A high crack arrest thick steel plate and a method for producing the same

Abstract

The present application relates to a production method of high crack arrest thick steel plate, which forms high crack arrest thick steel plate from molten steel with certain chemical composition through the following steps: raw material preparation step S1, preparing raw material with the following chemical composition, in mass %, containing C: 0.06-0.12%, Si: 0.3-0.4%, Mn: 1.4-1.8%, Al: 0.20-0.40%, Nb: 0.03-0.05%, Ti: 0.02-0.03%, the rest being Fe and other inevitable impurities; smelting step S2, smelting the raw material and forming continuous casting billet after molten steel pretreatment, converter smelting, LF refining, RH vacuum refining and continuous casting; rolling step S4, forming steel plate after heating, holding and rolling the continuous casting billet and water cooling to room temperature. The present application produces high toughness crack arrest steel plate with thickness of 100-120mm by adopting low carbon low alloy composition design and specific process flow, and the steel plate-10℃ crack arrest toughness Kca≥9000N / mm 3 / 2 .

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel metallurgy, and in particular to a high-crack-arrest thick steel plate and a production method thereof. BACKGROUND

[0002] The field of marine transportation is developing rapidly, and the performance of the deck of a ship plays an important role in the amount of transportation equivalent. The main problem of current ship transportation is brittle fracture of hatch coaming and deck, so the development of shipbuilding urgently needs thick plate crack arrest steel with high strength, especially high toughness, so as to increase the single transportation capacity of the ship and ensure the safety performance.

[0003] The main high-performance thick plate crack arrest steel currently used in the world is EH40 and EH47, with a thickness of 40-100 mm, and a steel plate crack arrest toughness Kca of-10 DEG C ≥ 6000 N / mm 3 / 2 This performance has gradually failed to guarantee the safety of large-scale ship transportation. Currently, there are two main problems with high-toughness steel plates: the thickness of the steel plate is generally less than 100 mm, and the crack arrest toughness at-10 DEG C is generally not more than 7000 N / mm 3 / 2 Therefore, it is necessary to develop a higher crack arrest performance thick steel plate.

[0004] In the prior art, patent CN112522626A discloses a method for producing low yield ratio high-strength steel by controlling phase transformation process, by adjusting the proportion of pro-eutectoid ferrite before entering the water, the yield ratio of high-strength steel is adjusted, and the yield strength reaches 580 MPa. The thickness of the steel plate produced by the patent technology is 30 mm, which is difficult to meet the requirements of thick steel plate, and a large amount of Ni and Cr elements are added, which increases the production cost, and the low-temperature crack arrest toughness and transverse impact performance are not optimized. Patent CN101619423A discloses a high-strength and tough low-yield ratio easy-to-weld structural steel plate and a manufacturing method thereof, the steel yield strength is not less than 510 MPa, mainly bainite + ferrite structure, wherein the volume fraction of bainite is 55% to 70%, and the volume fraction of ferrite is 30% to 45%. The patent adds a large amount of Cr element, which has high production cost, and the low-temperature crack arrest toughness and transverse impact performance of the steel plate are not clear. The above patents do not provide a targeted solution for high crack arrest performance thick steel plate.

[0005] In view of the above problems, the present application is proposed. SUMMARY

[0006] The present application discloses a production method of a high-crack-arrest thick steel plate, and aims to solve the technical problems in the prior art.

[0007] The present application adopts the following technical scheme:

[0008] In one aspect, the present application provides a method for producing a high crack arrest thick steel plate,

[0009] The production method is performed according to the following steps:

[0010] The raw material preparation step S1: the raw material is prepared with the following chemical composition, in mass %, C: 0.06-0.12%, Si: 0.3-0.4%, Mn: 1.4-1.8%, Al: 0.20-0.40%, Nb: 0.03-0.05%, Ti: 0.02-0.03%, the rest is Fe and other inevitable impurities;

[0011] The smelting step S2: the raw material is smelted and after the molten steel pretreatment, through converter smelting, LF refining, RH vacuum refining and continuous casting, the continuous casting billet is formed;

[0012] The rolling step S4: after the continuous casting billet is heated, insulated and rolled and water cooled to room temperature, the steel plate is formed;

[0013] The steel plate has a microstructure of textured ferrite and bainite, and the microstructure includes {112} <110> texture.

