A GPa-level nanophase particle reinforced steel plate for marine engineering and preparation method thereof

Abstract

The invention relates to a marine engineering steel plate reinforced with GPa-level nano-phase particles and a preparation method thereof, belonging to the technical field of marine steel, and used to solve the problem that the existing high-strength steel cannot have both excellent high strength and low-temperature toughness and cannot be used for marine engineering steel plates. The marine engineering steel plate comprises: C: 0.040-0.12%, Ni: 5.0-12.00%, Al: 0.60-1.50%, Cr: 0.50-1.0%, Mo: 0.50-1.0%, V: 0.040-0.10%, Mn: 0.80-1.50%, Si: 0.10-0.50%, Ti: 0.01-0.020%, P≤0.01%, S≤0.005%, the remainder is Fe and unavoidable impurities, and meets the welding carbon equivalent: Ceq=C+(Mn+Si) / 6+(Ni+Cu) / 15+(Cr+Mo+V) / 5≤1.45. The present invention forms carbide nano-precipitation phases such as nano-scale intermetallic compounds Ni3Al, (V, Mo)C and Mo2C during the aging process by a reasonable ratio of Al and Ni, so that the steel plate has ultra-high strength and good low-temperature toughness.

Description

Technical Field

[0001] The present invention relates to the technical field of marine engineering steel, and in particular to a marine engineering steel plate reinforced with GPa-level nano-phase particles and a preparation method thereof. Background Art

[0002] With the rise of the 21st Century Maritime Silk Road, countries around the world have accelerated the development and utilization of marine resources. Deep-sea and offshore resources, in particular, have been the focus of exploration both domestically and internationally. Consequently, the ultra-high-strength structural steel required for deep-sea and offshore equipment is gaining increasing attention. Ultra-high-strength structural steel is widely used in the construction of deep-sea probes, offshore platforms, and other equipment, requiring high strength and toughness, as well as weldability and corrosion resistance. Furthermore, the increasing size, weight, and deep-sea deployment of these equipment are placing even higher demands on the strength, toughness, and weldability of high-strength structural steel.

[0003] Traditional ultra-high-strength marine engineering steels above 1000 MPa are generally designed with low carbon (carbon content 0.10-0.20 wt.%) and alloying elements such as Ni, Cr, Mo, and V. After rolling, they are manufactured using a quenching and high-temperature tempering heat treatment process. The microstructure of the steel after quenching and tempering heat treatment is tempered lath martensite plus a large amount of nano-carbides, which has excellent strength and toughness. However, due to the high carbon content and carbon equivalent of this type of steel, it is in a difficult-to-weld zone and requires preheating before welding and even heat treatment after welding. The poor weldability leads to high welding time and cost. In recent years, to improve the weldability of ultra-high-strength steels, researchers have developed nano-phase-reinforced ultra-high-strength ferritic steels through low-carbon design (C content ≤ 0.08), the use of nano-scale Cu-rich clusters, or the composite strengthening of nano-scale Cu-rich phases and intermetallic compounds NiAl phases. The yield strength can reach up to 1900 MPa. For example, the invention patents with publication numbers CN104046917A and CN105177425A both describe a Cu-rich nanocluster reinforced ultra-high strength steel with yield strengths of 1141 MPa and 1500 MPa, respectively. The invention patent with publication number CN104046891A describes a B2-structured nano-scale intermetallic compound NiAl precipitation-strengthened ultra-high strength ferritic steel with a yield strength of 1531 MPa. The above-mentioned steels generally adopt a low-carbon design, which greatly reduces the C content and does not use C as the main strengthening element. The process mainly involves high-temperature solution treatment to fully dissolve the alloying elements, and then rapidly cooling to room temperature and performing heat treatment at the aging peak temperature to fully precipitate the nanophase, which plays a significant precipitation strengthening role and thus obtains the ultra-high strength of the steel.

[0004] However, because these ultra-high-strength steels are typically aged at peak temperatures, their low-temperature toughness is very low, far from meeting the service performance requirements of ultra-high-strength steels used in special environments such as deep-sea and open-ocean environments. Furthermore, the use of Cu nanophase-reinforced high-strength steels poses the risk of radiation embrittlement and should be avoided in some marine equipment with nuclear facilities. Summary of the Invention

[0005] In view of the above analysis, the embodiments of the present invention aim to provide a GPa-level nanophase particle reinforced marine engineering steel plate and a preparation method to solve the problem that ultra-high strength steel in the existing technology has a low level of low-temperature toughness and cannot meet the manufacturing needs of some marine equipment with nuclear facilities.

[0006] On the one hand, the present invention provides a GPa-level nanophase particle reinforced marine engineering steel plate, which includes, in terms of mass percentage, C: 0.040-0.12%, Ni: 5.0-12.00%, Al: 0.60-1.50%, Cr: 0.50-1.0%, Mo: 0.50-1.0%, V: 0.040-0.10%, Mn: 0.80-1.50%, Si: 0.10-0.50%, Ti: 0.01-0.020%, P≤0.01%, S≤0.005%, the remainder being Fe and unavoidable impurities, and satisfies the welding carbon equivalent: Ceq=C+(Mn+Si) / 6+(Ni+Cu) / 15+(Cr+Mo+V) / 5≤1.45.

