CN114507823B

CN114507823B - Ultrahigh-strength non-magnetic high manganese steel and preparation method thereof

Info

Publication number: CN114507823B
Application number: CN202210088185.0A
Authority: CN
Inventors: 张中武; 程浩; 孙利昕
Original assignee: Harbin Engineering University
Current assignee: Harbin Engineering University
Priority date: 2022-01-25
Filing date: 2022-01-25
Publication date: 2023-03-31
Anticipated expiration: 2042-01-25
Also published as: CN114507823A

Abstract

The invention provides ultrahigh-strength non-magnetic high manganese steel and a preparation method thereof, wherein the main alloy components are as follows: c:0.7 to 1.2%, mn:15.0 to 25.0%, mo:3.0 to 5.0%, al:0.1 to 0.3%, si: 0.1-0.5%, and the balance of Fe and other inevitable impurity elements, and the preparation method comprises the following steps: smelting, hot rolling or hot forging, cold rolling or cold forging, and annealing. The high manganese steel provided by the invention has the advantages that: the component design ensures that the matrix is nonmagnetic single-phase austenite, and avoids deformation in the deformation process to induce martensite phase transformation to generate ferromagnetic martensite; high strength is provided by using high-density nanometer size deformation twin crystals; mo element is utilized to improve the thermal stability of the nano structure. The nonmagnetic high manganese steel prepared by the components and the preparation method has the relative magnetic permeability of 1.002 and the strength of 2082MPa.

Description

Ultrahigh-strength non-magnetic high manganese steel and preparation method thereof

Technical Field

The invention belongs to the field of metal materials, and particularly relates to ultrahigh-strength non-magnetic high manganese steel and a preparation method thereof.

The background art comprises the following steps:

with the development of science and technology, more and more devices are used in strong electromagnetic environment, such as large-scale accelerators, nuclear magnetic resonance imagers, magnetic levitation track transportation systems, etc., which put higher demands on the strength of non-magnetic structural materials used in strong magnetic field environment. The common high-performance structural steel has excellent comprehensive mechanical properties, but generally has strong ferromagnetism, such as ferrite steel, martensite steel and the like, and can induce magnetism under strong electromagnetic environment. The common nonmagnetic engineering alloy such as aluminum alloy, copper alloy, titanium alloy and the like has low strength, high cost and large manufacturing difficulty. Some austenitic stainless steels also have good nonmagnetic properties, but have low yield strength and can produce ferromagnetic martensite phases due to temperature changes or plastic deformation during manufacture and use.

Rapid development in the field of microelectronics has led to miniaturization and popularization of high-precision instruments, sensors, communication equipment, and the like, but improvement of sensor sensitivity and improvement of circuit integration level have put higher demands on electromagnetic compatibility. In order to avoid interference of a structural material induced electromagnetic field to a signal in a complex electromagnetic environment, non-ferrous metal materials such as aluminum, copper and other alloys are generally used, and a lower-price steel material is difficult to apply in the field due to ferromagnetism.

High manganese austenitic steel is a non-magnetic steel solution. The nonmagnetic austenite existing at a high temperature is stabilized to a room temperature range by a stabilizing effect of the manganese element on the austenite. Compared with high-nickel austenitic steel, high-nickel chromium austenitic stainless steel and the like, the cost of the austenitic steel is obviously reduced. But austenitic non-magnetic steels are generally very low in strength. Because martensite transformation strengthening cannot be utilized, an effective means for improving the strength is lacked, and the performance of the alloy is difficult to meet new use requirements. The most common 20Mn23AlV series high-manganese nonmagnetic steel is widely applied to magnetic shielding, generator stator protective rings and the like in a transformer oil tank at present, and the yield strength is more than or equal to 255MPa; the 40Mn18Cr3 series high manganese steel has slightly higher strength and the yield strength of more than or equal to 300MPa. The yield strength of the 50Mn18Cr5 series high manganese steel produced by some manufacturers can reach 585MPa. The difficulty of continuously improving the austenitic high manganese steel is high according to the design idea.

The recent technology discloses some high-manganese non-magnetic steels with higher strength, for example, patent application publication No. CN 110541121A discloses a non-magnetic steel, the alloy components of which by mass percent include 0.25-0.3% of C, 0.25-0.4% of Si, 17.5-19.5% of Mn, 1-1.5% of Al, 0.4-0.9% of V, 0.12-0.18% of rare earth elements, 0.02-0.04% of Ti, 0.02-0.04% of Mo, less than or equal to 0.01% of P, less than or equal to 0.01% of S, and the balance of Fe and other inevitable impurities. The rare earth elements are added to purify molten steel, improve as-cast structure and improve mechanical strength of the non-magnetic steel, and the Ti and Mo elements are added to improve corrosion resistance of the non-magnetic steel. In the examples provided by this technique, the highest yield strength was 681MPa, the tensile strength was 1120MPa, and the relative permeability was 1.008.

