阅读说明：本技术 一种复合马氏体钢及其制备方法 (Composite martensitic steel and preparation method thereof ) 是由 杨志南 张福成 姜锋 李靖宇 于 2019-11-07 设计创作，主要内容包括：本发明涉及高强度钢制备技术领域,尤其涉及一种复合马氏体钢及其制备方法。本发明提供的制备方法,包括以下步骤：将马氏体钢和奥氏体钢复合,得到所述复合马氏体钢；所述马氏体钢与所述奥氏体钢的质量比为(1～5):1。利用上述制备方法制备得到的复合马氏体钢具有较好的强度和韧性。(The invention relates to the technical field of high-strength steel preparation, in particular to composite martensitic steel and a preparation method thereof. The preparation method provided by the invention comprises the following steps: combining martensitic steel and austenitic steel to obtain the composite martensitic steel; the mass ratio of the martensite steel to the austenite steel is (1-5): 1. The composite martensitic steel prepared by the preparation method has better strength and toughness.)

1. The preparation method of the composite martensitic steel is characterized by comprising the following steps of:

combining martensitic steel and austenitic steel to obtain the composite martensitic steel;

the mass ratio of the martensite steel to the austenite steel is (1-5): 1.

2. The production method according to claim 1, wherein when the martensitic steel is a martensitic steel sheet and the austenitic steel is an austenitic steel sheet, the recombination process is:

stacking the martensite steel plate and the austenite steel plate to obtain an initial plate;

and sequentially carrying out thermal deformation and tempering treatment on the initial plate to obtain the composite martensitic steel.

3. The production method according to claim 2, wherein the ratio of the total thickness of the martensitic steel sheet to the total thickness of the austenitic steel sheet is (1.5 to 3.5): 1.

4. the preparation method according to claim 2, further comprising heating the initial plate to 1150-1250 ℃ and holding for 0.5-2 hours before the hot deformation;

after the thermal deformation, the total deformation amount of the initial plate is more than or equal to 30 percent, and the final deformation temperature is more than or equal to 1050 ℃;

the tempering temperature is 150-280 ℃, and the tempering time is 30-120 min.

5. The production method according to any one of claims 2 to 4, wherein the martensitic steel sheet comprises the following components in percentage by mass:

c: 0.05 to 0.40%, Si: 0.5-2.0%, Mn: 0.40-0.80%, Cr: 0.80-1.30%, Ni: 0-2.0%, Mo: 0-1.0%, Al: 0.05-2.0%, V: 0 to 0.2%, the balance being iron and unavoidable impurities;

the austenitic steel plate comprises the following components in percentage by mass:

c: 0.8 to 1.10%, Si: 0.30-1.60%, Mn: 9.5-18.0%, Cr: 0 to 2.0%, and the balance of iron and inevitable impurities.

6. The production method according to claim 1, wherein when the martensitic steel is martensitic steel powder and the austenitic steel is austenitic steel powder, the recombination process is:

mixing the martensitic steel powder with the austenitic steel powder to obtain a mixed powder;

and sequentially sintering, heat treating and tempering the mixed powder to obtain the composite martensitic steel.

7. The production method according to claim 6, wherein the sintering is hot press sintering or spark plasma sintering;

the hot-pressing sintering conditions are as follows: the temperature is 1000-1350 ℃, the pressure is 20-60 MPa, and the time is 10-60 min;

the discharge plasma sintering conditions are as follows: the temperature is 1000-1150 ℃, the pressure is 15-50 MPa, and the time is 5-30 min.

8. The method according to claim 6, wherein the heat treatment temperature is 800 to 1000 ℃, and the heat treatment time is 5 to 30 min;

the tempering temperature is 150-280 ℃, and the tempering time is 30-120 min.

9. The method according to any one of claims 6 to 8, wherein the martensitic steel powder comprises the following components in percentage by mass:

c: 0.20 to 0.40%, Si: 1.10-1.60%, Mn: 1.00-2.00%, Cr: 0.90-1.30%, Mo: 0.20-40%, Al: 0-0.60%, and the balance of Fe and inevitable impurities;

the austenitic steel powder comprises the following components in percentage by mass:

c: 0.50 to 1.20%, Mn: 9.0 to 13.0%, Al: 0.80-1.50%, Si: 0 to 2.0%, and the balance of iron and inevitable impurities.

10. The composite martensitic steel produced by the production method according to any one of claims 1 to 9.

Technical Field

The invention relates to the technical field of high-strength steel preparation, in particular to composite martensitic steel and a preparation method thereof.