[0007] Furthermore, in terms of mass percentage, the marine engineering steel plate includes: C: 0.053-0.074%, Ni: 5.53-6.01%, Al: 0.65-0.95%, Cr: 0.51-0.71%, Mo: 0.52-0.72%, V: 0.041-0.065%, Mn: 0.82-0.95%, Si: 0.12-0.32%, Ti: 0.011-0.015%, P≤0.008%, S≤0.005%, and the balance is Fe and unavoidable impurities; and satisfies the welding carbon equivalent: Ceq=C+(Mn+Si) / 6+(Ni+Cu) / 15+(Cr+Mo+V) / 5≤1.2.

[0008] Furthermore, in terms of mass percentage, the marine engineering steel plate includes: C: 0.075-0.12%, Ni: 6.15-10.80%, Al: 0.69-1.48%, Cr: 0.72-0.98%, Mo: 0.74-0.97%, V: 0.071-0.088%, Mn: 0.95-1.49%, Si: 0.34-0.48%, Ti: 0.016-0.019%, P≤0.005%, S≤0.003%, and the balance is Fe and unavoidable impurities; and satisfies the welding carbon equivalent: Ceq=C+(Mn+Si) / 6+(Ni+Cu) / 15+(Cr+Mo+V) / 5≤1.4.

[0009] Furthermore, the microstructure of the marine engineering steel plate is composed of martensite, austenite and nano-scale precipitation phases.

[0010] Furthermore, in terms of volume percentage, the martensite is 88-96%, the austenite is 3-10%, the nanoscale precipitate phase is 0.5-3%, and the size of the nanoscale precipitate phase is less than 60 nm.

[0011] Furthermore, the martensite accounts for 90-94%, the austenite accounts for 5-8%, the nanoscale precipitate accounts for 0.8-2.5%, and the size of the nanoscale precipitate is 5-30 nm.

[0012] Furthermore, the nano-precipitated phases include Ni3Al, (V,Mo)C and Mo2C.

[0013] Furthermore, the yield strength of the marine steel plate is ≥1300 MPa, the elongation is ≥14%, the impact toughness at -80°C is ≥50 J, and the fiber ratio at -80°C section is ≥50%.

[0014] In another aspect, the present invention provides a method for preparing a steel plate for marine engineering according to any one of claims 1 to 5, comprising the following steps:

[0015] (1) Slab continuous casting: The slab is cast to obtain a continuous casting billet.

[0016] (2) Low-temperature reheating: heating the continuous casting billet at a temperature of 1100-1200° C. and keeping the temperature for 60-120 minutes;

[0017] (3) Rolling: Rough rolling is performed in the recrystallization zone and finish rolling is performed in the non-recrystallization zone;

[0018] (4) Solution heat treatment: The rolled steel plate is subjected to solution treatment at a temperature of 860-900°C for 1-2 hours, and then quenched;

[0019] (5) Aging treatment: The quenched steel plate is placed in the AC1 The temperature is below 10 to 60° C., aging is performed for 90 to 150 minutes, and cooling is performed to obtain the GPa-level nano-phase particle reinforced steel plate for marine engineering.

[0020] Furthermore, in step (3), the starting rolling temperature of the rough rolling in the recrystallization zone is 1100-1180°C, the finishing rolling temperature is 980-900°C, 2-4 passes of high reduction rolling are performed, the reduction of each pass is not less than 20%, and the rolling speed is not higher than 1.5 m / s;

[0021] The starting rolling temperature for finishing rolling in the amorphous zone is 900-980°C, the final rolling temperature is 850-900°C, and 3-10 passes of high reduction rolling are carried out, with the reduction of each pass not less than 10%, and the compression ratio is not less than 5 when rolling in the amorphous zone.

[0022] Furthermore, in the quenching treatment in step (4), the water quenching speed is controlled at 1-2 m / min, the cooling rate is ≥20°C / s, and the final cooling temperature of the steel plate surface is not higher than 200°C.

[0023] Furthermore, in step (4), the solution temperature is 870° C. and the solution time is 120 min.

[0024] Furthermore, the aging treatment temperature in step (5) is 550-600°C.

[0025] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0026] (1) The inexpensive alloying element Al is added to the marine engineering steel plate of the present invention. By utilizing the solid solubility characteristics of Al and Ni in the steel matrix and through a reasonable ratio of Al and Ni, nano-scale intermetallic compounds Ni3Al and carbide nano-precipitates such as (V,Mo)C and Mo2C are formed during the aging process, so that the steel plate has ultra-high strength and good low-temperature toughness, meeting the service performance requirements of deep-sea and ocean-going equipment in severe cold and low-temperature marine environments. Compared with traditional ultra-high strength steels with a yield strength greater than 1300 MPa, the steel of the present invention ensures excellent high strength and low-temperature toughness.

