阅读说明：本技术 新型含铝奥氏体耐热钢及其制备方法和用途 (Novel aluminum-containing austenitic heat-resistant steel and preparation method and application thereof ) 是由 高秋志 江琛琛 屈福 刘子昀 于 2019-08-08 设计创作，主要内容包括：本发明涉及合金领域,具体涉及一种新型含铝奥氏体耐热钢及其制备方法和用途。该含铝奥氏体耐热钢含有铬,镍,铝,硅,铌,钛,锰,钼和铁,所述铬的质量分数为10％～20％,镍的质量分数为15％～25％,铝的质量分数为3％～5％,硅的质量分数为0.1％～0.2％,铌的质量分数为1.5％～2.5％,钛的质量分数为0.01％～0.02％,锰的质量分数为1.5％～3％,钼的质量分数为2％～3％。所提供的含铝奥氏体耐热钢具有优良的蠕变性能以及高温抗氧化性能以及具有合适的硬度。经过冷变形处理硬度值和屈服极限会而增加,从而可以通过冷变形处理提高含铝奥氏体耐热钢的强度,应用于多种冷处理工艺或者冷变形处理环境中。(The invention relates to the field of alloys, in particular to novel aluminum-containing austenitic heat-resistant steel and a preparation method and application thereof. The aluminum-containing austenitic heat-resistant steel contains 10-20% of chromium, 15-25% of nickel, 3-5% of aluminum, 0.1-0.2% of silicon, 1.5-2.5% of niobium, 0.01-0.02% of titanium, 1.5-3% of manganese and 2-3% of molybdenum. The provided aluminum-containing austenitic heat-resistant steel has excellent creep property and high-temperature oxidation resistance and has proper hardness. The hardness value and the yield limit of the steel subjected to cold deformation treatment can be increased, so that the strength of the aluminum-containing austenitic heat-resistant steel can be improved through cold deformation treatment, and the steel can be applied to various cold treatment processes or cold deformation treatment environments.)

1. An aluminum-containing austenitic heat-resistant steel is characterized by containing 10-20% by mass of chromium, 15-25% by mass of nickel, 3-5% by mass of aluminum, 0.1-0.2% by mass of silicon, 1.5-2.5% by mass of niobium, 0.01-0.02% by mass of titanium, 1.5-3% by mass of manganese and 2-3% by mass of molybdenum.

2. The aluminum-containing austenitic heat-resistant steel of claim 1, further comprising at least one of the following elements: carbon, boron, tungsten, copper and phosphorus, wherein the mass fraction of each element is below 1%.

3. The aluminum-containing austenitic heat-resistant steel according to claim 1, further comprising carbon, boron, tungsten, copper, and phosphorus, wherein the mass fraction of carbon is 0.03% to 0.1%, the mass fraction of boron is less than 0.01%, the mass fraction of tungsten is 0.03% to 0.1%, the mass fraction of copper is 0.03% to 0.1%, and the mass fraction of phosphorus is less than 0.05%.

4. The aluminum-containing austenitic heat-resistant steel as claimed in claim 1, wherein the mass fraction of chromium is 10% to 15%, the mass fraction of nickel is 18% to 23%, the mass fraction of aluminum is 4% to 5%, the mass fraction of silicon is 0.13% to 0.18%, the mass fraction of niobium is 1.8% to 2.2%, the mass fraction of titanium is 0.013% to 0.015%, the mass fraction of manganese is 1.8% to 2.5%, and the mass fraction of molybdenum is 1.8% to 2.5%.

5. The aluminum-containing austenitic heat-resistant steel as claimed in claim 1, wherein the mass fraction of chromium is 11.16%, the mass fraction of nickel is 20.54%, the mass fraction of aluminum is 3.96%, the mass fraction of silicon is 0.14%, the mass fraction of niobium is 2.02%, the mass fraction of titanium is 0.013%, the mass fraction of manganese is 2.06%, and the mass fraction of molybdenum is 2.25%;

the alloy further comprises carbon, boron, tungsten, copper and phosphorus, wherein the mass fraction of the carbon is 0.06%, the mass fraction of the boron is less than 0.01%, the mass fraction of the tungsten is 0.05%, the mass fraction of the copper is 0.05%, the mass fraction of the phosphorus is less than 0.04%, and the balance of iron.

6. The aluminum-containing austenitic heat-resistant steel according to claim 1, wherein the aluminum-containing austenitic heat-resistant steel is cold-rolled at normal temperature, and the pressing force of the aluminum-containing austenitic heat-resistant steel is 10% to 60%, preferably the rolling reduction is 25% to 60%.

