阅读说明：本技术 通过Mn微合金化提高耐热铝合金高温强度的方法 (Method for improving high-temperature strength of heat-resistant aluminum alloy through Mn microalloying ) 是由 廖恒成 李广敬 潘星惠 郑基伟 陆丽珍 于 2021-08-17 设计创作，主要内容包括：本发明公开了一种通过Mn微合金化提高耐热铝合金高温强度的方法,将中间合金锭按所需成分比例称取,在电阻炉中熔化,静置、精炼处理后浇注在金属模具或砂型中进行成形。熔炼过程中为了减小烧损,确保合金成分的准确性,需按一定顺序加入不同中间合金锭。将成形后的Mn微合金化耐热铝合金在热处理炉中进行常规的固溶+人工时效处理,然后进行长时间的热暴露处理,即可获得一种具有优异高温力学性能的耐热铝合金。本发明的制备方法能显著提高析出强化相粒子的抗粗化能力并抑制高温过程中有害的相转变；所制备的通过Mn微合金化的耐热铝合金能显著提高合金的高温力学性能；制备的高强耐热铝合金显现出优异的高温力学性能,制备工艺简单。(The invention discloses a method for improving high-temperature strength of heat-resistant aluminum alloy through Mn microalloying. In the smelting process, different intermediate alloy ingots are added in a certain sequence in order to reduce burning loss and ensure the accuracy of alloy components. And carrying out conventional solid solution and artificial aging treatment on the formed Mn microalloyed heat-resistant aluminum alloy in a heat treatment furnace, and then carrying out long-time heat exposure treatment to obtain the heat-resistant aluminum alloy with excellent high-temperature mechanical properties. The preparation method can obviously improve the coarsening resistance of the precipitation strengthening phase particles and inhibit harmful phase transformation in the high-temperature process; the prepared heat-resistant aluminum alloy microalloyed by Mn can obviously improve the high-temperature mechanical property of the alloy; the prepared high-strength heat-resistant aluminum alloy has excellent high-temperature mechanical property and simple preparation process.)

1. A method for improving the high-temperature strength of a heat-resistant aluminum alloy through Mn microalloying is characterized by comprising the following steps:

(1) preparing a Mn-containing heat-resistant aluminum alloy metal block by using a commercial intermediate alloy ingot as a raw material;

(2) placing the commercial intermediate alloy ingot prepared in the step (1) in a resistance furnace, heating and melting, standing after heating, then cooling for refining treatment, and pouring after the temperature is stable;

(3) carrying out solid solution treatment on the alloy ingot smelted in the step (2) in a heat treatment furnace, and then taking out and water-quenching to room temperature;

(4) carrying out artificial aging treatment on the alloy ingot subjected to the solution treatment in the step (3) in a heat treatment furnace, and then taking out and air-cooling to room temperature;

(5) and (4) carrying out thermal exposure treatment on the alloy ingot subjected to the aging treatment in the step (4) in a thermal treatment furnace, and then taking out the alloy ingot to be air-cooled to room temperature to prepare the Mn microalloyed high-strength heat-resistant aluminum alloy.

2. The method for improving high temperature strength of a heat resistant aluminum alloy by Mn microalloying according to claim 1, wherein, in the step (1), the commercial master alloy ingot comprises a master alloy ingot of Al- (10-20) wt.% Si, Al- (10-20) wt.% Cu, Al- (10-20) wt.% Mn, industrial pure aluminum, and other added elements.

3. The method for improving the high-temperature strength of the heat-resistant aluminum alloy through Mn microalloying according to claim 1, wherein in the step (1), the Mn content in the Mn-containing heat-resistant aluminum alloy metal block is 0.02 to 0.3 percent by mass.

4. The method for improving the high-temperature strength of the heat-resistant aluminum alloy through Mn microalloying according to claim 1, wherein in the step (2), the alloy is heated to 620-680 ℃ for melting, the temperature is raised to 760-800 ℃, the alloy is kept still for 30-60 min, the temperature is lowered to 715-725 ℃ for refining treatment, after the temperature is stabilized, other easily-burnt intermediate alloy ingots are sequentially added, and the casting is carried out when the temperature is stabilized again at 720 ℃.

5. A method for improving high temperature strength of a heat resistant aluminum alloy through Mn microalloying according to claim 1 or 4, wherein in the step (2), the casting is a metal mold which is kept at 250 ℃ for more than 3h or a sand mold at room temperature.

