阅读说明：本技术 一种高强钢板退火过渡的控制方法 (Control method for annealing transition of high-strength steel plate ) 是由 关淑巧 刘春雨 周国平 王凯飞 李山 史小伟 王春虎 么建 马林 于 2021-06-07 设计创作，主要内容包括：一种高强钢带退火过渡的控制方法,过渡钢卷P退火过程温度和张力控制如下：缓冷段SJC温度设定值逐步降低至高强钢带所需温度T-(G(SJC)),设定值与实际值的温差T-(SP-PV(SJC))≤5℃；快冷段RJC温度设定值逐步降低至高强钢带所需温度T-(G(RJC)),设定值与实际值的温差T-(SP-PV(RJC))≤5℃,每个钢卷在RJC段的温度设定值的降低量T-(SP降(RJC))≤20℃；在过渡卷P退火温度设定值开始降低后,将缓冷段SJC、快冷段RJC、过时效段OA、终冷段FJC的张力增加10%～30%。本发明能够避免带钢在炉内跑偏、机组降速甚至停车事故,保证带钢在退火炉内稳定运行。(A control method for annealing transition of a high-strength steel strip is characterized in that the temperature and the tension of a transition steel coil P in the annealing process are controlled as follows: the temperature set value of the slow cooling section SJC is gradually reduced to the temperature T required by the high-strength steel strip G（SJC） Temperature difference T between set value and actual value SP‑PV（SJC） Less than or equal to 5 ℃; the temperature set value of the RJC in the quick cooling section is gradually reduced to the temperature T required by the high-strength steel strip G（RJC） Temperature difference T between set value and actual value SP‑PV（RJC） The temperature of each steel coil in the RJC section is less than or equal to 5 ℃, and the reduction quantity T of the temperature set value of each steel coil in the RJC section SP lowering (RJC) At most 20 ℃; after the annealing temperature set value of the transition roll P begins to decrease, the tension of a slow cooling section SJC, a fast cooling section RJC, an overaging section OA and a final cooling section FJC is increased by 10-30%. The inventionThe device can avoid the accidents of the deviation of the strip steel in the furnace, the speed reduction of a unit and even the stop of the unit, and ensure the stable operation of the strip steel in the annealing furnace.)

1. The utility model provides a control method of high-strength steel strip annealing transition, high-strength steel continuous annealing stove includes preheating section PH, heating section RTH, soaking section RTS, slow cooling section SJC, fast cooling section RJC, overaging section OA, final cooling section FJC, its characterized in that, before high-strength steel strip G anneals, anneals transition steel coil P, transition steel coil P annealing process reduces annealing furnace temperature to the required temperature of high-strength steel strip G gradually, transition steel coil P annealing process temperature and tension control as follows:

1) and (3) controlling the temperature of a slow cooling section SJC:

the temperature set value of the slow cooling section SJC is gradually reduced to the temperature T required by the high-strength steel strip_G（SJC）Temperature difference T between set value and actual value_{SP-PV（SJC）}≤5℃；

2) And (3) controlling the temperature of the rapid cooling section RJC:

the temperature set value of the RJC in the quick cooling section is gradually reduced to the temperature T required by the high-strength steel strip_G（RJC）Temperature difference T between set value and actual value_{SP-PV（RJC）}The temperature of each steel coil in the RJC section is less than or equal to 5 ℃, and the reduction quantity T of the temperature set value of each steel coil in the RJC section_{SP lowering (RJC)}≤20℃；

3) Tension control:

after the annealing temperature set value of the transition roll P begins to decrease, the tension of a slow cooling section SJC, a fast cooling section RJC, an overaging section OA and a final cooling section FJC is increased by 10-30%.

2. The method for controlling the annealing transition of a high-strength steel strip according to claim 1, wherein the overaging section OA comprises a first overaging section OA1 and a second overaging section OA2,

in the OA2 section, a zone temperature control mode is selected, and the zone temperature is set to be the temperature T required by the high-strength steel strip G_G（OA）；

In OA1 stage, zone temperature control mode is selected and zone temperature is set to T_（OA）Said T is_（OA）＝T_G（OA）＋（15℃～25℃）。

3. The method for controlling the annealing transition of the high-strength steel strip according to claim 2, wherein the cooling fan of the overaging section OA defines a maximum load of 40-70%.

