Casting method for reducing high-carbon steel small square billet continuous casting first billet waste

Abstract

The invention relates to the technical field of ferrous metallurgy, and particularly discloses a casting method for reducing high-carbon steel small square billet continuous casting first billet waste, which comprises the following steps: considering the condition that a casting billet does not generate bulging in a first cooling area, and firstly using the maximum water distribution amount to prevent bulging; other cold areas have little influence on bulging, and the opening degree of a water regulating valve does not need to be increased to the maximum, so that the normal process water distribution state is directly adjusted in the shortest time, a stable liquid phase cavity is formed in the shortest time, and the optimal solid phase rate distribution state is provided for pressure; therefore, correct liquid phase cavity position distribution can be matched through a normal pressing process, segregation quality is stable in the shortest time, and waste picking amount increase caused by segregation quality deterioration is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of iron and steel metallurgy, and in particular to a pouring method for reducing waste products of high-carbon steel billet continuous casting head billet. Background Art

[0002] During the continuous casting process of small square billets, high carbon steel is easily affected by electromagnetic stirring, the speed of the hot billet head passing through the cooling area, secondary cooling water, and light pressure, which leads to changes in segregation quality. Electromagnetic stirring and the speed of the hot billet head passing through the cooling area can be stabilized through short-term control and have little effect on the segregation quality, but the secondary cooling water distribution and light pressure input logic are the most critical to segregation quality control. During the continuous casting process, in order to prevent the billet from bulging and deformation and steel leakage, the traditional practice is to adjust the secondary cooling water to the maximum opening in each zone for a few seconds before slowly adjusting it back to the normal process water distribution. This practice causes a huge change in the entire liquid phase hole life cycle of the billet, resulting in inaccurate light pressure reduction position during the pouring, and the segregation quality of the pouring head billet is seriously deteriorated. In more serious cases, it directly causes the overload alarm of the straightening machine, affecting the smooth production. When this practice is adopted, the continuous casting of high carbon steel small square billets leads to more than 12m of scrap per stream head billet due to unstable segregation quality, which increases production costs.

[0003] In order to reduce the amount of waste high carbon steel billet continuous casting head billet and improve product quality, the present invention provides a pouring method for reducing the waste high carbon steel billet continuous casting head billet. Summary of the invention

[0004] In view of the deficiencies of the prior art, the present invention provides a pouring method for reducing waste of the head billet of high carbon steel billet continuous casting.

[0005] The method for reducing the waste of the head billet of high carbon steel billet continuous casting of the present invention is used for the production of high carbon steel by a continuous casting machine with a light pressure reduction function, and is characterized in that the method comprises:

[0006] The first step is to divide the secondary cooling area into multiple cooling areas according to demand, wherein the multiple cooling areas are the primary cooling area and other cooling areas;

[0007] Step 2: When the hot billet head passes through the first cooling area, the water flow regulating valve in the first cooling area is first opened to 100%, and then adjusted back to the opening required for the process water distribution;

[0008] Step 3: When the hot billet head continues to pass through other cold zones, the water regulating valves in other cold zones are opened from 0 to the opening required for the process water distribution.

[0009] In the second and third steps, the process water supply generated by the water control valve is Q 0 The process water supply Q 0 =MV;

[0010] Where V is the speed at which the hot billet head passes through the cooling area; M is the water volume factor, which is a fixed constant under the conditions of water distribution required by normal process, and the specific value is related to the type of steel.

[0011] In the second and third steps, the time for the water flow regulating valve opening to change from 0 to 100% is S 1 , the water volume Q when the water flow regulating valve is 100% open 1 Adjust to process water supply Q 0 The time is S 2 The total time for adjusting the opening of the water regulating valve is S 3 .

[0012] In the second and third steps, the water flow regulating valve opening of the first cooling area is adjusted for a time period S 3 =S 1 +S 2 ; Other cold zone water control valve opening adjustment time S 3 =S 2 .

[0013] In the second and third steps, the time length S for the hot billet head to move in the corresponding area is 4 =A / V; where A is the stroke length of the hot billet head, and V is the speed at which the hot billet head passes through the cooling area.

[0014] In the second step, the water flow regulating valve opening time S in the first cooling area is adjusted. 3 The time S that the hot billet head moves in the corresponding area 4 The relationship is as follows:

[0015] S 3 =S 1 +S 2 ≤S 4 ;

[0016] Ensure that when the hot billet enters other cooling zones, the water flow regulating valve in the first cooling zone reaches the process water flow of Q 0 .