[0027] (2) The steel plate of the present invention does not contain Cu element and does not improve strength by precipitation strengthening of Cu-rich phase. Therefore, the steel plate of the present invention can be used for manufacturing radiation embrittlement resistant materials;

[0028] (3) The method of the present invention obtains a marine steel plate with excellent comprehensive mechanical properties through slab continuous casting, low-temperature reheating, two-stage large-reduction rolling in the recrystallization and non-recrystallization zones, solution heat treatment, two-phase zone quenching, and aging heat treatment. The marine steel plate has a yield strength of ≥1300MPa, an elongation of ≥14%, an impact toughness of ≥50J at -80°C, and a fiber rate of ≥50% at a section of -80°C, which can meet the service performance requirements of deep-sea and ocean-going equipment in severe cold and low-temperature marine environments.

[0029] In the present invention, the above-mentioned technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of the present invention will be described in the following description, and some advantages will become apparent from the description or be learned through practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like parts throughout the drawings.

[0031] Figure 1 This is a scanning electron microscope photograph of the steel plate prepared in Example 1 of the present invention;

[0032] Figure 2 This is a nanoscale precipitation phase morphology of the steel plate prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0033] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, and are not used to limit the scope of the present invention.

[0034] A specific embodiment of the present invention discloses a GPa-level nanophase particle reinforced marine engineering steel plate. The marine engineering steel plate comprises, in percentage by mass: C: 0.040-0.12%, Ni: 5.0-12.00%, Al: 0.60-1.50%, Cr: 0.50-1.0%, Mo: 0.50-1.0%, V: 0.040-0.10%, Mn: 0.80-1.50%, Si: 0.10-0.50%, Ti: 0.01-0.020%, P≤0.01%, S≤0.005%, the remainder being Fe and unavoidable impurities, and satisfies the welding carbon equivalent: Ceq=C+(Mn+Si) / 6+(Ni+Cu) / 15+(Cr+Mo+V) / 5≤1.45.

[0035] The marine engineering steel plate of the present invention adds the inexpensive alloying element Al. By utilizing the solid solubility characteristics of Al and Ni in the steel matrix and through a reasonable ratio of Al and Ni, nano-scale intermetallic compounds Ni3Al and carbide nano-precipitation phases such as (V,Mo)C and Mo2C are formed during the aging process. This allows the steel plate to have ultra-high strength while also having good low-temperature toughness, meeting the service performance requirements of deep-sea and ocean-going equipment in severe cold and low-temperature marine environments.

[0036] It should be noted that, in the present invention, only the mass percentage of the components is expressed in %.

[0037] The role and proportion of each element in the present invention are as follows:

[0038] C: has a significant solid solution strengthening effect and can improve the hardenability of steel, but an increase in the C content in steel is very detrimental to the steel's low-temperature toughness and weldability. Therefore, the present invention adopts an ultra-low carbon design, with the C content controlled at 0.04-0.12%.

[0039] Ni: During the aging process, Ni forms the intermetallic compound Ni3Al with Al, which strengthens the steel. Ni also improves the hardenability of the steel, refines the grain size, and lowers the ductile-brittle transition temperature. Considering the strength and toughness of the steel plate of this invention, the Ni content is controlled within a range of 5.0 to 12.0%.

[0040] Al: The purpose of adding a relatively high amount of Al in the present invention is to form a nanoscale intermetallic compound Ni3Al phase with Ni, which provides a certain precipitation strengthening effect. Because Ni3Al has a high solid solubility in the iron matrix, too low an Al addition hinders precipitation, while too high an Al addition makes continuous casting difficult. Precipitation at a high volume fraction also reduces the steel's low-temperature toughness. Therefore, in the present invention, the Al content is controlled between 0.60% and 1.50%. Furthermore, trace amounts of Al can combine with trace amounts of N to form AlN, which prevents aging brittleness in the steel and refines the grain size.

[0041] Cr: Solid solution Cr can significantly improve the hardenability of steel (while reducing A c3 The Cr content in the present invention is controlled at 0.50-1.0%.

[0042] Mo: Solid solution Mo can significantly improve the hardenability of steel and also has a certain solid solution strengthening effect. At the same time, Mo can improve tempering stability and significantly reduce temper brittleness. In the present invention, the Mo content is controlled at 0.50-1.0%.

[0043] V: is a strong carbide-forming element, which can combine with C during the aging process to form nano-scale VC particles, and can play a good precipitation strengthening role. Considering the strength of the present invention, the V content in the present invention is controlled at 0.04-0.1%.

[0044] Mn: It can significantly improve the hardenability of steel, and has a certain solid solution strengthening effect, and can also reduce A c3 Temperature, making the temperature window for rolling in the non-recrystallization zone wider, but when the Mn content is too high, the corrosion resistance of the steel is reduced, and coarse M / A islands are easily formed in the weld heat affected zone, seriously affecting the low-temperature toughness of the weld heat affected zone. In the present invention, the Mn content is controlled at 0.80-1.50%.

