Process for overcoming hot-rolled soft and hard edges of ferritic stainless steel

Abstract

The application discloses a process for overcoming the soft and hard edges of ferrite stainless steel hot rolling, and the process steps are as follows: 1) preparing a steel billet to a heating furnace for heating, and the heating steps are sequentially divided into a preheating section, a first heating section, a second heating section and a soaking section; 2) high-pressure water descaling, removing the oxide skin on the surface of the heated steel billet through a high-pressure water spraying mechanism; 3) rough rolling: the heated steel billet is conveyed to a rough rolling mill through a transmission roller, and a corresponding heat preservation cover is arranged on the conveying device; 4) finish rolling: entering the finish rolling mechanism through the transmission, the finish rolling adopts speed-up rolling, the finish rolling opening rolling temperature is set to 1000-1050 DEG C, and the finish rolling end temperature is 900-980 DEG C; 5) coiling: after the finish rolling, the steel coil is sent to a coiling mechanism for coiling; and 6) heat preservation and slow cooling: the steel coil is hoisted to the heat preservation device for heat preservation and slow cooling. The application can solve the problem of the soft and hard edges of the steel coil caused by the uneven cooling speed of the steel coil through heat preservation of the steel coil.

Description

Technical Field

[0001] This invention belongs to the field of stainless steel rolling technology, and specifically relates to a process for overcoming the soft and hard edges of hot-rolled ferritic stainless steel. Background Technology

[0002] The process of hot rolling stainless steel generally involves feeding, heating, billet descaling, rough rolling, finish rolling, and coiling. Because stainless steel sheets are rolled into coils, the internal and external cooling rates are uneven. The internal heat dissipation is slow, while the external edges dissipate heat quickly, resulting in uneven mechanical properties, i.e., the soft and hard edges of stainless steel.

[0003] A search revealed a manufacturing method for overcoming the soft and hard edges of hot-rolled ferritic stainless steel with application number 202111355959.3. This method involves using a heat-insulating pit for slow cooling of the hot-rolled steel coil, while simultaneously utilizing heat provided by other hot-rolled coils to allow the temperature in the area where the hot-rolled steel coil is located to decrease slowly, enabling the steel coil to be heated evenly and cooled slowly. This invention employs a special slow cooling measure, utilizing the heat-insulating function of the heat-insulating pit, as well as heat provided by other hot-rolled coils, to allow the temperature in a certain area to decrease slowly, enabling the steel coil to achieve the purpose of uniform heating and slow cooling, effectively improving its mechanical properties and solving the problem of poor forming performance of stainless steel sheet coils.

[0004] This solution addresses the issue of soft and hard edges by using insulation pits to slow down cooling, but it does not specify what type of insulation pit structure is suitable to achieve the desired effect.

[0005] This invention provides a heat preservation device that can effectively and reasonably achieve heat preservation and slow cooling. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a process to overcome the soft and hard edges of hot-rolled ferritic stainless steel, which can solve the problem of soft and hard edges of steel coils caused by uneven cooling rate by heat preservation of the steel coil.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A process for overcoming the soft and hard edges of hot-rolled ferritic stainless steel, comprising the following steps:

[0009] 1) Prepare the steel billet for heating in the heating furnace. The heating steps are divided into a preheating section, a first heating section, a second heating section, and a soaking section. In the preheating section, the temperature is controlled at 555-600℃ and the heating time is 90-100 minutes. After the preheating section, the first heating section is started, with the temperature controlled at 900-1000℃ and the heating time being 75-85 minutes. After the first heating section, the second heating section is started, with the temperature controlled at 1100-1200℃ and the heating time being 60-70 minutes. After the second heating section, the soaking section is started, with the temperature controlled at 1150-1200℃ and the heating time being 50-60 minutes. The total heating time is 275-315 minutes.

[0010] 2) High-pressure water descaling: The oxide scale on the surface of the heated steel billet is removed by a high-pressure water jetting mechanism.

[0011] 3) Rough rolling: The heated steel billet is conveyed to the rough rolling mill via transfer rollers. The conveying device is equipped with a corresponding heat preservation cover. During rough rolling, the steel billet is rolled in 6 passes; the reduction rate for the first pass is 31-32.6%; the reduction rate for the second pass is 27-28.5%; the reduction rate for the third pass is 27-28.5%; the reduction rate for the fourth pass is 23-24%; the reduction rate for the fifth pass is 23-24%; and the reduction rate for the sixth pass is 22-22.5%.

[0012] 4) Finishing rolling: After being conveyed, the steel enters the finishing rolling mechanism. The finishing rolling adopts speed-increasing rolling. The starting temperature of finishing rolling is set to 1000-1050℃; the finishing rolling ending temperature is 900-980℃.

[0013] 5) Winding: After precision rolling, the rolls are fed into the winding mechanism for winding.

[0014] 6) Insulation and slow cooling: The steel coil is hoisted into the insulation device for insulation and slow cooling;

[0015] 6-1) Clean the accumulated oxide scale inside the insulation device box, and then check the sealing condition of each part;

[0016] 6-2) The steel coils are hoisted into the insulation device for insulation, resulting in a steel coil temperature >920℃ inside the insulation device; the steel coils are evenly arranged.

