A negative enthalpy duplex stainless steel material with high strength, high plasticity and high corrosion resistance and a preparation method thereof

Abstract

This invention relates to the field of metallic materials technology, and more particularly to a negative enthalpy duplex stainless steel material and its preparation method, which possesses high strength, high plasticity, and high corrosion resistance. The negative enthalpy duplex stainless steel material is Fe... a Cr b Ni c Mo d Mn e C f Si g Ti h Al i V j Wherein, a, b, c, d, e, f, g, h, i, and j correspond to the mass percentages of each element: a = 60-70 wt%, b = 15-20 wt%, c = 10-15 wt%, d = 0-5 wt%, e = 1-5 wt%, f = 0.015 wt%, g = 0-1 wt%, h = 0-3 wt%, i = 0-0.5 wt%, j = 0-0.5 wt%, and d, g, h, i, and j are not zero. This series of negative enthalpy duplex stainless steel materials all contain ferrite and austenite in their structure, and the microstructure and mechanical properties of the alloy can be controlled by adjusting the proportions of different metal elements. This series of negative enthalpy duplex stainless steel materials exhibits high strength and high ductility. Simultaneously, negative enthalpy duplex stainless steel materials exhibit excellent corrosion resistance.

Description

Technical Field

[0001] This invention relates to the field of metal materials technology, and in particular to a negative enthalpy duplex stainless steel material and its preparation method that combines high strength, high plasticity and high corrosion resistance. Background Technology

[0002] Metal structural materials are the foundation of marine engineering materials, widely used in warships, carrier-based aircraft, manned / unmanned deep-sea submersibles, offshore wind power equipment, marine vessels, offshore platforms, and marine structures. Facing the extreme service environments of the ocean, such as high temperature, high humidity, and high salinity, as well as complex stress loads from tidal fluctuations and waves, metallic materials are required to possess excellent mechanical properties, such as high strength, high toughness, corrosion resistance, and wear resistance. Traditional stainless steel and low-alloy steels (such as typical E690, Q355, and 304 and 316L stainless steels) have good toughness and corrosion resistance. However, their yield strength is usually low, only ~300MPa, which is insufficient to meet the strength requirements of advanced high-end equipment. Secondly, high-strength alloy steels, such as medium duplex steel and medium Mn steel, are prone to corrosion in the extreme marine environment, leading to early catastrophic failure and making long-term service unsuitable. Therefore, developing new marine steel materials that combine high strength, toughness, and corrosion resistance has become the greatest challenge facing marine engineering materials in service.

[0003] Traditional steel chemical composition design concepts are often based on empirical methods and rules. For example, adding chromium (Cr) and molybdenum (Mo) can increase the corrosion resistance of steel and improve the ferrite content, thereby increasing the yield strength. Nickel (Ni) can stabilize the austenite phase, thus controlling the volume fraction of austenite to adjust the two-phase ratio and promote improved toughness. Refractory metals such as niobium (Nb) and tantalum (Ta) play a solid solution strengthening role, improving the strength of steel.

[0004] However, with the rapid development of modern science and technology and industry, there is an urgent need to develop new types of steel with higher strength, plasticity, and corrosion resistance to meet more demanding service environments. This poses a significant challenge to the design and preparation of alloy chemical compositions.

[0005] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the purpose of this invention is to provide a negative enthalpy duplex stainless steel material and preparation method that combines high strength, high plasticity and high corrosion resistance, in order to solve the problem of developing new stainless steel materials with higher strength, plasticity and corrosion resistance to meet more stringent service environments.

[0007] The technical solution of the present invention is as follows:

[0008] In a first aspect, the present invention provides a negative enthalpy duplex stainless steel material that combines high strength, high plasticity, and high corrosion resistance, wherein the negative enthalpy duplex stainless steel material is Fe a Cr b Ni c Mo d Mn e C f Si g Ti h Al i V j ;

[0009] Where: a, b, c, d, e, f, g, h, i, and j correspond to the mass percentage of each element, a = 60-70 wt%, b = 15-20 wt%, c = 10-15 wt%, d = 0-5 wt%, e = 1-5 wt%, f = 0.015 wt%, g = 0-1 wt%, h = 0-3 wt%, i = 0-0.5 wt%, j = 0-0.5 wt%, and d, g, h, i, and j are not all zero;

[0010] The negative enthalpy duplex stainless steel material contains ferrite and austenite in its structure.

