CN115961190A - Sr Zr Ti Ce quaternary composite microalloyed 800MPa strength grade aluminum alloy and preparation method thereof - Google Patents

Abstract

A Sr, zr, ti and Ce quaternary composite microalloyed 800MPa strength level aluminum alloy and a preparation method thereof are characterized in that: the alloy mainly comprises aluminum, zinc, magnesium, copper, strontium, zirconium, titanium and cerium, wherein the mass percent of zinc is 11.3-11.7%, the mass percent of magnesium is 2.95-3.09%, the mass percent of copper is 1.15-1.28%, the mass percent of strontium (Sr) is 0.0126-0.0189%, the mass percent of zirconium is 0.211-0.279%, the mass percent of titanium is 0.077-0.123%, the mass percent of cerium is 0.15-0.45% (nominal), and the balance is aluminum and a small amount of impurity elements; the sum of all the components is 100 percent. The preparation of the alloy sequentially comprises the following steps: (1) fusion casting; (2) homogenizing; (3) hot extrusion; (4) solution treatment; and (5) aging treatment. The alloy of the invention has the highest strength of 810.66MPa, the elongation after fracture of 6.0 percent and the maximum depth of intercrystalline corrosion of 66.67 microns according to the national standard GB/T7998-2005 (aluminum alloy intercrystalline corrosion determination method).

Description

Sr Zr Ti Ce Quaternary Composite Microalloyed 800MPa Strength Grade Aluminum Alloy and Its Preparation Method

technical field

The present invention relates to an aluminum alloy material, especially a novel 7000-series aluminum alloy and its preparation method, specifically a 800MPa strength class ultra-high strength and high Intergranular corrosion resistant aluminum alloy and preparation method thereof.

Background technique

As an important lightweight, high-strength, corrosion-resistant structural material, high-strength aluminum alloys are widely used in military and civilian fields. The leap-forward improvement of its strength and comprehensive performance is of great significance for reducing weight, improving mobility and reducing energy consumption of aerospace vehicles (aircraft, missiles, rockets, etc.) and ground vehicles (rail transit, automobiles, armored vehicles, etc.). Significance. For a long time, the development of high-strength aluminum alloys with higher strength levels has always been a high-tech field that countries all over the world attach importance to. At present, with the continuous improvement of service performance indicators of various weapons and equipment such as fighter planes, missiles, heavy rockets, and military satellites, there is an urgent need for 800MPa strength class ultra-high strength and high comprehensive performance aluminum alloys as support.

As an important means to improve the performance of aluminum alloys, microalloying has been widely used in industrial aluminum alloy systems. Although it is well known that rare earth elements can greatly improve the microstructure and properties of aluminum alloys, there are many unsolved problems, such as: which rare earth element is the most effective for aluminum alloys of different alloy systems and different strength levels? What is its optimal quality? etc.

Strontium (Sr) is an alkaline earth element and a long-acting modifier in aluminum alloys, which can purify aluminum alloy melts and refine coarse intermetallic compounds. Both zirconium (Zr) and titanium (Ti) are 3d transition group elements, and cerium (Ce) is a rare earth element, which forms a dispersed phase (Al ₃ Zr, Al ₃ Ti, Al ₃ Ce, Al ₃ (Zr, Ti, Ce, etc.) precipitates in the form of fine size (10-200nm), compared with Al ₃ Ti, A1 ₃ Zr, Al ₃ Ce, Al ₃ (Zr, Ti, Ce) and matrix Al The degree of coherence is higher, so the composite microalloying of Zr, Ti, and Ce elements has better microalloying effects such as inhibiting recrystallization than single Zr, Ti, and Ce elements. In addition, Ce also has the ability to purify the aluminum alloy melt, refine The role of aluminum alloy structure. Therefore, Sr, Zr, Ti, Ce quaternary composite microalloying can improve the performance of 800MPa strength class ultra-high strength aluminum alloy.

It is well known that there is usually an inverse relationship between the strength and corrosion resistance of aluminum alloys. Intergranular corrosion is a common corrosion form of high-strength aluminum alloys, and it is also a basic corrosion form, which brings great damage to the service life and safety of high-strength aluminum alloys. Generally speaking, the higher the strength of high-strength aluminum alloy, the lower the intergranular corrosion performance. The maximum depth of intergranular corrosion of existing 7000 series high-strength aluminum alloys is generally much higher than 100 μm.

