A pickling process for hot-rolled 2205 duplex stainless steel coil

Abstract

The present invention discloses a pickling process for hot-rolled coils of 2205 duplex stainless steel, and the specific process steps are as follows: 1) heating; 2) high-pressure water descaling; 3) rough rolling: the steel ingot is rolled for 7 passes during rough rolling; 4) finishing rolling: after transmission, it enters the finishing rolling mechanism, and the finishing rolling adopts speed-increasing rolling; 5) coiling: after finishing rolling, it is sent to the coiling mechanism for coiling; 6) uncoiling and welding: 7) annealing: 8) phosphorus-breaking shot blasting: the annealed stainless steel plate is shot blasted by a shot blasting machine; 9) pickling: the stainless steel plate is pickled by the pickling mechanism to remove the oxide scale; 10) cleaning and drying. The present invention avoids the edge crack defect in the hot rolling process by optimizing the process.

Description

Technical Field

[0001] The invention belongs to the technical field of stainless steel production, and particularly relates to a pickling process for a 2205 duplex stainless steel hot-rolled coil. Background Art

[0002] 2205 duplex stainless steel is a typical ultra-low carbon duplex (ferrite + austenite) stainless steel containing N.Mo elements. It combines the advantages of ferrite stainless steel and austenite stainless steel, so it has good mechanical properties and corrosion resistance. It is widely used in shipbuilding, petroleum, chemical industry, papermaking and other fields. Duplex stainless steel is a kind of stainless steel in which the ferrite phase and austenite phase each account for nearly half of the solid solution structure. It has excellent mechanical properties and welding properties, as well as good corrosion resistance in a variety of corrosive environments.

[0003] However, while the duplex structure gives duplex stainless steel excellent properties, it also brings the disadvantage of being difficult to process. During the hot working process, due to the different hardness of the ferrite phase and the austenite phase, and the different softening mechanisms of the two phases, the deformation of the two phases is not coordinated, cracks are easily generated between the phases, and the thermoplasticity is deteriorated. 2205, as the second generation of duplex stainless steel, has been widely used in many fields, but due to the addition of 0.15% to 0.20% nitrogen in the composition, the austenite phase is greatly strengthened, the hardness difference between the two phases is increased, and its hot workability is worse.

[0004] 1) During the hot rolling process, 2205 duplex stainless steel is prone to edge crack defects, which seriously restricts the production of this stainless steel. Many scholars at home and abroad have studied the formation mechanism of edge crack defects in duplex stainless steel and believe that the grain boundary between austenite and ferrite in duplex stainless steel is a relatively weak bonding site, which is prone to form crack sources, and the crack sources expand to form edge crack defects.

[0005] 2) Before the heated plate is fed into the rolling mill, high-pressure water descaling is required to prevent the iron oxide from being pressed into the steel strip. Usually, high-pressure water descaling uses a fixed nozzle-steel strip distance and a fixed spray pressure. When a single variety is the majority, there is no problem. However, with the diversification of hot-rolled products, the thickness variation range of steel strips has increased significantly. For steel strips of different thicknesses, the same pressure is used for spraying, and the descaling effect cannot be guaranteed. For example, when the thickness of the inlet billet becomes thinner, the spray distance increases, resulting in a decrease in the descaling effect. Summary of the invention

[0006] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a pickling process for hot-rolled coils of 2205 duplex stainless steel, which avoids edge cracking defects during the hot rolling process by optimizing the process.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] The specific process steps of a pickling process for hot-rolled 2205 duplex stainless steel coil are as follows:

[0009] 1) Prepare the steel billet to be heated in a heating furnace, and the heating steps are divided into a preheating section, a heating section, a second heating section, and a soaking section; in the preheating section, the temperature is controlled at 810-850°C, and the heating time is 45-75min; after the preheating section is completed, the first heating section is heated, the temperature is controlled at 1080-1120°C, and the heating time is 35-60min; after the first heating section is completed, the second heating section is heated, the temperature is controlled at 1040-1060°C, and the heating time is 40-90min; after the second heating section is completed, the soaking section is heated, the temperature is controlled at 1270-1280°C, and the heating time is 50-80min; the high temperature section includes the second heating section and the soaking section, the temperature is 90-170min, and the total heating time is 170-305min.

