Method for producing low-cost 16MnDR low-temperature pressure vessel steel plate

Abstract

The invention discloses a method for producing a low-cost 16MnDR low-temperature pressure vessel steel plate. The steel plate comprises the following chemical components in percentage by mass: 0.15-0.17% of C, 0.25-0.30% of Si, 1.40-1.55% of Mn, less than or equal to 0.015% of P, less than or equal to 0.005% of S, 0.20-0.33% of Al s, less than or equal to 0.0060% of N and the balance of iron and inevitable impurities. The production process of the steel plate comprises the steps of KR desulfurization, converter smelting, LF refining, RH refining, continuous casting, heating, hot charging and hot delivery, rolling, cooling, hot straightening, shearing, flaw detection, normalizing, air cooling and warehousing. According to the method, the hardenability of the direct charging plate blank can be effectively improved, so that the optimal performance is obtained under the condition of saving energy, particularly, the surface crack problem of the direct charging steel plate is solved, and the qualification rate of the direct charging steel plate is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of steel rolling heating, and in particular relates to a method for producing low-cost 16MnDR low-temperature pressure vessel steel plates. Background Art

[0002] 16MnDR is a steel for low-temperature pressure vessels, which is generally delivered in normalized or normalized + tempered state. It is widely used in the manufacture of various liquid olefin storage containers and pipelines, natural gas liquefaction equipment, petroleum gas equipment and storage and transportation facilities, hydrogenation reaction equipment, etc. 16MnDR steel plates are used in low-temperature environments and are usually used under welding conditions, so the steel plates are required to have good low-temperature toughness and excellent welding performance.

[0003] The patent with publication number CN 102605241 A, "A normalized 16MnDR low-temperature pressure vessel steel plate and its manufacturing method", provides a process design for micro-alloying vanadium. This patent does not add vanadium and uses hot charging and hot delivery to save energy, providing a low-cost process method with excellent low-temperature toughness and good weldability.

[0004] The patent "Low-carbon high-toughness 16MnDR steel plate and its production method" with publication number CN 116145031 A adopts a method for designing and producing 16mm 16MnDR steel plates with low-carbon niobium-containing components. Compared with the literature, this patent has lower component costs and covers the process design of 10-60mm steel plates. It also adopts a heat transfer and heat transport heating process, which has lower manufacturing costs.

[0005] The patent with publication number CN 108772550 A, "A production method for steel slabs suitable for direct heating of low-temperature pressure vessels", provides a smelting and continuous casting process method for steel slabs suitable for direct heating of low-temperature pressure vessels. This patent provides a full-process process method for smelting, continuous casting, heating, rolling and heat treatment of 16MnDR steel plates with a thickness of 10-60mm, which is more specific and comprehensive. Summary of the invention

[0006] The purpose of the present invention is to provide a method for producing low-cost 16MnDR low-temperature pressure vessel steel plates, which can effectively improve the hardenability of direct-installed slabs, thereby obtaining optimal performance under the condition of saving energy, especially improving the surface crack problem of direct-installed steel plates and improving the qualified rate of direct-installed steel plates.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0008] The present invention provides a method for producing a low-cost 16MnDR low-temperature pressure vessel steel plate, comprising:

[0009] The chemical composition of the steel plate by mass percentage is: C: 0.15-0.17%, Si: 0.25-0.30%, Mn: 1.40-1.55%, P: ≤0.015%, Al s: 0.20-0.33%, N: ≤0.0060%, and the rest is iron and unavoidable impurities;

[0010] The production process of the steel plate is KR desulfurization → converter smelting → LF refining → RH refining → continuous casting → heating-hot charging and hot delivery → rolling → cooling → hot straightening → shearing → flaw detection → normalizing → air cooling → storage; wherein:

[0011] (1) In order to ensure the quality of slabs with a certain compression ratio, 250 mm and 300 mm thick continuous casting slabs are selected, and the center segregation of the slab is not greater than B1.0;

[0012] (2) Converter production process: molten iron S≤0.005%, spot blowing≤1 time, no slag, fixed oxygen≤800ppm, carbon drawing temperature≥1620℃, steel tapping P≤0.012%, tank sample Al s≥0.030%, and lime in the tank≥400kg;