So far, there is no composition design and preparation method of Sr, Zr, Ti, Ce quaternary composite microalloyed 800MPa strength grade ultra-high strength and high intergranular corrosion resistance aluminum alloy with independent intellectual property rights. To a certain extent, it has restricted the development of my country's aerospace, weaponry and other industries.

Contents of the invention

The purpose of the present invention is to solve the problem that the strength and corrosion resistance of the existing 800MPa strength grade aluminum alloy are difficult to balance, through the design of the microalloying composition of the alloy and the design of the preparation and processing technology, a Sr, Zr, Ti, Ce quaternary composite microalloyed 800MPa strength class ultra-high strength and high intergranular corrosion resistance aluminum alloy and its preparation method.

One of technical solutions of the present invention is:

A Sr, Zr, Ti, Ce quaternary composite microalloyed 800MPa strength class ultra-high strength and high resistance to intergranular corrosion aluminum alloy, characterized in that: it is mainly composed of aluminum (Al), zinc (Zn), magnesium (Mg ), copper (Cu), strontium (Sr), zirconium (Zr), titanium (Ti) and cerium (Ce), wherein the mass percentage of zinc (Zn) is 11.3-11.7%, and the mass percentage of magnesium (Mg) The mass percentage of copper (Cu) is 1.15-1.28%, the mass percentage of strontium (Sr) is 0.0126-0.0189%, the mass percentage of zirconium (Zr) is 0.211-0.279%, and the mass percentage of titanium (Ti) The mass percentage is 0.077-0.123%, the mass percentage of cerium (Ce) is 0.15-0.45% (nominal), and the balance is aluminum and a small amount of impurity elements; the sum of each component is 100%.

The second technical scheme of the present invention is:

A method for preparing an 800MPa-strength ultra-high-strength and high-intergranular corrosion-resistant aluminum alloy with Sr, Zr, Ti, and Ce quaternary composite micro-alloying, which is characterized in that it sequentially includes: (1) melting and casting; (2) homogeneous chemical treatment; (3) hot extrusion; (4) solid solution treatment; (5) aging treatment;

The melting and casting process: after heating the furnace to 900°C, put pure Al, Al-Cu master alloy, Al-Sr master alloy, Al-Zr master alloy, Al-Ti-B master alloy into the crucible of the furnace for melting 45 minutes, keep warm for 60 minutes, then lower the temperature to 750°C, add pure Zn, pure Mg and stir the melt, let it stand for 15 minutes, add hexachloroethane refining agent to refine until no gas escapes, keep it for 15 minutes, Add the Al-Ce master alloy, keep it warm for 15 minutes, remove the slag, and cast it into a cast iron mold preheated to 400°C to cast an ingot;

The homogenization treatment: it is characterized in that the process is 450°C×24h;

The hot extrusion: it is characterized in that the process is to heat the alloy to 400°C and hold it for ≥ 1h, and then perform extrusion with an extrusion ratio of 10:1;

The solid solution treatment: it is characterized in that the process is 450°C×2h+460°C×2h+470°C×2h and then water quenching at room temperature;

The aging treatment is characterized in that the process is T6I4 (121°C×4h (water cooling at room temperature)+65°C×120h).

The 800MPa strength class ultra-high strength and high resistance to intergranular corrosion aluminum alloy and the preparation method thereof can be obtained by Sr, Zr, Ti, Ce quaternary composite microalloying.

The mass percentage of Cu in the described Al-Cu master alloy is 50.12%, the mass percentage of Sr in the Al-Sr master alloy is 9.89%, the mass percentage of Zr in the Al-Zr master alloy is 4.11%, and the Al-Ti-B The mass percentage of Ti in the master alloy is 5.11%, and the mass percentage of Ce in the Al-Ce master alloy is 10%.

Beneficial effects of the present invention:

(1) The present invention obtains the composition and preparation method of an 800MPa strength class ultra-high strength and high intergranular corrosion resistance aluminum alloy composed of Sr, Zr, Ti, Ce quaternary composite microalloying.

(2) The highest strength of the alloy of the present invention can reach 810.66 MPa, and the elongation after fracture is 6.0%. According to the national standard GB/T7998-2005 (method for measuring intergranular corrosion of aluminum alloy), the maximum depth of intergranular corrosion is 66.67 μm.

(3) The present invention discloses the composition and preparation method of a Sr, Zr, Ti, Ce quaternary composite micro-alloyed 800 MPa strength grade ultra-high strength and high resistance to intergranular corrosion aluminum alloy, which to a certain extent breaks the foreign standards for high The technical blockade of high-performance aluminum alloys can meet the needs of my country's aerospace, weaponry and other fields.