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

[0011] 3) Rough rolling: The heated ingot is transferred to the rough rolling mill through the transfer roller, and the transfer device is provided with a corresponding heat preservation cover; the ingot is rolled in 7 passes during the rough rolling; the first pass reduction rate is 16-19%; the second pass reduction rate is 16-19%; the third pass reduction rate is 16-19%; the fourth pass reduction rate is 21-23%; the fifth pass reduction rate is 21-23%; the sixth pass reduction rate is 22-24%; the seventh pass reduction rate is 25-26%;

[0012] 4) Finishing rolling: After transmission, it enters the finishing rolling mechanism, and the finishing rolling adopts speed-increasing rolling. The starting temperature of the finishing rolling is set at 1070-1090°C; the ending temperature of the finishing rolling is greater than 900°C.

[0013] 5) Coiling: After finishing rolling, the steel is sent to the coiling mechanism for coiling.

[0014] 6) Uncoiling and welding: The two adjacent sets of steel plates are welded and fixed by welding mechanism to facilitate the overall pickling of the steel plates.

[0015] 7) Annealing: The stainless steel plate is annealed by an annealing mechanism and then cooled.

[0016] 8) Phosphorus-breaking shot blasting: The annealed stainless steel plate is shot blasted by a shot blasting machine.

[0017] 9) Pickling: The stainless steel plate is pickled to remove the oxide scale by the pickling mechanism, and the transmission speed is 28-32m / min; the pickling process has a mixed acid stage and a mixed acid stage; the HNO3 concentration of the mixed acid stage is 80±5g / L, the HF concentration is 35±5g / L, the metal ion is <40g / L, and the temperature is 50-55°C; the HNO3 concentration of the mixed acid stage is 65±5g / L, the HF concentration is 35±5g / L, the metal ion is <40g / L, and the temperature is 40-45°C.

[0018] 10) Cleaning and drying: The pickled stainless steel plate is cleaned by a cleaning mechanism, and then dried by a drying system before curling.

[0019] In step 2), the high-pressure water jetting mechanism includes a frame, a fixed seat, a jetting mechanism, an adjusting mechanism I, and an adjusting mechanism II; the adjusting mechanism I is arranged on one side of the frame, the adjusting mechanism II is arranged on the top of the frame, the fixed seat is arranged on the frame and movably connected to the adjusting mechanism II, and the adjusting mechanism I is movably connected to the adjusting mechanism II; a rolling mill is arranged on one side of the high-pressure water jetting mechanism, and a heat preservation mechanism is arranged between adjacent rolling mills.

[0020] The heat preservation mechanism comprises a fixed cover, a fixed frame I, a mounting frame I, a fixed frame II, a mounting frame II, and a support beam; a pair of support beams are provided and are respectively arranged on both sides of the rolling mill, and the support beams are fixedly connected to the rolling mill; a transmission roller is arranged between the support beams; a pair of fixed covers are provided and are symmetrically fixed on the upper and lower sides of the support beam; the fixed frame I and the mounting frame I are arranged in the fixed cover, a T-shaped slot is arranged on the fixed frame I, a T-shaped block is arranged on the mounting frame I, and the mounting frame I is connected to the fixed frame I through the T-shaped block arranged in the T-shaped slot; a socket I is arranged on the mounting frame I; the structures of the fixed frame II and the mounting frame II are the same as those of the fixed frame I and the mounting frame I, and the mounting frame II is provided with a socket II;

[0021] The frame is provided with a fixed arm and a plurality of transmission rollers, and the fixed arm is provided with a slide groove.

[0022] The fixing seats are provided with two groups and are respectively arranged in the slide grooves on the fixing arms at both sides of the frame, each group of fixing seats is provided with a pair of fixing seats and are symmetrically distributed up and down; a T-shaped groove is provided on one side of the fixing seat.

[0023] The adjusting mechanism I comprises a support plate, a connecting arm, a rack I, an electric push rod, a motor I, a rotating shaft, a mounting plate, and a rack II; a T-slot is provided on one side of the frame, a T-block I is provided on one side of the support plate and is arranged in the T-slot on one side of the frame, a groove and a fixing block are provided at one end of the support plate, and the fixing block is fixed by bolts; the motor I is fixed on the support plate, a gear I is provided at the shaft end of the motor I, a limit plate, a gear II, and a cam are provided on the rotating shaft, and the limit plate is arranged at the end of the rotating shaft; during installation, the limit plate is arranged on the support plate, and the limit plate is arranged on the end of the rotating shaft. The plate is then fixed in the groove at the end by a fixing block, gear I meshes with gear II, and the cam is provided with a plurality of slots; the mounting plate is fixed on the frame, the mounting plate is provided with a T-slot, the electric push rod is fixed on the mounting plate, a T-block is provided at the bottom of the rack I and is arranged in the T-slot on the mounting plate; a T-block II is provided on one side of the rack II and is arranged in the T-slot of the fixing seat, a fixed shaft is provided on one side of the rack II, and a pair of through slots are provided on the rack II; one end of the connecting arm is hinged to the fixed shaft, and the other end is hinged to the support plate.