6. The method for improving high temperature strength of a heat-resistant aluminum alloy by Mn microalloying according to claim 1, wherein in the step (3), the temperature of the solution treatment is set to 500 to 580 ℃ and the temperature is kept for 3 to 15 hours.

7. The method for improving the high-temperature strength of the heat-resistant aluminum alloy through Mn microalloying according to claim 1, wherein in the step (4), the temperature of the artificial aging treatment is set to be 150-200 ℃ and is kept for 5-15 h.

8. The method for improving high-temperature strength of a heat-resistant aluminum alloy through Mn microalloying as recited in claim 1, wherein in the step (5), the temperature of the exposure treatment is set to 250 to 350 ℃ and is kept for 50 to 200 hours.

Technical Field

The invention relates to the field of metal material preparation, in particular to a method for improving high-temperature strength of heat-resistant aluminum alloy through Mn microalloying.

Background

The cast aluminum alloy has excellent mechanical properties, casting properties, low density, high heat conductivity, high electric conductivity and the like, so that the cast aluminum alloy is widely applied to the fields of transportation, aerospace and the like, particularly in the automobile industry. Along with the increasingly outstanding environmental problems, the energy utilization rate is more and more emphasized, and the light weight of the automobile is an effective method for improving the energy utilization rate. In the automobile industry, aluminum is gradually a trend to replace steel, the utilization rate of aluminum alloy in structural parts is greatly improved, but some parts need to bear certain high temperature when in use, such as an engine cylinder body, a cylinder cover, an intake manifold and the like, and the popularization and application of the aluminum alloy are limited by the high-temperature environment.

The addition of Cu or Mg and the proper heat treatment process can separate out a great amount of fine dispersed separated phases in the aluminum alloy matrix, so that the mechanical property of the alloy is obviously improved. However, as the use temperature is increased (generally when the use temperature is more than 200 ℃), or the holding time is prolonged, the main precipitation strengthening phases (beta ', beta', theta 'or theta' phases) in the alloy can be rapidly coarsened, or the main precipitation strengthening phases are converted into the beta and theta phases with lower strengthening effects, so that the mechanical properties of the alloy are rapidly reduced. Therefore, researchers have tried various methods to improve the high temperature mechanical properties of alloys. At present, the main strengthening means is to improve the high-temperature mechanical property of the alloy by adding Er, Sc, Zr and the like into the alloy and forming Al3Er, Al3Sc, Al3Zr and other nanometer precipitated phases with excellent thermal stability after heat treatment, but the solubility of the alloy elements in the aluminum alloy is limited, so that the number density of the precipitated phases is not high, the performance improvement is limited, and the price is high and is difficult to popularize; secondly, a large amount of transition group metal elements are added into the alloy to form coarse second phase structures with good thermal stability, and although the structures can improve the high-temperature mechanical property, the room-temperature mechanical property and the plasticity of the alloy can be damaged to a certain extent, and the casting property of the alloy can be influenced to a certain extent, so that the comprehensive mechanical property of the alloy is not ideal.

Disclosure of Invention

The purpose of the invention is as follows: the invention aims to provide a method for improving the high-temperature strength of a heat-resistant aluminum alloy through Mn micro-alloying, which can obviously improve the coarsening resistance of precipitation strengthening phase particles and inhibit harmful phase transformation in a high-temperature process.

The technical scheme is as follows: the method for improving the high-temperature strength of the heat-resistant aluminum alloy through Mn microalloying comprises the following steps:

(1) preparing a Mn-containing heat-resistant aluminum alloy metal block by using a commercial intermediate alloy ingot as a raw material;

(2) placing the commercial intermediate alloy ingot prepared in the step (1) in a resistance furnace, heating and melting, standing after heating, then cooling for refining treatment, and pouring after the temperature is stable;

(3) carrying out solid solution treatment on the alloy ingot smelted in the step (2) in a heat treatment furnace, and then taking out and water-quenching to room temperature;

(4) carrying out artificial aging treatment on the alloy ingot subjected to the solution treatment in the step (3) in a heat treatment furnace, and then taking out and air-cooling to room temperature;

(5) and (4) carrying out thermal exposure treatment on the alloy ingot subjected to the aging treatment in the step (4) in a thermal treatment furnace, and then taking out the alloy ingot to be air-cooled to room temperature to prepare the Mn microalloyed high-strength heat-resistant aluminum alloy.

Further, in step (1), the commercial master alloy ingot comprises an Al- (10-20) wt.% Si, Al- (10-20) wt.% Cu, Al- (10-20) wt.% Mn, commercial purity aluminum, and other additive element master alloy ingots.