4. The method for controlling the annealing transition of the high-strength steel strip as claimed in claim 1, wherein the speed of the steel strip is adjusted after the steel strip with different specifications enters the furnace and the welding seam reaches the cooling section, the adjustment step is 1.5-2.5 m/min each time, and the change of the yield of two coils before and after the time is less than 10%.

5. The method for controlling the annealing transition of the high-strength steel strip as claimed in claim 1, wherein the tensions of the slow cooling section SJC, the fast cooling section RJC, the overaging section OA and the final cooling section FJC are increased by 10% to 15% after the annealing temperature set value of the transition coil P starts to be lowered.

6. The method for controlling annealing transition of the high-strength steel strip as claimed in any one of claims 1, 2, 4 and 5, wherein the number of the transition steel coils is 6-8 coils, and the difference between the thickness specifications of the adjacent steel coils is less than or equal to 0.3 mm.

7. The method for controlling the annealing transition of the high-strength steel strip according to any one of claims 1, 2, 4 and 5, wherein the annealing temperatures required for the high-strength steel strip G are as follows: the RTS temperature of the soaking section is 770-790 ℃, the SJC temperature of the slow cooling section is 640-660 ℃, the RJC temperature of the fast cooling section is 270-290 ℃, and the OA temperature of the overaging section is 250-270 ℃.

8. The method for controlling the annealing transition of the high-strength steel strip according to any one of claims 1, 2, 4 and 5, wherein the annealing temperatures required for the transition steel coil P are as follows: the RTS temperature of the soaking section is 790-810 ℃, the SJC temperature of the slow cooling section is 670-690 ℃, the RJC temperature of the fast cooling section is 390-410 ℃, and the OA temperature of the overaging section is 360-380 ℃.

Technical Field

The invention belongs to the technical field of steel plate cold rolling annealing, and particularly relates to a control method for annealing transition of a high-strength steel plate.

Background

In order to save energy and improve the safety performance of automobiles, high-strength steel has been developed into novel high-strength stamping steel with good formability, and becomes an important component of modern automobile steel. The production of the high-strength steel of the cold-rolled continuous annealing line has the characteristics of equipment and process, the annealing temperature of the high-strength steel in a fast cooling section and an overaging section is 100-120 ℃ lower than that of a common material, the furnace temperature is gradually cooled and transited to the production requirement of the high-strength steel by using the common material before the high-strength steel is produced, and the deviation accident of strip steel in the furnace is frequently generated in the transition process, so that the speed of a unit is reduced, even the unit is stopped, and the normal production of the high-strength steel is seriously influenced.

Disclosure of Invention

According to the equipment and process characteristics of dual-phase steel production of an annealing unit, a common material transition coil is controlled from the aspects of temperature adjustment, tension control, speed, production scheduling and the like, and the method can solve the problems that in the production process of a continuous annealing line transitioning from a common material to a high-strength steel annealing temperature, strip steel deviates, scrapes steel, reduces the speed and even stops, and the stable production of the high-strength steel and the surface quality of a product are influenced.

The high-strength steel comprises the following components: dual-phase steel DP, martensitic steel MS and quenching distribution steel QP;

the common material of the invention is: ordinary low carbon steel DC01, namely transition steel coil.

The technical scheme of the invention is that the high-strength steel continuous annealing furnace comprises a preheating section PH, a heating section RTH, a soaking section RTS, a slow cooling section SJC, a fast cooling section RJC, an overaging section OA and a final cooling section FJC, before the high-strength steel strip G is annealed, the annealing furnace temperature is gradually reduced to the temperature required by the high-strength steel strip G in the annealing process of the transition steel strip P, and the temperature and the tension in the annealing process of the transition steel strip P are controlled as follows:

1) and (3) controlling the temperature of a slow cooling section SJC:

the temperature set value of the slow cooling section SJC is gradually reduced to the temperature T required by the high-strength steel strip_G（SJC）Temperature difference T between set value and actual value_{SP-PV（SJC）}≤5℃；

2) And (3) controlling the temperature of the rapid cooling section RJC:

the temperature set value of the RJC in the quick cooling section is gradually reduced to the temperature T required by the high-strength steel strip_G（RJC）Temperature difference T between set value and actual value_{SP-PV（RJC）}The temperature of each steel coil in the RJC section is less than or equal to 5 ℃, and the reduction quantity T of the temperature set value of each steel coil in the RJC section_{SP lowering (RJC)}≤20℃；

3) Tension control:

after the annealing temperature set value of the transition roll P begins to decrease, the tension of a slow cooling section SJC, a fast cooling section RJC, an overaging section OA and a final cooling section FJC is increased by 10-30%.