[0011] Optionally, the negative enthalpy duplex stainless steel material is Fe. a Cr b Ni c Mo d Mn e C f Si g Ti h Al i V j ;

[0012] Wherein: a, b, c, d, e, f, g, h, i, and j correspond to the mass percentage of each element, a = 62-65 wt%, b = 16-18 wt%, c = 12-14 wt%, d = 2-4 wt%, e = 1.5-2.5 wt%, f = 0.015 wt%, g = 0.45-0.55 wt%, h = 0.5-3 wt%, i = 0.1-0.5 wt%, and j = 0.03-0.2 wt%.

[0013] Optionally, the negative enthalpy duplex stainless steel is Fe 64.2 Cr 16.6 Ni 12.8 Mo 3.2 Mn 1.8 C 0.015 Si 0.5 Ti 0.7 Al 0.1 6V 0.03 Fe63.6 Cr 16.5 Ni 12.7 Mo 3.1 Mn 1.8 C 0.015 Si 0.5 Ti 1.4 Al 0.23 V 0.06 Fe 63.1 Cr 16.3 Ni 12.7 Mo 3.1 Mn 1.7 8C 0.015 Si 0.5 Ti 2.1 Al 0.3 V 0.1 Fe 62.5 Cr 16.2 Ni 12.5 Mo 3.1 Mn 1.76 C 0.015 Si 0.5 Ti 2.8 Al 0.36 V 0.13 and Fe 62 Cr 16 Ni 12.5 Mo3Mn 1.75 C 0.015 Si 0.5 Ti 3.5 Al 0.4 V 0.16 One of them.

[0014] Optionally, the purity of each element in the negative enthalpy duplex stainless steel material is Fe≥99.95%, Cr≥99.95%, Ni≥99.95%, Mo≥99.99%, Mn≥99.8%, C≥99.99%, Si≥99.99%, Ti≥99.99%, Al≥99.99%, and V≥99.95%.

[0015] A second aspect of the present invention provides a method for preparing a negative enthalpy duplex stainless steel material that combines high strength, high plasticity, and high corrosion resistance, comprising the following steps: placing each raw material into an electric arc melting furnace according to the component ratio, and melting the raw materials by arc ignition in an inert atmosphere to obtain the negative enthalpy duplex stainless steel material.

[0016] Optionally, the preparation method specifically includes the following steps: first, ultrasonically cleaning each raw material; second, according to the component ratio, placing the cleaned raw materials into a water-cooled copper crucible in an electric arc melting furnace in order of melting point from low to high; placing sponge titanium in the middle crucible of the water-cooled copper crucible; and igniting an arc to melt the raw materials in an inert atmosphere until they are fully mixed to obtain the negative enthalpy duplex stainless steel material.

[0017] Optionally, the inert atmosphere environment is a vacuum oxygen-free environment, which is obtained by the following operation: evacuating the electric arc melting furnace to a vacuum degree <4 Pa using a mechanical pump, and then evacuating it to a vacuum degree <4 × 10 Pa using a molecular pump. -4 Pa, then 99.99% pure argon gas is introduced to 0.08 MPa; the above process is repeated twice, and finally the argon gas is introduced to 0.06 MPa, followed by arc melting of sponge titanium twice to absorb residual oxygen.

[0018] Optionally, in the step of arc-igniting and melting the raw material in an inert atmosphere, the number of times the raw material is arc-ignited and melted is greater than 4 times. After each arc-igniting and melting, the arc-ignited material in the water-cooled copper crucible is turned over before the next arc-igniting and melting. Before the next arc-igniting and melting, the sponge titanium is arc-ignited and melted.