[0017] 6-3) The heat preservation time should be controlled at 25-26.5 hours, and the cooling rate should be 30-55℃ / h. Wait for the steel coil to cool down slowly. When the temperature of the steel coil is below 35℃, lift the steel coil out.

[0018] 6-4) Clean up the fallen oxide scale inside the insulation device.

[0019] The insulation device includes a box body, an insulation layer, a buffer mechanism, a cleaning mechanism, and a support mechanism; the insulation layer is located on the inner wall of the box body, the cleaning mechanism and the support mechanism are spaced apart and located at the bottom of the box body, and the buffer mechanism is located on both sides of the box body and corresponds to the support mechanism.

[0020] The box body has fixed plates on both sides, and electric push rods on the fixed plates. The top of the box body has a guide rail and a cover. One end of the cover is slidably connected to the guide rail, and the other end is fixedly connected to the top shaft of the electric push rod. The electric push rod drives the cover to slide along the guide rail to open or close the box body. The bottom of the box body has a first cleaning groove, a first guide groove, a second cleaning groove, a second guide groove, and a third cleaning groove. The first cleaning groove is connected to the first guide groove. The second cleaning groove is connected to the second guide groove and the third cleaning groove. The first cleaning groove and the second cleaning groove are spaced apart. The inner wall of the box body has a first mounting groove and a second mounting groove.

[0021] The insulation layer includes a first bracket, a second bracket, a locking pin, a mesh frame, and rock wool. The first bracket has a first insertion hole and an insertion rod on one side. The second bracket has an insertion sleeve on one side corresponding to the insertion rod. The second bracket has a second insertion hole and a slot. The other side of the second bracket has a first slide rail located in a first mounting groove. The rock wool is placed between the first bracket and the second bracket. The first bracket passes through the rock wool and fits into the insertion sleeve via the insertion rod. The locking pin has symmetrical limiting blocks at both ends. After the locking pin passes through the first insertion hole and the second insertion hole, it rotates to fix the first bracket, the second bracket, and the rock wool. The mesh frame is inserted into the slot to surround and fix the rock wool.

[0022] The buffer mechanism includes a mounting plate, a second slide rail, a first housing, and a second housing. The second slide rail is located in a second mounting groove and is interlocked with each other. One end of the second housing is fixedly connected to the second slide rail. The first housing is slidably sleeved onto the second housing. The mounting plate has several rollers on one side and a telescopic shaft on the other side. The telescopic shaft passes through the first housing and is fixedly connected to the second slide rail. A limiting plate is provided on the telescopic shaft and located on one side of the first housing. A spring is sleeved on the telescopic shaft, and both ends of the spring abut against the limiting plate and the second slide rail, respectively. The spring pushes the limiting plate, the first housing, and the mounting plate outward. The first housing and the second housing are used to protect the spring and prevent it from losing its mechanical elasticity under prolonged high temperatures.

[0023] The cleaning mechanism includes a first motor, a scraper frame, a first bidirectional lead screw, a first telescopic plate, a support rod, a first fixed seat, and a first baffle. A pair of first fixed seats are located at both ends of the second cleaning groove. The first bidirectional lead screw is rotatably connected to the first fixed seats at both ends. The first motor is fixed to one side of the housing, and its shaft is connected to the first bidirectional lead screw. The first baffle is slidably connected to the first fixed seats and can slide up and down to open or close the two ends of the second cleaning groove. A pair of support rods are located and fixed to the inner wall of the second cleaning groove. A stop block is provided on the support rod. The first telescopic plate is located in the second cleaning groove and corresponds to the third cleaning groove. The first telescopic plate is supported on both sides by the support rod. One end of the first telescopic plate pushes against the stop block, and a stop rod is provided on the first telescopic plate. The scraper frame includes a sliding plate and an arc-shaped... The scraper, top rod, and sliding plate are connected to the first bidirectional screw via threads, with the sliding plate positioned within the second guide groove. An arc-shaped scraper is fixedly connected to the sliding plate, and a top rod with a corresponding stop rod is located on the arc-shaped scraper away from the stop block. The first motor drives the first bidirectional screw to rotate, thereby causing the scraper frame to slide along the second guide groove. The arc-shaped scraper then scrapes and collects the oxide scale on the bottom surface of the housing. The top rod contacts the stop rod, causing the first telescopic plate to retract and open the seal on the third cleaning groove, allowing the oxide scale collected by the arc-shaped scraper to enter the second cleaning groove through the third cleaning groove. The first bidirectional screw reverses, causing the scraper frame to reset, which in turn resets the first telescopic plate. After the insulation work stops, the first stop plate can be lifted to open the second cleaning groove for unified cleaning of the internal oxide scale.