[0024] The adjustment mechanism II includes a motor II, a bidirectional lead screw, a through shaft, and a fixed plate; the bidirectional lead screw is connected to a fixed seat through a thread, a bevel gear is provided on the top of the bidirectional lead screw, the fixed plate is fixedly connected to a fixed arm, both ends of the through shaft are fixed to the fixed plate through a bearing seat, a bevel gear is provided on the through shaft and meshes with the bevel gear on the top of the bidirectional lead screw, the motor II is fixed on the fixed plate, and the output shaft of the motor II is fixedly connected to the through shaft.

[0025] The spray mechanism includes a high-pressure nozzle, a hose, a water pipe, a water pump, and a water tank; the water tank is arranged below the fixed arm and fixedly connected to the frame, both ends of the high-pressure nozzle are rotatably connected to the fixed seat, one end of the high-pressure nozzle is provided with a gear and meshes with the rack II, the water pipe is fixed to the frame through a fixed clamp, one end of the water pipe is connected to the high-pressure nozzle through a hose, and the other end is connected to the water pump, and the water pump is arranged in the water tank.

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

[0027] 1) A high-pressure water descaling device is provided in the rolling process step, and the stainless steel surface is descaled by high-pressure water spraying through a high-pressure water spraying mechanism; the rack II can be pulled up and down by the adjusting mechanism I to control the rotation of the high-pressure nozzle, change the spray angle, and quickly remove the oxide scale on the stainless steel surface. Further, in order to improve the descaling effect, the fixing seat can be controlled to move up and down by the adjusting mechanism II, thereby driving the high-pressure nozzle to move up and down, so as to achieve the effect of adjusting the distance between the high-pressure nozzle and the stainless steel plate; when it is necessary to adjust the height of the fixing seat and the high-pressure nozzle, firstly, the rack II is fixed to the fixing seat through the through groove by bolts, and then the motor I drives the rotating shaft to rotate, so that the slot on the cam is disengaged from the meshing with the rack I. At this time, the up and down movement of the fixing seat will drive the support plate to slide along the T-slot through the connecting arm. When the height adjustment is completed, the slot on the cam is first engaged with the rack I, and then the fixing bolts between the rack II and the fixing seat are released to facilitate the subsequent adjustment of the high-pressure nozzle angle; the oxide scale is effectively cleared, and the disadvantage of the oxide scale being rolled into the stainless steel is avoided;

[0028] 2) The use of 2205 duplex stainless steel produced by this process and the insulation mechanism for stainless steel insulation effectively avoids the situation of excessive temperature drop during the rolling process, thereby reducing the probability of edge cracking of stainless steel plates during production. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Attached Figure 1 It is a structural schematic diagram of a high-pressure water jetting mechanism and a heat preservation mechanism in a pickling process of a 2205 duplex stainless steel hot-rolled coil according to the present invention;

[0030] Attached Figure 2 It is a structural schematic diagram of a high-pressure water jetting mechanism in a pickling process of a 2205 duplex stainless steel hot-rolled coil according to the present invention;

[0031] Attached Figure 3 Yes Figure 2 A schematic diagram of the structure of the middle fixed seat;

[0032] Attached Figure 4 Yes Figure 2 Schematic diagram of the structure of the middle rack II;

[0033] Attached Figure 5 Yes Figure 2 Schematic diagram of the structure of the middle adjustment mechanism I;

[0034] Attached Figure 6 Yes Figure 5 A schematic diagram of the structure of the rotating shaft;

[0035] Attached Figure 7 Yes Figure 1 Schematic diagram of the structure of the middle insulation mechanism Figure 1 ;

[0036] Attached Figure 8 Yes Figure 7 Schematic diagram of the structure of the middle insulation mechanism Figure 2 ;

[0037] In the figure: 1, frame; 101, transmission roller; 102, fixed arm; 1021, slide; 2, fixed seat; 201, T-slot; 3, injection mechanism; 301, high-pressure nozzle; 302, hose; 303, water pipe; 304, water pump; 305, water tank; 4, adjustment mechanism I; 401, support plate; 4011, T-block I; 4012, fixed block; 402, connecting arm; 403, rack I; 404, electric push rod; 405, motor I; 4051, gear I; 406, rotating shaft; 4061, limit plate; 4062, gear Ⅱ; 4063, cam; 40631, slot; 407, mounting plate; 408, rack Ⅱ; 4081, T-block Ⅱ; 4082, through slot; 4083, fixed shaft; 5, adjustment mechanism Ⅱ; 501, motor Ⅱ; 502, two-way screw; 503, through shaft; 504, fixed plate; 6, stainless steel plate; 7, insulation mechanism; 701, fixed cover; 702, fixed frame Ⅰ; 703, mounting frame Ⅰ; 7031, socket Ⅰ; 704, fixed frame Ⅱ; 705, mounting frame Ⅱ; 7051, socket Ⅱ; 706, support beam; 8, rolling mill. DETAILED DESCRIPTION

[0038] To facilitate the understanding of those skilled in the art, Figure 1-8 , the technical solution of the present invention is further specifically described.