[0019] Optionally, the time for each arc ignition melting is 1.0-2.0 min, and in addition to the first and last arc ignition melting, the arc ignition melting of the raw materials also includes magnetic stirring of the raw materials.

[0020] Optionally, the voltage for each arc ignition melting is 10-15V, and the current for each arc ignition melting is 300-350A.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] This invention provides a Fe a Cr b Ni c Mo d Mn e C f Si g Ti h Al i V jThis series of negative enthalpy duplex stainless steel materials are composed of iron, chromium, nickel, molybdenum, manganese, carbon, silicon, titanium, aluminum, and vanadium in the above-mentioned proportions, and are produced by vacuum arc melting furnace. Structurally, this series of negative enthalpy duplex stainless steel materials contains both ferrite (α, body-centered cubic (BCC)) and austenite (γ, face-centered cubic (FCC)), and the microstructure and mechanical properties of the alloy can be controlled by adjusting the proportions of different metal elements. This series of negative enthalpy duplex stainless steel materials exhibits high strength and high ductility. Simultaneously, it demonstrates excellent corrosion resistance. Attached Figure Description

[0023] Figure 1 The Fe prepared in Examples 1-5 of this invention a Cr b Ni c Mo d Mn e C f Si g Ti h Al i V j X-ray diffraction patterns of a series of negative enthalpy duplex stainless steel materials;

[0024] Figure 2 The Fe prepared in Examples 1-5 of this invention a Cr b Ni c Mo d Mn e C f Si g Ti h Al i V j Room temperature tensile stress-strain curves of a series of negative enthalpy duplex stainless steel materials;

[0025] Figure 3 The Fe prepared in Examples 1-4 of this invention a Cr b Ni c Mo d Mn e C f Si g Ti h Al i V j Polarization curves of a series of negative enthalpy duplex stainless steel materials in 3.5 wt.% NaCl. Detailed Implementation

[0026] This invention provides a negative enthalpy duplex stainless steel material and its preparation method that combine high strength, high plasticity, and high corrosion resistance. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0027] This invention provides a negative enthalpy duplex stainless steel material that combines high strength, high plasticity, and high corrosion resistance, wherein the negative enthalpy duplex stainless steel material is Fe a Cr b Ni c Mo d Mn e C f Si g Ti h Al i V j ;

[0028] Where: a, b, c, d, e, f, g, h, i, and j correspond to the mass percentage of each element, a = 60-70 wt%, b = 15-20 wt%, c = 10-15 wt%, d = 0-5 wt%, e = 1-5 wt%, f = 0.015 wt%, g = 0-1 wt%, h = 0-3 wt%, i = 0-0.5 wt%, j = 0-0.5 wt%, and d, g, h, i, and j are not all zero;

[0029] The negative enthalpy duplex stainless steel material contains ferrite and austenite in its structure, and the volume fraction of austenite is between 50% and 90%.

[0030] The series of negative enthalpy duplex stainless steel materials provided in this invention are composed of iron, chromium, nickel, molybdenum, manganese, carbon, silicon, titanium, aluminum, and vanadium in the above-mentioned proportions. Structurally, this series of negative enthalpy duplex stainless steel materials all contain ferrite (BCC) and austenite (FCC), and the microstructure and mechanical properties of the alloy can be controlled by adjusting the proportions of different metal elements. This series of negative enthalpy duplex stainless steel materials exhibits high strength and high ductility. Simultaneously, it demonstrates excellent corrosion resistance. Therefore, this series of negative enthalpy duplex stainless steel materials shows great application potential, for example, in marine vessels, marine engineering platforms, nuclear power plants, and chemical plants.

