A tungsten-containing maraging ultra-high strength steel and its preparation method

Abstract

The present invention relates to the technical field of steel materials, and discloses a tungsten-containing maraging ultra-high strength steel and a preparation method thereof. In terms of mass percentage, the tungsten-containing maraging ultra-high strength steel comprises: 14.5-16.0% of Co, 17.0-18.0% of Ni, 6.0-8.0% of Mo, 1.0-1.5% of Ti, 0.5-1.0% of W, and the balance is Fe and inevitable impurities. The control requirements for impurity elements are: C≤0.008%, Si≤0.1%, Mn≤0.1%, P≤0.005%, S≤0.005%, N≤0.0015%, O≤0.0015%. Based on the first-principles calculation and research results of the influence of element doping on the precipitated phases in maraging steels, 0.5-1.0% of W element is added to the maraging steel composition system, and at the same time, the content of Mo element in the steel is increased, so that when the grain size of the steel is ≥8.0 grade, the tensile strength Rm≥2800 MPa and the elongation A≥5%.

Description

Technical Field

[0001] The present invention relates to the technical field of steel materials, and in particular to a tungsten-containing maraging ultra-high strength steel and a preparation method thereof. Background Art

[0002] Maraging steels have ultra-high strength and high plasticity, and are widely used in the aerospace and communication fields. The shape and size of the material, such as bars, wires, and plates, have a great influence on the performance, and the requirements for the shape and size of the material vary greatly in different fields. Therefore, it is urgent to develop a maraging steel that meets ultra-high strength and high plasticity (strength ≥ 2800 MPa, elongation ≥ 5.0%) under different shape and size conditions.

[0003] There are some problems in the existing preparation methods. For example, CN 115558853 A discloses a high-strength and tough maraging steel and a preparation method thereof. By adding trace amounts of Nb and Ce, the electroslag remelting process necessary for the conventional process is omitted, and the high-strength and tough maraging steel is prepared. However, the method of this patent requires cold rolling of the material to obtain the required strength, and the process is long. At the same time, the strength of the maraging steel in this patent has a great relationship with the material size: for materials with a diameter ≥ 8.0 mm, the tensile strength Rm < 2500 MPa. CN 115786813 A discloses a maraging steel sheet and a preparation method thereof. This patent improves the strength of the steel by increasing the Mo content of the maraging steel and adding Al elements. By hot rolling + cold rolling, the sheet thickness is 0.5 mm to 2 mm, and the grain size reaches 9.5 to 11.5 grades to ensure high strength and plasticity. However, this method has great limitations on the final shape and specifications of the steel.

[0004] Therefore, there is a need to improve the tungsten-containing maraging ultra-high strength steel and its preparation method in the prior art. Summary of the Invention

[0005] In view of this, the purpose of the embodiments of the present invention is to provide a tungsten-containing maraging ultra-high strength steel and a preparation method thereof. Based on the first-principles calculation and research results of the influence of element doping on the precipitated phases in maraging steels, 0.5 to 1.0% of W element is added to the maraging steel composition system, and at the same time, the Mo element content in the steel is increased, so that when the grain size of the steel ≥ 8.0 grades, the tensile strength Rm ≥ 2800 MPa and the elongation A ≥ 5%.

[0006] For the above purpose, an embodiment of the present invention provides a tungsten-containing maraging ultra-high strength steel, which is characterized in that, by mass percentage, it includes Co 14.5 - 16.0%, Ni 17.0 - 18.0%, Mo 6.0 - 8.0%, Ti 1.0 - 1.5%, W 0.5 - 1.0%, and the balance is Fe and inevitable impurities. The control requirements for impurity elements are: C ≤ 0.008%, Si ≤ 0.1%, Mn ≤ 0.1%, P ≤ 0.005%, S ≤ 0.005%, N ≤ 0.0015%, O ≤ 0.0015%.