[0024] The support mechanism includes a second motor, a support base, a second bidirectional lead screw, a second fixed base, and a second baffle. A pair of second fixed bases are respectively fixed to both ends of the first cleaning groove. The two ends of the second bidirectional lead screw are rotatably connected to the second fixed bases. The second motor is fixed to one side of the housing, and its shaft is connected to the second bidirectional lead screw. The second baffle is slidably connected to the second fixed base and slides up and down to close or open the two ends of the first cleaning groove to prevent excessive heat loss from the housing. A handle is provided on the second baffle for lifting. A pair of support bases are provided, each threadedly connected to the second bidirectional lead screw and passing through the first guide groove. The support base has an arc-shaped surface to accommodate the steel coil. Several drainage holes are provided on the arc-shaped surface of the support base, and a ramp is provided inside the support base. Oxide scale on the steel coil falls through the drainage holes, slides down the ramp to both sides of the support base, and is then collected and cleaned by the cleaning mechanism. The second motor drives the second bidirectional lead screw to rotate, thereby causing the support base to slide along the first guide groove to accommodate steel coils of different diameters.

[0025] Furthermore, a telescopic plate is provided between the support seats, and the two ends of the telescopic plate are fixedly connected to the support seats; a second telescopic plate is provided between the support seats and the second fixed seat, and the two ends of the second telescopic plate are fixedly connected to the second fixed seat and the support seat respectively; the second telescopic plate is designed as an inverted V shape and covers the second bidirectional screw to prevent oxide scale from entering the threads of the second bidirectional screw and affecting its use; the support seat slides to push the second telescopic plate to compress or unfold; the second telescopic plate can be set above the first bidirectional screw in the same way.

[0026] The advantages of this invention compared to existing technologies are as follows:

[0027] 1) The mounting plate in the buffer mechanism uses a telescopic shaft to buffer and offset the impact of the steel coil on the inner wall of the box caused by the unstable swing during hoisting, which can effectively prevent the steel coil from being damaged by direct collision with the inner wall of the box; at the same time, the first box and the second box are connected to protect the spring, which can effectively prevent the spring from losing its mechanical elasticity under long-term high temperature; the second slide rail can slide and insert in the second mounting groove, which can realize quick installation or disassembly and replacement.

[0028] 2) In the cleaning mechanism, the first motor drives the first bidirectional screw to rotate, which in turn drives the scraper to slide along the second guide groove. The arc-shaped scraper then scrapes and collects the oxide scale on the bottom surface of the box. During this process, the top rod in the scraper contacts the stop rod, causing the first telescopic plate to retract and open the seal on the third cleaning groove. This allows the oxide scale collected by the arc-shaped scraper to enter the second cleaning groove through the third cleaning groove. Then, the first bidirectional screw reverses to reset the scraper, which in turn resets the first telescopic plate. After the insulation work stops, the first baffle can be lifted to open the second cleaning groove for unified cleaning of the internal oxide scale. This process avoids the inconvenience of manual entry into the box for cleaning, ensuring the personal safety of employees.

[0029] 3) The insulation layer is formed by interlocking the first and second brackets and securing them with locking pins to fix the rock wool. The insert rod and sleeve play a pre-guiding role during the interlocking of the first and second brackets. Secondly, when the rock wool needs to be replaced after a long period of use, simply rotate the locking pin to make the limiting block fit with the first and second insertion holes, and then pull out the locking pin to release the locking of the first and second brackets, which can quickly replace the rock wool. Furthermore, the interlocking of the first slide rail with the first mounting groove can also enable the quick replacement of the insulation layer.

[0030] 4) A second telescopic plate is provided between the support seats, and the two ends of the second telescopic plate are fixedly connected to the support seats; a second telescopic plate is provided between the support seats and the second fixed seat, and the two ends of the second telescopic plate are fixedly connected to the second fixed seat and the support seat respectively; the second telescopic plate is designed as an inverted V shape and covers the second bidirectional lead screw. During use, the sliding of the support seat can push the inverted V-shaped second telescopic plate to compress or unfold, so that the second telescopic plate can effectively prevent oxide scale from entering the threads of the second bidirectional lead screw and affecting its use. Attached Figure Description

[0031] Appendix Figure 1 This is a schematic diagram of a process structure for overcoming the soft and hard edges of hot-rolled ferritic stainless steel according to the present invention. Figure 1 ;

[0032] Appendix Figure 2 This is a schematic diagram of a process structure for overcoming the soft and hard edges of hot-rolled ferritic stainless steel according to the present invention. Figure 2 ;

[0033] Appendix Figure 3 This is a schematic diagram of the internal structure of the box;

[0034] Appendix Figure 4 This is a structural exploded view of the insulation layer;

[0035] Appendix Figure 5 This is a top view of the internal structure of the box;

[0036] Appendix Figure 6 This is a structural diagram of the support mechanism and the buffer mechanism. Figure 1 ;

[0037] Appendix Figure 7 This is a structural diagram of the support mechanism and the buffer mechanism. Figure 2 ;

[0038] Appendix Figure 8 This is a schematic diagram of the support structure. Figure 1 ;

[0039] Appendix Figure 9 This is a schematic diagram of the support structure. Figure 2 ;

[0040] Appendix Figure 10 This is a structural diagram of the cleaning mechanism. Figure 1 ;

[0041] Appendix Figure 11 This is a structural diagram of the cleaning mechanism. Figure 2 ;