[0013] (3) LF refining temperature ≥ 1530℃, de-position temperature 1595-1610℃, refining time greater than 40min, lime addition amount 1200kg / furnace, molten steel composition P ≤ 0.015%, S ≤ 0.003%, Al s ≥ 0.020%;

[0014] (4) RH refining treatment cycle is greater than 36min, RH vacuum treatment time is ≥20min, pure degassing time is ≥5min, minimum vacuum degree is ≤266Pa, vacuum degree rebound is not allowed, H content is ≤2.0ppm, N content is ≤50ppm, soft blowing time is ≥10min;

[0015] (5) Optimize and adjust the acceleration time of the roller in the quenching beam so that the slab surface quenching cooling time is controlled within 180S-250S, and design 16 sets of quenching cooling water beams; the cooling time is slow cooling time ≤250min, the slab furnace temperature is 550-620℃, and the total furnace time is ≥150min. The slab is heated by a three-stage walking beam heating furnace. The heating temperature of the first heating section is ≥1100℃, and the heating time is 40-60 minutes; the heating temperature of the second heating section is 1200-1280℃, and the heating time is 40-60min; the ambulation temperature is 1230-1300℃, the heating time is ≥30min, and the total heating time is not less than 150min; the slab furnace temperature is 1210-1250℃;

[0016] (6) Rolling and cooling process: After the slab is heated, two-stage controlled rolling is carried out. The first stage rolling is completed on the roughing mill. The first stage rolling thickness is the slab thickness. The first stage rolling temperature is 1090-1180°C. The single pass reduction rate in the high temperature extension stage is not less than 15%; the second stage rolling is completed on the finishing mill. The second stage rolling temperature is 850-1025°C. The second stage rolling thickness is 50-125mm. The second stage final rolling temperature is 820-900°C. During the second stage rolling, the set torque is 2200kNm, the set rolling force is 85MN, the set reduction is 20mm, and the final pass reduction rate is 5%-10% to ensure the plate shape; after the steel plate is rolled, laminar cooling is carried out. The ACC water temperature is 17-20°C, the cooling rate is 7-14°C / s, and the final cooling temperature is 660-740°C.

[0017] Furthermore, in the (6) rolling and cooling process, during cooling, the head is shielded by 0-2.0m, the tail is shielded by 0-2.5m, and the edge is shielded by 0-2.0m, and the overall temperature difference of the steel plate after returning to red is controlled to be ≤50°C.

[0018] Furthermore, the chemical composition of the steel plate in terms of mass percentage is: C: 0.15%, Si: 0.29%, Mn: 1.45%, P: 0.012%, S: 0.001%, Al s: 0.032%, N: 0.0020%, and the rest is iron and unavoidable impurities.

[0019] Furthermore, the chemical composition of the steel plate in terms of mass percentage is: C: 0.16%, Si: 0.25%, Mn: 1.42%, P: 0.010%, S: 0.001%, Al s: 0.028%, N: 0.0041%, and the rest is iron and unavoidable impurities.

[0020] Furthermore, the chemical composition of the steel plate in terms of mass percentage is: C: 0.16%, Si: 0.30%, Mn: 1.50%, P: 0.011%, S: 0.002%, Al s: 0.025%, N: 0.0035%, and the rest is iron and unavoidable impurities.

[0021] Furthermore, the chemical composition of the steel plate in terms of mass percentage is: C: 0.17%, Si: 0.26%, Mn: 1.51%, P: 0.010%, S: 0.002%, Al s: 0.030%, N: 0.0030%, and the rest is iron and unavoidable impurities.

[0022] Furthermore, the method effectively improves the hardenability of the direct-installed slab, thereby obtaining the best performance under the condition of saving energy, especially improving the surface crack problem of the direct-installed steel plate and improving the qualified rate of the direct-installed steel plate.

