CN112765535A

CN112765535A - Method for calculating solid phase rate of continuous casting roller row position

Info

Publication number: CN112765535A
Application number: CN202011451154.4A
Authority: CN
Inventors: 任一峰; 饶立华; 许晓红; 葛洪硕; 白云; 马晓东; 杜建峰
Original assignee: Jiangyin Xingcheng Special Steel Works Co Ltd
Current assignee: Jiangyin Xingcheng Special Steel Works Co Ltd
Priority date: 2020-12-10
Filing date: 2020-12-10
Publication date: 2021-05-07
Anticipated expiration: 2040-12-10
Also published as: CN112765535B

Abstract

The invention relates to a method for calculating the solid phase rate of a continuous casting roller row position, which can construct a parabolic equation of initial central solid phase rate and blank shell thickness under soft reduction without the help of a continuous casting solidification mathematical model under the condition of knowing the blank shell thickness of the roller row position, and can sequentially calculate the central solid phase rate of each roller by utilizing the rule that the central solid phase rate increases linearly along with the increase of the blank shell thickness. The invention is a simplified calculation method obtained by fitting based on mass production practice data and operation results of continuous casting solidification mathematical models of multiple scientific research institutions, and can be widely applied to the research of continuous casting soft reduction processes of square billets and rectangular billets.

Description

Method for calculating solid phase rate of continuous casting roller row position

Technical Field

The invention belongs to the technical field of metal smelting, and particularly relates to a method for calculating the solid phase ratio of a continuous casting roller array position.

Background

In the continuous casting process, the temperature and solid fraction change of the steel in the process of solidifying the steel from liquid to solid is the most important process parameter and is the decisive factor for finally determining the quality of the casting blank, and all the operations of continuous casting are used for obtaining the overall reasonable temperature and solid fraction distribution of the casting flow.

The central solid phase ratio is an important parameter which must be relied upon for studying electromagnetic stirring at the end under a light pressure. In the actual production process, the temperature and solid phase rate of a casting blank are difficult to determine due to the complexity and the variability of steel type components, casting machine structures, process parameters and external conditions, and the difficulty which cannot be overcome is brought to the actual test work due to the severe field conditions in the continuous casting production. From classical calculation formulas

(in the formula, T_LIs the liquidus temperature, T_SIs the solidus temperature, and T is the temperature of the center of the cast slab), it is known that the center solidus ratio is related to the temperature of the center point of the cast slab. The temperature cannot be directly measured and is generally calculated by a continuous casting solidification mathematical model. However, purchasing a commercial mathematical model of continuous casting solidification usually requires a very expensive cost, and with the model, basic physical parameters suitable for the current casting machine need to be obtained through debugging, and the process usually needs months or even years.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a method for calculating the solid phase ratio of the position of a continuous casting roller row in the prior art, which can sequentially calculate the central solid phase ratio of the position of the roller row under the condition of knowing the blank shell thickness of the roller row by a simple function equation without a solidification mathematical model.

The technical scheme adopted by the invention for solving the problems is as follows: a method for calculating the solid phase rate of the position of a continuous casting roller train is characterized in that fitting regression is carried out on a large number of data obtained by continuous casting production practice and the calculation results of continuous casting solidification mathematical models of multiple scientific research institutions, and a method for calculating the central solid phase rate of the position of the continuous casting roller train in a simplified mode without the aid of the continuous casting solidification mathematical models is obtained.

The method specifically comprises the following steps: the shell thickness of the roller row position can be obtained from the point crack position on the continuous casting billet. The ideal starting central solid phase ratio at a light reduction was set to 0.3, and the position corresponding thereto was defined as a virtual starting roller. By constructing a parabolic equation of the relation between the central solid phase fraction and the thickness of the blank shell when Fs is 0.3

The shell thickness at the virtual starting roll can be determined. The solid phase ratio at each roll can be sequentially obtained by utilizing the rule that the central solid phase ratio increases linearly from the beginning to the end along with the increase of the thickness of the blank shell.

The rule that the central solid phase rate increases linearly along with the increase of the thickness of the blank shell from the beginning to the end is characterized by a variation value j of the solid phase rate Fs corresponding to the unit variation thickness of the blank shell, and the value j is calculated according to the following formula:

in the above formula: m is the nominal thickness of the cast slab, C' is the shell thickness when the solid fraction Fs is 0.3, and n is the roll row number.

The solid phase ratio Fsn at each roll was calculated from the above variation value j according to the following equation.