[0042] In the diagram: 1. Box body; 101. Fixing plate; 102. Electric actuator; 103. Guide rail; 104. Cover; 105. First cleaning groove; 106. First guide groove; 107. Second cleaning groove; 108. Second guide groove; 109. Third cleaning groove; 110. First mounting groove; 111. Second mounting groove; 2. Insulation layer; 21. First bracket; 211. First insertion hole; 212. Insert rod; 22. Second bracket; 221. Second insertion hole; 222. Insert sleeve; 223. Slot; 224. First slide rail; 23. Locking pin; 231. Limiting block; 25. Grid frame; 26. Rock wool; 3. Buffer mechanism; 31. Mounting plate; 311. Roller shaft; 312. Telescopic shaft; 3121, Limiting plate; 313, Spring; 32, Second slide rail; 33, First box body; 34, Second box body; 4, Cleaning mechanism; 41, First motor; 42, Scraper frame; 421, Sliding plate; 422, Arc-shaped scraper; 423, Top rod; 43, First double-acting screw; 44, First telescopic plate; 441, Stop bar; 45, Support rod; 451, Stop block; 46, First fixed seat; 47, First baffle; 5, Support mechanism; 51, Second motor; 52, Support seat; 521, Drain hole; 522, Slope; 523, Arc-shaped surface; 53, Second double-acting screw; 54, Second fixed seat; 55, Second baffle; 551, Handle; 56, Second telescopic plate; 6, Steel coil. Detailed Implementation

[0043] To facilitate understanding by those skilled in the art, the following is a detailed explanation in conjunction with the appendix. Figure 1-11 The technical solution of the present invention will be further described in detail below.

[0044] Example 1: Taking the production of 309s stainless steel coils as an example:

[0045] A process for overcoming the soft and hard edges of hot-rolled ferritic stainless steel, comprising the following steps:

[0046] 1) Prepare the steel billet for heating in the heating furnace. The heating steps are divided into a preheating section, a first heating section, a second heating section, and a soaking section. In the preheating section, the temperature is controlled at 555℃ and the heating time is 90 minutes. After the preheating section, the first heating section is heated at 900℃ and the heating time is 75 minutes. After the first heating section, the second heating section is heated at 1100℃ and the heating time is 60 minutes. After the second heating section, the soaking section is heated at 1150℃ and the heating time is 50 minutes. The total heating time is 275 minutes.

[0047] 2) High-pressure water descaling: The oxide scale on the surface of the heated steel billet is removed by a high-pressure water jetting mechanism.

[0048] 3) Rough rolling: The heated steel billet is conveyed to the rough rolling mill via transfer rollers. The conveying device is equipped with a corresponding heat preservation cover. During rough rolling, the steel billet is rolled in 6 passes; the reduction rate for the first pass is 31%; the reduction rate for the second pass is 27%; the reduction rate for the third pass is 27%; the reduction rate for the fourth pass is 23%; the reduction rate for the fifth pass is 23%; and the reduction rate for the sixth pass is 22%.

[0049] 4) Finishing rolling: After being conveyed, the material enters the finishing rolling mechanism. The finishing rolling adopts speed-increasing rolling. The starting temperature of finishing rolling is set to 1000℃; the finishing rolling ending temperature is 965℃.

[0050] 5) Winding: After precision rolling, the rolls are fed into the winding mechanism for winding.

[0051] 6) Insulation and slow cooling: The steel coil is hoisted into the insulation device for insulation and slow cooling;

[0052] 6-1) Clean the accumulated oxide scale inside the insulation device box, and then check the sealing condition of each part;

[0053] 6-2) The steel coils are hoisted into the insulation device for insulation; resulting in a steel coil temperature of 960℃ inside the insulation device; the steel coils are evenly arranged.

[0054] 6-3) The heat preservation time is controlled at 25.5 hours, the cooling rate is 35℃ / h, and the steel coil is lifted out when the temperature of the steel coil reaches 30℃.

[0055] 6-4) Clean up the fallen oxide scale inside the insulation device.

[0056] The insulation device includes a box body 1, an insulation layer 2, a buffer mechanism 3, a cleaning mechanism 4, and a support mechanism 5. The insulation layer 2 is located on the inner wall of the box body 1. The cleaning mechanism 4 and the support mechanism 5 are spaced apart and located at the bottom of the box body 1. The buffer mechanism 3 is located on both sides of the box body 1 and corresponds to the support mechanism 5.

[0057] The box body 1 has fixing plates 101 on both sides, and electric push rods 102 on the fixing plates 101. The top of the box body 1 has a guide rail 103 and a cover 104. One end of the cover 104 is slidably connected to the guide rail 103, and the other end is fixedly connected to the top shaft of the electric push rod 102. The electric push rod 102 drives the cover 104 to slide along the guide rail 103 to open or close the box body 1. The bottom of the box body 1 has a first cleaning groove 105, a first guide groove 106, a second cleaning groove 107, a second guide groove 108, and a third cleaning groove 109. The first cleaning groove 105 is connected to the first guide groove 106. The second cleaning groove 107 is connected to the second guide groove 108 and the third cleaning groove 109. The first cleaning groove 105 and the second cleaning groove 107 are spaced apart. The inner wall of the box body 1 has a first mounting groove 110 and a second mounting groove 111.