[0031] Compared to traditional 304 and 316 stainless steel, the negative enthalpy duplex stainless steel material of this invention is characterized by the addition of Al, Ti, and V alloying elements. This is because iron has a relatively negative mixing enthalpy (ΔH) with aluminum, titanium, and vanadium. mix ), where ΔH mix(Fe-Al)=-11kJ / mol, ΔH mix (Fe-Ti)=-17kJ / mol, ΔH mix (Fe-V) = -7 kJ / mol. Therefore, by adding negative enthalpy elements (Al, Ti, and V), it is hoped that differences in chemical affinity between elements can be generated in ideal entropy solid solutions, thereby forming localized negative enthalpy chemical affinity clusters of heterostructures, such as compositional fluctuations and localized order. These nanoscale heterogeneous interfaces can not only effectively pin dislocation movement and promote its movement and proliferation through multi-system slip and cross-slip, but also serve as intragranular dislocation sources, generating ultra-high density dislocations, thereby significantly improving the work hardening ability of stainless steel and achieving a synergistic effect of ultra-high yield strength and high tensile plasticity.

[0032] In addition, by adjusting the ranges of h, i, and j, the mixing enthalpy of the alloy (-9kJ / mol to -4kJ / mol) can be controlled, thereby achieving the effects of high strength, toughness, and high corrosion resistance.

[0033] In a preferred embodiment, the negative enthalpy duplex stainless steel material is Fe. a Cr b Ni c Mo d Mn e C f Si g Ti h Al i V j ;

[0034] Wherein: a, b, c, d, e, f, g, h, i, and j correspond to the mass percentage of each element, a = 62-65 wt%, b = 16-18 wt%, c = 12-14 wt%, d = 2-4 wt%, e = 1.5-2.5 wt%, f = 0.015 wt%, g = 0.45-0.55 wt%, h = 0.5-3 wt%, i = 0.1-0.5 wt%, and j = 0.03-0.2 wt%.

[0035] Under the above ratio, the series of negative enthalpy duplex stainless steel materials exhibit a synergistic effect of excellent strength, plasticity and corrosion resistance.

[0036] As an example, the negative enthalpy duplex stainless steel is Fe 64.2 Cr 16.6 Ni 12.8 Mo 3.2 Mn 1.8 C 0.015 Si 0.5 Ti 0.7 Al 0.1 6V 0.03 Fe63.6 Cr 16.5 Ni 12.7 Mo 3.1 Mn 1.8 C 0.015 Si 0.5 Ti 1.4 Al 0.23 V 0.06 Fe 63.1 Cr 16.3 Ni 12.7 Mo 3.1 Mn 1.7 8C 0.015 Si 0.5 Ti 2.1 Al 0.3 V 0.1 Fe 62.5 Cr 16.2 Ni 12.5 Mo 3.1 Mn 1.76 C 0.015 Si 0.5 Ti 2.8 Al 0.36 V 0.13 and Fe 62 Cr 16 Ni 12.5 Mo3Mn 1.75 C 0.015 Si 0.5 Ti 3.5 Al 0.4 V 0.16 One of them.

[0037] The Fe provided in the embodiments of the present invention a Cr b Ni c Mo d Mn e C f Si g Ti h Al i V j The series of negative enthalpy duplex stainless steel materials possess both high strength and high ductility in terms of mechanical properties. Among them, Fe... 64.2 Cr 16.6 Ni 12.8 Mo 3.2 Mn 1.8 C 0.015 Si 0.5 Ti 0.7 Al 0.16 V 0.03The room temperature tensile yield strength is 400 MPa, the tensile strength is 580 MPa, the uniform elongation is 26%, and the pitting site in a 3.5 wt% NaCl aqueous solution is 0.24 V; Fe 63.6 Cr 16.5 Ni 12.7 Mo 3.1 Mn 1.8 C 0.015 Si 0.5 Ti 1.4 Al 0.23 V 0.06 The room temperature tensile yield strength is 440 MPa, the tensile strength is 670 MPa, the uniform elongation is 27%, and the pitting site in a 3.5 wt% NaCl aqueous solution is 0.45 V; Fe 63.1 Cr 16.3 Ni 12.7 Mo 3.1 Mn 1.78 C 0.015 Si 0.5 Ti 2.1 Al 0.3 V 0.1 The room temperature tensile yield strength is 643 MPa, the tensile strength is 925 MPa, the uniform elongation is 25%, and the pitting site in a 3.5 wt% NaCl aqueous solution is 0.47 V; Fe 62.5 Cr 16.2 Ni 12.5 Mo 3.1 Mn 1.76 C 0.015 Si 0.5 Ti 2.8 Al 0.36 V 0.13 The room temperature tensile yield strength is 870 MPa, the tensile strength is 1070 MPa, the uniform elongation is 11.5%, and the pitting site in a 3.5 wt% NaCl aqueous solution is 0.49 V; Fe 62 Cr 16 Ni 12.5 Mo3Mn 1.75 C 0.01 5Si 0.5 Ti 3.5 Al 0.4 V 0.16 The yield strength is 950 MPa, the tensile strength is 1150 MPa, and the uniform elongation is 3.5%.