[0007] Another aspect of the present invention also provides a preparation method of tungsten-containing maraging ultra-high strength steel, including the following steps:

[0008] S1 According to the composition of the tungsten-containing maraging ultra-high strength steel, use the vacuum induction and vacuum consumable double melting process to smelt a maraging steel ingot;

[0009] S2 Perform high-temperature homogenization treatment on the steel ingot;

[0010] S3 Use the three-upsetting and three-drawing process to forge and bloom the steel ingot to obtain a forged material;

[0011] S4 Reheat the forged material in the furnace and then perform precision forging or rolling to the target size;

[0012] S5 Perform heat treatment and aging treatment on the rolled forged material to obtain maraging ultra-high strength steel.

[0013] In some embodiments, in S2, the high-temperature homogenization treatment includes: the temperature range is 1250°C - 1260°C, the holding time is 36h - 48h, and after the holding ends, it is taken out of the furnace and cooled to the forging start temperature before forging and blooming.

[0014] In some embodiments, in S3, the three-upsetting and three-drawing process includes: the upsetting reduction for each time is ≥ 50%, and the drawing ratio for each time is ≥ 200%.

[0015] In some embodiments, during forging, the forging start temperature is 1180 - 1200°C. When the temperature is lower than 1050°C, it is reheated in the furnace at 1150°C for 2h and then continues to be upset; the final forging temperature is ≥ 1000°C. When the temperature is lower than 1000°C, it is reheated in the furnace at 1100°C for 2h and then continues to be upset and drawn.

[0016] In some embodiments, in S4, the forged material is reheated in the furnace to 1150°C, held for 2h, and the single-pass reduction during precision forging or rolling is ≤ 35%, and the final forging or final rolling temperature is ≥ 950°C.

[0017] In some embodiments, in S5, the heat treatment process includes:

[0018] Keep it at 850 - 860°C for 1 - 2 hours, and then immediately oil quench to room temperature;

[0019] Keep it at 820 - 830°C for 1 - 1.5 hours, and then immediately oil quench to room temperature, repeat twice;

[0020] Perform cryogenic treatment within 4 hours and then naturally warm back in air;

[0021] Perform aging treatment on the material that has returned to room temperature within 8 hours.

[0022] In some embodiments, the cryogenic treatment includes: controlling the temperature at -70 to -80°C, and placing the forged material in a cryogenic device to cool for 1 - 2 hours.

[0023] In some embodiments, the aging treatment includes: the treatment temperature is 480 - 500°C, and the treatment time is 5 - 8 hours.

[0024] In some embodiments, in S1, it further includes: performing peeling treatment on the martensitic age hardened steel ingot obtained by smelting.

[0025] The present invention has at least the following beneficial technical effects:

[0026] By increasing the content of Mo element and adding W element, the number of precipitation phases is increased, the precipitation strengthening effect is improved, and at the same time, the brittleness of Ni3Ti can be alleviated by doping; moreover, by increasing the content of Ni element, the plasticity and toughness of the steel are improved; the steel prepared by using the components and methods of the present invention has a tensile strength Rm ≥ 2800 MPa and an elongation A ≥ 5% when the grain size ≥ 8.0 grade, and there is no strict limit on the final external dimensions of the material.

[0027] The preparation method of the present invention does not require cold rolling, which can optimize the preparation process; moreover, the room temperature deformation processing of high alloy ultra-high strength steel is difficult, and the absence of the cold rolling process greatly reduces the risk of cold rolling cracking and is easy to be industrially produced and prepared. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other embodiments can also be obtained based on these drawings.

[0029] Figure 1 It is a schematic diagram of an embodiment of the preparation method of the tungsten-containing martensitic age hardened ultra-high strength steel provided by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the following further elaborates on the embodiments of the present invention in detail with reference to specific embodiments and the accompanying drawings.

[0031] The terms "comprising" and "having" and any variations thereof in the description and claims of the present invention and the above description of the accompanying drawings are intended to cover non-exclusive inclusion; the terms "first", "second", etc. in the description and claims of the present invention or the above drawings are used to distinguish different objects and not to describe a specific order. The meaning of "a plurality" is two or more, unless otherwise specifically defined.