According to the method, the high-temperature coarsening resistance of age-precipitated heat-resistant phase particles in the Al-Si-Cu or Al-Cu heat-resistant aluminum alloy is improved through Mn microalloying, and the phase transformation in the high-temperature process is inhibited; the microalloying of Mn obviously reduces the coarsening rate of precipitation strengthening phase particles of the alloy in the heat exposure process and inhibits the phase transformation in the high-temperature process, thereby improving the high-temperature mechanical property of the Al-Si-Cu or Al-Cu heat-resistant aluminum alloy.

Further, in the step (1), the Mn content of the Mn component in the Mn-containing heat-resistant aluminum alloy metal block is 0.02-0.3% by mass.

Further, in the step (2), heating to 620-680 ℃ for melting, heating to 760-800 ℃, standing for 30-60 min, cooling to 715-725 ℃ for refining, adding other easily-burnt intermediate alloy ingots in sequence after the temperature is stable, and pouring when the temperature is again stable at 720 ℃.

Further, in the step (2), the casting is a metal mold which is insulated for more than 3 hours at 250 ℃ or a sand mold at room temperature.

Further, in the step (3), the temperature of the solution treatment is set to be 500-580 ℃, and the temperature is kept for 3-15 h.

Further, in the step (4), the temperature of the artificial aging treatment is set to be 150-200 ℃, and the temperature is kept for 5-15 h.

Further, in the step (5), the temperature of the exposure treatment is set to be 250-350 ℃, and the temperature is kept for 50-200 h.

Has the advantages that: compared with the prior art, the invention has the following remarkable advantages:

(1) according to the method for improving the high-temperature strength of the heat-resistant aluminum alloy through Mn microalloying, the thermal stability and the high-temperature mechanical property of the Al-Si-Cu or Al-Cu heat-resistant aluminum alloy can be obviously improved only by adding Mn with the mass percentage of less than 0.3%;

(2) the preparation method provided by the application can obviously improve the coarsening resistance of the precipitation strengthening phase particles and inhibit harmful phase transformation in the high-temperature process;

(3) the Mn microalloyed heat-resistant aluminum alloy prepared by the method can obviously improve the high-temperature mechanical property of the alloy;

(4) the preparation method of the material is resistance furnace smelting, the heat treatment process is solid solution, artificial aging and high-temperature heat exposure, and the preparation process is simple.

Detailed Description

The technical solution of the present invention is further explained below.

Example 1

1. Composition design and preparation of alloy

The Al-Si-Cu containing heat resistant aluminum alloy was designed to have a composition of Al-11.5 wt.% Si-4 wt.% Cu as a base alloy, while 0.3 wt.% Mn was added to the Al-11.5 wt.% Si-4 wt.% Cu heat resistant aluminum alloy to produce a Mn microalloyed high strength heat resistant aluminum alloy as a comparative alloy. The preparation of Al-11.5 wt.% Si-4 wt.% Cu heat resistant aluminum alloy under the same conditions is to reflect the effect of the addition of Mn on the Al-Si-Cu heat resistant aluminum alloy and is not within the scope of the present invention.

A preparation method of Mn microalloyed high-strength heat-resistant aluminum alloy comprises the following steps:

(1) preparing a master alloy block containing Al, Si, Cu and Mn according to the mass percentage of the designed components of the alloy;

(2) placing the intermediate alloy metal blocks of the industrial pure aluminum, Al-20 wt.% Si, Al-10 wt.% Mn and Al-20 wt.% Cu prepared in the step (1) into a resistance furnace, turning on a power supply, heating to 720 ℃ for melting, heating to 760 ℃ for standing for 30min, cooling to 720 ℃ for refining, and after the temperature is stabilized at 720 ℃, adding Al-10 wt.% Sr intermediate alloy for modification. The temperature is stabilized at 720 ℃ again for pouring, and the pouring mould is a metal plate-shaped mould which is insulated for more than 3 hours at 250 ℃;

(3) carrying out solution treatment on the alloy ingot smelted in the step (2) in a heat treatment furnace, setting the temperature to 510 ℃, preserving the heat for 5 hours, and then taking out and water-quenching to room temperature;

(4) carrying out artificial aging treatment on the alloy ingot subjected to the solution treatment in the step (3) in a heat treatment furnace, setting the temperature to be 165 ℃, preserving the heat for 6 hours, and then taking out and air-cooling to room temperature;

(5) and (4) carrying out thermal exposure treatment on the alloy ingot subjected to the aging treatment in the step (4) in a thermal treatment furnace, setting the temperature at 300 ℃, preserving the heat for 100 hours, taking out the alloy ingot and air-cooling the alloy ingot to room temperature, thus preparing the Mn microalloyed high-strength heat-resistant aluminum alloy.

