A hot continuous rolling method for stainless steel clad plate with constant reduction ratio

Abstract

A hot continuous rolling production method for stainless steel composite plates with constant reduction rate belongs to the field of composite material preparation technology. It includes composite slab preparation, slab heating, rough rolling, finish rolling, laminar flow cooling, coiling, and cross-cutting processes. The composite slab consists of two layers: a carbon steel substrate and a stainless steel cladding. The substrate has a thickness of H1 and a length of L1; the cladding has a thickness of H2 and a length of L2, where L2 = L1 × (1 - 0.1ε), and both have the same width. The thickness ratio of the composite slab is ε = H2 / H1, and 0.1 ≤ ε ≤ 0.2. After cleaning the surfaces of the substrate and cladding, they are assembled, welded, and vacuum-sealed to form the composite slab. In the slab heating process, the substrate side uses 'a' burners, where a = 8–12; the cladding side uses 'b' burners, where b = a × (1 + ε). In the rough rolling process, a constant reduction rate rolling is used. This invention achieves efficient hot continuous rolling production of composite plates, with a 100% interface bonding rate between the cladding and substrate.

Description

Technical Field

[0001] This invention belongs to the field of composite material preparation technology, specifically relating to a hot continuous rolling production method for stainless steel composite plates with constant reduction rate. Background Technology

[0002] With societal development, traditional single-metal materials can no longer meet societal needs, while the high cost of precious metals prevents their large-scale production. New stainless steel composite materials have emerged as a breakthrough. Stainless steel composite plates are composite materials with carbon steel as the base material and stainless steel as the cladding. This not only reduces the use of precious alloys and saves costs, but also combines the excellent mechanical properties of carbon steel with the superior corrosion resistance of stainless steel. Therefore, they are widely used in industrial fields such as shipbuilding, bridge construction, and chemical containers.

[0003] Currently, the main production methods for composite panels include explosive rolling and rolling. Explosive rolling results in low production efficiency, poor product quality, and severe environmental pollution. Rolling, on the other hand, combines the base material and the cladding material through rolling, resulting in high production efficiency and good product shape, thus becoming the mainstream method. However, rolling production often faces challenges such as uneven heating of the cast billet, poor interfacial bonding between the base material and the cladding material, and difficulties in coordinating rolling deformation due to inconsistent materials on the upper and lower surfaces of the billet.

[0004] Patent application No. 202310384402.5 discloses a stainless steel composite plate with excellent shape and its preparation method. The composite plate with excellent shape can be obtained by intermittent cooling, straightening and stacking cooling. However, the method uses a four-layer slab composed of substrate + composite material + composite material + substrate, which not only makes the blanking process complicated, but also requires the composite plate to be separated and straightened after rolling, resulting in a complicated process flow. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a hot continuous rolling production method for stainless steel composite plates with a constant reduction rate. Based on the thickness ratio of the base material and the composite material in the slab, the number of burners on the upper and lower surfaces of the slab is adjusted to ensure the heating temperature and uniformity of the slab. By setting a constant reduction rate during rough rolling, the quality of the composite interface of the product is guaranteed. At the same time, the constant reduction rate can avoid coordination difficulties caused by different materials on the upper and lower surfaces of the slab during rolling, thus ensuring smooth production.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows:

[0007] A hot continuous rolling production method for stainless steel composite plates with constant reduction rate includes composite slab preparation, slab heating, rough rolling, finish rolling, laminar flow cooling, coiling, and cross-cutting processes.

[0008] The composite slab preparation process involves a composite slab comprising two layers: a carbon steel substrate and a stainless steel cladding. The carbon steel substrate has a thickness of H1 and a length of L1; the stainless steel cladding has a thickness of H2 and a length of L2; the composite slab has a thickness of H, where H = H1 + H2, and the thickness ratio of the composite slab is ε, where ε = H2 / H1, and 0.1 ≤ ε ≤ 0.2; the length of the cladding is related to the length of the substrate by L2 = L1 × (1 - 0.1ε), and the substrate and cladding have the same width; after cleaning the surfaces of the substrate and cladding, the composite slab is assembled, welded, and then vacuum-sealed to form the composite slab.

[0009] In the slab heating process, to ensure the uniformity of slab heating, the number of burners used on the base material side is a, where a = 8 to 12; the number of burners used on the composite material side is b, where b = a × (1 + ε).

[0010] In the slab rough rolling process, a constant reduction rate is used to ensure good interfacial bonding between the substrate and the composite material. The constant reduction rate is set to 80%.

[0011] Furthermore, the thickness H of the composite slab is 170–220 mm.

[0012] Furthermore, in the slab heating process, the heating time is 190-280 min, the holding time is 30-60 min, and the furnace exit temperature is 1240±20℃.

[0013] In the slab roughing process, when the target thickness h of the rolled product is 4mm ≤ h ≤ 10mm, 3+5 passes are used for roughing; when the target thickness h is 10mm < h ≤ 16mm, 3+3 passes are used for roughing. By using different roughing passes for products with different target thicknesses, a constant reduction rate is ensured. In addition, a constant reduction rate avoids coordination difficulties caused by different materials on the upper and lower surfaces of the slab during rolling, reduces the risk of steel accumulation caused by frequent adjustments to the rolling forces of the upper and lower rolls during production, and thus ensures smooth production.