Background

The martensite steel is the most widely applied steel, has the advantages of simple heat treatment process, convenient realization of on-line heat treatment and the like, and can be applied to different engineering fields, such as wear-resistant steel plates, automobile steel, bearing steel and the like. The martensite steel obtains a high-strength martensite structure after simple quenching and tempering treatment, but the martensite steel has low overall plasticity, especially uniform plasticity due to high internal dislocation density and low content of residual austenite in a microstructure. Generally, a method of obtaining a ferrite + martensite dual-phase steel by introducing some ferrite or a method of improving uniform plasticity by increasing the content of residual austenite in a martensitic steel are used, but these methods all cause the strength of the martensitic steel to be reduced.

From this point of view, the toughness of the conventional martensitic steel is to be improved.

Disclosure of Invention

The invention aims to provide composite martensitic steel and a preparation method thereof. The composite martensitic steel prepared by the preparation method has higher strength and toughness.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a preparation method of composite martensitic steel, which comprises the following steps:

combining martensitic steel and austenitic steel to obtain the composite martensitic steel;

the mass ratio of the martensite steel to the austenite steel is (1-5): 1.

Preferably, when the martensitic steel is a martensitic steel plate and the austenitic steel is an austenitic steel plate, the compounding process is as follows:

stacking the martensite steel plate and the austenite steel plate to obtain an initial plate;

and sequentially carrying out thermal deformation and tempering treatment on the initial plate to obtain the composite martensitic steel.

Preferably, the ratio of the total thickness of the martensitic steel sheet to the total thickness of the austenitic steel sheet is (1.5-3.5): 1.

preferably, before the thermal deformation, the initial plate is heated to 1150-1250 ℃ and is kept warm for 0.5-2 hours;

after the thermal deformation, the total deformation amount of the initial plate is more than or equal to 30 percent, and the final deformation temperature is more than or equal to 1050 ℃;

the tempering temperature is 150-280 ℃, and the tempering time is 30-120 min.

Preferably, the martensitic steel plate comprises the following components in percentage by mass:

c: 0.05 to 0.40%, Si: 0.5-2.0%, Mn: 0.40-0.80%, Cr: 0.80-1.30%, Ni: 0-2.0%, Mo: 0-1.0%, Al: 0.05-2.0%, V: 0 to 0.2%, the balance being iron and unavoidable impurities;

the austenitic steel plate comprises the following components in percentage by mass:

c: 0.8 to 1.10%, Si: 0.30-1.60%, Mn: 9.5-18.0%, Cr: 0 to 2.0%, and the balance of iron and inevitable impurities.

Preferably, when the martensitic steel is martensitic steel powder and the austenitic steel is austenitic steel powder, the compounding process is as follows:

mixing the martensitic steel powder with the austenitic steel powder to obtain a mixed powder;

and sequentially sintering, heat treating and tempering the mixed powder to obtain the composite martensitic steel.

Preferably, the sintering is hot-pressing sintering or spark plasma sintering;

the hot-pressing sintering conditions are as follows: the temperature is 1000-1350 ℃, the pressure is 20-60 MPa, and the time is 10-60 min;

the discharge plasma sintering conditions are as follows: the temperature is 1000-1150 ℃, the pressure is 15-50 MPa, and the time is 5-30 min.

Preferably, the heat treatment temperature is 800-1000 ℃, and the heat treatment time is 5-30 min;

the tempering temperature is 150-280 ℃, and the tempering time is 30-120 min.

Preferably, the martensitic steel powder comprises the following components in percentage by mass:

c: 0.20 to 0.40%, Si: 1.10-1.60%, Mn: 1.00-2.00%, Cr: 0.90-1.30%, Mo: 0.20-40%, Al: 0-0.60%, and the balance of Fe and inevitable impurities;

the austenitic steel powder comprises the following components in percentage by mass:

c: 0.50 to 1.20%, Mn: 9.0 to 13.0%, Al: 0.80-1.50%, Si: 0 to 2.0%, and the balance of iron and inevitable impurities.

The invention also provides the composite martensitic steel prepared by the preparation method in the technical scheme.

The invention provides a preparation method of composite martensitic steel, which comprises the following steps: combining martensitic steel and austenitic steel to obtain the composite martensitic steel; the mass ratio of the martensite steel to the austenite steel is (1-5): 1. The invention utilizes the high work hardening capacity of the austenitic steel, so that the austenitic steel can effectively assist the martensite deformation in the deformation process, and the work hardening capacity of the whole material is improved, thereby ensuring the plasticity and the toughness of the composite austenitic steel. In addition, part of carbon elements in the austenitic steel can be diffused into the martensitic steel in the compounding process, so that the solid-solution carbon content of the composite martensitic steel is improved, the strength of the composite martensitic steel is further improved, and meanwhile, a transition layer with high Mn content is formed at an interface to assist in martensitic deformation. The finally obtained composite martensitic steel has better strength and toughness.