[0038] In one embodiment, the purity of each element in the negative enthalpy duplex stainless steel material is Fe≥99.95%, Cr≥99.95%, Ni≥99.95%, Mo≥99.99%, Mn≥99.8%, C≥99.99%, Si≥99.99%, Ti≥99.99%, Al≥99.99%, and V≥99.95%.

[0039] This invention provides a method for preparing a negative enthalpy duplex stainless steel material that combines high strength, high plasticity, and high corrosion resistance. The negative enthalpy duplex stainless steel material is Fe... a Cr b Ni c Mo d Mn e C f Si g Ti h Al i V j Where a = 60-70wt%, b = 15-20wt%, c = 10-15wt%, d = 0-5wt%, e = 1-5wt%, f = 0.015wt%, g = 0-1wt%, h = 0-3wt%, i = 0-0.5wt%, j = 0-0.5wt%, and d, g, h, i, and j are not all 0;

[0040] The preparation method includes the following steps: according to the component ratio, each raw material is put into an electric arc melting furnace, and the raw materials are melted by arc ignition in an inert atmosphere to obtain the negative enthalpy duplex stainless steel material.

[0041] The negative enthalpy duplex stainless steel materials provided in this invention all contain ferrite (BCC) and austenite (FCC) in their structure, and the microstructure and mechanical properties of the alloy can be controlled by adjusting the proportion of different metal elements. These negative enthalpy duplex stainless steel materials exhibit high strength and high ductility. Simultaneously, they demonstrate excellent corrosion resistance. Therefore, this series of negative enthalpy duplex stainless steel materials shows great application potential, for example, in marine vessels, marine engineering platforms, nuclear power plants, and chemical plants.

[0042] In one embodiment, the preparation method of the negative enthalpy duplex stainless steel material specifically includes the following steps: First, each raw material is ultrasonically cleaned with anhydrous ethanol; second, to ensure that each element is fully melted, the cleaned raw materials are placed in a water-cooled copper crucible in an electric arc melting furnace in order of increasing melting point according to the component ratio, with non-metallic raw materials placed at the bottom of the copper crucible, and then the metals are added in order of increasing melting point. Sponge titanium is placed in the middle crucible of the water-cooled copper crucible, and the raw materials are melted by arcing in an inert atmosphere (such as an argon atmosphere) until they are fully mixed to obtain the negative enthalpy duplex stainless steel material.

[0043] The aforementioned inert atmosphere environment can be a high-vacuum oxygen-free environment, which first undergoes multiple cycles of vacuuming and argon filling, and then the sponge titanium is melted to absorb residual oxygen before the raw materials are melted.

[0044] The process of vacuuming, argon filling, and oxygen absorption during sponge titanium melting specifically involves using a mechanical pump to evacuate the electric arc melting furnace to a vacuum level <4 Pa, followed by using a molecular pump to evacuate to a vacuum level <4 × 10⁻⁶ Pa. -4 Pa, then 99.99% pure argon gas is introduced to 0.08 MPa. The above process is repeated twice, and finally the argon gas is introduced to 0.06 MPa. Then the sponge titanium is melted twice by arc ignition to absorb residual oxygen.