[0045] Si: One of the deoxidizing elements in steel. Silicon is also a non-carbide-forming element. It exists in the steel matrix in the form of solid solution and has a certain solid solution strengthening effect. However, excessive silicon is detrimental to the low-temperature toughness of steel and increases the sensitivity of steel to cold cracks and hot cracks during welding. In the present invention, the Si content is controlled to 0.10-0.50%.

[0046] Ti: A strong carbonitride-forming element. A trace amount of Ti combines with nitrogen in the steel to form TiN, which prevents austenite grain growth during soaking and in the heat-affected zone, thereby improving weldability. In the present invention, the Ti content is controlled to 0.01-0.02%.

[0047] P and S: impurity elements in steel, which are very detrimental to the properties of steel, especially low-temperature toughness. Their contents in the steel of the present invention should be strictly controlled, not exceeding 0.01% and 0.005% respectively.

[0048] Specifically, in terms of mass percentage, the marine engineering steel plate includes: C: 0.053-0.074%, Ni: 5.53-6.01%, Al: 0.65-0.95%, Cr: 0.51-0.71%, Mo: 0.52-0.72%, V: 0.041-0.065%, Mn: 0.82-0.95%, Si: 0.12-0.32%, Ti: 0.011-0.015%, P≤0.008%, S≤0.005%, and the balance is Fe and unavoidable impurities; and meets the welding carbon equivalent: Ceq=C+(Mn+Si) / 6+(Ni+Cu) / 15+(Cr+Mo+V) / 5≤1.2.

[0049] Specifically, in terms of mass percentage, the marine engineering steel plate includes: C: 0.075-0.12%, Ni: 6.15-10.80%, Al: 0.69-1.48%, Cr: 0.72-0.98%, Mo: 0.74-0.97%, V: 0.071-0.088%, Mn: 0.95-1.49%, Si: 0.34-0.48%, Ti: 0.016-0.019%, P≤0.005%, S≤0.003%, and the balance is Fe and unavoidable impurities; and meets the welding carbon equivalent: Ceq=C+(Mn+Si) / 6+(Ni+Cu) / 15+(Cr+Mo+V) / 5≤1.4.

[0050] Specifically, the microstructure of the marine engineering steel plate is composed of martensite, austenite and nano-scale precipitation phases.

[0051] Specifically, in terms of volume percentage, the martensite accounts for 88-96%, the austenite accounts for 3-10%, the nanoscale precipitate phase accounts for 0.5-3%, and the size of the nanoscale precipitate phase is less than 60 nm.

[0052] It should be noted that the microstructure of the marine engineering steel plate is composed of tempered lath martensite, reversed austenite and nano-scale precipitation phase.

[0053] Specifically, the martensite accounts for 90-94%, the austenite accounts for 5-8%, the nanoscale precipitate accounts for 0.8-2.5%, and the size of the nanoscale precipitate is 5-30 nm.

[0054] Specifically, the nano-precipitated phase includes Ni3Al and multiple composite precipitated phases such as (V, Mo)C and Mo2C, and the precipitation strengthening increment accounts for more than 30% of the yield strength.

[0055] It should be noted that the precipitation strengthening increment is generally calculated based on the content and size of the nano-precipitated phase through an empirical formula.

[0056] It should be noted that the yield strength of the marine steel plate described in this embodiment is ≥1300 MPa, the elongation is ≥14%, the impact toughness at -80°C is ≥50 J, and the fiber ratio at -80°C section is ≥50%.

[0057] This embodiment provides a method for preparing the marine engineering steel plate, comprising the following steps:

[0058] (1) Slab continuous casting: The slab is cast to obtain a continuous casting billet.

[0059] (2) Low-temperature reheating: heating the continuous casting billet at a temperature of 1100-1200° C. and keeping the temperature for 60-120 minutes;

[0060] (3) Rolling: Rough rolling is performed in the recrystallization zone and finish rolling is performed in the non-recrystallization zone;

[0061] (4) Solution heat treatment: The rolled steel plate is subjected to solution treatment at a temperature of 860-900°C for 1-2 hours, and then quenched;

[0062] (5) Aging treatment: The quenched steel plate is placed in the A C1 The temperature is below 10 to 60° C., aging is performed for 90 to 150 minutes, and cooling is performed to obtain the GPa-level nano-phase particle reinforced steel plate for marine engineering.

[0063] It should be noted that in step (1), the continuous casting of the slab adopts low superheat pouring, the pouring superheat is not greater than 20°C, and the light pressure and electromagnetic stirring technology are adopted to reduce the degree of segregation in the core of the steel plate.

[0064] It should be noted that in step (2), heating at a temperature of 1100-1200° C. and keeping the temperature for 60-120 minutes is to allow the alloy elements to fully dissolve.

[0065] Exemplarily, in step (2), heating is performed at 1100°C, 1110°C, 1120°C, 1130°C, 1140°C, 1150°C, 1160°C, 1170°C, 1180°C, 1190°C, or 1200°C, and the temperature is kept constant for 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, or 120 min.