[0017] In the third step, the water flow regulating valve opening time S of other cold zones is adjusted. 3 The time S that the hot billet head moves in the corresponding area 4 The relationship is as follows:

[0018] S3=S2<S 4 ;

[0019] Ensure that the water volume in other cooling zones reaches the water volume Q required by the process 0 The required time S3 is less than the time S that the hot billet head takes to pass through other cold zones. 4, thus ensuring that when the hot billet head is in the middle of other cooling zones, the water regulating valve reaches the process water supply volume of Q 0 ;

[0020] Among them, S3 approaches 0.

[0021] Furthermore, the secondary cooling area is divided into secondary cooling area 1, secondary cooling area 2, secondary cooling area 3 and secondary cooling area 4, wherein secondary cooling area 1 is the first cooling area, and secondary cooling area 2, secondary cooling area 3 and secondary cooling area 4 are other cooling areas; the continuous casting machine is equipped with 7 tensioning and leveling machines with light pressure reduction function, the length of secondary cooling area 1 is 0.84m, the length of secondary cooling area 2 is 3.96m, the length of secondary cooling area 3 is 3.96m, and the length of secondary cooling area 4 is 3.24m;

[0022] The first of the 7 straightening machines is installed at the end of the secondary cooling area, the second straightening machine is 750 mm away from the first straightening machine, and the subsequent straightening machines are 700 mm adjacent to the second straightening machine in sequence;

[0023] The tension and leveling machine adopts a fixed reference value for pressing down the roll gap, which shortens the time for forming a stable liquid phase cavity to the maximum extent and avoids a pressure overload alarm.

[0024] Pressing starts from the second frame. When the hot billet pressed by the second frame reaches the third frame, the third frame starts pressing, and so on, until the last tensioning and straightening machine required by the process is put into pressing, and then stable production is achieved.

[0025] When the second straightening machine is pressed down, the pressure value is ≤800kN. The hot billet pressed down by the second straightening machine is accurately tracked into place and pressed down step by step by the subsequent straightening machines until the pouring is completed and stable production is achieved.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] In the present invention, the first cooling area will take into account the situation that the ingot will not bulge, and it is necessary to use the maximum water distribution amount to prevent bulging; while other cold zones have little effect on bulging, and there is no need to increase the opening of the water volume regulating valve to the maximum first, so it is directly considered to adjust to the normal process water distribution state in the shortest time, so that a stable liquid phase hole is formed in the shortest time, providing the best solid phase ratio distribution state for pressing, so as to match the correct liquid phase hole position distribution with the normal pressing process, and realize the stability of segregation quality in the shortest time, thereby reducing the increase in scrap picking due to deterioration of segregation quality. DETAILED DESCRIPTION

[0028] The following will disclose multiple embodiments of the present invention. For the purpose of clear description, many physical details will be described together in the following description. However, it should be understood that these physical details should not be used to limit the present invention. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0029] Embodiment 1:

[0030] Taking X55SiCrA steel as an example, the secondary cooling area is divided into multiple cooling areas according to demand, wherein the multiple cooling areas are the primary cooling area and other cooling areas, and the secondary cooling area is divided into secondary cooling area 1, secondary cooling area 2, secondary cooling area 3 and secondary cooling area 4, wherein the secondary cooling area 1 is the primary cooling area, and the secondary cooling area 2, secondary cooling area 3 and secondary cooling area 4 are all other cooling areas; the length of the secondary cooling area 1 is 0.84m, the length of the secondary cooling area 2 is 3.96m, the length of the secondary cooling area 3 is 3.96m, and the length of the secondary cooling area 4 is 3.24m;

[0031] The water volume factors in secondary cooling zone 1, secondary cooling zone 2, secondary cooling zone 3 and secondary cooling zone 4 are M1, M2, M3 and M4 respectively.

[0032] The process water supply Q 0 =MV;

[0033] The speed of the hot billet head passing through the cooling area is V=2.2m / min, and the water volume factors are M1=40, M2=52, M3=20, and M4=15.

[0034] Therefore, the second cooling zone Q 0 =88L / min, secondary cooling zone 2 Q 0 =114.4L / min, secondary cooling zone 3 Q 0 =44L / min and secondary cooling zone 4 Q 0 =33L / min.

[0035] The time S for the hot billet head to move in the corresponding area 4 =A / V; where A is the stroke length of the hot billet head.