2. Characterization of Room temperature and high temperature mechanical Properties of the alloys

Quasi-static tensile property at room temperature and high temperature

Cutting the plate-shaped alloy ingot away from a pouring gate by using linear cutting to obtain a gauge length of 18mm and a cross section area of 3 x 3mm²Is stretchedAnd (6) testing the sample, and polishing the surface of the tensile sample to be flat by using sand paper. Tensile test was carried out at room temperature and at a high temperature of 300 ℃ on a CTM5105 electronic universal tester (high and low temperatures), and the loading rate was 1.00 mm/min. At least 3 experiments were performed on each alloy group to obtain the tensile properties of the alloy at room temperature and elevated temperature of 300 ℃. The mechanical properties obtained in the experiment are shown in table 1.

3, experimental results:

after the Mn microalloyed high-strength heat-resistant aluminum alloy smelted according to the designed components is subjected to corresponding solid solution, artificial aging and high-temperature heat exposure treatment, the mechanical property of the alloy at the high temperature of 300 ℃ is remarkably improved.

TABLE 1

Example 2

1. Composition design and preparation of alloy

The Al-Cu containing heat resistant aluminum alloy was designed to have a composition of Al-4 wt.% Cu as a base alloy, while 0.2 wt.% Mn was added to the Al-4 wt.% Cu heat resistant aluminum alloy to prepare a Mn microalloyed high strength heat resistant aluminum alloy as a comparative alloy. The preparation of Al-4 wt.% Cu heat resistant aluminum alloy under the same conditions is to reflect the influence of the addition of Mn on the Al-Cu heat resistant aluminum alloy and is not within the scope of the present invention.

A preparation method of Mn microalloyed high-strength heat-resistant aluminum alloy comprises the following steps:

(1) preparing a master alloy block containing Al, Cu and Mn according to the mass percentage of the designed components of the alloy;

(2) placing the intermediate alloy metal blocks of the industrial pure aluminum, the Al-20 wt.% Cu and the Al-20 wt.% Mn prepared in the step (1) into a resistance furnace, turning on a power supply, heating to 720 ℃ for melting, heating to 760 ℃ for standing for 30min, cooling to 720 ℃ for refining, pouring when the temperature is stable at 720 ℃, and preserving the heat for more than 3h at 250 ℃ by using a pouring mold;

(3) carrying out solution treatment on the alloy ingot smelted in the step (2) in a heat treatment furnace, setting the temperature to be 515 ℃, preserving the heat for 6h +575 ℃ for 3h, and then taking out and water-quenching to room temperature;

(4) carrying out artificial aging treatment on the alloy ingot subjected to solution treatment in the step (3) in a heat treatment furnace, setting the temperature to be 165 ℃, preserving the heat for 5 hours, and then taking out and air-cooling to room temperature;

(5) and (4) carrying out thermal exposure treatment on the alloy ingot subjected to the aging treatment in the step (4) in a thermal treatment furnace, setting the temperature at 300 ℃, preserving the heat for 100 hours, taking out the alloy ingot and air-cooling the alloy ingot to room temperature, thus preparing the Mn microalloyed high-strength heat-resistant aluminum alloy.

2. Characterization of Room temperature and high temperature mechanical Properties of the alloys

Quasi-static tensile property at room temperature and high temperature

Cutting the plate-shaped alloy ingot away from a pouring gate by using linear cutting to obtain a gauge length of 18mm and a cross section area of 3 x 3mm²The surface of the tensile test sample is polished to be flat by sand paper. Tensile test was carried out at room temperature and at a high temperature of 300 ℃ on a CTM5105 electronic universal tester (high and low temperatures), and the loading rate was 1.00 mm/min. At least 3 experiments were performed on each alloy group to obtain the tensile properties of the alloy at room temperature and elevated temperature of 300 ℃. The mechanical properties obtained in the experiment are shown in table 2.

TABLE 2

3, experimental results:

after the Mn microalloyed high-strength heat-resistant aluminum alloy smelted according to the designed components is subjected to corresponding solid solution, artificial aging and high-temperature heat exposure treatment, the mechanical property of the alloy at the high temperature of 300 ℃ is remarkably improved.