[0066] Specifically, in step (3), the starting rolling temperature of the rough rolling in the recrystallization zone is 1100-1180° C., the finishing rolling temperature is 980-900° C., 2-4 passes of high reduction rolling are performed, the reduction of each pass is not less than 20%, and the rolling speed is not higher than 1.5 m / s;

[0067] The starting rolling temperature for finishing rolling in the amorphous zone is 900-980°C, the final rolling temperature is 850-900°C, and 3-10 passes of high reduction rolling are carried out, with the reduction of each pass not less than 10%, and the compression ratio is not less than 5 when rolling in the amorphous zone.

[0068] Exemplarily, in step (3), three passes of high reduction rolling are performed within the temperature range of the recrystallization zone, with the starting rolling temperature being 1120°C, the final rolling temperature being 1000°C, the rolling speed being 1.5 m / s, and the reduction per pass being 21%; and five passes of rolling are performed within the temperature range of the non-recrystallization zone, with the starting rolling temperature being 950°C, the final rolling temperature being 850°C, and the reduction per pass being 15.7%.

[0069] Specifically, in the quenching treatment in step (4), the water quenching speed is controlled at 1-2 m / min, the cooling rate is ≥20°C / s, and the final cooling temperature of the steel plate surface is not higher than 200°C.

[0070] Specifically, in step (4), the solution temperature is 870° C. and the solution time is 120 min.

[0071] Specifically, the aging treatment temperature in step (5) is 550-600°C.

[0072] Exemplarily, the aging treatment temperature in step (5) is 550°C, 560°C, 570°C, 580°C, 590°C, or 600°C.

[0073] It should be noted that after aging treatment, air cooling to room temperature is performed.

[0074] Example 1

[0075] This embodiment provides a method for preparing a marine engineering steel plate reinforced with GPa-level nanophase particles, which specifically includes the following steps:

[0076] (1) Slab continuous casting: The slab is cast at a low superheat temperature, with the casting superheat not exceeding 20°C. The electromagnetic stirring technology is used under light pressure to reduce the degree of segregation in the core of the steel plate to obtain a continuously cast slab.

[0077] (2) Low-temperature reheating: heating the continuous casting billet at 1120°C for 60 minutes to allow the alloy elements to fully dissolve;

[0078] (3) Rolling: The starting rolling temperature for rough rolling in the recrystallization zone is 1100°C, the finishing rolling temperature is 980°C, and two passes of high reduction rate rolling are performed, with a reduction of 22.2% per pass and a rolling speed of 1.4 m / s; the starting rolling temperature for finish rolling in the amorphous zone is 970°C, the finishing rolling temperature is 860°C, and three passes of high reduction rate rolling are performed, with a reduction of not less than 12.5% ​​per pass and a rolling speed of 1.4 m / s, and the reduction ratio in the amorphous zone is 5;

[0079] (4) Solution heat treatment: The rolled steel plate is solution treated at 880°C for 70 min and then quenched. The water quenching speed is controlled at 1.5 m / min, the cooling rate is 20°C / s, and the final cooling temperature of the steel plate surface is not higher than 200°C.

[0080] (5) Aging treatment: The quenched steel plate is aged at 550° C. for 120 min and then air-cooled to room temperature to obtain the GPa-level nanophase particle reinforced marine engineering steel plate.

[0081] The steel plate prepared in this embodiment has a chemical composition, in percentage by mass, including: C: 0.06%, Ni: 6.5%, Al: 1.10%, Cr: 0.6%, Mo: 0.7%, V: 0.06%, Mn: 0.80%, Si: 0.28%, Ti: 0.013%, P: 0.006%, S: 0.004%, and the remainder is Fe and unavoidable impurities.

[0082] The scanning electron microscope photograph of the steel plate prepared in Example 1 of the present invention is as follows: Figure 1 As shown in Figure 1, the microstructure is lath martensite, in which the white granular structure is cementite. Figure 2 As shown, a large number of dispersed and precipitated nano-scale particles are distributed on the matrix, which can hinder the movement of dislocations and thus play a strengthening role.

[0083] This embodiment provides a method for preparing a marine engineering steel plate reinforced with GPa-level nanophase particles, which specifically includes the following steps:

[0084] (1) Slab continuous casting: The slab is cast at a low superheat temperature, with the casting superheat not exceeding 20°C. The electromagnetic stirring technology is used under light pressure to reduce the degree of segregation in the core of the steel plate to obtain a continuously cast slab.

[0085] (2) Low-temperature reheating: heating the continuous casting billet at 1130°C for 80 minutes to allow the alloy elements to fully dissolve;

[0086] (3) Rolling: The starting rolling temperature for rough rolling in the recrystallization zone is 1120°C, the final rolling temperature is 990°C, and three passes of high reduction rate rolling are performed, with a reduction of 21.5% per pass and a rolling speed of 1.5 m / s; the starting rolling temperature for finish rolling in the amorphous zone is 985°C, the final rolling temperature is 850°C, and five passes of high reduction rate rolling are performed, with a reduction of not less than 13.5% per pass and a rolling speed of 1.3 m / s, and the reduction ratio in the amorphous zone is 6;

[0087] (4) Solution heat treatment: The rolled steel plate is solution treated at 870°C for 80 min and then quenched. The water quenching speed is controlled at 1.5 m / min, the cooling rate is 22°C / s, and the final cooling temperature of the steel plate surface is not higher than 200°C.