[0032] In addition, the mention of "embodiments" in this document means that the specific features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of the present invention. The appearance of this phrase at various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0033] On the one hand, the present invention provides a tungsten-containing maraging ultra-high strength steel, which, by mass percentage, includes Co 14.5 - 16.0%, Ni 17.0 - 18.0%, Mo 6.0 - 8.0%, Ti 1.0 - 1.5%, W 0.5 - 1.0%, and the balance is Fe and unavoidable impurities. The control requirements for impurity elements are: C ≤ 0.008%, Si ≤ 0.1%, Mn ≤ 0.1%, P ≤ 0.005%, S ≤ 0.005%, N ≤ 0.0015%, O ≤ 0.0015%.

[0034] The present invention uses carbon-free steel (ultra-low carbon), tries to eliminate the C element in the steel, controls the C element below 0.008%, increases the number of precipitation phases and the precipitation strengthening effect by increasing the content of the Mo element and adding the W element, and can also alleviate the brittleness of Ni3Ti through doping; moreover, the content of the Ni element is increased to improve the plasticity and toughness of the steel.

[0035] On the other hand, the present invention also provides a preparation method for a tungsten-containing maraging ultra-high strength steel, which includes the following steps:

[0036] S1 According to the composition of the tungsten-containing maraging ultra-high strength steel for batching, use a vacuum induction and vacuum consumable double process to smelt and obtain a maraging steel ingot;

[0037] S2 Perform a high-temperature homogenization treatment on the steel ingot;

[0038] S3 Use a three-upsetting and three-drawing process to forge and bloom the steel ingot to obtain a forged material;

[0039] S4 reheats the forged material and then performs precision forging or rolling to the target size;

[0040] S5 performs heat treatment and aging treatment on the rolled forged material to obtain maraging super high strength steel.

[0041] In some embodiments, in S2, the high-temperature homogenization treatment includes: the temperature range is 1250°C to 1260°C, the holding time is 36h to 48h, and after the holding is completed, it is taken out of the furnace and cooled to the forging start temperature before forging and blooming.

[0042] In some embodiments, in S3, the three-upsetting and three-drawing process includes: the upsetting reduction per time ≥ 50%, and the drawing ratio per time ≥ 200%;

[0043] In some embodiments, during forging, the forging start temperature is 1180~1200°C. When the temperature is lower than 1050°C, it is reheated in the furnace at 1150°C for 2h and then continues to be upset; the final forging temperature ≥ 1000°C. When the temperature is lower than 1000°C, it is reheated in the furnace at 1100°C for 2h and then continues to be upset and drawn.

[0044] In some embodiments, in S4, the forged material is reheated in the furnace to 1150°C, held for 2h, the single-pass reduction of precision forging or rolling ≤ 35%, and the final forging or final rolling temperature ≥ 950°C.

[0045] In some embodiments, in S5, the heat treatment process includes:

[0046] Hold at 850~860°C for 1~2 hours, and then immediately oil-cool to room temperature;

[0047] Hold at 820~830°C for 1~1.5 hours, and then immediately oil-cool to room temperature, repeating twice;

[0048] Perform cryogenic treatment within 4 hours and then naturally warm back in the air;

[0049] Age the material that has returned to room temperature within 8 hours.

[0050] In some embodiments, the cryogenic treatment includes: controlling the temperature to -70~-80°C and placing the forged material in a cryogenic device for cooling for 1~2 hours.

[0051] In some embodiments, the aging treatment includes: the treatment temperature is 480~500°C and the treatment time is 5~8 hours.

[0052] In some embodiments, in S1, it further includes: peeling the maraging steel ingot obtained by smelting.

[0053] Based on the first-principles calculations and research results on the influence of element doping on the precipitates in maraging steel, 0.5-1.0% of W element is added to the maraging steel composition system, which is doped into the Ni3Ti precipitates during the aging treatment, increasing the number of precipitates and improving the brittleness of the precipitates. At the same time, the content of Mo element in the steel is increased, so that when the grain size of the steel is ≥ 8.0 grade, the tensile strength Rm ≥ 2800 MPa and the elongation A ≥ 5%. This material can be widely applied in the fields of aerospace and 3C electronics, and this material design method can be widely applied to the design of other maraging steels with personalized mechanical property requirements, with broad application prospects.