Fsn＝0.3+(C_n-C＇)×j

C_nAs the thickness of the shell at the n-th roll, Fsn is the solid fraction at the n-th roll, and j is the variation of the solid fraction Fs corresponding to the unit variation thickness of the shell.

Compared with the prior art, the invention has the advantages that:

the method is convenient and quick, and analysis can be completed within half an hour generally (the model calculation usually needs a computer to run for several hours);

the method does not need to increase extra cost (buying a commercial continuous casting solidification mathematical model usually needs cost with high price), does not need to prepare a sample additionally, and can completely analyze the low-power sample of the conventional casting blank production;

according to the method, the influence of solid phase rate and solidification tail end change caused by changes of tools or environmental conditions and the like in the same metallurgical process can be analyzed (the difference cannot be calculated by a mathematical model), so that the continuous casting process can be properly adjusted, and the expected metallurgical effect is realized.

Drawings

FIG. 1 is a schematic diagram of the thickness of a shell at the position of a 240-square casting blank longitudinal low-magnification point crack measuring roller array in the embodiment of the invention. 1, 2, 3, 4 on the left side of the figure correspond to the 1# roller, the 2# roller, the 3# roller, and the 4# roller; the

right sides

72, 84, 102 and 119 respectively show the shell thicknesses of 72mm, 84mm, 102mm and 119mm passing through the 1# roll, the 2# roll, the 3# roll and the 4# roll when judging the production of the spot cracks from the upper magnification of the cast slab.

Detailed Description

The invention is described in further detail below with reference to the accompanying examples.

Examples are: and (5) longitudinally and lowly drawing a certain 240 square casting blank, and solving the solid phase rate of each roller row.

The thickness of the shell of the 1# to 4# roller is measured by the low-power point crack of the casting blank and is 72mm, 84mm, 102mm and 119mm in sequence, as shown in figure 1;

wherein the ideal initial center solid fraction

According to the formula of the variation value of the solid fraction corresponding to the unit variation thickness of the shell, the variation value is obtained

And obtaining the center solid phase rate of the blank shell corresponding to the rollers from 1# to 4# according to the change value as follows:

Fs1＝0.3+(C₁-C_0.3)×j＝0.3+(72-66)×0.0128＝0.38

Fs2＝0.3+(C₂-C_0.3)×j＝0.3+(84-66)×0.0128＝0.53

Fs3＝0.3+(C₃-C_0.3)×j＝0.3+(102-66)×0.0128＝0.77

Fs4＝0.3+(C₄-C_0.3)×j＝0.3+(119-66)×0.0128＝0.98

namely, the solid phase ratios at the continuous 4 rolls were 0.38, 0.53, 0.77, and 0.98 in this order.

Meanwhile, the solid phase ratios of the 240 square cast slab at 1# to 4# rolls calculated according to a solidification mathematical model provided by a scientific research institution are 0.39, 0.53, 0.78 and 1 in sequence.

Through comparison, the calculation result of the method is very close to that of a mathematical model. The method can be used for replacing a mathematical model to calculate the solid phase ratio of the roller array position.

The results of the above calculations are summarized in the following table.

In addition to the above embodiments, the present invention also includes other embodiments, and any technical solutions formed by equivalent transformation or equivalent replacement should fall within the scope of the claims of the present invention.

Claims

1. A method for calculating the solid phase ratio of the position of a continuous casting roll row is characterized by comprising the following steps: the method can obtain the thickness of a blank shell at the position of a roller row from the position of a punctiform crack on a continuous casting billet at a low magnification, adopts the central solid phase rate Fs (0.3) as the ideal initial central solid phase rate under a soft reduction condition, and constructs a parabolic equation of the relation between the central solid phase rate and the thickness of the blank shell when the Fs is 0.3

And (3) calculating the thickness of the blank shell at the virtual initial roller, and sequentially calculating the solid phase ratio of each roller by utilizing the rule that the central solid phase ratio increases linearly along with the increase of the thickness of the blank shell from the initial point to the final point.

2. The method for calculating the solid phase ratio of the position of a continuous casting roll according to claim 1, wherein: the rule that the central solid phase rate increases linearly along with the increase of the thickness of the blank shell from the beginning to the end is characterized by a variation value j of the solid phase rate Fs corresponding to the unit variation thickness of the blank shell, and the value j is calculated according to the following formula:

3. The method for calculating the solid phase ratio of the position of a continuous casting roll according to claim 2, wherein: the solid phase ratio Fsn at each roll was calculated from the above variation value j according to the following equation.

Fsn＝0.3+(C_n-C＇)×j