The invention discloses a controlled rolling and controlled cooling production method of a high-yield-ratio high-manganese high-aluminum nonmagnetic steel plate, which comprises the following alloy components in percentage by mass: 0.14-0.20%, si is less than or equal to 0.50%, mn: 21.50-25.50%, S is less than or equal to 0.030%, P is less than or equal to 0.030%, al:1.50-2.50%, V:0.04-0.10 percent of the total weight of the alloy, less than or equal to 1.0 percent of Cr and Ni, and the balance of Fe and inevitable impurities. The invention replaces the traditional hot rolling, quenching and tempering heat treatment process with the controlled rolling and cooling process to obtain a yield ratio higher than that of the traditional process, but the proposal still does not solve the defect of lower yield strength of the high manganese austenitic steel, and has the highest yield strength of 463MPa, the tensile strength of 671MPa, the elongation after fracture of 48.5 percent and the relative magnetic permeability of 1.005.

The patent application of the publication No. CN111235493A discloses a non-magnetic steel and a preparation method of a non-magnetic steel bolt, and the non-magnetic steel comprises the following components: 0.3 to 0.5%, si:0.3 to 0.6%, mn:18 to 19%, cr:17 to 19%, cu:0.2 to 0.3%, ni:0.4 to 0.5%, V:1.0 to 1.3%, RE:0.05 to 0.1 percent of the total weight of the alloy, less than or equal to 0.2 percent of P, less than or equal to 0.01 percent of S and the balance of Fe, and the non-magnetic steel with the yield strength of 721MPa and the relative permeability of 1.001 can be obtained by the preparation method.

Besides, the austenitic stainless steel disclosed in patent application with publication number CN 112831639A has yield strength not less than 700MPa, and the yield strength of the austenitic steel prepared by cold rolling treatment and nitriding annealing is 700-973 MPa and the tensile strength is 995-1186 MPa. The high-manganese austenite non-magnetic steel is prepared by adopting powder metallurgy, and as reported in research on preparation and performance of the high-manganese austenite non-magnetic steel material prepared by the method (Liuyanshou, university of southern China, 2019.), the prepared high-manganese non-magnetic steel Fe-20Mn-0.6C-15Cu has the tensile strength of 510MPa and the elongation after fracture of 6.3 percent.

In conclusion, the high-manganese austenitic non-magnetic steel has wider application prospect due to the low cost advantage, but the application range is limited due to the lower strength, and a new idea for designing the ultrahigh-strength non-magnetic high-manganese austenitic steel is needed.

Disclosure of Invention

The invention aims to provide a high-manganese austenitic steel with low cost, high strength and no magnetism and a preparation method thereof. In order to achieve the above purpose, the invention provides the following technical scheme:

the invention provides high-manganese austenitic steel, which comprises the following main alloy components in percentage by mass: c:1.0 to 1.2%, mn:15 to 25%, mo:1 to 5%, al:0.1 to 0.3%, si:0.1 to 0.5 percent, and the balance of Fe and other inevitable impurity elements.

Preferably, the composite material comprises the following components in percentage by mass: 1.0%, mn:15%, mo:5.0%, al:0.1 to 0.3%, si:0.1 to 0.5 percent, and the balance of Fe.

Preferably, the paint comprises the following components in percentage by mass: 0.85%, mn:15%, mo:5.0%, al:0.1 to 0.3%, si:0.1 to 0.5 percent, and the balance of Fe.

Preferably, the composite material comprises the following components in percentage by mass: 1.2%, mn:20.6%, mo:4.8%, al:0.1 to 0.3%, si:0.1 to 0.5 percent, and the balance of Fe.

Preferably, the paint comprises the following components in percentage by mass: 0.7%, mn:25%, mo:3.5%, al:0.1 to 0.3%, si:0.1 to 0.5 percent, and the balance of Fe.

The high manganese steel provided by the invention can be subjected to microalloying of Nb, V, ti and the like according to application conditions. The content of micro-alloying elements is not more than 1wt%.

The raw materials of the high-manganese austenitic steel are not specially limited, the composition proportion of the technical scheme can be met, and links such as deoxidization, sulfur removal, phosphorus removal and the like can be added.

The invention provides a preparation method of the high-manganese austenitic steel, which comprises the steps of smelting, hot deformation, cold deformation and annealing treatment.

S1, obtaining a blank by die casting or continuous casting after smelting.