(4) the present invention has obtained ideal preparation method by a large amount of tests, especially by adopting the method that adds each intermediate alloy and pure metal in order to control each component content, can obtain meeting requirement easily by technique of the present invention Aluminum alloy material.

Description of drawings

Fig. 1 is an optical microscope photo of a solid solution metallographic structure in Example 1 of the present invention.

Fig. 2 is the metallographic diagram of the cross section after the T6I4 aging state intergranular corrosion test of Example 1 of the present invention.

Fig. 3 is a cross-sectional metallographic diagram after T6 aging state intergranular corrosion test of Example 1 of the present invention.

Fig. 4 is an optical microscope photo of the solid solution metallographic structure of Example 2 of the present invention.

Fig. 5 is a cross-sectional metallographic diagram of T6I4 aging state intergranular corrosion test in Example 2 of the present invention.

Fig. 6 is an optical microscope photo of the three solid solution metallographic structures of the embodiment of the present invention.

Fig. 7 is a cross-sectional metallographic diagram of T6I4 aging state intergranular corrosion test in Example 3 of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Embodiment one.

A Sr, Zr, Ti, Ce quaternary composite microalloyed 800MPa strength class ultra-high strength and high intergranular corrosion resistance aluminum alloy is prepared by the following method:

First of all, melting and casting, the process is to heat the furnace to 900 ° C, and the pure Al, Al-Cu master alloy, Al-Sr master alloy, Al-Zr master alloy in the formula obtained through conventional calculation (taking 100kg as an example) , Al-Ti-B intermediate alloy is put into the furnace crucible to melt for 45 minutes, heat preservation for 60 minutes, then cool down to 750°C, add pure Zn, pure Mg and stir the melt, let stand for 15 minutes, add hexachloroethane refining agent to refine Until there is no gas escape, after standing for 15 minutes, add Al-Ce master alloy, heat for 15 minutes, remove slag, and cast it into a cast iron mold preheated to 400°C to cast an ingot;

Secondly, the aluminum alloy ingot is homogenized, and the process is: 450℃×24h;

Thirdly, hot extrusion is carried out. The process is to heat the alloy to 400°C and hold it for ≥1h, then perform extrusion with an extrusion ratio of 10:1;

Fourth, carry out solid solution treatment, the process is 450°C×2h+460°C×2h+470°C×2h after heat preservation and then water quenching at room temperature;

Finally, aging treatment is carried out, and the process is T6I4 (121°C×4-8h (room temperature water cooling)+65°C×120h) or T6 (121°C×24h).

The 800MPa strength class ultra-high strength and high resistance to intergranular corrosion aluminum alloy can be obtained by Sr, Zr, Ti, Ce quaternary composite microalloying.

The composition of the aluminum alloy in this example is measured by spectrum: 11.3% Zn, 2.95% Mg, 1.15% Cu, 0.0126% Sr, 0.279% Zr, 0.077% Ti, 0.45% Ce (nominal), the balance is aluminum and unavoidable impurity elements.

The aluminum alloy grain of this embodiment is fine (Fig. 1), and the tensile strength of T6I4 (121 ℃ × 4-8h (room temperature water cooling) + 65 ℃ × 120h) aging state is 810.66MPa, and the elongation after fracture is 6.0%, According to the national standard GB/T 7998-2005 (method for the determination of intergranular corrosion of aluminum alloys), the maximum depth of intergranular corrosion is 66.67μm (Figure 2); the tensile strength of T6 (121℃×24h) aging state is 794.749MPa, and The elongation rate is 6.2%. According to the national standard GB/T 7998-2005 (method for the determination of intergranular corrosion of aluminum alloys), the maximum depth of intergranular corrosion is 84.93 μm (Figure 3).

Embodiment two.

Its preparation method is identical with embodiment one.

The composition of the aluminum alloy in this example is measured by spectrum: 11.5% Zn, 3.09% Mg, 1.21% Cu, 0.0189% Sr, 0.211% Zr, 0.123% Ti, 0.30% Ce (nominal), the balance is aluminum and unavoidable impurity elements.

Compared with Example 1, the grains of the aluminum alloy in this example are coarser (Fig. 4), and the tensile strength of the aged state of T6I4 (121°C×4h (room temperature water cooling)+65°C×120h) is 795.545MPa, and the elongation after fracture is The rate is 5.2%. According to the national standard GB/T7998-2005 (method for measuring intergranular corrosion of aluminum alloys), the maximum depth of intergranular corrosion is 147.26 μm (Fig. 5).