[0045] During the smelting process, the raw material undergoes arc-ignition melting more than four times. After each arc-ignition melting, the smelted material in the water-cooled copper crucible is flipped over before the next arc-ignition melting. Before the next arc-ignition melting of the alloy, the sponge titanium undergoes arc-ignition melting and oxygen absorption.

[0046] Each arc-ignition melting process takes 1.0-2.0 minutes, and in addition to the first and last arc-ignition melting processes, the arc-ignition melting of the raw materials also includes magnetic stirring of the raw materials.

[0047] The voltage for each arc ignition melting is 10-15V, and the current for each arc ignition melting is 300-350A.

[0048] The present invention will be further described in detail below through several specific embodiments.

[0049] Example 1

[0050] This embodiment provides a Fe 64.2 Cr 16.6 Ni 12.8 Mo 3.2 Mn 1.8 C 0.015 Si 0.5 Ti 0.7 Al 0.16 V 0.03 Negative enthalpy duplex stainless steel material and its preparation method, the preparation method specifically includes the following steps:

[0051] S1. Ten kinds of high-purity raw material particles (Fe, Cr, Ni, Mo, Mn, C, Si, Al, Ti and V) are cleaned twice in an ultrasonic bath. Then, they are accurately weighed according to the group ratio and placed into a water-cooled copper crucible in order of melting point from low to high. The element with the lowest melting point is placed at the bottom and the element with the highest melting point is placed at the top. At the same time, sponge titanium is placed in the middle copper mold position.

[0052] S2. Close the electric arc melting furnace door, turn on the circulating water, turn on the mechanical pump, and begin vacuuming. When the vacuum level is below 4 Pa, turn on the molecular pump for further vacuuming. When the vacuum level is below 4 × 10 Pa... -4 When the pressure reaches 0.08 MPa, high-purity argon gas is introduced (pressure approximately 0.08 MPa); after repeating the above process twice, the final step is to fill the gas with argon gas to 0.06 MPa.

[0053] S3. Arc ignition is performed in a high-purity argon atmosphere to melt the sponge titanium twice and absorb residual oxygen in the furnace.

[0054] S4. First, high-current melting (melting voltage 12V, melting current 330A) is used to melt and mix all raw material particles evenly. After the alloy button is cast and cooled, it is flipped by a robotic arm and melted in the same way. Magnetic stirring is turned on during each subsequent melting process. After each melting, the alloy button is flipped 180 degrees. A total of 4 melting processes are carried out to make the alloy composition more uniform. During the last melting, magnetic stirring is turned off to make it into a smooth ingot, which is then suction-cast.

[0055] S5. After the alloy button ingot has completely cooled, open the furnace door and take out the sample.

[0056] Example 2

[0057] This embodiment provides a Fe 63.6 Cr 16.5 Ni 12.7 Mo 3.1 Mn 1.8 C 0.015 Si 0.5 Ti 1.4 Al 0.23 V 0.06 The preparation method of the negative enthalpy duplex stainless steel material is basically the same as that of Example 1, except that the composition ratio is different.

[0058] Example 3

[0059] This embodiment provides a Fe 63.1 Cr 16.3 Ni 12.7 Mo 3.1 Mn 1.78 C 0.015 Si 0.5 Ti 2.1 Al 0.3 V 0.1 The preparation method of the negative enthalpy duplex stainless steel material is basically the same as that of Example 1, except that the composition ratio is different.

[0060] Example 4

[0061] This embodiment provides a Fe 62.5 Cr 16.2 Ni 12.5 Mo 3.1 Mn 1.76 C 0.015 Si 0.5 Ti 2.8 Al 0.36 V 0.13 The preparation method of the negative enthalpy duplex stainless steel material is basically the same as that of Example 1, except that the composition ratio is different.

[0062] Example 5

[0063] This embodiment provides a Fe 62 Cr 16 Ni 12.5 Mo3Mn 1.75 C 0.015 Si 0.5 Ti 3.5 Al 0.4 V 0.16 The preparation method of the negative enthalpy duplex stainless steel material is basically the same as that of Example 1, except that the composition ratio is different.