Further, the overaging section OA comprises a first overaging section OA1 and a second overaging section OA2,

in the OA2 section, a zone temperature control mode is selected, and the zone temperature is set to be the temperature T required by the high-strength steel strip G_G（OA）；

In OA1 stage, zone temperature control mode is selected and zone temperature is set to T_（OA）Said T is_（OA）＝T_G（OA）＋（15℃～25℃）。

Further, in the aging section OA, the maximum load of the cooling fan is limited to 40-70%.

Further, after the strip steels with different specifications enter the furnace, the speed of the strip steel is adjusted slightly after the welding seam reaches the cooling section so as to ensure the stability of the load of the rapid cooling fan, the adjustment step is 1.5-2.5 m/min each time, and the change of the yield of two coils of the strip steel before and after is less than 10%.

Furthermore, after the annealing temperature set value of the transition roll P begins to decrease, the tensions of the slow cooling section SJC, the fast cooling section RJC, the over-aging section OA and the final cooling section FJC are increased by 10-15%.

Furthermore, the number of the transition steel coils is 6-8 coils, and the thickness specification difference of adjacent steel coils is less than or equal to 0.3 mm.

Further, the annealing temperature required by the high-strength steel strip G is as follows: the RTS temperature of the soaking section is 770-790 ℃, the SJC temperature of the slow cooling section is 640-660 ℃, the RJC temperature of the fast cooling section is 270-290 ℃, and the OA temperature of the overaging section is 250-270 ℃.

Further, the annealing temperature required by the transition steel coil P is as follows: the RTS temperature of the soaking section is 790-810 ℃, the SJC temperature of the slow cooling section is 670-690 ℃, the RJC temperature of the fast cooling section is 390-410 ℃, and the OA temperature of the overaging section is 360-380 ℃.

Tension control of the transition steel coil: after the transition coil begins to cool, the tension of the cooling section, the overaging section and the final cooling section is increased by 10-15%, and the operation stability of the strip steel is ensured. The tension is increased by 10-15%, which means that the tension is increased by 10-15% on the basis of the tension before the annealing temperature is reduced. In the transition process, the running condition of the strip steel in the furnace needs to be closely observed through a camera, and if deviation occurs, the tension can be properly increased by 10-15%.

Adopt the produced beneficial effect of above-mentioned technical scheme to lie in: according to the production control method for the annealing stable transition of the high-strength steel, the temperature of the band steel at the relevant furnace section is stably adjusted in the process of gradually adjusting the annealing temperature of the transition steel coil to the target temperature of the high-strength steel, so that the large fluctuation of the load of a cooling fan is avoided, the stable operation of the band steel in the annealing furnace is ensured, the smooth transition to the production of the high-strength steel is realized, and a good foundation is laid for the batch stable production of the high-strength steel and the improvement of the product quality.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The high-strength steel G takes the dual-phase steel with three grades of HC420/780DP, CR340/590DP and HC700/980DP as an example, and the transition steel coil P takes the steel strip with the grade of DC01 as an example, and the method of the invention is explained. Table 1 shows the annealing temperatures required for the high-strength steel G and the transition steel coil P.

TABLE 1

Example 1

Before the high-strength steel HC420/780DP is annealed, the transition steel coil is DC01, 6 transition steel coils are adopted, and before the transition steel coil is annealed, the annealing furnace continuously produces a steel strip DC 01. The specification of the steel strip is shown in Table 2, and the temperature set values of the RTS section, the SJC section, the RJC section and the OA section of the annealing furnace are shown in Table 2. The serial numbers 0-7 in the table 2 represent the sequence of feeding steel coils into the furnace.