[0054] Example 1

[0055] This example provides a tungsten-containing maraging ultra-high strength steel and its preparation method, and the specific steps are as follows:

[0056] Step 1: Vacuum smelting

[0057] Adopt the double process of vacuum induction and vacuum consumable electrode to smelt a maraging steel ingot; carry out peeling treatment on the ingot.

[0058] The alloy element composition of the maraging steel ingot is: Co 15.5%, Ni 17.7%, Mo 7.12%, Ti 1.45%, W 0.5%, and the balance is Fe and inevitable impurities.

[0059] The content of the key impurity elements is: C 0.003%, Si 0.01%, Mn 0.01%, P 0.0018%, S 0.0010%, N 0.0010%, O 0.0012%.

[0060] Step 2: High-temperature homogenization

[0061] Put the maraging steel ingot after the above peeling treatment into a heating furnace with a furnace temperature of 1000 °C and heat it with the furnace for high-temperature homogenization treatment.

[0062] The conditions for the homogenization treatment include: the holding temperature is 1250 °C, the holding time is 48 h, and after the holding is completed, the furnace is taken out and cooled to the forging starting temperature of 1200 °C and then forging is carried out to break the billet.

[0063] Step 3: Forging and billet breaking

[0064] The forging and billet breaking adopts "upsetting three times and drawing out three times", the forging starting temperature is 1200 °C, the first upsetting reduction is 55%, and the drawing ratio is 250%; the second upsetting reduction is 55%, and the drawing ratio is 250%; the third upsetting reduction is 50%, and the drawing ratio is 200%. The billet is formed into a round bar with a diameter of φ300 mm.

[0065] Step 4: Hot deformation

[0066] The round bar forgings after the above "three upsetting and three drawing" are reheated to 1150 °C and held for 2 h. Then they are taken out of the furnace for precision forging. The reduction ratio of the first pass of precision forging is 30%, and the reduction ratio of the subsequent passes is 10%. Finally, a round bar with a diameter of φ50 mm is obtained, and the final forging temperature of precision forging is 960 °C.

[0067] Step 5: Heat treatment

[0068] The heat treatment process is as follows: holding at 860 °C for 1 hour and then immediately oil-cooling to room temperature; holding at 820 °C for 1 hour and then immediately oil-cooling to room temperature, repeating twice; placing in a -73 °C cryogenic device for cooling for 1.5 hours within 4 hours, and then taking out of the cryogenic device and naturally warming up in the air; aging the material that has returned to room temperature within 8 hours, with the aging temperature being 485 °C and the time being 5 hours.

[0069] Example 2

[0070] This example provides a tungsten-containing maraging ultra-high strength steel and a preparation method thereof, and the specific steps are as follows:

[0071] Step 1: Vacuum smelting

[0072] Adopt a double process of vacuum induction and vacuum consumable electrode melting to smelt a maraging steel ingot; perform peeling treatment on the ingot.

[0073] The alloy element composition of the maraging steel ingot is: Co 16.0%, Ni 18.0%, Mo 7.80%, Ti 1.10%, W 0.7%, and the balance is Fe and unavoidable impurities.

[0074] The contents of the key impurity elements are: C 0.002%, Si 0.02%, Mn 0.01%, P 0.0015%, S 0.0012%, N 0.0007%, O 0.0010%.

[0075] Step 2: High-temperature homogenization

[0076] Put the above-mentioned peeled maraging steel ingot into a heating furnace with a furnace temperature of 1000 °C and heat it with the furnace for high-temperature homogenization treatment.

[0077] The conditions of the homogenization treatment include: the holding temperature is 1280 °C, the holding time is 36 h, and after the holding is completed, it is taken out of the furnace and cooled to the forging start temperature of 1200 °C and then forged and bloomed.

