Production method of ultra-thin ni-based ultra-low temperature environment steel

Abstract

The application discloses a production method of an ultrathin Ni-based super-low-temperature environment steel plate, and the steel plate is produced by using a composite blank, and the production process comprises the following steps: heating the composite blank, rolling, trimming, and delivering in a quenched and tempered state; wherein, in the rolling stage, the rolling reduction of the first five passes is 3-7 mm, and then the rolling reduction is 5-10 mm to the finished product thickness, and the rolled product is air-cooled. The steel plate produced by using the method has a rolling success rate of more than 97%, a good plate shape, no obvious plate shape defects such as cupping and hard bending, a flatness control within 6 mm / m and 11 mm / 2m, and a good surface quality of the steel plate, and no obvious surface defects such as iron oxide skin and hot pressing pit.

Description

Technical Field

[0001] The invention belongs to the technical field of steel metallurgy, and in particular relates to a production method of ultra-thin Ni-based steel for ultra-low temperature environments. Background Art

[0002] While producing wide and thick plate is not a major challenge for manufacturers, producing 4-7mm thick plate remains challenging. This is primarily due to the high risk of shape, surface finish, and thickness issues when rolling these ultra-thin plates, leading to unexpected production schedules. As the steel industry's market conditions become increasingly challenging, the availability of extremely thin plate has become a competitive area for many mills, with only a limited number of manufacturers capable of producing them.

[0003] Ni-based ultra-low-temperature steel is often used in the manufacture of LNG / LEG storage tanks for use in ultra-low-temperature environments. However, the rolling of ultra-thin Ni-based steel plates (4-7mm) and the avoidance of unplanned shape, surface finish, and thickness have long been difficult challenges for steel mills. Summary of the Invention

[0004] The purpose of the present invention is to provide a production method for ultra-thin Ni-based steel for ultra-low temperature environments. By precisely controlling the billet heating temperature, rolling reduction and quenching machine roll gap, the steel plate shape is effectively controlled and the rolling success rate reaches more than 97%.

[0005] To achieve the above objectives, the technical solution provided by the present invention is:

[0006] A method for producing ultra-thin Ni-based steel for ultra-low temperature environments, wherein the steel plate is produced from a composite billet, and the production process includes heating the composite billet, rolling, trimming, and delivering the steel plate in a quenched and tempered state. In the rolling stage, the first five rolling passes have a reduction of 3-7 mm, followed by a reduction of 5-10 mm until the steel plate reaches the finished product thickness, and then air cooling is performed after rolling.

[0007] Furthermore, the composite billet of the present invention is formed by cutting a 200-300 mm thick continuous casting billet to 50-100 mm, and mechanically peeling the upper and lower surfaces to remove defects such as oxidized iron scale.

[0008] Furthermore, when the composite blank of the present invention is heated, the temperature of the lower portion is 7-13° C. higher than the temperature of the upper portion.

[0009] Furthermore, the steel plates of the present invention are separated by vacuum suction cups after trimming.

[0010] Furthermore, during the quenching process of the steel plate of the present invention, the gap between the quenching machine rolls after leaving the quenching furnace is 0.1-0.5 mm smaller than the thickness of the steel plate.

[0011] Furthermore, the chemical composition and mass percentage of the steel plate of the present invention are: C: 0.04-0.07%, Si: 0.20-0.30%, Mn: 0.60-0.80%, Ni: 9.0-9.5%.

[0012] Furthermore, the thickness of the steel plate of the present invention is 4-7 mm.

[0013] The ultra-low temperature Ni-based steel plate described in the present invention refers to the standard GB / T 3531-2014.

[0014] The present invention provides a production method for ultra-thin Ni-based steel for ultra-low temperature environments. During the rolling process, a small reduction rolling process is adopted in the first five passes, and the rolling reduction is precisely controlled according to the composition, so as to ensure that the metal structure at the weld of the composite billet is completely bridged and sufficient strength is ensured between the upper and lower billets; the lower temperature is 7-13°C higher than the upper temperature, which reduces the metal elongation of the upper billet and ensures the flatness of the rolled steel plate; after leaving the quenching furnace, the quenching machine roll gap is 0.1-0.5mm smaller than the thickness of the steel plate, which ensures the flatness of the steel plate after quenching treatment.