[0058] The insulation layer 2 includes a first support 21, a second support 22, a locking pin 23, a mesh frame 25, and rock wool 26. The first support 21 is provided with a first insertion hole 211 and an insertion rod 212 on one side. The second support 22 is provided with an insertion sleeve 222 on one side corresponding to the insertion rod 212. The second support 22 is provided with a second insertion hole 221 and a slot 223. The other side of the second support 22 is provided with a first slide rail 224 and is located in the first mounting groove 110. The rock wool 26 is located between the first support 21 and the second support 22. The first support 21 passes through the rock wool 26 through the insertion rod 212 and fits into the insertion sleeve 222. The locking pin 23 is provided with symmetrical limiting blocks 231 at both ends. After the locking pin 23 passes through the first insertion hole 211 and the second insertion hole 221, it rotates to fix the first support 21, the second support 22, and the rock wool 26. The mesh frame 25 is inserted into the slot 223 to surround and fix the rock wool 26.

[0059] The buffer mechanism 3 includes a mounting plate 31, a second slide rail 32, a first housing 33, and a second housing 34. The second slide rail 32 is disposed in the second mounting groove 111 and is interlocked with each other. One end of the second housing 34 is fixedly connected to the second slide rail 32. The first housing 33 is slidably sleeved on the second housing 34. The mounting plate 31 has several rollers 311 on one side and a telescopic shaft 312 on the other side. The telescopic shaft 312 passes through the first housing 33 and is fixedly connected to the second slide rail 32. A limiting plate 3121 is provided on the telescopic shaft 312 and is disposed on one side of the first housing 33. A spring 313 is sleeved on the telescopic shaft 312. The two ends of the spring 313 respectively abut against the limiting plate 3121 and the second slide rail 32. The spring 313 pushes the limiting plate 3121, the first housing 33, and the mounting plate 31 out. The first housing 33 and the second housing 34 are used to protect the spring 313 and prevent the spring 313 from losing its mechanical elasticity under prolonged high temperature.

[0060] The cleaning mechanism 4 includes a first motor 41, a scraper frame 42, a first bidirectional lead screw 43, a first telescopic plate 44, a support rod 45, a first fixed seat 46, and a first baffle 47. A pair of first fixed seats 46 are provided at both ends of the second cleaning groove 107. The first bidirectional lead screw 43 is rotatably connected to the first fixed seats 46 at both ends. The first motor 41 is fixed to one side of the housing 1, and its motor shaft is connected to the first bidirectional lead screw 43. The first baffle 47 is slidably connected to the first fixed seats 46 and can slide up and down to open or close the two ends of the second cleaning groove 107 for heat preservation. A pair of support rods 45 are provided and fixed to the inner wall of the second cleaning groove 107. A stop block 451 is provided on the support rod 45. The first telescopic plate 44 is located inside the second cleaning groove 107 and corresponds to the third cleaning groove 109. The first telescopic plate 44 is supported on both sides by the support rod 45. One end of the first telescopic plate 44 pushes against the stop block 451, and a stop rod 441 is provided on the first telescopic plate 44. The scraper frame 42 includes a sliding plate 421 and an arc-shaped scraper. Plate 422, top rod 423, and sliding plate 421 are connected to the first bidirectional lead screw 43 by threads and are located in the second guide groove 108. Arc-shaped scraper 422 is fixedly connected to the sliding plate 421. The arc-shaped scraper 422 away from the stop block 451 is provided with a top rod 423 and a corresponding stop rod 441. The first motor 41 drives the first bidirectional lead screw 43 to rotate, thereby driving the scraper frame 42 to slide along the second guide groove 108, and then the arc-shaped scraper 422 removes oxygen from the bottom surface of the box 1. The oxide scale is scraped and collected. The first telescopic plate 44 retracts and opens the seal on the third cleaning groove 109 by the top rod 423 touching the stop rod 441, so that the oxide scale collected by the arc-shaped scraper 422 can enter the second cleaning groove 107 through the third cleaning groove 109. The first bidirectional screw 43 reverses and drives the scraper frame 42 to reset, so that the first telescopic plate 44 is reset. Then, after the heat preservation work is stopped, the first baffle 47 can be lifted to open the second cleaning groove 107 for uniform cleaning of the oxide scale inside.

[0061] The support mechanism 5 includes a second motor 51, a support base 52, a second bidirectional lead screw 53, a second fixed base 54, and a second baffle 55. The second fixed base 54 is provided in pairs and is respectively fixed to both ends of the first cleaning groove 105. The two ends of the second bidirectional lead screw 53 are rotatably connected to the second fixed base 54. The second motor 51 is fixed to one side of the housing 1, and the motor shaft is connected to the second bidirectional lead screw 53. The second baffle 55 is slidably connected to the second fixed base 54 and slides up and down to close or open the two ends of the first cleaning groove 105 to prevent excessive heat loss from the housing 1. The second baffle 55 is provided with a handle 551 for lifting the second baffle 55. The support base... A pair of support seats 52 are provided. The support seats 52 are connected to the second bidirectional lead screw 53 by threads. The support seats 52 pass through the first guide groove 106. The support seats 52 have an arc-shaped surface 523 to accommodate the steel coil 6. The arc-shaped surface 523 of the support seats 52 has several drainage holes 521. The support seats 52 have a ramp 522 inside. After the oxide scale on the bottom of the steel coil 6 falls through the drainage holes 521, it slides through the ramp 522 to both sides of the support seats 52 and is then collected and cleaned by the cleaning mechanism 4. The second motor 51 drives the second bidirectional lead screw 53 to rotate, which in turn drives the support seats 52 to slide along the first guide groove 106 to accommodate steel coils 6 of different diameters.