S2, annealing the die casting blank at the temperature of 1000-1200 ℃, and then carrying out hot rolling or hot forging at the temperature of 850-1150 ℃.

And S3, continuously rolling the continuous casting slab at the temperature of 900-1200 ℃.

And S4, cold rolling or cold forging the hot rolled, hot forged or continuously rolled blank at room temperature.

S5, annealing the cold rolled or cold forged blank at the temperature of 500-850 ℃.

Preferably, the hot rolling temperature in the steps 2 and 3 is 1200 ℃, the total hot rolling deformation is 50-80%, the final rolling temperature is more than or equal to 950 ℃, and water cooling is performed after the hot rolling is finished.

Preferably, the total deformation amount of cold deformation in the step 4 is more than or equal to 10 percent.

Preferably, the annealing temperature in the step 5 is 600 ℃, and the cooling mode is water cooling.

The smelting equipment is not particularly limited in the invention, and smelting equipment well known to those skilled in the art can be adopted.

The high manganese austenitic steel has simple preparation process, cheap and easily obtained raw materials, and is suitable for industrial production.

The components of the high-manganese austenitic steel and the preparation method provided by the invention have the design idea that the prepared high-manganese austenitic steel has high strength and high plasticity, and simultaneously, the matrix of austenite can not generate a ferromagnetic martensite phase due to the martensite phase transformation induced by the deformation caused by the lower stacking fault energy, so that the high-manganese steel shows magnetism. According to the invention, the high-content C element is added into the steel, and the processing and hardening capacity of the steel is improved by utilizing the interaction of interstitial C atoms and dislocation; meanwhile, the C element can improve the fault energy of austenite, so that the occurrence of deformation induced martensite is avoided. Mn is an element stabilizing austenite, and the influence on the stacking fault energy is nonlinear, when the Mn content is less than 15%, the stacking fault energy is reduced by increasing the Mn content, and when the Mn content is more than 15%, the stacking fault energy is increased along with the increase of the Mn content. The lowest-stacking fault energy component is Mn:15wt%, C:1.0wt%, mo:5.0wt%, its fault energy is about 20mJ/m ² And no martensitic transformation occurs at room temperature. The high manganese austenitic steel is strengthened mainly by a high-density nanometer-sized twin crystal structure obtained by a deformation induced twinning mechanism. The invention adopts Mo alloying to improve the stability of nanometer twin crystal, and solves the problem that the nanometer scale microstructure has high strength but poor thermal stability and can not be applied in engineering by separating and pinning the nanometer scale interface through the carbide of Mo.

Compared with the prior austenite nonmagnetic steel, the components and the preparation method provided by the invention have the advantages that:

the ultrahigh strength and excellent plasticity can be obtained, and simultaneously the nonmagnetic characteristic of austenitic steel is still kept, as shown in the embodiment, the high-strength and high-plasticity nonmagnetic steel with the magnetic permeability of 1.002, the yield strength of 1548MPa and the elongation of 23.7 percent and the ultrahigh-strength nonmagnetic steel with the yield of 1783MPa, the tensile strength of 2082MPa and the elongation of 7.5 percent can be obtained by the components and the preparation method provided by the invention. The high manganese steel provided by the invention does not contain precious metal elements, has a simple preparation method and strong universality, and can be applied to the fields of transformers, generators, large-scale medical equipment, extreme electromagnetic environment military and civil devices and the like.

Drawings

FIG. 1 is a graph of quasi-static tensile test specimen size;

FIG. 2 is a drawing curve of examples 1 to 4, wherein (a) to (d) correspond to examples 1 to 4, respectively;

FIG. 3 is an XRD pattern for examples 1-4;

FIG. 4 is an M-H curve of the VSM test of examples 1-4.

Detailed Description

The high manganese austenitic steel of the present invention is further described below with reference to specific examples. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments of the present invention, belong to the protection scope of the present invention.

Example 1

The components: according to the mass percentage, the material comprises C:1.0%, mn:15.0%, mo:5.0%, al:0.1 to 0.3%, si:0.1 to 0.5 percent, and the balance of Fe.

Preparation: arc melting; hot rolling at 1000 ℃, wherein the total deformation of the hot rolling is more than or equal to 75 percent; cold rolling at room temperature, wherein the total deformation is 40%; annealing at 600 ℃ for 30 minutes and water cooling.

The mechanical and magnetic properties of the non-magnetic steel are shown in table 1, fig. 2 and fig. 3.

Example 2

The components: according to the mass percentage, the material comprises C:0.85%, mn:15.0%, mo:5.0%, al:0.1 to 0.3%, si:0.1 to 0.5 percent, and the balance of Fe.