[0023] Compared with the prior art, the beneficial technical effects of the present invention are:

[0024] Through the full process component process design and the use of slab direct quenching technology, the hot charging ratio of 16MnDR low-temperature pressure vessel steel plates is increased to achieve the goal of energy saving, consumption reduction and production cost reduction. DETAILED DESCRIPTION

[0025] A method for producing low-cost 16MnDR low-temperature pressure vessel steel plate, comprising:

[0026] 1. Smelting

[0027] 1.1 Converter

[0028] The specific situation of converter production process is shown in Table 1

[0029] Table 1 Converter production process parameters

[0030]

[0031] 1.2LF Refining

[0032] Table 2 LF refining converter production process parameters

[0033]

[0034] 1.3RH refining

[0035] Table 3 RH refining converter production process parameters

[0036]

[0037]

[0038] 2. Continuous Casting

[0039] 2.1 Melting composition

[0040] Table 4 Melting composition

[0041] Furnace No. C Si Mn P S Als N Example 1 0.15 0.29 1.45 0.012 0.001 0.032 0.0020 Example 2 0.16 0.25 1.42 0.010 0.001 0.028 0.0041 Example 3 0.16 0.30 1.50 0.011 0.002 0.025 0.0035 Example 4 0.17 0.26 1.51 0.010 0.002 0.030 0.0030

[0042] 2.2 Preparation before production

[0043] Table 5 RH continuous casting production process parameters

[0044]

[0045] The argon blowing pressure of the long nozzle is ≥0.1Mpa, the argon pressure between the plates of the tundish immersed nozzle is ≤0.2bar, and the flow rate is 3-5L / min.

[0046] The temperature gun was calibrated before pouring, and the temperature of the middle bag was continuously measured during the casting process, at least once for each furnace; an automatic slag feeder was used, and the middle bag worker checked the internal condition of the crystallizer at any time, and the liquid slag layer was measured every 2 furnaces; there was no abnormality in the opening degree of the fan-shaped section during the casting process.

[0047] 3. Heating rolling

[0048] 3.1 Quenching beam cooling

[0049] Table 6 Slab direct quenching production process parameters

[0050]

[0051]

[0052] 3.2 Heating rolling

[0053] The steel plate rolling and cooling process shall comply with the requirements of Table 7.

[0054] Table 7 Rolling and cooling process

[0055]

[0056]

[0057] 3.3 Normalizing

[0058] Steel plates need to be shot blasted before normalizing, and the normalizing process should comply with the requirements of Table 8.

[0059] Table 8

[0060] Example Insulation temperature ℃ Insulation time min Cooling system after tempering Example 1 400 20 air cooling Example 2 390 21 air cooling Example 3 400 22 air cooling Example 4 410 20 air cooling

[0061] 3.4 Performance

[0062] Table 9 Mechanical properties of Examples 1-4

[0063]

[0064] 4. Surface quality

[0065] Four heats of steel were produced using this process and 35 steel plates were rolled with good surface quality and no hot-loading cracks were found.