[0062] Furthermore, a telescopic plate is provided between the support seats 52, with both ends of the telescopic plate fixedly connected to the support seats 52; a second telescopic plate 56 is provided between the support seats 52 and the second fixed seat 54, with both ends of the second telescopic plate 56 fixedly connected to the second fixed seat 54 and the support seat 52 respectively; the second telescopic plate 56 is designed as an inverted V-shape and covers the second bidirectional lead screw 53 to prevent oxide scale from entering the threads of the second bidirectional lead screw 53 and affecting its use; the support seats 52 slide to push the second telescopic plate 56 to compress or unfold; the second telescopic plate 56 can also be provided above the first bidirectional lead screw 43 in the same way.

[0063] When using the insulation device, the cover 104 is opened by the electric push rod 102, and then the steel coil 6 is lowered into the support mechanism 5 inside the box 1 by the gantry crane. During the hoisting process, the buffer mechanism 3 buffers and offsets the impact of the steel coil 6 on the inner wall of the box 1 caused by the unstable swing during hoisting. Then, the support seat 52 is adjusted according to the diameter of the steel coil 6 to meet the support requirements. After the steel coil 6 is hoisted, the cover 104 is closed. During the insulation process, the oxide scale generated on the surface of the steel coil 6 will fall off. The cleaning mechanism 4 collects and cleans the fallen oxide scale. The first motor 41 drives the first bidirectional lead screw 43 to rotate, which in turn drives the scraper 42. Sliding along the second guide groove 108, the oxide scale on the bottom surface of the box 1 is scraped and collected by the arc-shaped scraper 422. The first telescopic plate 44 retracts and opens the seal on the third cleaning groove 109 by the push rod 423 touching the stop rod 441, so that the oxide scale collected by the arc-shaped scraper 422 enters the second cleaning groove 107 through the third cleaning groove 109. The first bidirectional screw 43 flips and drives the scraper frame 42 to reset, so that the first telescopic plate 44 resets. When there is a lot of oxide scale accumulated in the first cleaning groove 105 or the second cleaning groove 107, the first baffle 47 and the second baffle 55 can be lifted for unified cleaning after the heat preservation work is completed.

[0064] Example 2: The difference from Example 1 is that;

[0065] In step 1), the preheating stage is controlled at 600℃ for 100 minutes. After the preheating stage, the first heating stage begins, with the temperature controlled at 1000℃ for 85 minutes. After the first heating stage, the second heating stage begins, with the temperature controlled at 1200℃ for 70 minutes. After the second heating stage, the homogenization stage begins, with the temperature controlled at 1200℃ for 60 minutes. The total heating time is 315 minutes.

[0066] Step 3) Rough rolling: First pass reduction rate 32.6%; Second pass reduction rate 28.5%; Third pass reduction rate 28.5%; Fourth pass reduction rate 24%; Fifth pass reduction rate 24%; Sixth pass reduction rate 22.5%;

[0067] Step 4) Finishing rolling: After being conveyed, the material enters the finishing rolling mechanism. The finishing rolling adopts speed-increasing rolling. The starting temperature of finishing rolling is set to 1050℃; the finishing rolling ending temperature is 980℃.

[0068] Step 6) Insulation and slow cooling: Hoist the steel coil into the insulation device for insulation and slow cooling;

[0069] 6-1) Clean the accumulated oxide scale inside the insulation device box, and then check the sealing condition of each part;

[0070] 6-2) The steel coils are hoisted into the insulation device for insulation; resulting in a steel coil temperature of 965℃ inside the insulation device; the steel coils are evenly arranged.

[0071] 6-3) The heat preservation time is controlled at 26 hours, the cooling rate is 50℃ / h, and the steel coil is lifted out when the temperature of the steel coil is 33℃.

[0072] Example 3: The difference from Example 1 is that;

[0073] 1) Prepare the steel billet for heating in the heating furnace. The heating steps are divided into a preheating section, a first heating section, a second heating section, and a soaking section. In the preheating section, the temperature is controlled at 580℃ and the heating time is 92.5 min. After the preheating section, the first heating section is started, with the temperature controlled at 980℃ and the heating time being 82 min. After the first heating section, the second heating section is started, with the temperature controlled at 1045℃ and the heating time being 68 min. After the second heating section, the soaking section is started, with the temperature controlled at 1175℃ and the heating time being 53 min. The total heating time is 295.5 min.

[0074] 3) Rough rolling: The heated steel billet is conveyed to the rough rolling mill via transfer rollers. The conveying device is equipped with a corresponding heat preservation cover. During rough rolling, the steel billet is rolled in 6 passes; the reduction rate for the first pass is 30.5%; the reduction rate for the second pass is 27.8%; the reduction rate for the third pass is 28.2%; the reduction rate for the fourth pass is 23.6%; the reduction rate for the fifth pass is 23.2%; and the reduction rate for the sixth pass is 22.15%.