[0015] The technical solution provided by the present invention has the following beneficial technical effects: 1) ultra-thin Ni-based ultra-low temperature steel is successfully rolled, and the steel plate rolling success rate reaches more than 97%; 2) the steel plate has a good plate shape, without obvious plate defects such as buckling and hard bending, and the inequality is controlled within 6mm / m and 11mm / 2m; 3) the steel plate surface quality is good, without obvious surface defects such as iron oxide scale and hot pressing pits, and the steel plate thickness tolerance is controlled within 0-0.8mm. DETAILED DESCRIPTION

[0016] The present invention will be further described in detail below with reference to specific embodiments.

[0017] Example 1

[0018] The steel plate in this embodiment has a thickness of 7 mm and a composition of C: 0.04%, Si: 0.20%, Mn: 0.60%, and Ni: 9.5%. It is produced from a composite billet. The production process includes heating the composite billet, rolling, trimming, and delivery in a quenched and tempered state. The details are as follows:

[0019] The composite billet is made by cutting the 200mm thick continuous casting billet into 50mm, and the upper and lower surfaces are mechanically peeled until there is no iron oxide scale defect.

[0020] When the composite billet is heated in a continuous furnace, the temperature of the lower part is 7°C higher than that of the upper part.

[0021] During the composite billet rolling stage, the first five rolling passes have a reduction of 7 mm, followed by a reduction of 10 mm until the finished product thickness is reached, and air cooling is performed after rolling.

[0022] After the steel plates are trimmed, they are separated using vacuum suction cups.

[0023] During the quenching process of the steel plate, the gap between the quenching machine rollers is 0.1mm smaller than the thickness of the steel plate after leaving the quenching furnace.

[0024] The rolling success rate, plate shape, roughness, surface quality and thickness tolerance of the steel plate in this embodiment are shown in Table 1.

[0025] Example 2

[0026] The steel plate in this embodiment has a thickness of 4 mm and a composition of C: 0.07%, Si: 0.30%, Mn: 0.80%, and Ni: 9.0%. It is produced from a composite billet. The production process includes heating the composite billet, rolling, trimming, and quenching and tempering. The details are as follows:

[0027] The composite billet is made by cutting the 300mm thick continuous casting billet into 100mm, and the upper and lower surfaces are mechanically peeled until there is no iron oxide scale defect.

[0028] When the composite billet is heated in a continuous furnace, the temperature of the lower part is 13°C higher than that of the upper part.

[0029] During the composite billet rolling stage, the first five rolling passes have a reduction of 3 mm, followed by a reduction of 5 mm until the finished product thickness is reached, and then air-cooled after rolling.

[0030] After the steel plates are trimmed, they are separated using vacuum suction cups.

[0031] During the quenching process of the steel plate, the gap between the quenching machine rollers is 0.5mm smaller than the thickness of the steel plate after leaving the quenching furnace.

[0032] The rolling success rate, plate shape, roughness, surface quality and thickness tolerance of the steel plate in this embodiment are shown in Table 1.

[0033] Example 3

[0034] The steel plate in this embodiment has a thickness of 6 mm and a composition of C: 0.05%, Si: 0.29%, Mn: 0.68%, and Ni: 9.3%. It is produced from composite billets. The production process includes heating the composite billets, rolling, trimming, and quenching and tempering. The details are as follows:

[0035] The composite billet is made by cutting the 200mm thick continuous casting billet into 60mm, and the upper and lower surfaces are mechanically peeled until there is no iron oxide scale defect.

[0036] When the composite billet is heated in a continuous furnace, the temperature of the lower part is 8°C higher than that of the upper part.

[0037] During the composite billet rolling stage, the first five rolling passes have a reduction of 5 mm, followed by a reduction of 7 mm until the finished product thickness is reached, and then air-cooled after rolling.