Embodiment three.

Its preparation method is identical with embodiment one.

The composition of the aluminum alloy in this example is measured by spectrum: 11.7% Zn, 3.05% Mg, 1.28% Cu, 0.0158% Sr, 0.249% Zr, 0.116% Ti, 0.15% Ce (nominal), the balance is aluminum and unavoidable impurity elements.

The aluminum alloy of this example has coarser grains than that of Example 1 (Figure 6), and the tensile strength of the aged state of T6I4 (121°C×4h (room temperature water cooling)+65°C×120h) is 793.95MPa, and the elongation after fracture is The rate is 5%, according to the national standard GB/T7998-2005 (method for the determination of intergranular corrosion of aluminum alloys), no intergranular corrosion was found, and the maximum depth of intergranular corrosion was 67 μm (Figure 7).

The above only lists the proportions and manufacturing methods of several common proportions of aluminum alloys. Those skilled in the art can properly adjust the proportions of each component according to the above examples and strictly follow the above steps to obtain the ideal aluminum alloy. Sr, Zr, Ti, Ce quaternary composite microalloyed 800MPa strength class ultra-high strength and high intergranular corrosion resistance aluminum alloy and its preparation method.

The parts not involved in the present invention are the same as the prior art or can be realized by adopting the prior art.

Claims (3)

1. A kind of Sr, Zr, Ti, the 800MPa strength class ultra-high strength high intergranular corrosion resistance aluminum alloy of Ce quaternary composite microalloying, it is characterized in that: it is mainly made of aluminum (Al), zinc (Zn), magnesium (Mg), copper (Cu), strontium (Sr), zirconium (Zr), titanium (Ti) and cerium (Ce), wherein the mass percentage of zinc (Zn) is 11.3-11.7%, magnesium (Mg) The mass percentage is 2.95-3.09%, the mass percentage of copper (Cu) is 1.15-1.28%, the mass percentage of strontium (Sr) is 0.0126-0.0189%, the mass percentage of zirconium (Zr) is 0.211-0.279%, the titanium (Ti ) is 0.077-0.123% by mass, cerium (Ce) is 0.15-0.45% by mass (nominal), and the balance is aluminum and a small amount of impurity elements; the sum of each component is 100%. 2. a kind of Sr as claimed in claim 1, Zr, Ti, the preparation method of the 800MPa strength class ultra-high strength high resistance to intergranular corrosion aluminum alloy of Ce quaternary composite microalloying, it is characterized in that it comprises successively: (1 ) casting; (2) homogenization treatment; (3) hot extrusion; (4) solution treatment; (5) aging treatment; The melting and casting process: after heating the furnace to 900°C, put pure Al, Al-Cu master alloy, Al-Sr master alloy, Al-Zr master alloy, Al-Ti-B master alloy into the crucible of the furnace for melting 45 minutes, keep warm for 60 minutes, then lower the temperature to 750°C, add pure Zn, pure Mg and stir the melt, let it stand for 15 minutes, add hexachloroethane refining agent to refine until no gas escapes, keep it for 15 minutes, Add the Al-Ce master alloy, keep it warm for 15 minutes, remove the slag, and cast it into a cast iron mold preheated to 400°C to cast an ingot; The homogenization treatment: the process is 450°C×24h; The hot extrusion: the process is to heat the alloy to 400°C and hold it for ≥ 1h, then perform extrusion with an extrusion ratio of 10:1; The solution treatment: the process is 450°C×2h+460°C×2h+470°C×2h and then water quenching at room temperature; The aging treatment: the process is T6I4 (121°C×4h (room temperature water cooling)+65°C×120h) aging; the 800MPa strength grade ultra-high strength of Sr, Zr, Ti, Ce quaternary composite microalloying can be obtained Intergranular corrosion resistant aluminum alloy and preparation method thereof. 3. The method according to claim 2, characterized in that the mass percentage of Cu in the described Al-Cu master alloy is 50.12%, the mass percentage of Sr in the Al-Sr master alloy is 9.89%, and the Al-Zr master alloy The mass percentage of Zr in the Al-Ti-B master alloy is 4.11%, the mass percentage of Ti in the Al-Ti-B master alloy is 5.11%, and the mass percentage of Ce in the Al-Ce master alloy is 10%.

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