[0088] (5) Aging treatment: The quenched steel plate is aged at 540° C. for 120 min and then air-cooled to room temperature to obtain the GPa-level nanophase particle reinforced marine engineering steel plate.

[0089] The steel plate prepared in this embodiment has a chemical composition, in percentage by mass, including: C: 0.07%, Ni: 8.8%, Al: 0.8%, Cr: 0.8%, Mo: 0.9%, V: 0.08%, Mn: 0.90%, Si: 0.15%, Ti: 0.015%, P: 0.008%, S: 0.002%, and the remainder is Fe and unavoidable impurities.

[0090] The inventors also tested the steel plate prepared in this example using a scanning electron microscope, and the results were basically consistent with those in Example 1. Due to limited space, they are not listed one by one.

[0091] Example 3

[0092] This embodiment provides a method for preparing a marine engineering steel plate reinforced with GPa-level nanophase particles, which specifically includes the following steps:

[0093] (1) Slab continuous casting: The slab is cast at a low superheat temperature, with the casting superheat not exceeding 20°C. The electromagnetic stirring technology is used under light pressure to reduce the degree of segregation in the core of the steel plate to obtain a continuously cast slab.

[0094] (2) Low-temperature reheating: heating the continuous casting billet at 1109°C for 90 minutes to allow the alloy elements to fully dissolve;

[0095] (3) Rolling: The starting rolling temperature for rough rolling in the recrystallization zone is 1140°C, the finishing rolling temperature is 970°C, and four passes of high reduction rate rolling are performed, with a reduction of 22.4% per pass and a rolling speed of 1.4 m / s; the starting rolling temperature for finish rolling in the amorphous zone is 960°C, the finishing rolling temperature is 855°C, and six passes of high reduction rate rolling are performed, with a reduction of not less than 15.5% per pass and a rolling speed of 1.5 m / s, and the reduction ratio in the amorphous zone is 6;

[0096] (4) Solution heat treatment: The rolled steel plate is solution treated at 890°C for 70 min and then quenched. The water quenching speed is controlled at 1.5 m / min, the cooling rate is 22°C / s, and the final cooling temperature of the steel plate surface is not higher than 200°C.

[0097] (5) Aging treatment: The quenched steel plate is aged at 560° C. for 120 min and then air-cooled to room temperature to obtain the GPa-level nanophase particle reinforced marine engineering steel plate.

[0098] The steel plate prepared in this embodiment has a chemical composition, in percentage by mass, of: C: 0.09%, Ni: 7.5%, Al: 0.65%, Cr: 0.7%, Mo: 0.75%, V: 0.05%, Mn: 1.5%, Si: 0.4%, Ti: 0.019%, P: 0.007%, S: 0.003%, and the remainder is Fe and unavoidable impurities.

[0099] The inventors also tested the steel plate prepared in this embodiment by scanning electron microscopy, and the results were basically consistent with those in Example 1. Due to limited space, they are not listed one by one.

[0100] This embodiment provides a method for preparing a marine engineering steel plate reinforced with GPa-level nanophase particles, which specifically includes the following steps:

[0101] (1) Slab continuous casting: The slab is cast at a low superheat temperature, with the casting superheat not exceeding 20°C. The electromagnetic stirring technology is used under light pressure to reduce the degree of segregation in the core of the steel plate to obtain a continuously cast slab.

[0102] (2) Low-temperature reheating: heating the continuous casting billet at 1150°C for 100 minutes to allow the alloy elements to fully dissolve;

[0103] (3) Rolling: The starting rolling temperature for rough rolling in the recrystallization zone is 1160°C, the final rolling temperature is 995°C, and three passes of high reduction rate rolling are performed, with a reduction of 20.5% per pass and a rolling speed of 1.5 m / s; the starting rolling temperature for finish rolling in the amorphous zone is 985°C, the final rolling temperature is 850°C, and eight passes of high reduction rate rolling are performed, with a reduction of not less than 16.4% per pass and a rolling speed of 1.4 m / s, and the reduction ratio in the amorphous zone is 5;

[0104] (4) Solution heat treatment: The rolled steel plate is solution treated at 860°C for 90 min and then quenched. The water quenching speed is controlled at 1.5 m / min, the cooling rate is 25°C / s, and the final cooling temperature of the steel plate surface is not higher than 200°C.

[0105] (5) Aging treatment: The quenched steel plate is aged at 545° C. for 100 min and then air-cooled to room temperature to obtain the GPa-level nano-phase particle reinforced marine engineering steel plate.

[0106] The steel plate prepared in this embodiment has a chemical composition, in percentage by mass, including: C: 0.10%, Ni: 8.0%, Al: 1.40%, Cr: 0.85%, Mo: 0.8%, V: 0.07%, Mn: 0.50%, Si: 0.35%, Ti: 0.015%, P: 0.004%, S: 0.002%, and the remainder is Fe and unavoidable impurities.