7. The aluminum-containing austenitic heat-resistant steel according to claim 1, wherein the aluminum-containing austenitic heat-resistant steel is cold-rolled at room temperature, and the aluminum-containing austenitic heat-resistant steel has a maximum tensile strength of 825MPa or more and a vickers hardness of 335 or more.

8. The method for producing an aluminum-containing austenitic heat-resistant steel according to any one of claims 1 to 7, comprising:

mixing and melting raw materials to obtain the aluminum-containing austenitic heat-resistant steel;

and cold rolling the aluminum-containing austenitic heat-resistant steel at normal temperature to ensure that the pressure of the aluminum-containing austenitic heat-resistant steel is 10-60%.

9. The production method according to claim 8, wherein the cold rolling treatment at normal temperature is 2 to 5 times of cold rolling treatment at normal temperature;

preferably, the first cold rolling treatment at normal temperature is carried out, and the reduction of the aluminum-containing austenitic heat-resistant steel is 10-30%; and carrying out cold rolling treatment at normal temperature for the second time or more, wherein the reduction of the aluminum-containing austenitic heat-resistant steel is 3-10%.

10. Use of the aluminum-containing austenitic heat-resistant steel according to any one of claims 1 to 7 for improving the strength of the aluminum-containing austenitic heat-resistant steel.

Technical Field

The invention relates to the field of alloys, in particular to novel aluminum-containing austenitic heat-resistant steel and a preparation method and application thereof.

Background

A novel aluminum-containing Austenitic Heat-resistant steel (AFA steel for short) is a high-temperature-resistant alloy which is developed soon and has wide application prospect. AFA steel is characterized by a surface layer of Al₂O₃The protective film still has excellent oxidation resistance in a high-temperature oxidation environment, and the high-temperature mechanical property of the protective film is also excellent, so that the protective film becomes a key material of an ultra-supercritical thermal power generating unit.

Since the emergence of AFA steel, the AFA steel with different properties is obtained by adjusting the addition ratio of each element in the alloy and the heat treatment process. However, the existing AFA steel material still cannot meet the production requirement and application. And the research on the cold deformation of the AFA steel is very little, and the AFA steel also has great application prospect and application range exploration.

Disclosure of Invention

One purpose of the invention is to provide a novel aluminum-containing austenitic heat-resistant steel, and a preparation method and application thereof. The novel aluminum-containing austenitic heat-resistant steel can form a continuous, compact and stable aluminum oxide oxidation resistant layer in a high-temperature oxidation environment, and the MC phase, the Laves phase, the NbC phase, the gamma' phase and the beta phase in the aluminum-containing austenitic heat-resistant steel after cold deformation treatment have no obvious influence, but the hardness value and the yield limit can be increased along with the cold deformation rolling process, so that the strength of the aluminum-containing austenitic heat-resistant steel can be improved through cold deformation treatment, and the aluminum-containing austenitic heat-resistant steel can be applied to various cold treatment processes or cold deformation treatment environments.

Specifically, the invention provides the following technical scheme:

according to a first aspect of the present invention, there is provided an aluminum-containing austenitic heat-resistant steel comprising 10% to 20% by mass of chromium, 15% to 25% by mass of nickel, 3% to 5% by mass of aluminum, 0.1% to 0.2% by mass of silicon, 1.5% to 2.5% by mass of niobium, 0.01% to 0.02% by mass of titanium, 1.5% to 3% by mass of manganese, and 2% to 3% by mass of molybdenum.