[0064] Test results:

[0065] Figure 1 The Fe prepared in Examples 1-5 of this invention a Cr b Ni c Mo d Mn e C f Si g Ti h Al i V j X-ray diffraction patterns of a series of negative enthalpy duplex stainless steel materials show the dual-phase structure of austenite (FCC) and ferrite (BCC);

[0066] Figure 2 The Fe prepared in Examples 1-5 of this invention a Cr b Ni c Mo d Mn e C f Si g Ti h Al i V j Room temperature tensile stress-strain curves of a series of negative enthalpy duplex stainless steel materials; the yield strength, tensile strength and uniform elongation of the alloy can be obtained from the figure.

[0067] Figure 3The Fe prepared in Examples 1-4 of this invention a Cr b Ni c Mo d Mn e C f Si g Ti h Al i V j Polarization curves of a series of negative enthalpy duplex stainless steel materials in 3.5 wt.% NaCl aqueous solution; the pitting potential of the alloy can be obtained from the figure (as shown by the dashed line).

[0068] In summary, this invention provides a negative enthalpy duplex stainless steel material and its preparation method that combine high strength, high plasticity, and high corrosion resistance. The Fe provided by this invention... a Cr b Ni c Mo d Mn e C f Si g Ti h Al i V j This series of negative enthalpy duplex stainless steel materials are composed of iron, chromium, nickel, molybdenum, manganese, carbon, silicon, titanium, aluminum, and vanadium in a specific ratio, and are produced through a vacuum arc melting furnace. Structurally, these negative enthalpy duplex stainless steel materials all contain ferrite (α, body-centered cubic (BCC)) and austenite (γ, face-centered cubic (FCC)), and the microstructure and mechanical properties of the alloy can be controlled by adjusting the proportions of different metal elements. This series of negative enthalpy duplex stainless steel materials exhibits high strength and high ductility. Simultaneously, they demonstrate excellent corrosion resistance.

[0069] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for preparing a negative enthalpy dual-phase stainless steel material with high strength, high plasticity and high corrosion resistance, characterized in that, The negative enthalpy duplex stainless steel material is Fe a Cr b Ni c Mo d Mn e C f Si g Ti h Al i V j ; Wherein: a, b, c, d, e, f, g, h, i and j respectively correspond to the mass percentage of each element, a = 60-70wt%, b = 15-20wt%, c = 10-15wt%, d = 0-5wt%, e = 1-5wt%, f = 0.015wt%, g = 0-1wt%, h = 0-3wt%, i = 0-0.5wt%, j = 0-0.5wt%, d, g, h, i and j are not all 0; The negative enthalpy duplex stainless steel material contains ferrite and austenite in structure; The preparation method of the negative enthalpy duplex stainless steel material comprises the following steps: first, ultrasonic cleaning of each raw material, second, according to the component ratio, the cleaned raw materials are sequentially placed in the water-cooled copper crucible in the electric arc smelting furnace in order from low to high melting point, titanium sponge is placed at the middle crucible position of the water-cooled copper crucible, and the raw materials are arc smelted under inert atmosphere until fully miscible, to obtain the negative enthalpy duplex stainless steel material.

2. The method for preparing the negative enthalpy duplex stainless steel material with high strength, high plasticity, and high corrosion resistance according to claim 1, characterized in that, The inert atmosphere environment is a vacuum oxygen-free environment, and the vacuum oxygen-free environment is obtained by the following operations: the electric arc smelting furnace is vacuumized to a vacuum degree < 4 Pa by a mechanical pump, then vacuumized to a vacuum degree < 4*10 -4 Pa by a molecular pump, then pure argon with a purity of 99.99 % is introduced to 0.08 Mpa; the above process is repeated twice, finally the argon is filled to 0.06 Mpa, then the arc smelting of the titanium sponge is carried out twice to absorb the residual oxygen.