[0036] When continuous casting starts, when the hot slab head passes through the secondary cooling zone 1, the opening of the water volume regulating valve in the secondary cooling zone 1 increases from 0 to 100%, and then the water volume is immediately reduced to the process water volume Q 0 =88L / min, then the water volume stabilizes, and the total time for the water volume regulating valve to adjust the opening is S 3 =21s≤S 4 ;

[0037] Ensure that when the hot billet enters other cooling zones, the water flow regulating valve in the first cooling zone reaches the process water flow of Q 0 .

[0038] When the hot billet head continues to pass through the secondary cooling zone 2, the secondary cooling zone 2 increases from 0 to the process water supply Q 0 =114.4L / min, then the water volume stabilizes, and the total time for the water volume regulating valve to adjust the opening is S 3 =33s, the travel length of the hot billet head in the second cooling zone 2 when the water volume changes is 1.21m.

[0039] When the hot billet head continues to pass through the secondary cooling zone 3, the secondary cooling zone 3 increases from 0 to the process water supply Q 0 = Adjust to process water supply Q 0 =44L / min, then the water volume stabilizes, and the total time for the water volume regulating valve to adjust the opening is S 3 =29s, the travel length of the hot billet head in the second cooling zone 3 when the water volume changes is 1.06m.

[0040] When the hot billet head continues to pass through the secondary cooling zone 4, the secondary cooling zone 4 is increased from 0 to the process water supply Q0 = adjusted to the process water supply Q 0 =33L / min, then the water volume stabilizes, the total adjustment time of the water volume regulating valve opening is 18s, and the stroke length of the hot billet head in the secondary cooling zone 4 when the water volume changes is 0.66m.

[0041] When the hot billet head reaches the third straightening machine, it is put into pressing. The pressing logic is to start pressing from the second frame, and the pressure value of the second frame is 240kN. When the hot billet pressed by the second frame reaches the third frame, the third frame starts pressing, and so on, until the last straightening machine required by the process is put into pressing, and then stable production is carried out. 1.45m of waste is cut from each head billet, and 5 groups of segregation are continuously taken for the head of the first qualified billet using the 5-point segregation method. The segregation indexes are 1.02, 0.98, 1.05, 1.07, and 1.08, respectively, all less than 1.10, that is, the remaining billets after 1.45m of waste is cut from each head billet are all qualified billets.

[0042] Embodiment 2:

[0043] Taking 60Si2Mn steel as an example, the secondary cooling area is divided into multiple cooling areas according to demand, wherein the multiple cooling areas are primary cooling areas and other cooling areas, and the secondary cooling area is divided into secondary cooling area 1, secondary cooling area 2, secondary cooling area 3 and secondary cooling area 4, wherein the secondary cooling area 1 is the primary cooling area, and the secondary cooling area 2, secondary cooling area 3 and secondary cooling area 4 are all other cooling areas; the length of the secondary cooling area 1 is 0.84m, the length of the secondary cooling area 2 is 3.96m, the length of the secondary cooling area 3 is 3.96m, and the length of the secondary cooling area 4 is 3.24m;

[0044] The water volume factors in secondary cooling zone 1, secondary cooling zone 2, secondary cooling zone 3 and secondary cooling zone 4 are M1, M2, M3 and M4 respectively.

[0045] The process water supply Q 0 =MV;

[0046] The speed of the hot billet head passing through the cooling area is V=2.2m / min, and the water volume factors are M1=35, M2=47, M3=15, and M4=10.

[0047] The time S for the hot billet head to move in the corresponding area 4 =A / V; where A is the stroke length of the hot billet head.

[0048] When continuous casting starts, when the hot slab head passes through the secondary cooling zone 1, the opening of the water volume regulating valve in the secondary cooling zone 1 increases from 0 to 100%, and then the water volume is immediately reduced to the process water volume Q 0 =77L / min, then the water volume stabilizes, and the total time for the water volume regulating valve to adjust the opening is S 3 =19s.

[0049] When the hot billet head continues to pass through the secondary cooling zone 2, the secondary cooling zone 2 increases from 0 to the process water supply Q 0 =103.4L / min, then the water volume stabilizes, and the total time for the water volume regulating valve to adjust the opening is S 3 =34s, the travel length of the hot billet head in the second cooling zone 2 when the water volume changes is 1.25m.

[0050] When the hot billet head continues to pass through the secondary cooling zone 3, the secondary cooling zone 3 increases from 0 to the process water supply Q 0 =33L / min, then the water volume stabilizes, and the total time for the water volume regulating valve to adjust the opening is S 3 =27s, the travel length of the hot billet head in the second cooling zone 3 when the water volume changes is 0.99m.