[0078] Step 3: Forging and blooming

[0079] Forging and blooming adopt "upsetting three times and drawing three times". The forging start temperature is 1200 °C. The reduction ratio of the first upsetting is 60%, and the drawing ratio is 300%; the reduction ratio of the second upsetting is 55%, and the drawing ratio is 250%; the reduction ratio of the third upsetting is 50%, and the drawing ratio is 200%. The bloomed slab has dimensions of 3000, 1000, and 500 mm in length, width, and height respectively.

[0080] Step 4: Hot deformation

[0081] The slab forging material after the above "upsetting three times and drawing three times" blooming is reheated to 1150 °C in a furnace and held for 2 h. Then it is taken out of the furnace for rolling. The reduction ratio of the first rolling pass is 20%, and the reduction ratio of subsequent passes is 10%. Finally, a sheet with a thickness of 20 mm is obtained, and the final rolling temperature is 950 °C.

[0082] Step 5: Heat treatment

[0083] The heat treatment process is as follows: hold at 850 °C for 2 hours, and then immediately oil cool to room temperature; hold at 820 °C for 1 hour, and then immediately oil cool to room temperature, repeat twice; place in a -73 °C cryogenic device for cooling for 2 hours within 4 hours, and then take out of the cryogenic device and naturally warm up in the air; perform aging treatment on the material that has warmed up to room temperature within 8 hours, the aging temperature is 480 °C, and the time is 7 hours.

[0084] Comparative example 1

[0085] This example provides a tungsten-containing maraging ultra-high strength steel and its preparation method, and the specific steps are as follows:

[0086] Step 1: Vacuum smelting

[0087] Adopt a double process of vacuum induction and vacuum consumable electrode to smelt a maraging steel ingot; perform skinning treatment on the ingot.

[0088] The alloy element composition of the maraging steel ingot is: Co 12.0%, Ni 18.2%, Mo 4.53%, Ti 1.43%, Al 0.12%, and the balance is Fe and unavoidable impurities.

[0089] The content of the key impurity elements is: C 0.0011%, Si 0.009%, Mn 0.01%, P 0.0013%, S 0.0016%, N 0.0011%, O 0.0008%.

[0090] Step 2: High-temperature homogenization

[0091] Put the maraging steel ingot after the above skinning treatment into a heating furnace with a furnace temperature of 1000 °C and heat it along with the furnace for high-temperature homogenization treatment.

[0092] The conditions for homogenization treatment include: holding temperature of 1250 °C, holding time of 48 h, and after the holding is completed, the material is taken out of the furnace and cooled to the forging starting temperature of 1200 °C before forging and blooming.

[0093] Step 3: Forging and blooming

[0094] For forging and blooming, the "three upsetting and three drawing out" process is adopted. The forging starting temperature is 1200 °C. The reduction ratio for the first upsetting is 55%, and the drawing out ratio is 250%; the reduction ratio for the second upsetting is 55%, and the drawing out ratio is 250%; the reduction ratio for the third upsetting is 50%, and the drawing out ratio is 200%. The bloom is formed into a round bar with a diameter of φ300 mm.

[0095] Step 4: Hot deformation

[0096] The round bar forgings after the above "three upsetting and three drawing out" blooming are reheated in the furnace to 1150 °C and held for 2 h. Then it is taken out of the furnace for finish forging. The reduction ratio for the first pass of finish forging is 30%, and the reduction ratio for the subsequent passes is 10%. Finally, a round bar with a diameter of φ50 mm is obtained, and the finish forging final forging temperature is 960 °C.

[0097] Step 5: Heat treatment

[0098] The heat treatment process is as follows: holding at 860 °C for 1 hour, and then immediately oil-cooling to room temperature; holding at 820 °C for 1 hour, and then immediately oil-cooling to room temperature, repeating twice; placing it in a -73 °C cryogenic device for cooling for 1.5 hours within 4 hours, and then taking it out of the cryogenic device and naturally warming up in the air; aging treatment is carried out on the material that has warmed up to room temperature within 8 hours, the aging temperature is 485 °C, and the time is 5 hours.