[0039] Embodiment 1:

[0040] A pickling process for hot-rolled 2205 duplex stainless steel coil, the specific process steps are as follows:

[0041] 1) Prepare the steel billet to be heated in the heating furnace. The heating steps are divided into preheating section, heating section one, heating section two, and soaking section. In the preheating section, the temperature is controlled at 812°C. After the preheating section is completed, the steel billet enters the heating section one and the temperature is controlled at 1110°C. After the heating section one, the steel billet enters the heating section two and the temperature is controlled at 1245°C. After the heating section two, the steel billet enters the soaking section and the temperature is controlled at 1278°C. The high temperature section includes the heating section two and the soaking section.

[0042] 2) High-pressure water descaling: The oxide scale on the surface of the heated steel billet is removed by a high-pressure water jet mechanism.

[0043] 3) Rough rolling: The heated ingot is transferred to the rough rolling mill through a transfer roller, and a corresponding heat preservation cover is provided on the conveying device; the ingot is rolled in 7 passes during the rough rolling; the reduction rate of the first pass is 16.5%; the reduction rate of the second pass is 17.5%; the reduction rate of the third pass is 16.5%; the reduction rate of the fourth pass is 21.5%; the reduction rate of the fifth pass is 21.8%; the reduction rate of the sixth pass is 22.5%; and the reduction rate of the seventh pass is 25.8%.

[0044] 4) Finishing rolling: After transmission, it enters the finishing rolling mechanism, and the finishing rolling adopts accelerated rolling, and the starting temperature of the finishing rolling is set to 1085℃; the ending temperature of the finishing rolling is 950℃.

[0045] 5) Coiling: After finishing rolling, the steel is sent to the coiling mechanism for coiling.

[0046] 6) Uncoiling and welding: The two adjacent sets of steel plates are welded and fixed by welding mechanism to facilitate the overall pickling of the steel plates.

[0047] 7) Annealing: The stainless steel plate is annealed by an annealing mechanism and then cooled.

[0048] 8) Phosphorus-breaking shot blasting: The annealed stainless steel plate is shot blasted by a shot blasting machine.

[0049] 9) Pickling: The stainless steel plate is pickled to remove the oxide scale by the pickling mechanism, and the transmission speed is 30m / min; the pickling process has a mixed acid stage and a mixed acid stage; the HNO3 concentration of the mixed acid stage is 75g / L, the HF concentration is 30g / L, the metal ion is 32g / L, and the temperature is 50°C; the HNO3 concentration of the mixed acid stage is 68g / L, the HF concentration is 31g / L, the metal ion is 36g / L, and the temperature is 45°C.

[0050] 10) Cleaning and drying: The pickled stainless steel plate is cleaned by a cleaning mechanism, and then dried by a drying system before curling.

[0051] In step 2), the high-pressure water jetting mechanism includes a frame 1, a fixed seat 2, a jetting mechanism 3, an adjusting mechanism I4, and an adjusting mechanism II5; the adjusting mechanism I4 is arranged on one side of the frame 1, the adjusting mechanism II5 is arranged on the top of the frame 1, the fixed seat 2 is arranged on the frame 1 and movably connected to the adjusting mechanism II5, and the adjusting mechanism I4 is movably connected to the adjusting mechanism II5; a rolling mill 8 is arranged on one side of the high-pressure water jetting mechanism, and a heat preservation mechanism 7 is arranged between adjacent rolling mills 8.