[0066] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for producing low-cost 16MnDR low-temperature pressure vessel steel plate, characterized in that: include: The chemical composition of the steel plate by mass percentage is: C: 0.15-0.17%, Si: 0.25-0.30%, Mn: 1.40-1.55%, P: ≤0.015%, S: ≤0.005%, Als: 0.20-0.33%, N: ≤0.0060%, and the rest is iron and unavoidable impurities; The production process of the steel plate is KR desulfurization → converter smelting → LF refining → RH refining → continuous casting → heating-hot charging and hot delivery → rolling → cooling → hot straightening → shearing → flaw detection → normalizing → air cooling → storage; wherein: (1) In order to ensure the quality of slabs with a certain compression ratio, 250 mm and 300 mm thick continuous casting slabs are selected, and the center segregation of the slab is not greater than B1.0; (2) Converter production process: S of molten iron in the converter is ≤0.005%, spot blowing is ≤1 time, no slag is added, fixed oxygen is ≤800ppm, carbon drawing temperature is ≥1620℃, steel tapping P is ≤0.012%, Als of tank sample is ≥0.030%, and lime in the tank is ≥400kg; (3) LF refining temperature ≥ 1530℃, de-position temperature 1595-1610℃, refining time greater than 40min, lime addition amount 1200kg / furnace, molten steel composition P ≤ 0.015%, S ≤ 0.003%, Als ≥ 0.020%; (4) RH refining treatment cycle is greater than 36min, RH vacuum treatment time is ≥20min, pure degassing time is ≥5min, minimum vacuum degree is ≤266Pa, vacuum degree rebound is not allowed, H content is ≤2.0ppm, N content is ≤50ppm, soft blowing time is ≥10min; (5) Optimize and adjust the acceleration time of the roller in the quenching beam so that the slab surface quenching cooling time is controlled within 180S-250S, and design 16 sets of quenching cooling water beams; the cooling time is slow cooling time ≤250min, the slab furnace temperature is 550-620℃, and the total furnace time is ≥150min. The slab is heated by a three-stage walking beam heating furnace. The heating temperature of the first heating section is ≥1100℃, and the heating time is 40-60 minutes; the heating temperature of the second heating section is 1200-1280℃, and the heating time is 40-60min; the ambulation temperature is 1230-1300℃, the heating time is ≥30min, and the total heating time is not less than 150min; the slab furnace temperature is 1210-1250℃; (6) Rolling and cooling process: After the slab is heated, two-stage controlled rolling is carried out. The first stage rolling is completed on the roughing mill. The first stage rolling thickness is the slab thickness. The first stage rolling temperature is 1090-1180°C. The single pass reduction rate in the high temperature extension stage is not less than 15%; the second stage rolling is completed on the finishing mill. The second stage rolling temperature is 850-1025°C. The second stage rolling thickness is 50-125mm. The second stage final rolling temperature is 820-900°C. During the second stage rolling, the set torque is 2200kNm, the set rolling force is 85MN, the set reduction is 20mm, and the final pass reduction rate is 5%-10% to ensure the plate shape; after the steel plate is rolled, laminar cooling is carried out. The ACC water temperature is 17-20°C, the cooling rate is 7-14°C / s, and the final cooling temperature is 660-740°C.

2. The method for producing low-cost 16MnDR low-temperature pressure vessel steel plate according to claim 1, characterized in that: In the rolling and cooling process (6), during cooling, the head is shielded by 0-2.0m, the tail is shielded by 0-2.5m, and the edge is shielded by 0-2.0m, and the overall temperature difference of the steel plate after it returns to red is controlled to be ≤50°C.

3. The method for producing low-cost 16MnDR low-temperature pressure vessel steel plate according to claim 1, characterized in that: The chemical composition of the steel plate in terms of mass percentage is: C: 0.15%, Si: 0.29%, Mn: 1.45%, P: 0.012%, S: 0.001%, Als: 0.032%, N: 0.0020%, and the rest is iron and unavoidable impurities.

4. The method for producing low-cost 16MnDR low-temperature pressure vessel steel plate according to claim 1, characterized in that: The chemical composition of the steel plate in terms of mass percentage is: C: 0.16%, Si: 0.25%, Mn: 1.42%, P: 0.010%, S: 0.001%, Als: 0.028%, N: 0.0041%, and the rest is iron and unavoidable impurities.

5. The method for producing low-cost 16MnDR low-temperature pressure vessel steel plate according to claim 1, characterized in that: The chemical composition of the steel plate in terms of mass percentage is: C: 0.16%, Si: 0.30%, Mn: 1.50%, P: 0.011%, S: 0.002%, Als: 0.025%, N: 0.0035%, and the rest is iron and unavoidable impurities.

6. The method for producing low-cost 16MnDR low-temperature pressure vessel steel plate according to claim 1, characterized in that: The chemical composition of the steel plate in terms of mass percentage is: C: 0.17%, Si: 0.26%, Mn: 1.51%, P: 0.010%, S: 0.002%, Als: 0.030%, N: 0.0030%, and the rest is iron and unavoidable impurities.

7. The method for producing low-cost 16MnDR low-temperature pressure vessel steel plate according to claim 1, characterized in that: The method effectively improves the hardenability of the direct-installed slab, thereby obtaining the best performance under the condition of saving energy, especially improving the surface crack problem of the direct-installed steel plate and improving the qualified rate of the direct-installed steel plate.

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