[0099] Comparative Example 2

[0100] This example provides a tungsten-containing maraging ultra-high strength steel and its preparation method. The specific steps are as follows:

[0101] Step 1: Vacuum smelting

[0102] The vacuum induction and vacuum consumable double melting process is adopted to smelt a maraging steel ingot; the ingot is peeled.

[0103] The alloy element composition of the maraging steel ingot is: Co 11.96%, Ni 18.18%, Mo 4.46%, Ti 1.39%, Al 0.14%, and the balance is Fe and unavoidable impurities.

[0104] The contents of the key impurity elements are: C 0.0027%, Si 0.014%, Mn 0.012%, P 0.0013%, S 0.0016%, N 0.0005%, O 0.0006%.

[0105] Step 2: High-temperature homogenization

[0106] Put the maraging steel ingot after the above-mentioned peeling treatment into a heating furnace with a furnace temperature of 1000 °C and heat it with the furnace for high-temperature homogenization treatment.

[0107] The conditions for the homogenization treatment include: the holding temperature is 1280 °C, the holding time is 36 h, and after the holding is completed, take it out of the furnace and cool it to the forging starting temperature of 1200 °C, and then carry out forging and blooming.

[0108] Step 3: Forging and blooming

[0109] For forging and blooming, adopt "upsetting three times and drawing out three times". The forging starting temperature is 1200 °C. The reduction ratio of the first upsetting is 60%, and the drawing ratio is 300%; the reduction ratio of the second upsetting is 55%, and the drawing ratio is 250%; the reduction ratio of the third upsetting is 50%, and the drawing ratio is 200%. The bloomed slab has dimensions of 3000, 1000, and 500 mm in length, width, and height respectively.

[0110] Step 4: Hot deformation

[0111] Heat the slab forging material after the above-mentioned "upsetting three times and drawing out three times" to 1150 °C and hold for 2 h. Then take it out of the furnace for rolling. The reduction ratio of the first rolling pass is 20%, and the reduction ratio of the subsequent passes is 10%. Finally, obtain a sheet with a thickness of 20 mm, and the final rolling temperature is 950 °C.

[0112] Step 5: Heat treatment

[0113] The heat treatment process is as follows: hold at 850 °C for 2 hours, and then immediately cool it in oil to room temperature; hold at 820 °C for 1 hour, and then immediately cool it in oil to room temperature, repeat twice; place it in a cryogenic device at -73 °C for 2 hours within 4 hours, and then take it out of the cryogenic device and naturally warm up in the air; within 8 hours, carry out aging treatment on the material that has returned to room temperature, the aging temperature is 510 °C, and the time is 3 hours.

[0114] The mechanical properties of the maraging steel after aging in the examples and comparative examples are as follows:

[0115] Table 1 Mechanical properties of the maraging steel after aging in the examples and comparative examples

[0116]

[0117] The above-mentioned examples are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various improvements made by those of ordinary skill in the art to the technical solutions of the present invention should fall within the protection scope determined by the claims of the present invention.

[0118] By means of the tungsten-containing maraging ultra-high strength steel and the preparation method thereof provided by the present invention, ultra-high strength steel with a strength Rm≥2800MPa and an elongation A≥5.0% or more can be obtained; and the preparation process is relatively simple, and the cold rolling process required by the prior art is not required, which can greatly improve the stability of industrial preparation and the product yield rate; at the same time, the present invention has no strict restrictions on the final external dimensions of the maraging steel product, and the material described in the present invention can be used in a variety of fields and service scenarios, which has important practical significance.

[0119] The above are exemplary embodiments disclosed in the present invention, but it should be noted that various changes and modifications may be made without departing from the scope disclosed in the embodiments of the present invention as defined in the claims. The functions, steps and / or actions of the method claims according to the disclosed embodiments described herein do not need to be performed in any particular order. In addition, although the elements disclosed in the embodiments of the present invention may be described or required in individual form, they may also be understood as multiple unless explicitly limited to the singular.