[0052] The heat preservation mechanism 7 includes a fixed cover 701, a fixed frame I 702, a mounting frame I 703, a fixed frame II 704, a mounting frame II 705, and a support beam 706; a pair of support beams 706 are respectively arranged on both sides of the rolling mill 8, and the support beams 706 are fixedly connected to the rolling mill 8; a transmission roller 101 is arranged between the support beams 706; the fixed cover 701 is provided with a pair of and symmetrically fixed on the upper and lower sides of the support beam 706; the fixed frame I 702 and the mounting frame I 703 are arranged in the fixed cover 701, a T-slot is arranged on the fixed frame I 702, a T-block is arranged on the mounting frame I 703, and the mounting frame I 703 is connected to the fixed frame I 702 through the T-block arranged in the T-slot; the mounting frame A socket I7031 is provided on I703 for placing thermal insulation rock wool; the structures of the fixing frame II704 and the mounting frame II705 are the same as those of the fixing frame I702 and the mounting frame I703, and a socket II7051 is provided on the mounting frame II705 for placing thermal insulation rock wool; the transmission process between the rolling mills 8 is insulated by the thermal insulation rock wool in the fixing cover 701 to avoid the rolling edge cracking caused by excessive temperature drop; when the thermal insulation rock wool needs to be replaced, it is only necessary to loosen the fixing bolts between the fixing cover 701 and the support beam 706, and then use a crane to lift the fixing cover 701 or a forklift to lift it, and then pull out the mounting frame I703 or the mounting frame II705 for replacement.

[0053] The frame 1 is provided with a fixed arm 102 and a plurality of transmission rollers 101 . The transmission rollers 101 are used to transmit the stainless steel plate 6 . The fixed arm 102 is provided with a slide groove 1021 .

[0054] The fixing seat 2 is provided with two groups and is respectively arranged in the slide grooves 1021 on the fixing arms 102 on both sides of the frame 1, and each group of fixing seats 2 is provided with a pair of fixing seats 2 and symmetrically distributed up and down; a T-shaped groove 201 is provided on one side of the fixing seat 2.

[0055] The adjusting mechanism I4 includes a support plate 401, a connecting arm 402, a rack I403, an electric push rod 404, a motor I405, a rotating shaft 406, a mounting plate 407, and a rack II408; a T-shaped slot is provided on one side of the frame 1, a T-shaped block I4011 is provided on one side of the support plate 401 and is arranged in the T-shaped slot on one side of the frame 1, a groove and a fixing block 4012 are provided at one end of the support plate 401, and the fixing block 4012 is fixed by bolts; the motor I405 is fixed On the support plate 401, a gear I 4051 is provided at the shaft end of the motor I 405, and a limit plate 4061, a gear II 4062, and a cam 4063 are provided on the rotating shaft 406. The limit plate 4061 is provided at the end of the rotating shaft 406. During installation, the limit plate 4061 is provided in a groove at the end of the support plate 401 and then fixed by a fixing block 4012, and the gear I 4051 meshes with the gear II 4062. The cam 4063 is provided with a plurality of slots 40631. The rotating shaft 406 is driven to rotate by the motor I 405, so that the slot 40631 engages with the teeth on the rack I 403; the mounting plate 407 is fixed on the frame 1, and a T-slot is provided on the mounting plate 407. The electric push rod 404 is fixed on the mounting plate 407. A T-block is provided at the bottom of the rack I 403 and is arranged in the T-slot on the mounting plate 407; a T-block II 4081 is provided on one side of the rack II 408 and is arranged in the T-slot 201 of the fixing seat 2. A fixed shaft 4083 is provided on one side of Ⅱ408, and a pair of through grooves 4082 are provided on the rack Ⅱ408; one end of the connecting arm 402 is hinged to the fixed shaft 4083, and the other end is hinged to the support plate 401; the rack Ⅰ403 is pushed to slide by the electric push rod 404, and then the cam 4063, the rotating shaft 406 and the support plate 401 are pushed along the T-slot, so that the rack Ⅱ408 is pushed to slide up and down along the T-slot 201 on the fixed seat 2 through the connecting arm 402.

[0056] The adjustment mechanism II5 includes a motor II501, a bidirectional lead screw 502, a through shaft 503, and a fixed plate 504; the bidirectional lead screw 502 is connected to the fixed seat 2 through a thread, a bevel gear is provided on the top of the bidirectional lead screw 502, the fixed plate 504 is fixedly connected to the fixed arm 102, both ends of the through shaft 503 are fixed to the fixed plate 504 through bearing seats, a bevel gear is provided on the through shaft 503 and meshes with the bevel gear on the top of the bidirectional lead screw 502, the motor II501 is fixed to the fixed plate 504, the output shaft of the motor II501 is fixedly connected to the through shaft 503, and the power provided by the motor II501 drives the bidirectional lead screw 502 to rotate, thereby driving the fixed seat 2 to move upward or downward in the slide groove 1021.

[0057] The spray mechanism 3 includes a high-pressure nozzle 301, a hose 302, a water pipe 303, a water pump 304, and a water tank 305; the water tank 305 is arranged below the fixed arm 102 and fixedly connected to the frame 1, both ends of the high-pressure nozzle 301 are rotatably connected to the fixed seat 2, one end of the high-pressure nozzle 301 is provided with a gear and meshes with the rack II 408, the water pipe 303 is fixed to the frame 1 through a fixed clamp, one end of the water pipe 303 is connected to the high-pressure nozzle 301 through the hose 302, and the other end is connected to the water pump 304, the water pump 304 is arranged in the water tank 305, water is supplied by the water pump 304, and then the surface of the stainless steel plate 6 is sprayed and descaled through the high-pressure nozzle 301.