The provided aluminum-containing austenitic heat-resistant steel contains a plurality of element components, wherein the content of three elements of aluminum, chromium and nickel reaches a certain proportion, so that the provided aluminum-containing austenitic heat-resistant steel can form a continuous, compact and stable aluminum oxide oxidation resistant layer under a high-temperature oxidation environment. When the content of any one of the elements of aluminum, chromium and nickel is changed, a stable and continuous alumina protective layer cannot be realized. Moreover, when the mass fraction of the niobium element is more than 1%, for example, between 1.5% and 2.5%, the formation of an alumina film can be promoted, the compactness and continuity of alumina can be ensured, and the high-temperature creep resistance of the aluminum-containing austenitic heat-resistant steel can be improved, mainly because the niobium element can form a stable nano-grade NbC phase in dispersion in the aluminum-containing austenitic heat-resistant steel, and the high-temperature creep resistance of the aluminum-containing austenitic heat-resistant steel is improved. The control of the addition of a proper mass fraction of silicon element to the aluminum-containing austenitic heat-resistant steel can promote the formation of an aluminum oxide film, and simultaneously can reduce the distance of a NiAl depleted zone between an oxide layer and a substrate so as to prolong the oxidation resistance time of the aluminum-containing austenitic heat-resistant steel. Meanwhile, the hardness of the aluminum-containing austenitic heat-resistant steel can be increased to a certain extent by adding a small amount of manganese, but the excessive content of manganese can bring certain influence on the oxidation resistance of AFA steel, so that the content of manganese is not easy to be too high. In addition, the AFA steel contains molybdenum element and titanium element with proper contents, and the balance of the oxidation resistance and hardness of the AFA steel can be further strengthened, so that the provided AFA steel can form a compact aluminum oxide oxidation film, has excellent creep property and high-temperature oxidation resistance, and has proper hardness. After cold deformation treatment, the MC phase, the Laves phase, the NbC phase, the gamma' phase and the beta phase in the AFA steel have no obvious influence, but the hardness value and the yield limit are increased along with the increase of the rolling amount, so that the strength of the aluminum-containing austenitic heat-resistant steel can be improved through cold deformation treatment, and the aluminum-containing austenitic heat-resistant steel can be applied to various cold treatment processes or cold deformation treatment environments.

Further, the aluminum-containing austenitic heat-resistant steel further includes at least one of the following elements: carbon, boron, tungsten, copper and phosphorus, wherein the mass fraction of each element is below 1%. The AFA steel contains one or more of carbon, boron, tungsten, copper, phosphorus and the like in proper amount, so that the high-temperature oxidation resistance of the AFA steel can be improved. For example, carbon and boron in appropriate amounts can improve the high temperature oxidation resistance of AFA steels.

Further, the aluminum-containing austenitic heat-resistant steel further comprises carbon, boron, tungsten, copper and phosphorus, wherein the mass fraction of the carbon is 0.03-0.1%, the mass fraction of the boron is less than 0.01%, the mass fraction of the tungsten is 0.03-0.1%, the mass fraction of the copper is 0.03-0.1%, and the mass fraction of the phosphorus is less than 0.05%. Therefore, the high-temperature oxidation resistance of the AFA steel can be improved. The AFA steel provided by the method can form a compact aluminum oxide film, has excellent creep property and high-temperature oxidation resistance, and has proper hardness. After cold deformation treatment, the MC phase, the Laves phase, the NbC phase, the gamma' phase and the beta phase in the AFA steel have no obvious influence, but the hardness value and the yield limit are increased along with the increase of the rolling amount, so that the strength of the aluminum-containing austenitic heat-resistant steel can be improved through cold deformation treatment, and the aluminum-containing austenitic heat-resistant steel can be applied to various cold treatment processes or cold deformation treatment environments.

Further, the mass fraction of chromium is 10% to 15%, the mass fraction of nickel is 18% to 23%, the mass fraction of aluminum is 4% to 5%, the mass fraction of silicon is 0.13% to 0.18%, the mass fraction of niobium is 1.8% to 2.2%, the mass fraction of titanium is 0.013% to 0.015%, the mass fraction of manganese is 1.8% to 2.5%, and the mass fraction of molybdenum is 1.8% to 2.5%. The AFA steel provided by the method can further form a compact aluminum oxide film, has excellent creep property and high-temperature oxidation resistance, and has proper hardness. After cold deformation treatment, the MC phase, the Laves phase, the NbC phase, the gamma' phase and the beta phase in the AFA steel have no obvious influence, but the hardness value and the yield limit are increased along with the increase of the rolling amount, so that the strength of the aluminum-containing austenitic heat-resistant steel can be improved through cold deformation treatment, and the aluminum-containing austenitic heat-resistant steel can be applied to various cold treatment processes or cold deformation treatment environments.

Further, the mass fraction of chromium is 11.16%, the mass fraction of nickel is 20.54%, the mass fraction of aluminum is 3.96%, the mass fraction of silicon is 0.14%, the mass fraction of niobium is 2.02%, the mass fraction of titanium is 0.013%, the mass fraction of manganese is 2.06%, and the mass fraction of molybdenum is 2.25%; and further comprises carbon, boron, tungsten, copper and phosphorus, the mass fraction of the carbon is 0.06%, the mass fraction of the boron is less than 0.01%, the mass fraction of the tungsten is 0.05%, the mass fraction of the copper is 0.05%, the mass fraction of the phosphorus is less than 0.04%, and the balance of iron. The AFA steel provided by the method can further form a compact aluminum oxide film, has excellent creep property and high-temperature oxidation resistance, and has proper hardness. After cold deformation treatment, the MC phase, the Laves phase, the NbC phase, the gamma' phase and the beta phase in the AFA steel have no obvious influence, but the hardness value and the yield limit are increased along with the increase of the rolling amount, so that the strength of the aluminum-containing austenitic heat-resistant steel can be improved through cold deformation treatment, and the aluminum-containing austenitic heat-resistant steel can be applied to various cold treatment processes or cold deformation treatment environments.