[0038] After the steel plates are trimmed, they are separated using vacuum suction cups.

[0039] During the quenching process of the steel plate, the gap between the quenching machine rollers is 0.2mm smaller than the thickness of the steel plate after leaving the quenching furnace.

[0040] The rolling success rate, plate shape, roughness, surface quality and thickness tolerance of the steel plate in this embodiment are shown in Table 1.

[0041] Example 4

[0042] The steel plate in this embodiment has a thickness of 4 mm and a composition of C: 0.06%, Si: 0.29%, Mn: 0.76%, and Ni: 9.4%. It is produced from composite billets. The production process includes heating, rolling, trimming, and quenching and tempering of the composite billets before delivery. The details are as follows:

[0043] The composite billet is made by cutting the 250mm thick continuous casting billet to 70mm, and the upper and lower surfaces are mechanically peeled until there is no iron oxide scale defect.

[0044] When the composite billet is heated in a continuous furnace, the temperature of the lower part is 12°C higher than that of the upper part.

[0045] During the composite billet rolling stage, the first five rolling passes have a reduction of 6 mm, followed by a reduction of 7 mm until the finished product thickness is reached, and then air-cooled after rolling.

[0046] After the steel plates are trimmed, they are separated using vacuum suction cups.

[0047] During the quenching process of the steel plate, the gap between the quenching machine rollers is 0.4mm smaller than the thickness of the steel plate after leaving the quenching furnace.

[0048] The rolling success rate, plate shape, roughness, surface quality and thickness tolerance of the steel plate in this embodiment are shown in Table 1.

[0049] Example 5

[0050] The steel plate in this embodiment has a thickness of 6 mm and a composition of C: 0.06%, Si: 0.22%, Mn: 0.71%, and Ni: 9.1%. It is produced from composite billets. The production process includes heating, rolling, trimming, and quenching and tempering of the composite billets before delivery. The details are as follows:

[0051] The composite billet is made by cutting 300mm thick continuous casting billets into 90mm thick billets, and the upper and lower surfaces are mechanically peeled until there is no iron oxide scale defect.

[0052] When the composite billet is heated in a continuous furnace, the temperature of the lower part is 8°C higher than that of the upper part.

[0053] During the composite billet rolling stage, the first five rolling passes have a reduction of 4 mm, followed by a reduction of 6 mm until the finished product thickness is reached, and air cooling is performed after rolling.

[0054] After the steel plates are trimmed, they are separated using vacuum suction cups.

[0055] During the quenching process of the steel plate, the gap between the quenching machine rollers is 0.3mm smaller than the thickness of the steel plate after leaving the quenching furnace.

[0056] The rolling success rate, plate shape, roughness, surface quality and thickness tolerance of the steel plate in this embodiment are shown in Table 1.

[0057] Example 6

[0058] The steel plate in this embodiment has a thickness of 4 mm and a composition of C: 0.05%, Si: 0.23%, Mn: 0.71%, and Ni: 9.0%. It is produced from composite billets. The production process includes heating, rolling, trimming, and quenching and tempering of the composite billets before delivery. The details are as follows:

[0059] The composite billet is made by cutting the 250mm thick continuous casting billet to 68mm, and the upper and lower surfaces are mechanically peeled until there is no iron oxide scale defect.

[0060] When the composite billet is heated in a continuous furnace, the temperature of the lower part is 10°C higher than that of the upper part.

[0061] During the composite billet rolling stage, the first five rolling passes have a reduction of 5 mm, followed by a reduction of 7 mm until the finished product thickness is reached, and then air-cooled after rolling.

[0062] After the steel plates are trimmed, they are separated using vacuum suction cups.

[0063] During the quenching process of the steel plate, the gap between the quenching machine rollers is 0.4mm smaller than the thickness of the steel plate after leaving the quenching furnace.

[0064] The rolling success rate, plate shape, roughness, surface quality and thickness tolerance of the steel plate in this embodiment are shown in Table 1.