[0058] The rack II 408 can be pulled up and down by the adjustment mechanism I4 to control the rotation of the high-pressure nozzle 301, change the spray angle, and quickly remove the oxide skin on the surface of the stainless steel. Furthermore, in order to improve the descaling effect, the fixing seat 2 can be controlled to move up and down by the adjustment mechanism II5, thereby driving the high-pressure nozzle 301 to move up and down, so as to achieve the effect of adjusting the distance between the high-pressure nozzle 301 and the stainless steel plate 6. When it is necessary to adjust the height of the fixing seat 2 and the high-pressure nozzle 301, firstly, the rack II 408 is bolted through the through slot 4082 to remove the oxide skin on the stainless steel surface. 08 is fixed to the fixing seat 2, and then the motor I 405 drives the rotating shaft 406 to rotate, so that the slot 40631 on the cam 4063 is disengaged from the gear rack I 403. At this time, the up and down movement of the fixing seat 2 will drive the support plate 401 to slide along the T-slot through the connecting arm 402. When the height adjustment is completed, the slot 40631 on the cam 4063 is first engaged with the gear rack I 403, and then the fixing bolts between the gear rack II 408 and the fixing seat 2 are released to facilitate the subsequent adjustment of the angle of the high-pressure nozzle 301.

[0059] Embodiment 2:

[0060] The difference compared with Example 1 is:

[0061] In step 1), the temperature of the preheating section is controlled at 825°C; after the preheating section is completed, the heating section enters the first heating section and the temperature is controlled at 1115°C; after the first heating section is completed, the heating section enters the second heating section and the temperature is controlled at 1250°C; after the second heating section is completed, the soaking section enters the second heating section and the temperature is controlled at 1272°C; the high temperature section includes the second heating section and the soaking section.

[0062] Step 3) Rough rolling: the heated ingot is transferred to the rough rolling mill via a transfer roller, and a corresponding heat preservation cover is provided on the transfer device; the ingot is rolled in 7 passes during the rough rolling; the reduction rate of the first pass is 17%; the reduction rate of the second pass is 18%; the reduction rate of the third pass is 17.2%; the reduction rate of the fourth pass is 22%; the reduction rate of the fifth pass is 22.6%; the reduction rate of the sixth pass is 22.8%; and the reduction rate of the seventh pass is 25.6%.

[0063] Step 4) Finishing rolling: After being transmitted, the steel enters the finishing rolling mechanism, and the finishing rolling adopts the speed increasing rolling, and the starting temperature of the finishing rolling is set to 1078°C; the finishing temperature of the finishing rolling is 945°C.

[0064] Step 9) Pickling: The stainless steel plate is pickled to remove the oxide scale by a pickling mechanism, and the transmission speed is 29m / min; the pickling process is provided with a mixed acid stage and a mixed acid stage; the HNO3 concentration of the mixed acid stage is 78g / L, the HF concentration is 35g / L, the metal ion is 28g / L, and the temperature is 52°C; the HNO3 concentration of the mixed acid stage is 62g / L, the HF concentration is 38g / L, the metal ion is 30g / L, and the temperature is 41°C.

[0065] Embodiment 3:

[0066] The difference compared with Example 1 is that;

[0067] In step 1), the temperature of the preheating section is controlled at 845°C; after the preheating section is completed, the heating is started in the first heating section, and the temperature is controlled at 1085°C; after the first heating section is completed, the heating is started in the second heating section, and the temperature is controlled at 1255°C; after the second heating section is completed, the soaking section is entered, and the temperature is controlled at 1280°C; the high temperature section includes the second heating section and the soaking section.

[0068] Step 3) Rough rolling: The heated ingot is transferred to the rough rolling mill via a transfer roller, and a corresponding heat preservation cover is provided on the transfer device; the ingot is rolled in 7 passes during the rough rolling; the reduction rate of the first pass is 18%; the reduction rate of the second pass is 18.8%; the reduction rate of the third pass is 17.8%; the reduction rate of the fourth pass is 22.5%; the reduction rate of the fifth pass is 22%; the reduction rate of the sixth pass is 23%; and the reduction rate of the seventh pass is 25%.