[0014] As a preferred technical solution, in the rolling step S4, it includes:

[0015] The rough rolling step S41: the step of rough rolling the continuous casting billet after heating and insulation;

[0016] The finish rolling step S42: the step of finish rolling when the temperature drops to A C3 50℃.

[0017] As a preferred technical solution, the thickness of the steel plate after the rough rolling step S41 is 135-200mm.

[0018] As a preferred technical solution, the thickness of the steel plate after the finish rolling step S42 is 80-120mm.

[0019] As a preferred technical solution, in the rolling step S4, the continuous casting billet is heated to 1150℃±30℃, and the insulation time is 120min.

[0020] As a preferred technical solution, it further includes the continuous casting billet pretreatment step S3: heating the continuous casting billet to 1150-1200℃, insulating for more than 120min and rapidly cooling to below 500℃.

[0021] As a preferred technical solution, as the steel plate properties, the steel plate core yield strength is >400MPa, the steel plate core low temperature impact toughness at -40℃ is >200J, and the steel plate 10℃ crack arrest toughness Kca is ≥9000N / mm 3 / 2 .

[0022] As a preferred technical solution, the thickness of the continuous casting embryo is greater than or equal to 300 mm.

[0023] In another aspect, the present application also provides a high crack arrest thick steel plate produced according to the production method of the high crack arrest thick steel plate.

[0024] As a preferred technical solution, the {112} <110> texture ratio in the steel plate is greater than 5%.

[0025] The technical solution adopted by the present application can achieve at least one of the following beneficial effects:

[0026] 1. The present application obtains a texture ferrite + bainite structure with a {112} <110> texture ratio greater than 5% through low-cost alloy design and a specific rolling process, thereby obtaining a high-toughness crack arrest steel plate with a thickness of 80-120 mm, a core yield strength greater than 400 MPa, a core low-temperature impact toughness at -40℃ greater than 200 J, and a steel plate crack arrest toughness Kca at -10℃ greater than or equal to 9000 N / mm 3 / 2 , and the crack arrest performance of the steel plate is greatly improved by utilizing the characteristics of the texture.

[0027] 2. The steel plate of the present application has simple chemical composition, and the production cost is reduced by removing alloying elements such as Ni and Cr. In addition, the segregation phenomenon in the core of the thick plate is reduced by low-C composition design, and the welding performance is improved.

[0028] 3. The present application uses Al as a ferrite stabilizing element to promote the formation of ferrite at the beginning of finish rolling, so that the ferrite deforms to produce texture in the later stage of finish rolling. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced as follows, which form a part of the present application. The schematic embodiments of the present application and their description explain the present application, and do not constitute an improper limitation on the present application. In the drawings:

[0030] Figure 1 The production step flow chart of the present application;

[0031] Figure 2 The microstructure schematic diagram of Example 1 of the present application. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the present application more clear, the technical solutions of the present application will be described clearly and completely in combination with specific embodiments of the present application and corresponding drawings. In the description of the present application, it should be noted that the term "or" is generally used in the sense of including "and / or", unless the context clearly indicates otherwise.

[0033] Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0034] The present application aims to provide a high crack resistance thick steel plate which can meet the performance requirements of shipbuilding materials and reduce the production cost of the material.

[0035] In order to achieve the above-mentioned purpose, the present application proposes an innovative technical solution, which includes the use of low-carbon low-alloy composition design and specific process flow.

[0036] Embodiment 1:

[0037] Referring to Figure 1 , the present embodiment is produced according to the following steps:

[0038] S1: The chemical composition of the present embodiment is, in mass%, C: 0.08%, Si: 0.3%, Mn: 1.4%, Nb: 0.03%, Ti: 0.03%, and the rest is Fe and other unavoidable impurities. The above chemical composition is used to prepare the required raw materials.