[0014] Furthermore, the finishing rolling process employs 7 passes, with the finishing rolling inlet temperature controlled at 950–1050°C and the final rolling temperature controlled at 860–900°C.

[0015] Furthermore, in the laminar flow cooling process, the laminar flow cooling stage adopts a front-end 1 / 2 cooling mode, the cooling water temperature is controlled at 25-35℃, the cooling rate is controlled at 20-40℃ / s, and the winding is performed after cooling to 620-660℃.

[0016] Furthermore, in the cross-cutting process, the composite steel coil is cross-cut to a fixed length, and both sides are cut off, with a cutting margin of 20-40mm.

[0017] Compared with existing technologies, the beneficial effects of this invention are: 1. By controlling the length of the substrate and composite material, this invention avoids the problem of substrate or composite material overflow at the tail end in the produced composite plate; 2. By controlling the number of burners in the heating furnace, the uniformity of heating temperature on the upper and lower surfaces of the composite slab is ensured, and the temperature difference between the upper and lower surfaces is controlled within 20℃; 3. By using a constant reduction rate, the quality of the interface composite is ensured, while avoiding coordination difficulties caused by different materials on the upper and lower surfaces of the slab during rolling, reducing the risk of steel accumulation caused by frequent adjustments of the rolling force of the upper and lower rolls during production, thereby ensuring smooth production. The resulting product has a 100% composite layer bonding rate, and both the internal and external bending of the product are qualified. Detailed Implementation

[0018] The dimensions of the substrate and composite material in Examples 1-5 of this invention are shown in Table 1, the heating process parameters are shown in Table 2, and the rolling and cross-cutting process parameters for each example are shown in Table 3.

[0019] Table 1 Dimensions of Substrate and Composite Materials for Each Embodiment

[0020]

[0021] Table 2 Heating process parameters for each embodiment

[0022] Example 1 2 3 4 5 a / each 9 8 11 10 12 b / each 10 9 13 12 14 Heating time / min 210 190 260 250 280 Insulation time / min 30 35 60 41 52 Furnace temperature / ℃ 1254 1220 1260 1235 1243

[0023] Table 3 Rolling and Cross-cutting Process Parameters for Each Embodiment

[0024]

[0025]

[0026] The stainless steel composite plates produced using the method of this invention avoid the problem of substrate or composite material overflow at the tail end, reducing material waste. The slab heating temperature is uniform, with the temperature difference between the upper and lower surfaces controlled within 20°C. The bonding between the composite material and the substrate is good, with a 100% composite layer bonding rate. The product passes both internal and external bending tests. The use of constant reduction rate rolling reduces the risk of steel piling caused by frequent adjustments to the rolling force of the upper and lower rolls during production. The overall production process is smooth, achieving the goal of efficient hot continuous rolling production of composite plates.

Claims

1. A method of hot continuous rolling of stainless steel clad plate with constant reduction ratio, characterized in that: It includes composite slab preparation, slab heating, rough rolling, finish rolling, laminar flow cooling, coiling, and cross-cutting processes; The composite slab preparation process involves a composite slab comprising two layers: a carbon steel substrate and a stainless steel cladding. The carbon steel substrate has a thickness of H1 and a length of L1; the stainless steel cladding has a thickness of H2 and a length of L2; the composite slab has a thickness of H, where H = H1 + H2, and the thickness ratio of the composite slab is ε, where ε = H2 / H1, and 0.1 ≤ ε ≤ 0.2; the length of the cladding is related to the length of the substrate by L2 = L1 × (1 - 0.1ε), and the substrate and cladding have the same width; after cleaning the surfaces of the substrate and cladding, the composite slab is assembled, welded, and then vacuum-sealed to form the composite slab; the thickness H of the composite slab is 170–220 mm. In the slab heating process, the number of burners used on the substrate side is a, where a = 8 to 12; and the number of burners used on the composite side is b, where b = a × (1 + ε). The roughing process uses a constant reduction rate, which is set to 80%. When the target thickness h of the rolled product is 4mm≤h≤10mm, 3+5 passes of roughing are used. When the target thickness h of the rolled product is 10mm<h≤16mm, 3+3 passes of roughing are used.

2. The method of hot continuous rolling production of stainless steel clad plate at constant rolling rate according to claim 1, characterized in that, The slab heating process has a heating time of 190–280 min, a holding time of 30–60 min, and a furnace exit temperature of 1240 ± 20℃.

3. The method of hot continuous rolling production of stainless steel clad plate at constant rolling rate according to claim 2, characterized in that, The finishing rolling process employs 7 passes, with the finishing rolling inlet temperature controlled at 950–1050℃ and the finishing rolling temperature controlled at 860–900℃.

4. The hot continuous rolling production method for stainless steel composite plates with constant reduction rate according to claim 3, characterized in that, The laminar flow cooling process adopts a front-stage 1 / 2 cooling mode, with the cooling water temperature controlled at 25-35℃ and the cooling rate controlled at 20-40℃ / s. The coil is then wound up after cooling to 620-660℃.

5. The hot continuous rolling production method of stainless steel composite plate with constant reduction rate according to any one of claims 1-4, characterized in that, The cross-cutting process involves cross-cutting the composite steel coil to a fixed length and removing both sides, with a cutting margin of 20-40mm.

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