[0069] Step 4) Finishing rolling: After being transmitted, the steel enters the finishing rolling mechanism, and the finishing rolling adopts the speed increasing rolling, and the starting temperature of the finishing rolling is set to 1085°C; the ending temperature of the finishing rolling is 965°C.

[0070] Step 9) Pickling: The stainless steel plate is pickled to remove the oxide scale by a pickling mechanism, and the transmission speed is 31m / min; the pickling process is provided with a mixed acid stage and a mixed acid stage; the HNO3 concentration of the mixed acid stage is 80g / L, the HF concentration is 38g / L, the metal ion is 38g / L, and the temperature is 54.5°C; the HNO3 concentration of the mixed acid stage is 60g / L, the HF concentration is 33g / L, the metal ion is 28g / L, and the temperature is 44°C.

[0071] Comparative Example: The plate is rolled by any hot rolling process in Examples 1-3, and then pickled by the pickling process in Patent Application Publication No. CN105543714A - A duplex stainless steel strip and a method for preparing near-net-shape thereof;

[0072] The mechanical properties of the above examples were tested according to GB / 4237-2015, and the test results are shown in the following table:

[0073]

[0074] According to the above standards, the appearance quality inspection of the plate and the results are as follows:

[0075] Surface inspection results of Example 1, Example 2 and Example 3: The plate surface is clean, without obvious scratches, indentations, pits and other defects; the surface has no cracks or peeling; at the same time, the surface quality of the rolled stainless steel is good, the plate shape is square, and the edges are neat without curling.

[0076] The surface inspection results of Comparative Examples 1 and 2: There are no obvious scratches, indentations, pits or other defects on the board surface; there are some dark spots on the surface.

[0077] According to the above conclusions, it can be known that the mechanical properties in the test results of the above-mentioned embodiments and comparative examples all meet the test standards of GB / 4237-2015; however, the surface quality of the boards in embodiments 1-3 is the best, and the surface quality of the comparative example boards shows different degrees of darkening of the surface.