[0039] S2: The above raw materials are smelted, and after pretreatment of molten iron, they are sequentially subjected to converter smelting, LF refining, RH vacuum refining and continuous casting to form a continuous casting billet. The thickness of the continuous casting billet is 300mm.

[0040] S3: The above continuous casting billet is pretreated, specifically, the continuous casting billet is heated to 1165℃, and kept for more than 118min, and then accelerated cooling to below 500℃ to obtain a uniform bainite structure.

[0041] S4: The rolling step includes S41 rough rolling step and S42 finish rolling step. The continuous casting billet is heated to 1148℃, and after keeping for 120min, it is rough rolled to 135-200mm. When the temperature drops to A C3 The S42 finish rolling is carried out at 50℃ below the Ar3 temperature (766℃ in the present embodiment), and the thickness of the steel plate is finish rolled to 80-120mm, and then water cooled to room temperature.

[0042] The production process parameters of the present embodiment are shown in the following table:

[0043]

[0044] The above steel plate is sampled and tested, and the mechanical property test results are shown in the following table:

[0045]

[0046] The high-rupture-resistance super-thick steel plate produced through the above production steps has a {112} <110> texture ratio of 7.3%.

[0047] Example 2

[0048] This example is produced according to the following steps:

[0049] S1: The chemical composition of this example is, in mass%, C: 0.08%, Si: 0.3%, Mn: 1.4%, Nb: 0.03%, Ti: 0.03%, and the rest is Fe and other inevitable impurities. The above chemical composition is used to prepare the required raw materials.

[0050] S2: The above raw materials are smelted, and after pretreatment of the molten iron, sequentially undergo converter smelting, LF refining, RH vacuum refining, and continuous casting to form a continuous casting billet. The thickness of the continuous casting billet is 300 mm.

[0051] S3: The above continuous casting billet is pretreated, specifically, the continuous casting billet is heated to 1165°C and held for more than 121 min, and then accelerated cooling is performed to below 500°C to obtain a uniform bainite structure.

[0052] S4: The rolling step includes S41 rough rolling step and S42 finish rolling step. The continuous casting billet is heated to 1160°C, and after holding for 120 min, it is rough rolled to 135-200 mm. When the temperature drops to A C3 S42 finish rolling is performed at 50°C (761°C in this example), and the thickness of the steel plate is finish rolled to 80-120 mm, and then water cooled to room temperature.

[0053] The production process parameters of this example are shown in the table:

[0054]

[0055] The above steel plate is sampled and tested, and the mechanical property test results are shown in the following table:

[0056]

[0057] The high-rupture-resistance super-thick steel plate produced through the above production steps has a {112} <110> texture ratio of 5.9%.

[0058] Example 3

[0059] This example is produced according to the following steps:

[0060] S1: The chemical composition of this embodiment is used, with mass %, C: 0.08%, Si: 0.4%, Mn: 1.8%, Nb: 0.05%, Ti: 0.02%, and the rest is Fe and other inevitable impurities. The above chemical composition is used to prepare the required raw material.

[0061] S2: The above raw material is smelted, and after pretreatment of the molten iron, it is sequentially subjected to converter smelting, LF refining, RH vacuum refining, and continuous casting to form a continuous casting billet. The thickness of the continuous casting billet is 300 mm.

[0062] S3: The above continuous casting billet is pretreated, specifically, the continuous casting billet is heated to 1208°C, and held for more than 119 min, and then accelerated cooling to below 500°C to obtain a uniform bainite structure.

[0063] S4: The rolling step includes S41 rough rolling step and S42 finish rolling step. The continuous casting billet is heated to 1176°C, and after holding for 120 min, it is rough rolled to 135-200 mm. When the temperature drops to A C3 The S42 finish rolling is carried out at 50°C (765°C in this embodiment), and the thickness of the steel plate is finish rolled to 80-120 mm, and then water cooled to room temperature.