Drawings

FIG. 1 is a photograph of the metallographic structure of the composite martensitic steel prepared in example 1;

FIG. 2 is a photograph of the metallographic structure of the composite martensitic steel prepared in example 2.

Detailed Description

The invention provides a preparation method of composite martensitic steel, which comprises the following steps:

combining martensitic steel and austenitic steel to obtain the composite martensitic steel;

the mass ratio of the martensite steel to the austenite steel is (1-5): 1.

In the present invention, all the raw material components are commercially available products well known to those skilled in the art unless otherwise specified.

In the present invention, the mass ratio of the martensitic steel to the austenitic steel is preferably (1.3 to 3.8): 1, more preferably (1.5 to 3.0): 1. in the present invention, by controlling the mass ratio of the martensitic steel to the austenitic steel within the above range, the synergistic effect between austenite and martensite can be more sufficiently exhibited, and the toughness of the composite martensitic steel can be improved to the maximum extent.

In the present invention, when the martensitic steel is a martensitic steel sheet and the austenitic steel is an austenitic steel sheet, the process of the recombination is preferably:

stacking the martensite steel plate and the austenite steel plate to obtain an initial plate;

and sequentially carrying out thermal deformation and tempering treatment on the initial plate to obtain the composite martensitic steel.

The martensite steel plate and the austenite steel plate are arranged in a laminated mode to obtain an initial plate; in the present invention, the martensitic steel sheet preferably includes, in terms of mass percent, the following components: c: 0.05 to 0.40%, Si: 0.5-2.0%, Mn: 0.40-0.80%, Cr: 0.80-1.30%, Ni: 0-2.0%, Mo: 0-1.0%, Al: 0.05-2.0%, V: 0 to 0.2%, the balance being iron and unavoidable impurities; more preferably comprises the following components: c: 0.23%, Si: 1.55%, Mn: 0.60%, Cr: 1.15%, Ni: 0.23%, Mo: 0.2%, Al: 0.06%, V: 0.03%, the balance being iron and unavoidable impurities. In the present invention, the austenitic steel sheet preferably includes the following components in mass percent: c: 0.8 to 1.10%, Si: 0.30-1.60%, Mn: 9.5-18.0%, Cr: 0 to 2.0%, the balance being iron and unavoidable impurities; more preferably comprises the following components: c: 1.05%, Si: 0.35%, Mn: 12.50%, Cr: 0.1%, and the balance of iron and inevitable impurities.

In the present invention, the ratio of the total thickness of the martensitic steel sheet to the total thickness of the austenitic steel sheet is preferably (1.5 to 3.5): 1, more preferably 2: 1. In the invention, the single-layer thickness of the martensitic steel plate is preferably millimeter (1-10 mm), centimeter (1-10 cm) or decimeter (1-10 dm), and more preferably millimeter; the thickness of the single layer of the austenitic steel plate is preferably millimeter (1-10 mm), centimeter (1-10 cm) or decimeter (1-10 dm), and is more preferably millimeter.

In the present invention, before the lamination setting, it is preferable that the austenitic steel sheet and the martensitic steel sheet are subjected to pretreatment; the pretreatment is preferably grinding and cleaning; the present invention is not limited to any particular type of sanding and cleaning, and sanding and cleaning processes known to those skilled in the art may be used. In the present invention, the stacking arrangement is preferably: from bottom to top, the arrangement is made in the order of the stack of martensitic/austenitic/martensitic/austenitic … …, wherein the last layer of the stack preferably ends with a martensitic steel sheet. In the invention, the arrangement can ensure that the finally formed composite steel has obvious martensite characteristics.

After the stacking arrangement is completed, the method also preferably comprises the steps of packaging and vacuumizing the stacked plates to obtain initial plates; the process of packaging and vacuum-pumping is not limited in any way, and can be performed by a process known to those skilled in the art.

After the initial plate is obtained, the thermal deformation and tempering treatment are sequentially carried out on the initial plate to obtain the composite martensitic steel. In the invention, before the thermal deformation, the initial plate is preferably heated to 1150-1250 ℃ and is kept warm for 0.5-2 h; the heating temperature is more preferably 1180-1220 ℃, and most preferably 1180 ℃; the heat preservation time is more preferably 1.0-1.5 h. In the present invention, the total deformation amount of the initial plate after the thermal deformation is preferably equal to or greater than 30%, more preferably 50%; the deformation temperature for termination is preferably 1050 ℃ or more, more preferably 1070 ℃. The invention does not have any special limitation on the thermal deformation mode, and the thermal deformation condition can be achieved.

After the thermal deformation is completed, the invention preferably performs tempering treatment after cooling to room temperature. In the present invention, the cooling method is preferably spray cooling, water cooling, oil cooling, or cooling after short-term heat preservation by salt bath quenching, and more preferably water cooling.