[0075] 4) Finishing rolling: After being conveyed, the material enters the finishing rolling mechanism. The finishing rolling adopts speed-increasing rolling. The starting temperature of finishing rolling is set to 978℃; the finishing rolling ending temperature is 962℃.

[0076] 6) Insulation and slow cooling: The steel coil is hoisted into the insulation device for insulation and slow cooling;

[0077] 6-1) Clean the accumulated oxide scale inside the insulation device box, and then check the sealing condition of each part;

[0078] 6-2) The steel coils are hoisted into the insulation device for insulation; resulting in a steel coil temperature of 945℃ inside the insulation device; the steel coils are evenly arranged.

[0079] 6-3) The heat preservation time is controlled at 26 hours, the cooling rate is 48℃ / h, and the steel coil is lifted out when the temperature of the steel coil reaches 32℃.

[0080] Example 4:

[0081] The difference between this embodiment and Example 1 is that the heat preservation and slow cooling process and its matching heat preservation device are not used in this embodiment.

[0082] Comparative example: According to the production method of a high oxidation-resistant electrothermal stainless steel strip with application number 201910331369.3, 309s stainless steel sheet coils are rolled.

[0083] Mechanical properties of Examples 1, 2, 3, 4, and Comparative Example 1 were tested according to GB / T4237-2015, and the results are shown in Table 1.

[0084] Table 1:

[0085]

[0086] According to the summary in Table 1, the 309s stainless steel produced by Examples 1, 2, 3, and 4 using the above-mentioned process meets the national standard requirements for mechanical properties. In particular, the hardness of the steel coil is uniform in the middle and on both sides, solving the problem of soft and hard edges of the steel coil. However, Example 4 and the comparative example did not use the heat preservation process of this invention or the heat preservation device to keep the steel coil warm. After testing, the hardness of the steel coil did not meet the standard. Due to the uneven cooling rate, the hardness of the middle of the steel coil was qualified, but the hardness of the two sides was not qualified, with a large difference.

[0087] The above description is merely an example and illustration of the structure of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A process for overcoming the soft and hard edges of hot-rolled ferritic stainless steel, characterized in that... The process steps are as follows: 1) Prepare steel billets for heating in a heating furnace. The heating steps are divided into preheating section, heating section one, heating section two, and soaking section. 2) High-pressure water descaling: The oxide scale on the surface of the heated steel billet is removed by a high-pressure water jetting mechanism; 3) Rough rolling: The heated steel billet is conveyed to the rough rolling mill via conveyor rollers, and the conveying device is equipped with a corresponding heat preservation cover; 4) Finishing rolling: After being conveyed, the material enters the finishing rolling mechanism. The finishing rolling adopts speed-increasing rolling. The starting temperature of finishing rolling is set to 1000-1050℃; the finishing rolling ending temperature is 900-980℃. 5) Winding: After precision rolling, the rolls are fed into the winding mechanism for winding; 6) Insulation and slow cooling: The steel coil is hoisted into the insulation device for insulation and slow cooling; 6-1) Clean the accumulated oxide scale inside the insulation device box, and then check the sealing condition of each part; 6-2) Hoist the steel coils into the insulation device for insulation; the temperature of the steel coils should be >920℃ when hoisting into the insulation device; the steel coils should be evenly arranged. 6-3) The heat preservation time should be controlled at 25-26.5 hours, and the cooling rate should be 30-55℃ / h. Wait for the steel coil to cool down slowly. When the temperature of the steel coil is below 35℃, lift the steel coil out. 6-4) Clean up any loose oxide scale that has fallen inside the insulation device; The insulation device includes a box body, an insulation layer, a buffer mechanism, a cleaning mechanism, and a support mechanism; the insulation layer is located on the inner wall of the box body, the cleaning mechanism and the support mechanism are spaced apart and located at the bottom of the box body, and the buffer mechanism is located on both sides of the box body and corresponds to the support mechanism; The enclosure has fixed plates on both sides, with electric push rods on the fixed plates. The top of the enclosure has a guide rail and a cover. One end of the cover is slidably connected to the guide rail, and the other end is fixedly connected to the top shaft of the electric push rod. The electric push rod drives the cover to slide along the guide rail to open or close the enclosure. The bottom of the enclosure has a first cleaning groove, a first guide groove, a second cleaning groove, a second guide groove, and a third cleaning groove. The first cleaning groove connects to the first guide groove; the second cleaning groove connects to the second guide groove and the third cleaning groove; the first and second cleaning grooves are spaced apart. The inner wall of the enclosure has a first mounting groove and a second mounting groove. The cleaning mechanism includes a first motor, a scraper frame, a first bidirectional lead screw, a first telescopic plate, a support rod, a first fixed seat, and a first baffle. A pair of first fixed seats are located at both ends of the second cleaning groove. The first bidirectional lead screw is rotatably connected to the first fixed seats at both ends. The first motor is fixed to one side of the housing, and its shaft is connected to the first bidirectional lead screw. The first baffle is slidably connected to the first fixed seats and can slide up and down to open or close the two ends of the second cleaning groove. A pair of support rods are located and fixed to the inner wall of the second cleaning groove. A stop block is provided on the support rod. The first telescopic plate is located inside the second cleaning groove and corresponds to the third cleaning groove. The first telescopic plate is supported on both sides by the support rod. One end of the first telescopic plate pushes against the stop block, and a stop rod is provided on the first telescopic plate. The scraper includes a sliding plate, an arc-shaped scraper, and a top rod. The sliding plate is connected to a first bidirectional screw via a thread and is located in a second guide groove. The arc-shaped scraper is fixedly connected to the sliding plate. The arc-shaped scraper away from the stop is provided with a top rod and a corresponding stop rod. The support mechanism includes a second motor, a support base, a second bidirectional lead screw, a second fixed base, and a second baffle. A pair of second fixed bases are respectively fixed to both ends of the first cleaning groove. The two ends of the second bidirectional lead screw are rotatably connected to the second fixed bases. The second motor is fixed to one side of the housing, and its shaft is connected to the second bidirectional lead screw. The second baffle is slidably connected to the second fixed base and slides up and down to close or open the two ends of the first cleaning groove to prevent excessive heat loss from the housing. A handle is provided on the second baffle for lifting. A pair of support bases are provided, each threadedly connected to the second bidirectional lead screw and passing through the first guide groove. The support base has an arc-shaped surface to accommodate the steel coil. Several drainage holes are provided on the arc-shaped surface of the support base, and a ramp is provided inside the support base. Oxide scale on the steel coil falls through the drainage holes, slides down the ramp to both sides of the support base, and is then collected and cleaned by the cleaning mechanism. The second motor drives the second bidirectional lead screw to rotate, thereby causing the support base to slide along the first guide groove to accommodate steel coils of different diameters.