[0064] The production process parameters of this embodiment are shown in the table:

[0065]

[0066] The mechanical property test results of the above steel plate are shown in the following table:

[0067]

[0068] In the high crack arrest thick steel plate produced by the above production steps, the {112} <110> texture ratio is 9.2%.

[0069] Example 4:

[0070] This embodiment is produced according to the following steps:

[0071] S1: The chemical composition of this embodiment is used, with mass %, C: 0.08%, Si: 0.4%, Mn: 1.8%, Nb: 0.05%, Ti: 0.02%, and the rest is Fe and other inevitable impurities. The above chemical composition is used to prepare the required raw material.

[0072] S2: The above raw material is smelted, and after pretreatment of the molten iron, it is sequentially subjected to converter smelting, LF refining, RH vacuum refining, and continuous casting to form a continuous casting billet. The thickness of the continuous casting billet is 300 mm.

[0073] S3: The continuous casting billet is heated to 1206°C, and held for 123 min or more, and then accelerated cooled to 500°C or less to obtain a bainite structure with uniform grains.

[0074] S4: The rolling step includes a S41 rough rolling step and a S42 finish rolling step. The continuous casting billet is heated to 1170°C, and held for 120 min, and then rough rolled to 135-200 mm by S41. When the temperature drops to A C3 The S42 finish rolling is performed at 50°C (771°C in this example), and the thickness of the steel plate is finish rolled to 80-120 mm, and then water cooled to room temperature.

[0075] The production process parameters of this example are shown in the table:

[0076]

[0077]

[0078] The steel plate is sampled and tested, and the mechanical property test results are shown in the table below:

[0079]

[0080] The high crack resistance ultra thick steel plate produced by the above production steps has a {112} <110> texture ratio of 6.3%.

[0081] Example 5:

[0082] This example is produced according to the following steps:

[0083] S1: The chemical composition of this example is used, with mass %, C: 0.12%, Si: 0.3%, Mn: 1.8%, Nb: 0.05%, Ti: 0.03%, and the rest is Fe and other unavoidable impurities. The required raw materials are prepared using the above chemical composition.

[0084] S2: The above raw materials are smelted, and after pretreatment of the molten iron, they are sequentially subjected to converter smelting, LF refining, RH vacuum refining, and continuous casting to form a continuous casting billet. The thickness of the continuous casting billet is 300 mm.

[0085] S3: The continuous casting billet is heated to 1243°C, and held for 119 min or more, and then accelerated cooled to 500°C or less to obtain a bainite structure with uniform grains.

[0086] S4: The rolling step includes a S41 rough rolling step and a S42 finish rolling step. The continuous casting billet is heated to 1142°C, and held for 120 min, and then rough rolled to 135-200 mm by S41. When the temperature drops to A C3The S42 finish rolling is performed at 50°C (760°C in this example), and the thickness of the steel plate is finished to 80-120 mm, and then water-cooled to room temperature.

[0087] The production process parameters of this example are shown in the table:

[0088]

[0089] The steel plate is sampled and tested, and the mechanical property test results are shown in the table below:

[0090]

[0091] The high crack resistance ultra-thick steel plate produced by the above production steps has a {112} <110> texture ratio of 5.4%.

[0092] Example 6:

[0093] This example is produced according to the following steps:

[0094] S1: The chemical composition of this example is used, with C: 0.12%, Si: 0.3%, Mn: 1.8%, Nb: 0.05%, Ti: 0.03%, and the rest is Fe and other unavoidable impurities. The above chemical composition is used to prepare the required raw materials.

[0095] S2: The above raw materials are smelted, and after pretreatment of the molten iron, they are sequentially subjected to converter smelting, LF refining, RH vacuum refining and continuous casting to form a continuous casting billet. The thickness of the continuous casting billet is 300 mm.

[0096] S3: The above continuous casting billet is pretreated, specifically, the continuous casting billet is heated to 1244°C and held for more than 123 min, and then accelerated cooling to below 500°C to obtain a uniform bainite structure.