[0078] The above contents are merely examples and explanations of the structure of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the structure of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A pickling process for hot-rolled 2205 duplex stainless steel coil, characterized in that The specific process steps are as follows: 1) Prepare the steel billet to be heated in a heating furnace, and the heating steps are divided into a preheating section, a heating section, a second heating section, and a soaking section in sequence; in the preheating section, the temperature is controlled at 810-850°C, and the heating time is 45-75min; after the preheating section is completed, enter the first heating section for heating, the temperature is controlled at 1080-1120°C, and the heating time is 35-60min; after the first heating section is completed, enter the second heating section for heating, the temperature is controlled at 1040-1060°C, and the heating time is 40-90min; after the second heating section is completed, enter the soaking section, the temperature is controlled at 1270-1280°C, and the heating time is 50-80min; the high temperature section includes the second heating section and the soaking section, the temperature is 90-170min, and the total heating time is 170-305min; 2) High-pressure water descaling: the oxide scale on the surface of the heated steel billet is removed by a high-pressure water jet mechanism; 3) Rough rolling: The heated ingot is transferred to the rough rolling mill through the transfer rollers, and a corresponding heat preservation cover is provided on the transfer device; during the rough rolling, the ingot is rolled for 7 passes; 4) Finishing rolling: After being transmitted, it enters the finishing rolling mechanism, and the finishing rolling adopts the speed-increasing rolling, and the starting temperature of the finishing rolling is set at 1070-1090°C; the finishing temperature of the finishing rolling is greater than 900°C; 5) Coiling: After finishing rolling, the steel is sent to the coiling mechanism for coiling; 6) Uncoiling and welding: The two adjacent sets of steel plates are welded and fixed by the welding mechanism to facilitate the overall pickling of the steel plates; 7) Annealing: The stainless steel plate is annealed by an annealing mechanism and then cooled; 8) Phosphorus breaking shot blasting: Shot blasting the annealed stainless steel plate through a shot blasting machine; 9) Pickling: The stainless steel plate is pickled to remove the oxide scale through the pickling mechanism, and the transmission speed is 28-32m / min; the pickling process is provided with mixed acid stage one and mixed acid stage two; 10) Cleaning and drying: The pickled stainless steel plate is cleaned by a cleaning mechanism, and then dried by a drying system before curling; In the step 2), the high-pressure water jetting mechanism comprises a frame, a fixed seat, a jetting mechanism, an adjusting mechanism I, and an adjusting mechanism II; the adjusting mechanism I is arranged on one side of the frame, the adjusting mechanism II is arranged on the top of the frame, the fixed seat is arranged on the frame and movably connected to the adjusting mechanism II, and the adjusting mechanism I is movably connected to the adjusting mechanism II; the frame is provided with a fixed arm and a plurality of transmission rollers, and the fixed arm is provided with a slide groove; the fixed seat is provided with two groups and is respectively arranged in the slide grooves on the fixed arms on both sides of the frame, and each group of fixed seats is provided with a pair of slide grooves and symmetrically distributed up and down; a T-shaped groove is provided on one side of the fixed seat; a rolling mill is provided on one side of the high-pressure water jetting mechanism, and a heat preservation mechanism is provided between adjacent rolling mills; The heat preservation mechanism comprises a fixed cover, a fixed frame I, a mounting frame I, a fixed frame II, a mounting frame II, and a support beam; a pair of support beams are provided and are respectively arranged on both sides of the rolling mill, and the support beams are fixedly connected to the rolling mill; a transmission roller is arranged between the support beams; a pair of fixed covers are provided and are symmetrically fixed on the upper and lower sides of the support beam; the fixed frame I and the mounting frame I are arranged in the fixed cover, a T-shaped slot is arranged on the fixed frame I, a T-shaped block is arranged on the mounting frame I, and the mounting frame I is connected to the fixed frame I through the T-shaped block arranged in the T-shaped slot; a socket I is arranged on the mounting frame I; the structures of the fixed frame II and the mounting frame II are the same as those of the fixed frame I and the mounting frame I, and the mounting frame II is provided with a socket II; The adjusting mechanism I comprises a support plate, a connecting arm, a rack I, an electric push rod, a motor I, a rotating shaft, a mounting plate, and a rack II; a T-slot is provided on one side of the frame, a T-block I is provided on one side of the support plate and is arranged in the T-slot on one side of the frame, a groove and a fixing block are provided at one end of the support plate, and the fixing block is fixed by bolts; the motor I is fixed on the support plate, a gear I is provided at the shaft end of the motor I, a limit plate, a gear II, and a cam are provided on the rotating shaft, and the limit plate is arranged at the end of the rotating shaft; during installation, the limit plate is arranged on the support plate, and the limit plate is arranged on the end of the rotating shaft. The plate is then fixed in the groove at the end thereof by a fixing block, gear I meshes with gear II, and the cam is provided with a plurality of slots; the mounting plate is fixed on the frame, the mounting plate is provided with a T-slot, the electric push rod is fixed on the mounting plate, a T-block is provided at the bottom of the rack I and is arranged in the T-slot on the mounting plate; a T-block II is provided on one side of the rack II and is arranged in the T-slot of the fixing seat, a fixing shaft is provided on one side of the rack II, and a pair of through slots are provided on the rack II; one end of the connecting arm is hinged to the fixing shaft, and the other end is hinged to the supporting plate; The adjustment mechanism II includes a motor II, a bidirectional lead screw, a through shaft, and a fixed plate; the bidirectional lead screw is connected to a fixed seat through a thread, a bevel gear is provided on the top of the bidirectional lead screw, the fixed plate is fixedly connected to a fixed arm, both ends of the through shaft are fixed to the fixed plate through a bearing seat, a bevel gear is provided on the through shaft and meshes with the bevel gear on the top of the bidirectional lead screw, the motor II is fixed to the fixed plate, and the output shaft of the motor II is fixedly connected to the through shaft; The spray mechanism includes a high-pressure nozzle, a hose, a water pipe, a water pump, and a water tank; the water tank is arranged below the fixed arm and fixedly connected to the frame, both ends of the high-pressure nozzle are rotatably connected to the fixed seat, one end of the high-pressure nozzle is provided with a gear and meshes with the rack II, the water pipe is fixed to the frame through a fixed clamp, one end of the water pipe is connected to the high-pressure nozzle through a hose, and the other end is connected to the water pump, and the water pump is arranged in the water tank.

2. A pickling process for hot-rolled 2205 duplex stainless steel coil according to claim 1, characterized in that Step 7) Rough rolling is performed in 7 passes, respectively: the first pass has a reduction rate of 16-19%; the second pass has a reduction rate of 16-19%; the third pass has a reduction rate of 16-19%; the fourth pass has a reduction rate of 21-23%; the fifth pass has a reduction rate of 21-23%; the sixth pass has a reduction rate of 22-24%; and the seventh pass has a reduction rate of 25-26%.

3. The pickling process for hot-rolled 2205 duplex stainless steel coil according to claim 1, characterized in that In step 9), the HNO3 concentration in the first mixed acid stage is 80±5g / L, the HF concentration is 35±5g / L, the metal ions are <40g / L, and the temperature is 50-55°C; the HNO3 concentration in the second mixed acid stage is 65±5g / L, the HF concentration is 35±5g / L, the metal ions are <40g / L, and the temperature is 40-45°C.

Images