Preparation: induction smelting; hot rolling at 1200 ℃, wherein the total deformation of the hot rolling is more than or equal to 75 percent; cold rolling at room temperature, wherein the total deformation is 70%; annealing at 700 ℃ for 15 minutes and water cooling.

Example 3

The components: according to the mass percentage, the material comprises C:1.2%, mn:20.6%, mo:4.8%, al:0.1 to 0.3%, si:0.1 to 0.5 percent, and the balance of Fe.

Preparation: induction smelting; hot rolling at 950 ℃, wherein the total deformation is more than or equal to 75 percent; cold rolling at room temperature, wherein the total deformation is 60%; annealing at 600 ℃ for 30 minutes and water cooling.

The mechanical and magnetic properties of the non-magnetic steel are shown in Table 1, FIG. 2, and FIG. 3

Example 4

The components: according to the mass percentage, the material comprises C:0.7%, mn:25%, mo:3.5%, al:0.1 to 0.3%, si:0.1 to 0.5 percent, and the balance of Fe.

Preparation: arc or induction melting; continuous casting and rolling; cold rolling at room temperature, wherein the total deformation is 40%; annealing at 850 deg.C for 10 min, and water cooling.

	Yield strength (MPa)	Tensile strength (MPa)	Elongation (%)	Relative magnetic permeability
					Example one	1437	1740	23.7	1.002
ExamplesII	1783	2083	7.5	1.002
					EXAMPLE III	1681	1948	14.2	1.002
Example four	1329	1619	26.4	1.001

The mechanical and magnetic properties of the non-magnetic steel are shown in table 1, fig. 2 and fig. 3, which are only preferred examples of the present invention, but it should not be understood that the scope of the present invention is limited thereto.

The invention provides ultrahigh-strength non-magnetic high manganese steel and a preparation method thereof, wherein the steel comprises the following main alloy components: c:0.7 to 1.2%, mn:15.0 to 25.0%, mo:3.0 to 5.0%, al:0.1 to 0.3%, si: 0.1-0.5 percent, and the balance of Fe and other inevitable impurity elements, and the preparation method comprises the following steps: smelting, hot rolling or hot forging, cold rolling or cold forging, and annealing. The high manganese steel provided by the invention has the advantages that: the component design ensures that the matrix is nonmagnetic single-phase austenite, and avoids deformation in the deformation process to induce martensite phase transformation to generate ferromagnetic martensite; high strength is provided by using high-density nanometer size deformation twin crystals; mo element is utilized to improve the heat stability of the nano structure. The nonmagnetic high manganese steel prepared by the components and the preparation method has the relative magnetic permeability of 1.002 and the strength of 2082MPa.

Claims

1. The preparation method of the ultrahigh-strength non-magnetic high manganese steel is characterized by comprising the following alloy components in percentage by mass: c:0.85 to 1.2%, mn:20.6 to 25.0%, mo:3.5 to 5.0%, al:0.1 to 0.3%, si:0.1 to 0.5 percent, and the balance of Fe and other inevitable impurity elements;

the preparation method of the ultrahigh-strength non-magnetic high manganese steel comprises the following steps:

s1, obtaining a blank by die casting or continuous casting after smelting;

s2, annealing the die casting blank at the temperature of 1000-1200 ℃, and then carrying out hot rolling or hot forging at the temperature of 850-1150 ℃;

s3, continuously rolling a continuous casting billet at the temperature of 900-1200 ℃;

s4, cold rolling or cold forging the hot rolled, hot forged or continuously rolled blank at room temperature;

s5, annealing the cold-rolled or cold-forged blank at the temperature of 500-850 ℃;

strengthening is realized by a high-density nanometer-size twin crystal structure obtained by means of a deformation induced twinning mechanism.

2. The method for preparing the ultrahigh-strength nonmagnetic high manganese steel according to claim 1, wherein the hot rolling temperature in the steps S2 and S3 is 1200 ℃, the total hot rolling deformation is 50-80%, the final rolling temperature is not less than 950 ℃, and water cooling is performed after the hot rolling is completed.

3. The method for preparing the ultrahigh-strength nonmagnetic high manganese steel according to claim 1, wherein the total cold deformation amount in the step S4 is not less than 10%.

4. The method for preparing the ultrahigh-strength non-magnetic high-manganese steel according to claim 1, wherein the annealing temperature in the step S5 is 600 ℃, and the cooling mode is water cooling.

5. An ultra-high strength non-magnetic high manganese steel prepared by the method of any one of claims 1 to 4.

6. The ultra-high strength non-magnetic high manganese steel of claim 5, wherein the steel comprises, by mass: c:1.2%, mn:20.6%, mo:4.8%, al:0.1 to 0.3%, si:0.1 to 0.5 percent, and the balance of Fe.