3. The method for preparing the negative enthalpy duplex stainless steel material with high strength, high plasticity, and high corrosion resistance according to claim 1, characterized in that, In the step of arc smelting the raw materials under inert atmosphere, the number of times of arc smelting of the raw materials is >4, and after each arc smelting, the arc smelted material in the water-cooled copper crucible is turned over before the next arc smelting, and the titanium sponge is arc smelted before the next arc smelting.

4. The method for preparing the negative enthalpy duplex stainless steel material with high strength, high plasticity, and high corrosion resistance according to claim 3, characterized in that, The time of each arc smelting is 1.0-2.0 min, and in addition to the first arc smelting and the last arc smelting, the raw materials are arc smelted while being subjected to magnetic stirring.

5. The method for preparing the negative enthalpy duplex stainless steel material with high strength, high plasticity, and high corrosion resistance according to claim 3, characterized in that, The voltage of each arc smelting is 10-15 V, and the current of each arc smelting is 300-350A.

6. A negative enthalpy dual-phase stainless steel material having high strength, high ductility and high corrosion resistance, characterized in that, The negative enthalpy duplex stainless steel material is Fe a Cr b Ni c Mo d Mn e C f Si g Ti h Al i V j ; Wherein: a, b, c, d, e, f, g, h, i and j respectively correspond to the mass percentage of each element, a = 60-70wt%, b = 15-20wt%, c = 10-15wt%, d = 0-5wt%, e = 1-5wt%, f = 0.015wt%, g = 0-1wt%, h = 0-3wt%, i = 0-0.5wt%, j = 0-0.5wt%, d, g, h, i and j are not all 0; The negative enthalpy duplex stainless steel material contains ferrite and austenite in structure; The negative enthalpy duplex stainless steel material is prepared by the preparation method of any one of claims 1-5.

7. The negative delta potential stainless steel material with high strength, high ductility and high corrosion resistance according to claim 6, characterized in that, The negative enthalpy duplex stainless steel material is Fe a Cr b Ni c Mo d Mn e C f Si g Ti h Al i V j ; Wherein: a, b, c, d, e, f, g, h, i and j respectively correspond to the mass percentage of each element, a = 62-65wt%, b = 16-18wt%, c = 12-14wt%, d = 2-4wt%, e = 1.5-2.5wt%, f = 0.015wt%, g = 0.45-0.55wt%, h = 0.5-3wt%, i = 0.1-0.5wt%, j = 0.03-0.2wt%.

8. The negative delta ferrite stainless steel material with high strength, high ductility and high corrosion resistance according to claim 6, characterized in that, The negative enthalpy duplex stainless steel is Fe 64.2 Cr 16.6 Ni 12.8 Mo 3.2 Mn 1.8 C 0.015 Si 0.5 Ti 0.7 Al 0.16 V 0.03 , Fe 63.6 Cr 16.5 Ni 12.7 Mo 3.1 Mn 1.8 C 0.015 Si 0.5 Ti 1.4 Al 0.23 V 0.06 , Fe 63.1 Cr 16.3 Ni 12.7 Mo 3.1 Mn 1.78 C 0.015 Si 0.5 Ti 2.1 Al 0.3 V 0.1 , Fe 62.5 Cr 16.2 Ni 12.5 Mo 3.1 Mn 1.76 C 0.015 Si 0.5 Ti 2.8 Al 0.36 V 0.13 and Fe 62 Cr 16 Ni 12.5 Mo3Mn 1.75 C 0.015 Si 0.5 Ti 3.5 Al 0.4 V 0.16 .

9. The negative delta potential stainless steel material with high strength, high ductility and high corrosion resistance according to claim 6, characterized in that, The purity of each element in the negative enthalpy duplex stainless steel material is Fe≥99.95%, Cr≥99.95%, Ni≥99.95%, Mo≥99.99%, Mn≥99.8%, C≥99.99%, Si≥99.99%, Ti≥99.99%, Al≥99.99% and V≥99.95%.

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