[0120] It should be understood that, as used herein, the singular forms "a", "an" are intended to include the plural forms as well, unless the context clearly supports an exception. It should also be understood that, as used herein, "and / or" refers to any and all possible combinations including one or more of the associated listed items.

[0121] The serial numbers of the embodiments disclosed in the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0122] A person skilled in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the disclosure of the embodiments of the present invention (including the claims) is limited to these examples; under the concept of the embodiments of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and there are many other changes in different aspects of the above embodiments of the present invention, which are not provided in detail for the sake of simplicity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present invention should be included in the protection scope of the embodiments of the present invention.

Claims

1. A tungsten-containing maraging ultra-high strength steel, characterized in that, By mass percentage, it includes Co 14.5 - 16.0%, Ni 17.0 - 18.0%, Mo 6.0 - 8.0%, Ti 1.0 - 1.5%, W 0.5 - 1.0%, and the balance is Fe and inevitable impurities. The impurity elements are controlled as follows: C ≤ 0.008%, Si ≤ 0.1%, Mn ≤ 0.1%, P ≤ 0.005%, S ≤ 0.005%, N ≤ 0.0015%, O ≤ 0.0015%.

2. A preparation method of tungsten-containing maraging ultra-high strength steel as described in claim 1, characterized in that, It includes: S1 According to the component distribution of tungsten-containing maraging ultra-high strength steel, a maraging steel ingot is smelted by using a vacuum induction and vacuum consumable double process. S2 The steel ingot is subjected to a high-temperature homogenization treatment. S3 The steel ingot is forged and bloomed to obtain a forging by using a three-upsetting and three-drawing process. S4 The forging is reheated in a furnace and then precision forged or rolled to the target size. S5 The rolled forging is held at 850 - 860 °C for 1 - 2 hours and then immediately oil-cooled to room temperature; held at 820 - 830 °C for 1 - 1.5 hours and then immediately oil-cooled to room temperature, repeated twice; cryogenic treatment is carried out within 4 hours and then naturally warmed to room temperature in the air; the material that has returned to room temperature is aged within 8 hours to obtain a maraging ultra-high strength steel.

3. The preparation method of the tungsten-containing maraging super high strength steel according to claim 2, characterized in that, In S2, the high-temperature homogenization treatment includes: the temperature range is 1250 °C - 1260 °C, the holding time is 36 h - 48 h, and after the holding is completed, it is taken out of the furnace and cooled to the forging start temperature and then forged and bloomed.

4. The preparation method of the tungsten-containing maraging ultra-high strength steel according to claim 2, wherein, In S3, the three-upsetting and three-drawing process includes: the upsetting reduction for each time ≥ 50%, and the drawing ratio for each time ≥ 200%.

5. The preparation method of the tungsten-containing maraging ultra-high strength steel according to claim 4, characterized in that, During forging, the forging start temperature is 1180 - 1200 °C. When the temperature is lower than 1050 °C, it is reheated in a furnace at 1150 °C for 2 h and then continued to be upset; the final forging temperature ≥ 1000 °C. When the temperature is lower than 1000 °C, it is reheated in a furnace at 1100 °C for 2 h and then continued to be upset and drawn.

6. The preparation method of the tungsten-containing maraging ultra-high strength steel according to claim 2, characterized in that, In S4, the forging is reheated in a furnace to 1150 °C, held for 2 h, and the single-pass reduction during precision forging or rolling ≤ 35%, and the final forging or final rolling temperature ≥ 950 °C.

7. The preparation method of the tungsten-containing maraging ultra-high strength steel according to claim 2, characterized in that, The cryogenic treatment includes: controlling the temperature to -70 - 80 °C, and placing the forging in a cryogenic device to cool for 1 - 2 hours.

8. The preparation method of the tungsten-containing maraging ultra-high strength steel according to claim 2, characterized in that, The aging treatment includes: the treatment temperature is 480 - 500 °C, and the treatment time is 5 - 8 hours.

9. The preparation method of the tungsten-containing maraging ultra-high strength steel according to claim 2, characterized in that, In S1, it also includes: skimming the smelted maraging steel ingot.

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