2. The process for overcoming the soft and hard edges of hot-rolled ferritic stainless steel according to claim 1, characterized in that... In step 1), the preheating stage is controlled at 555-600℃ for 90-100 minutes. After the preheating stage, the first heating stage begins, with the temperature controlled at 900-1000℃ for 75-85 minutes. After the first heating stage, the second heating stage begins, with the temperature controlled at 1100-1200℃ for 60-70 minutes. After the second heating stage, the homogenization stage begins, with the temperature controlled at 1150-1200℃ for 50-60 minutes. The total heating time is 275-315 minutes.

3. The process for overcoming the soft and hard edges of hot-rolled ferritic stainless steel according to claim 1, characterized in that... In step 3), the billet is rolled in 6 passes during rough rolling; the reduction rate for the first pass is 31-32.6%; the reduction rate for the second pass is 27-28.5%; the reduction rate for the third pass is 27-28.5%; the reduction rate for the fourth pass is 23-24%; the reduction rate for the fifth pass is 23-24%; and the reduction rate for the sixth pass is 22-22.5%.

4. The process for overcoming the soft and hard edges of hot-rolled ferritic stainless steel according to claim 1, characterized in that... The insulation layer includes a first bracket, a second bracket, a locking pin, a mesh frame, and rock wool. The first bracket has a first insertion hole and an insertion rod on one side. The second bracket has an insertion sleeve on one side corresponding to the insertion rod. The second bracket has a second insertion hole and a slot. The other side of the second bracket has a first slide rail located in a first mounting groove. The rock wool is placed between the first bracket and the second bracket. The first bracket passes through the rock wool and fits into the insertion sleeve via the insertion rod. The locking pin has symmetrical limiting blocks at both ends. After the locking pin passes through the first insertion hole and the second insertion hole, it rotates to fix the first bracket, the second bracket, and the rock wool. The mesh frame is inserted into the slot to surround and fix the rock wool.

5. The process for overcoming the soft and hard edges of hot-rolled ferritic stainless steel according to claim 1, characterized in that... The buffer mechanism includes a mounting plate, a second slide rail, a first housing, and a second housing. The second slide rail is located in a second mounting groove and is interlocked with each other. One end of the second housing is fixedly connected to the second slide rail. The first housing is slidably sleeved onto the second housing. The mounting plate has several rollers on one side and a telescopic shaft on the other side. The telescopic shaft passes through the first housing and is fixedly connected to the second slide rail. A limiting plate is provided on the telescopic shaft and located on one side of the first housing. A spring is sleeved on the telescopic shaft, and both ends of the spring abut against the limiting plate and the second slide rail, respectively. The spring pushes the limiting plate, the first housing, and the mounting plate outward. The first housing and the second housing are used to protect the spring and prevent it from losing its mechanical elasticity under prolonged high temperatures.

6. The process for overcoming the soft and hard edges of hot-rolled ferritic stainless steel according to claim 1, characterized in that... A second telescopic plate is provided between the support seats, and the two ends of the second telescopic plate are fixedly connected to the support seats; a second telescopic plate is provided between the support seats and the second fixed seat, and the two ends of the second telescopic plate between the support seats and the second fixed seat are fixedly connected to the second fixed seat and the support seat respectively; the second telescopic plate is designed as an inverted V shape and covers the second bidirectional screw to prevent oxide scale from entering the threads of the second bidirectional screw and affecting its use; the support seats slide to push the second telescopic plate to compress or unfold.

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