[0097] S4: The rolling step includes S41 rough rolling step and S42 finish rolling step. The continuous casting billet is heated to 1139°C, and after holding for 120 min, it is rough rolled to 135-200 mm. When the temperature drops to A C3 The S42 finish rolling is performed at 50°C (760°C in this example), and the thickness of the steel plate is finished to 80-120 mm, and then water-cooled to room temperature.

[0098] The production process parameters of this example are shown in the table:

[0099]

[0100] The steel plate is sampled and tested, and the mechanical property test results are shown in the table below:

[0101]

[0102] The high-rupture-resistance ultra-heavy steel plate produced by the above production steps has a {112} <110> texture ratio of 7.4%.

[0103] The embodiments of the present application are described above with reference to the accompanying drawings, but the present application is not limited to the above-described specific embodiments, and the above-described specific embodiments are merely illustrative, but not restrictive, and a person of ordinary skill in the art can make many forms under the inspiration of the present application without departing from the purpose of the present application and the scope protected by the claims, which all belong to the protection of the present application.

Claims

1. A method for producing a high crack arrest thick steel plate, characterized in that, the production method is performed according to the following steps: a raw material preparation step S1: preparing the raw material with the following chemical composition, in mass %, C: 0.06-0.12%, Si: 0.3-0.4%, Mn: 1.4-1.8%, Al: 0.20-0.40%, Nb: 0.03-0.05%, Ti: 0.02-0.03%, the rest being Fe and other inevitable impurities; a smelting step S2: smelting the raw material and after pretreatment of the molten steel, forming a continuous casting billet through converter smelting, LF refining, RH vacuum refining and continuous casting; a continuous casting billet pretreatment step S3: heating the continuous casting billet to 1150-1200°C, holding for 120 min or more and rapidly cooling to 500°C or less; a rolling step S4: heating, holding and rolling the continuous casting billet and water cooling to room temperature to form the steel plate; As the steel sheet properties, a core yield strength of the steel sheet > 400 MPa, a low-temperature impact toughness of the steel sheet at -40 °C > 200 J, a 10 °C fracture toughness Kca of the steel sheet ≥ 9000 N / mm 3 / 2 ; the steel plate has a microstructure of textured ferrite and bainite, the microstructure including {112} <110> texture, the proportion of {112} <110> texture in the steel plate being >5%.

2. The method of producing a high-ri s t-resistance extra-thick steel plate according to claim 1, characterized by, in the rolling step S4, including: a rough rolling step S41: a step of rough rolling the heated and held continuous casting billet; Finish rolling step S42: When the temperature drops to A C3 The following step is performed at 50 °C.

3. The method of producing a high crack resistance extra thick steel plate according to claim 2, characterized by, the thickness of the steel plate after the rough rolling step S41 is 135-200 mm.

4. The method of producing a high crack resistance extra thick steel plate according to claim 2, characterized by, the thickness of the steel plate after the finish rolling step S42 is 80-120 mm.

5. The method of producing a high crack resistance extra thick steel plate according to claim 1, characterized by, in the rolling step S4, the continuous casting billet is heated to 1150°C±30°C, and the holding time is 120 min.

6. The method of producing a high crack resistance extra thick steel plate according to any one of claims 1 to 5, characterized by, the thickness of the continuous casting billet is ≥300 mm.

7. A high crack arrest thick steel plate characterized by comprising: the high crack arrest thick steel plate is produced using the production method according to any one of claims 1-6, and the proportion of {112} <110> texture in the steel plate is >5%.

2. The method for producing a high crack arrest thick steel plate according to claim 1, wherein the thickness of the continuous casting billet is ≥350 mm.

3. The method for producing a high crack arrest thick steel plate according to claim 1, wherein the thickness of the continuous casting billet is ≥400 mm.

4. The method for producing a high crack arrest thick steel plate according to claim 1, wherein the thickness of the continuous casting billet is ≥450 mm.

5. The method for producing a high crack arrest thick steel plate according to claim 1, wherein the thickness of the continuous casting billet is ≥500 mm.

6. The method for producing a high crack arrest thick steel plate according to claim 1, wherein the thickness of the continuous casting billet is ≥550 mm.

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