[0051] When the hot billet head continues to pass through the secondary cooling zone 4, the secondary cooling zone 4 increases from 0 to the process water supply Q 0 =22L / min, then the water volume stabilizes, and the total time for the water volume regulating valve to adjust the opening is S 3 =18s, the travel length of the hot billet head in the second cooling zone 4 when the water volume changes is 0.66m.

[0052] When the hot billet head reaches the third straightening machine, it is put into pressing. The pressing logic is to start pressing from the second frame, and the pressure value of the second frame is 260kN. When the hot billet pressed by the second frame reaches the third frame, the third frame starts pressing, and so on, until the last straightening machine required by the process is put into pressing, and then stable production is produced. 1.4m of waste is cut from each head billet, and 5 groups of segregation are continuously taken for the head of the first qualified billet using the 5-point segregation method. The segregation indexes are 1.01, 0.99, 1.03, 1.02, and 1.07, respectively, all less than 1.10, that is, after 1.4m of waste is cut from each head billet, the remaining billets are all qualified billets.

[0053] Embodiment three:

[0054] Taking XSWRCH82B steel as an example, the secondary cooling area is divided into multiple cooling areas according to demand, wherein the multiple cooling areas are the primary cooling area and other cooling areas, and the secondary cooling area is divided into secondary cooling area 1, secondary cooling area 2, secondary cooling area 3 and secondary cooling area 4, wherein the secondary cooling area 1 is the primary cooling area, and the secondary cooling area 2, secondary cooling area 3 and secondary cooling area 4 are all other cooling areas; the length of the secondary cooling area 1 is 0.84m, the length of the secondary cooling area 2 is 3.96m, the length of the secondary cooling area 3 is 3.96m, and the length of the secondary cooling area 4 is 3.24m;

[0055] The water volume factors in secondary cooling zone 1, secondary cooling zone 2, secondary cooling zone 3 and secondary cooling zone 4 are M1, M2, M3 and M4 respectively.

[0056] The process water supply Q 0 =MV;

[0057] The speed of the hot billet head passing through the cooling area is V=2.2m / min, and the water volume factors are M1=45, M2=57, M3=25, and M4=20.

[0058] When continuous casting starts, when the hot slab head passes through the secondary cooling zone 1, the opening of the water volume regulating valve in the secondary cooling zone 1 increases from 0 to 100%, and then the water volume is immediately reduced to the process water volume Q 0 =94.5L / min, then the water volume stabilizes, and the total time for the water volume regulating valve to adjust the opening is S 3 =21s.

[0059] When the hot billet head continues to pass through the secondary cooling zone 2, the secondary cooling zone 2 increases from 0 to the process water supply Q 0 =119.7L / min, then the water volume stabilizes, and the total time for the water volume regulating valve to adjust the opening is S 3 =33s, the travel length of the hot billet head in the second cooling zone 2 when the water volume changes is 1.16m.

[0060] When the hot billet head continues to pass through the secondary cooling zone 3, the secondary cooling zone 3 increases from 0 to the process water supply Q 0=52.5L / min, then the water volume stabilizes, and the total time for the water volume regulating valve to adjust the opening is S 3 =29s, the travel length of the hot billet head in the second cooling zone 3 when the water volume changes is 1.02m.

[0061] When the hot billet head continues to pass through the secondary cooling zone 4, the secondary cooling zone 4 increases from 0 to the process water supply Q 0 =42L / min, then the water volume stabilizes, and the total time for the water volume regulating valve to adjust the opening is S 3 =17s, the travel length of the hot billet head in the secondary cooling zone 4 when the water volume changes is 0.60m.

[0062] When the hot billet head reaches the third straightening machine, it is put into pressing. The pressing logic is to start pressing from the second frame, and the pressure value of the second frame is 275kN. When the hot billet pressed by the second frame reaches the third frame, the third frame starts pressing, and so on, until the last straightening machine required by the process is put into pressing, and then stable production is carried out. 1.45m of waste is cut from each head billet, and 5 groups of segregation are continuously taken for the head of the first qualified billet using the 5-point segregation method. The segregation indexes are 1.03, 0.96, 1.08, 1.04, and 0.98, respectively, all less than 1.10, that is, after 1.45m of waste is cut from each head billet, the remaining billets are all qualified billets.

[0063] The above description is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention shall be included within the scope of the claims of the present invention.