[0065] Example 7

[0066] The steel plate in this embodiment has a thickness of 7 mm and a composition of C: 0.06%, Si: 0.23%, Mn: 0.62%, and Ni: 9.2%. It is produced from composite billets. The production process includes heating, rolling, trimming, and quenching and tempering of the composite billets before delivery. The details are as follows:

[0067] The composite billet is made by cutting the 200mm thick continuous casting billet into 60mm, and the upper and lower surfaces are mechanically peeled until there is no iron oxide scale defect.

[0068] When the composite billet is heated in a continuous furnace, the temperature of the lower part is 12°C higher than that of the upper part.

[0069] During the composite billet rolling stage, the first five rolling passes have a reduction of 6 mm, followed by a reduction of 9 mm until the finished product thickness is reached, and air cooling is performed after rolling.

[0070] After the steel plates are trimmed, they are separated using vacuum suction cups.

[0071] During the quenching process of the steel plate, the gap between the quenching machine rollers is 0.2mm smaller than the thickness of the steel plate after leaving the quenching furnace.

[0072] The rolling success rate, plate shape, roughness, surface quality and thickness tolerance of the steel plate in this embodiment are shown in Table 1.

[0073] Example 8

[0074] The steel plate in this embodiment has a thickness of 4 mm and a composition of C: 0.05%, Si: 0.27%, Mn: 0.73%, and Ni: 9.1%. It is produced from composite billets. The production process includes heating, rolling, trimming, and quenching and tempering of the composite billets before delivery. The details are as follows:

[0075] The composite billet is made by cutting the 300mm thick continuous casting billet into 80mm, and the upper and lower surfaces are mechanically peeled until there is no iron oxide scale defect.

[0076] When the composite billet is heated in a continuous furnace, the temperature of the lower part is 8°C higher than that of the upper part.

[0077] During the composite billet rolling stage, the first five rolling passes have a reduction of 6 mm, followed by a reduction of 7 mm until the finished product thickness is reached, and then air-cooled after rolling.

[0078] After the steel plates are trimmed, they are separated using vacuum suction cups.

[0079] During the quenching process of the steel plate, the gap between the quenching machine rollers is 0.5mm smaller than the thickness of the steel plate after leaving the quenching furnace.

[0080] The rolling success rate, plate shape, roughness, surface quality and thickness tolerance of the steel plate in this embodiment are shown in Table 1.

[0081] Table 1

[0082]

[0083] The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. Any modification or partial replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A method for producing ultra-thin Ni-based steel for ultra-low temperature environments, characterized in that: The steel plate is produced from composite billets. The production process includes heating, rolling, trimming, and quenching and tempering. During the rolling stage, the first five passes are rolled with a reduction of 3-7mm, followed by a reduction of 5-10mm to the finished thickness, and air cooling after rolling. When the composite blank is heated, the temperature of the lower portion is 7-13°C higher than the temperature of the upper portion; During the quenching process of the steel plate, the gap between the quenching machine rolls is 0.1-0.5 mm smaller than the thickness of the steel plate after leaving the quenching furnace.

2. The method for producing ultra-thin Ni-based steel for ultra-low temperature environments according to claim 1, characterized in that: The composite billet is formed by cutting a 200-300 mm thick continuous casting billet into a thickness of 50-100 mm, and the upper and lower surfaces are mechanically peeled until there is no iron oxide scale.

3. The method for producing ultra-thin Ni-based steel for ultra-low temperature environments according to claim 1, characterized in that: After trimming, vacuum suction cups are used for separation.

4. The method for producing ultra-thin Ni-based steel for ultra-low temperature environments according to any one of claims 1 to 3, characterized in that: The chemical composition of the steel plate and its mass percentage are: C: 0.04-0.07%, Si: 0.20-0.30%, Mn: 0.60-0.80%, Ni: 9.0-9.5%.

5. The method for producing ultra-thin Ni-based steel for ultra-low temperature environments according to any one of claims 1 to 3, characterized in that: The steel plate has a thickness of 4-7 mm.

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