TABLE 2

1. In the continuous annealing furnace, the set temperature of each steel coil in the SJC section is reduced by 5 ℃ relative to the previous steel coil, and the difference between the set temperature and the actual temperature of the transition steel coil is ensured to be 0-5 ℃.

2. The strip steel with different specifications is put into a furnace for annealing, after the strip steel is welded to a cooling section, the running speed of the strip steel is gradually adjusted in steps of 2m/min each time, and the load of a fan at the fast cooling section is controlled to be 55-65%;

3. after the first transition coil begins to cool, the tension of the cooling section, the overaging section and the final cooling section is increased by 10 percent, and the strip steel runs stably and gradually transits to the annealing temperature required by HC420/780DP, thereby ensuring the normal production of the high-strength steel.

Example 2

Before the high-strength steel CR340/590DP is annealed, the transition steel coil is DC01, 7 transition steel coils are adopted, and before the transition steel coil is annealed, the annealing furnace continuously produces a steel strip DC 01. The specification of the steel strip is shown in Table 3, and the temperature set values of the RTS section, the SJC section, the RJC section and the OA section of the annealing furnace are shown in Table 3. The serial numbers 0-8 in the table 3 represent the sequence of feeding steel coils into the furnace.

TABLE 3

1. In continuous annealing, the set temperature of each steel coil in the SJC section is reduced by 3-5 ℃ relative to the previous steel coil, and the difference between the set temperature and the actual temperature of the transition steel coil is ensured to be 0-3 ℃.

2. The strip steel with different specifications is put into a furnace for annealing, after the strip steel is welded to a cooling section, the running speed of the strip steel is gradually adjusted in steps of 1.5m/min each time, and the load of a fan at the fast cooling section is controlled between 70% and 85%;

3. after the first transition coil begins to cool, the tension of the cooling section, the overaging section and the final cooling section is gradually increased by 15%, in the transition process, the running condition of the strip steel in the furnace needs to be closely observed through a camera, the deviation sign appears, the tension is properly increased by 10%, the total increase of the tension of the transition coil is 25% relative to the tension of the steel coil normally produced before, the transition is gradually carried out to the annealing temperature required by DP590, and the normal production of the high-strength steel is ensured.

Example 3

Before the high-strength steel HC700/980DP is annealed, the transition steel coil is DC01, 8 transition steel coils are adopted, and before the transition steel coil is annealed, the annealing furnace continuously produces the steel strip DC 01. The specification of the steel strip is shown in Table 4, and the temperature set values of the RTS section, the SJC section, the RJC section and the OA section of the annealing furnace are shown in Table 4. The serial numbers 0-9 in Table 4 represent the sequence of feeding steel coils into the furnace.

TABLE 4

1. In continuous annealing, the set temperature of each steel coil in the SJC section is reduced by 3-5 ℃ relative to the previous steel coil, and the difference between the set temperature and the actual temperature of the transition steel coil is ensured to be 0-3 ℃.

2. The strip steels with different specifications are put into a furnace for annealing, after the strip steels are welded to a cooling section, the running speed of the strip steels is gradually adjusted in steps of 2.5m/min each time, and the load of a fan at the fast cooling section is controlled between 55% and 65%;

3. after the first transition coil begins to cool, the tension of the cooling section, the overaging section and the final cooling section is gradually increased by 15 percent, and the annealing temperature required by DP980 is gradually transited, so that the normal production of the high-strength steel is ensured.

In the embodiment 1-3, the continuous annealing process and the temperature of the band steel at the relevant furnace section are stably adjusted, so that the load of a cooling fan is prevented from being greatly fluctuated, the stable operation of the band steel in an annealing furnace is ensured, the production of high-strength steel is smoothly transited, the whole production process is stable, and the deviation phenomenon does not occur.

The above embodiment is described by taking the transition rolls as 6-8 rolls as an example, and increasing the number of the transition rolls and simultaneously reducing the temperature reduction speed, i.e. further slowly reducing the temperature, makes the production process more stable.

Although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that: modifications and equivalents may be made thereto without departing from the spirit and scope of the invention and it is intended to cover in the claims the invention as defined in the appended claims.