Claims

1. A method for reducing the waste of high carbon steel billet continuous casting head billet, used for high carbon steel production of continuous casting machine with light pressure reduction function, characterized in that: The method comprises: The first step is to divide the secondary cooling area into multiple cooling areas according to demand, wherein the multiple cooling areas are the primary cooling area and other cooling areas; Step 2: When the hot billet head passes through the first cooling area, the water flow regulating valve in the first cooling area is first opened to 100%, and then adjusted back to the opening required for the process water distribution; Step 3: When the hot billet head continues to pass through other cold zones, the water regulating valves in other cold zones are opened from 0 to the opening required for the process water distribution.

2. A method for reducing high carbon steel billet continuous casting head billet waste according to claim 1, characterized in that: The process water distribution volume generated by the water flow regulating valve is Q 0 The process water supply Q 0 =MV; Where V is the speed at which the hot billet head passes through the cooling area; M is the water volume factor.

3. A method for reducing high carbon steel billet continuous casting head billet waste according to claim 2, characterized in that: The time for the water flow regulating valve opening to change from 0 to 100% is S 1 , the water volume Q when the water flow regulating valve is 100% open 1 Adjust to process water supply Q 0 The time is S 2 The total time for adjusting the opening of the water regulating valve is S 3 .

4. A method for reducing high carbon steel billet continuous casting head billet waste according to claim 3, characterized in that: The opening adjustment time length S of the water flow regulating valve in the first cooling area 3 =S 1 +S 2 ; Other cold zone water control valve opening adjustment time S 3 =S 2 .

5. A method for reducing high carbon steel billet continuous casting head billet waste according to claim 4, characterized in that: The time S for the hot billet head to move in the corresponding area 4 =A / V; where A is the stroke length of the hot billet head, and V is the speed at which the hot billet head passes through the cooling area.

6. A method for reducing high carbon steel billet continuous casting head billet waste according to claim 5, characterized in that: The opening adjustment time of the water flow regulating valve in the first cooling area S 3 The time S that the hot billet head moves in the corresponding area 4 The relationship is as follows: S 3 =S 1 +S 2 ≤S 4 ; Ensure that when the hot billet enters other cooling zones, the water flow regulating valve in the first cooling zone reaches the process water flow of Q 0 .

7. A method for reducing the waste of high carbon steel billet continuous casting head billet according to claim 5, characterized in that: Other cold zone water control valve opening adjustment time S 3 The time S that the hot billet head moves in the corresponding area 4 The relationship is as follows: <h2 style=";text-align:left;direction:ltr">S3 = S2 = S<h2 style=";text-align:left;direction:ltr"> 4 <h2 style=";text-align:left;direction:ltr"> ; Ensure that the water volume in other cooling zones reaches the water volume Q required by the process 0 The required time S3 is less than the time S that the hot billet head takes to pass through other cold zones. 4 , thus ensuring that when the hot billet head is in the middle of other cooling zones, the water regulating valve reaches the process water supply volume of Q 0 .

8. The method for reducing the waste of the first billet of high carbon steel billet continuous casting according to claim 1, characterized in that: The secondary cooling area is divided into secondary cooling area 1, secondary cooling area 2, secondary cooling area 3 and secondary cooling area 4, wherein secondary cooling area 1 is the first cooling area, and secondary cooling area 2, secondary cooling area 3 and secondary cooling area 4 are other cooling areas; The length of secondary cooling zone 1 is 0.84m, the length of secondary cooling zone 2 is 3.96m, the length of secondary cooling zone 3 is 3.96m, and the length of secondary cooling zone 4 is 3.24m.

9. A method for reducing high carbon steel billet continuous casting head billet waste according to claim 8, characterized in that: The continuous casting machine is equipped with 7 tension levelers with light pressure reduction function; The first of the 7 straightening machines is installed at the end of the secondary cooling area, the second straightening machine is 750 mm away from the first straightening machine, and the subsequent straightening machines are 700 mm adjacent to the second straightening machine in sequence; The tension leveler presses down the roll gap using a fixed reference value.

10. A method for reducing high carbon steel billet continuous casting head billet waste according to claim 9, characterized in that: Start pressing from the second stand. When the hot billet pressed by the second stand reaches the third stand, the third stand starts pressing, and so on, until the last straightening machine required by the process is put into pressing, and then stable production is achieved; When the second straightening machine is pressed down, the pressure value is ≤800kN. The hot billet pressed down by the second straightening machine is accurately tracked into place and pressed down step by step by the subsequent straightening machines until the pouring is completed and stable production is achieved.