[0107] The inventors also tested the steel plate prepared in this example using a scanning electron microscope, and the results were basically consistent with those in Example 1. Due to limited space, they are not listed one by one.

[0108] Example 5

[0109] This embodiment provides a method for preparing a marine engineering steel plate reinforced with GPa-level nanophase particles, which specifically includes the following steps:

[0110] (1) Slab continuous casting: The slab is cast at a low superheat temperature, with the casting superheat not exceeding 20°C. The electromagnetic stirring technology is used under light pressure to reduce the degree of segregation in the core of the steel plate to obtain a continuously cast slab.

[0111] (2) Low-temperature reheating: heating the continuous casting billet at 1160°C for 120 minutes to allow the alloy elements to fully dissolve;

[0112] (3) Rolling: The starting rolling temperature for rough rolling in the recrystallization zone is 1200°C, the final rolling temperature is 985°C, and 4 passes of high reduction rate rolling are performed, with a reduction of 21.5% per pass and a rolling speed of 1.3 m / s; the starting rolling temperature for finish rolling in the amorphous zone is 975°C, the final rolling temperature is 855°C, and 10 passes of high reduction rate rolling are performed, with a reduction of not less than 14.8% per pass and a rolling speed of 1.4 m / s, and the reduction ratio in the amorphous zone is 5;

[0113] (4) Solution heat treatment: The rolled steel plate is solution treated at 870°C for 80 min, and then quenched. The water quenching speed is controlled at 1.5 m / min, the cooling rate is 20°C / s, and the final cooling temperature of the steel plate surface is not higher than 200°C.

[0114] (5) Aging treatment: The quenched steel plate is aged at 550° C. for 110 min and then air-cooled to room temperature to obtain the GPa-level nano-phase particle reinforced marine engineering steel plate.

[0115] The steel plate prepared in this embodiment has a chemical composition, in percentage by mass, including: C: 0.12%, Ni: 8.6%, Al: 0.90%, Cr: 0.95%, Mo: 0.95%, V: 0.09%, Mn: 0.90%, Si: 0.42%, Ti: 0.013%, P: 0.005%, S: 0.003%, and the balance is Fe and unavoidable impurities.

[0116] The inventors also tested the steel plate prepared in this example using a scanning electron microscope, and the results were basically consistent with those in Example 1. Due to limited space, they are not listed one by one.

[0117] Example 6

[0118] The steel plate preparation method and composition of this embodiment are the same as those of Example 1, except that: C: 0.04%, Ni: 12.0%, Al: 1.50%, Cr: 0.50%, Mo: 0.50%, V: 0.04%, Si: 0.50%, and Ti: 0.01%.

[0119] The inventors also tested the steel plate prepared in this example using a scanning electron microscope, and the results were basically consistent with those in Example 1. Due to limited space, they are not listed one by one.

[0120] Comparative Example 1

[0121] The preparation method and composition of the steel plate of this comparative example are the same as those of Example 1, except that the Al content in the steel plate is 0.5%.

[0122] Comparative Example 2

[0123] The method for preparing the steel plate of this comparative example is the same as that of Example 1, except that the Al content in the steel plate is 1.6%.

[0124] The composition and process parameters of the steel plates prepared in Examples 1-6 are shown in Table 1-3.

[0125] Table 1 Chemical composition of steel plates prepared in Examples 1-6 (%)

[0126]

[0127] Table 2 Specific rolling process parameters for preparing steel plates in Examples 1-6

[0128]

[0129] Table 3 Heat treatment process parameters of steel plates prepared in Examples 1-6

[0130]

[0131] Test Example 1

[0132] The strength and low-temperature toughness of the steel plates prepared in Examples 1-6 and Comparative Examples 1-2 were tested respectively. The results are shown in Table 4.

[0133] Table 4 Strength and low temperature toughness of the steel plates prepared in Examples 1-6 and Comparative Examples 1-2

[0134]

[0135] Test Example 2

[0136] The microstructures of the steel plates prepared in Examples 1-6 were observed using a scanning electron microscope. The results are shown in Table 5.

[0137] Table 5 Microstructure composition of the steel plates prepared in Examples 1-6

[0138] Group Martensite (%) Austenite (%) Nanoprecipitated phase (%) Example 1 98.2 1.3 0.5 Example 2 97.4 2.2 0.4 Example 3 96.4 3.2 0.4 Example 4 95.6 3.6 0.8 Example 5 94.2 5.2 0.6 Example 6 95.6 3.8 0.6

[0139] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed by the present invention should be covered by the scope of protection of the present invention.