In the invention, the tempering temperature is preferably 150-280 ℃, more preferably 220-260 ℃, and most preferably 220 ℃; the tempering time is preferably 30-120 min, more preferably 50-100 min, and most preferably 60-80 min. After the tempering treatment is completed, the invention preferably further comprises cooling to room temperature; the cooling is preferably air cooling.

In the present invention, when the martensitic steel is martensitic steel powder and the austenitic steel is austenitic steel powder, the process of the recombination is preferably:

mixing the martensitic steel powder with the austenitic steel powder to obtain a mixed powder;

and sequentially sintering, heat treating and tempering the mixed powder to obtain the composite martensitic steel.

Mixing the martensitic steel powder and the austenitic steel powder to obtain mixed powder; in the present invention, the martensitic steel powder preferably comprises, in mass percent, the following components: c: 0.20 to 0.40%, Si: 1.10-1.60%, Mn: 1.00-2.00%, Cr: 0.90-1.30%, Mo: 0.20-40%, Al: 0-0.60%, and the balance of Fe and inevitable impurities; more preferably comprises the following components: c: 0.30%, Si: 1.44%, Mn: 1.58%, Cr: 1.13%, Mo: 0.40%, Al: 0.48%, and the balance of Fe and inevitable impurities. In the present invention, the austenitic steel powder preferably comprises, in mass percent: c: 0.50 to 1.20%, Mn: 9.0 to 13.0%, Al: 0.80-1.50%, Si: 0 to 2.0%, the balance being iron and unavoidable impurities; more preferably comprises the following components: c: 0.61%, Si: 0.01%, Mn: 11.7%, Al: 1.10%, Si: 0.3%, and the balance of iron and inevitable impurities.

In the invention, the average grain diameter of the martensitic steel powder is preferably 50-150 μm, and more preferably 120 μm; the average grain diameter of the austenitic steel powder is preferably 20-80 mu m, and more preferably 60 mu m; the ratio of the average grain size of the martensitic steel powder to the average grain size of the austenitic steel powder is preferably (1.5-5): 1, more preferably 2: 1.

In the present invention, the mass ratio of the martensitic steel powder to the austenitic steel powder is preferably (1-5): 1, more preferably (2.0-4.0): 1, most preferably 3: 1. In the present invention, the mass ratio can further ensure that the finally formed composite austenitic steel has obvious martensite matrix characteristics.

In the present invention, the mixing method is preferably ball milling, and the conditions of the ball milling are not particularly limited, and the conditions known to those skilled in the art can be adopted; the mixing is preferably carried out in a ball mill.

After the mixed powder is obtained, the mixed powder is sequentially subjected to sintering, heat treatment and tempering treatment to obtain the composite martensitic steel. In the invention, the sintering mode is preferably hot-pressing sintering or spark plasma sintering; when the sintering mode is hot-pressing sintering, the temperature of the hot-pressing sintering is preferably 1000-1350 ℃, and more preferably 1120 ℃; the pressure of the hot-pressing sintering is preferably 20-60 MPa, and more preferably 50 MPa; the time for hot-pressing sintering is preferably 10-60 min, and more preferably 30 min. When the sintering mode is spark plasma sintering, the temperature of the spark plasma sintering is preferably 1000-1150 ℃, and more preferably 1050 ℃; the pressure of the spark plasma sintering is preferably 15-50 MPa, and more preferably 40 MPa; the time for the spark plasma sintering is preferably 5-30 min, and more preferably 20 min.

In the invention, the temperature of the heat treatment is preferably 800-1000 ℃, and more preferably 830-950 ℃; the time of the heat treatment is preferably 5-30 min, and more preferably 20 min.

After the heat treatment is finished, the cooling is preferably carried out, and the cooling mode is preferably spray cooling, water cooling, oil cooling or cooling after short-time heat preservation of salt bath quenching, and more preferably water cooling.

In the invention, the tempering temperature is preferably 150-280 ℃, and more preferably 180-220 ℃; the tempering time is preferably 30-120 min, and more preferably 40-80 min. After the tempering treatment is completed, the product after the tempering treatment is preferably cooled, and the cooling is preferably air cooling.

The invention also provides the composite martensitic steel prepared by the preparation method in the technical scheme, wherein the composite martensitic steel has a structure that 17-50% of stable austenite exists, the plasticity and the toughness are improved by utilizing the TWIP effect, meanwhile, a transition layer with higher residual austenite content exists at the interface position of the austenite and the martensite, the plasticity and the toughness can be improved by utilizing the TRIP effect, and the remainder is a martensitic structure.

The composite martensitic steel and the method for producing the same according to the present invention will be described in detail with reference to examples, but they should not be construed as limiting the scope of the present invention.