the first content Si1 as an evaluation basic value;
step 2: measuring a second content Si2 of the Si element in the molten steel after tapping of the converter, and calculating a first variation quantity delta Si1 of the Si element in the molten steel after tapping of the converter;
and step 3: judging whether a first variation quantity delta Si1 of Si element in molten steel after converter tapping is larger than a first limited threshold value, if so, judging that the slag discharge quantity is too large during converter tapping, replacing a tapping hole, and if not, executing a step 4;
and 4, step 4: measuring a third content Si3 of the Si element in the refined molten steel, and calculating a second variation quantity delta Si2 of the Si element in the refined molten steel;
and 5: judging whether a second variable quantity delta Si2 of an Si element in the molten steel after refining treatment is larger than a second limit threshold, if so, judging that the source of the raw materials of the metallurgical auxiliary materials added in the refining treatment has a problem, replacing the metallurgical auxiliary materials, and if not, executing a step 6;
step 6: measuring the fourth content Si4 of the Si element in the molten steel after the continuous casting of the tundish, and calculating the third variation delta Si3 of the Si element in the molten steel after the continuous casting of the tundish;
and 7: and judging whether a third variation quantity delta Si3 of Si element in the molten steel after the continuous casting of the tundish is larger than a third limited threshold, if so, judging that the tundish covering agent has a problem, replacing the covering agent, and if not, entering the molten steel into a CSP crystallizer for continuous production.
2. The method for rapidly evaluating the inclusion of molten steel in CSP production according to claim 1, wherein the method comprises the following steps: the first defined threshold value is 6.5-7.7 x 10 -4 %。
3. The method for rapidly evaluating inclusion of molten steel in CSP production as claimed in claim 1, wherein the method comprises the following steps: the second defined threshold value is 2.80-3.88 x 10 -4 %。
4. The method for rapidly evaluating the inclusion of molten steel in CSP production according to claim 1, wherein the method comprises the following steps: the third defined threshold value is 2.80-3.88 x 10 -4 %。
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07179924A (en) * | 1993-12-22 | 1995-07-18 | Aichi Steel Works Ltd | Alumina slag forming agent |
| CN103045806A (en) * | 2013-01-15 | 2013-04-17 | 北京科技大学 | Method for controlling low-melting-point inclusion in high-strength low-alloy steel |
| CN103255263A (en) * | 2013-04-16 | 2013-08-21 | 武汉钢铁(集团)公司 | Method for controlling Als in low carbon aluminum free steel |
| CN109014096A (en) * | 2018-05-25 | 2018-12-18 | 邯郸钢铁集团有限责任公司 | A kind of trace analysis method of steel Large Inclusions |
| CN111220614A (en) * | 2018-11-27 | 2020-06-02 | 宝山钢铁股份有限公司 | Method for rapidly evaluating quality of molten steel |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH1121614A (en) * | 1997-07-02 | 1999-01-26 | Nkk Corp | Method for melting molten high clean steel |
| JP5803824B2 (en) * | 2012-06-27 | 2015-11-04 | 新日鐵住金株式会社 | Method of melting carburized bearing steel |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07179924A (en) * | 1993-12-22 | 1995-07-18 | Aichi Steel Works Ltd | Alumina slag forming agent |
| CN103045806A (en) * | 2013-01-15 | 2013-04-17 | 北京科技大学 | Method for controlling low-melting-point inclusion in high-strength low-alloy steel |
| CN103255263A (en) * | 2013-04-16 | 2013-08-21 | 武汉钢铁(集团)公司 | Method for controlling Als in low carbon aluminum free steel |
| CN109014096A (en) * | 2018-05-25 | 2018-12-18 | 邯郸钢铁集团有限责任公司 | A kind of trace analysis method of steel Large Inclusions |
| CN111220614A (en) * | 2018-11-27 | 2020-06-02 | 宝山钢铁股份有限公司 | Method for rapidly evaluating quality of molten steel |
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