Claims

1. A GPa-level nano-phase particle reinforced steel plate for marine engineering, characterized in that: According to the mass percentage, the marine engineering steel plate comprises: C: 0.090-0.12%, Ni: 8.8-12.00%, Al: 0.60-1.50%, Cr: 0.70-1.0%, Mo: 0.50-1.0%, V: 0.060-0.08%, Mn: 0.80-1.50%, Si: 0.28-0.42%, Ti: 0.01-0.020%, P≤0.01%, S≤0.005%, the balance is Fe and unavoidable impurities, and meets the welding carbon equivalent: Ceq=C+(Mn+Si) / 6+(Ni+Cu) / 15+(Cr+Mo+V) / 5≤1.45; The microstructure of the marine engineering steel plate is composed of martensite, austenite and nano-scale precipitation phases; The nano-precipitated phase includes Ni3Al, (V, Mo)C and Mo2C; The marine engineering steel plate is prepared by the following method: (1) Slab continuous casting: The slab is cast to obtain a continuous casting billet. The slab continuous casting adopts low superheat casting, the casting superheat is not more than 20°C, and the light pressure and electromagnetic stirring technology are adopted to reduce the degree of segregation in the center of the steel plate; (2) low temperature reheating: heating the continuous casting billet at a temperature of 1100-1200° C. and keeping the temperature for 60-120 min; (3) Rolling: The starting rolling temperature of the rough rolling in the recrystallization zone is 1100-1180°C, the final rolling temperature is 980-900°C, and 2-4 passes of high reduction rate rolling are carried out, with the reduction of each pass not less than 20% and the rolling speed not higher than 1.5 m / s; The start rolling temperature of the finish rolling in the amorphous region is 900-980°C, the final rolling temperature is 850-900°C, and 3-10 passes of high reduction rate rolling are performed, the reduction amount of each pass is not less than 10%, and the compression ratio is not less than 5 when rolling in the amorphous region; (4) Solution heat treatment: The rolled steel plate is subjected to solution treatment at a temperature of 860-900°C for 1-2 hours, and then quenched; (5) Aging treatment: The quenched steel plate is placed in the A C1 The temperature is below 10-60° C., the aging is performed for 90-150 minutes, and the steel plate for marine engineering reinforced with GPa-level nano-phase particles is obtained.

2. The marine engineering steel plate reinforced with GPa-level nanophase particles according to claim 1, characterized in that: According to mass percentage, the marine engineering steel plate includes: C: 0.090-0.12%, Ni: 8.8-12.00%, Al: 0.65-0.95%, Cr: 0.70-1.0%, Mo: 0.52-0.72%, V: 0.060-0.065%, Mn: 0.82-0.95%, Si: 0.28-0.32%, Ti: 0.011-0.015%, P≤0.008%, S≤0.005%, and the balance is Fe and unavoidable impurities; and meets the welding carbon equivalent: Ceq=C+(Mn+Si) / 6+(Ni+Cu) / 15+(Cr+Mo+V) / 5≤1.

2.

3. The marine engineering steel plate reinforced with GPa-level nano-phase particles according to claim 1, characterized in that: According to mass percentage, the marine engineering steel plate includes: C: 0.090-0.12%, Ni: 8.8-10.80%, Al: 0.69-1.48%, Cr: 0.72-0.98%, Mo: 0.74-0.97%, V: 0.071-0.080%, Mn: 0.95-1.49%, Si: 0.34-0.42%, Ti: 0.016-0.019%, P≤0.005%, S≤0.003%, and the remainder is Fe and unavoidable impurities; and meets the welding carbon equivalent: Ceq=C+(Mn+Si) / 6+(Ni+Cu) / 15+(Cr+Mo+V) / 5≤1.

4.

4. The GPa-level nano-phase particle reinforced marine engineering steel plate according to claim 1, characterized in that: According to volume percentage, the martensite is 88-96%, the austenite is 3-10%, the nano-scale precipitate phase is 0.5-3%, and the size of the nano-precipitate phase is less than 60nm.

5. The marine engineering steel plate reinforced with GPa-level nano-phase particles according to any one of claims 1 to 4, characterized in that: The yield strength of the marine steel plate is ≥1300MPa, the elongation is ≥14%, the impact toughness at -80°C is ≥50J, and the fiber rate of the cross section at -80°C is ≥50%.

6. A method for preparing a steel plate for marine engineering according to any one of claims 1 to 5, characterized in that: The steps include: (1) Slab continuous casting: The slab is cast to obtain a continuous casting billet; (2) low temperature reheating: heating the continuous casting billet at a temperature of 1100-1200° C. and keeping the temperature for 60-120 min; (3) Rolling: Rough rolling is performed in the recrystallization zone and finish rolling is performed in the non-recrystallization zone; (4) Solution heat treatment: The rolled steel plate is subjected to solution treatment at a temperature of 860-900°C for 1-2 hours, and then quenched; (5) Aging treatment: The quenched steel plate is placed in the A C1 The temperature is below 10-60° C., the aging is performed for 90-150 minutes, and the steel plate for marine engineering reinforced with GPa-level nano-phase particles is obtained.

7. The preparation method according to claim 6, characterized in that: In step (4), the water quenching speed in the quenching treatment is controlled at 1-2 m / min, the cooling rate is ≥20°C / s, and the final cooling temperature of the steel plate surface is not higher than 200°C.

8. The preparation method according to claim 6, characterized in that: The aging treatment temperature in step (5) is 550-600°C.

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