Further, the aluminum-containing austenitic heat-resistant steel is subjected to cold rolling treatment at normal temperature, the pressure of the aluminum-containing austenitic heat-resistant steel is 10% -60%, and the preferred reduction is 25% -60%. As used herein, "ambient temperature" is used in its ordinary sense in the art, i.e., 25 degrees Celsius.

Further, the aluminum-containing austenitic heat-resistant steel is subjected to cold rolling treatment at normal temperature, the maximum tensile strength of the aluminum-containing austenitic heat-resistant steel is 825MPa or more, and the Vickers hardness of the aluminum-containing austenitic heat-resistant steel is 335HV or more. The AFA steel provided by the application is subjected to cold rolling treatment at normal temperature, the hardness value and the yield limit can be increased, the MC phase, the Laves phase, the NbC phase, the gamma' phase and the beta phase in the AFA steel are equal and have no obvious influence, the strength of the AFA steel can be improved by applying cold deformation treatment, and meanwhile, other performances of the AFA steel can be hardly influenced.

According to a second aspect of the present invention, there is provided a method for producing an aluminum-containing austenitic heat-resistant steel according to the first aspect of the present invention, comprising: mixing and melting raw materials to obtain the aluminum-containing austenitic heat-resistant steel; and cold rolling the aluminum-containing austenitic heat-resistant steel at normal temperature to ensure that the pressure of the aluminum-containing austenitic heat-resistant steel is 10-60%.

Further, the normal-temperature cold rolling treatment is performed for 2-5 times. For example, the first cold rolling treatment at normal temperature is carried out, and the reduction of the aluminum-containing austenitic heat-resistant steel is 10 to 30 percent; and carrying out cold rolling treatment at normal temperature for the second time or more, wherein the reduction of the aluminum-containing austenitic heat-resistant steel is 3-10%. That is, in the process of cold rolling at room temperature, since the AFA steel has not been subjected to any cold rolling at room temperature at the beginning, the rolling reduction may be slightly large, for example, 10% to 30% at the first cold rolling, and in the subsequent cold rolling at room temperature such as the second, third, fourth, etc., the AFA steel may have undergone a certain change in the structure due to the fact that it has undergone a cold rolling at room temperature once, and in the subsequent cold rolling at room temperature, if the rolling reduction is too large, the internal structure of the AFA steel may be greatly affected, for example, cracks, coarse particles, etc. may be caused. Therefore, when the cold rolling treatment at normal temperature is carried out subsequently, the reduction can be controlled to be between 3 percent and 10 percent, and the corresponding purpose is achieved through multiple cold rolling treatments at normal temperature. In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

According to a third aspect of the present invention, the present invention provides a use of an aluminum-containing austenitic heat-resistant steel in the field of improving the strength of the aluminum-containing austenitic heat-resistant steel, which is the aluminum-containing austenitic heat-resistant steel according to the first aspect of the present invention.

Drawings

FIG. 1 is a graph of metallographic observations of AFA steels at 1000 times different reductions provided in accordance with an embodiment of the present invention, where in FIG. 1 (a) is the original sample, (b) is the 10% reduction sample, and (c) is the 30% reduction sample; (d) sample at 60% reduction; (e) the scale is 20 μm for the 80% reduction sample.

Fig. 2 is a surface topography diagram of AFA steels with different rolling reductions of 5000 times under a scanning electron microscope, wherein (a) in fig. 2 is an original sample, (b) is a 10% rolling reduction sample, (c) is a 30% rolling reduction sample, (d) is a 60% rolling reduction sample, and (e) is an 80% rolling reduction sample.

Fig. 3 is a distribution diagram of small particles below 2 μm for samples with different reduction amounts provided according to an embodiment of the present invention, wherein (a) in fig. 3 is the original sample, (b) is the 10% reduction sample, and (c) is the 30% reduction sample.

FIG. 4 is a graph showing the results of hardness change of AFA steels at different rolling reductions according to examples of the present invention.

Detailed Description

The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.