CN107815575A - A kind of magnesium aluminum alloy casting ingot - Google Patents

Abstract

The invention discloses a magnesium-aluminum alloy ingot, which contains the following raw materials in mass percentage: Al 8.5-9.5%, Zn 0.45-0.9%, Mn 0.17-0.4%, Al-Ti-B master alloy 0.18-0.2%, Al-Ti-C master alloy 0.19-0.21%, the total amount of impurity elements Si, Cu, Ni and Fe is less than 0.1%, and the balance is magnesium. The preparation method of the magnesium-aluminum alloy ingot includes a smelting process and a heat treatment process, wherein the smelting process includes weighing and baking, smelting, refining and standing, and casting, and the heat treatment process includes solution treatment and aging treatment. After adding a refiner, the magnesium-aluminum alloy ingot obtained by the present invention has greatly improved the grain size, tensile and other mechanical properties of the magnesium-aluminum alloy; after heat treatment, the strength of the alloy ingot is further improved.

Description

A kind of magnesium aluminum alloy casting ingot

technical field

The invention belongs to the field of alloys, and in particular relates to a magnesium-aluminum alloy ingot.

Background technique

Magnesium alloy is the lightest metal structure material, its specific strength and specific stiffness are very high, its specific elastic modulus is roughly the same as that of high-strength aluminum alloy and alloy steel, and it has good damping performance. Therefore, the use of magnesium alloy materials can give full play to the characteristics of good electromagnetic shielding effect, small weight, strong shock absorption ability and easy forming of the material, and has great application potential in the industrial field. So far, magnesium alloy materials have been widely used in the fields of aerospace science and automobile manufacturing. With the development of material technology, magnesium alloy materials will have broader application prospects and use value.

AZ91 is a commonly used Mg-Al alloy, and its alloy has high strength and good casting performance. However, since the grains of AZ91 before refining are usually relatively large, the overall mechanical properties are reduced. The present invention adjusts and tests the refiner and the process based on the research on the composition and process of the AZ91 alloy, thereby obtaining an improved AZ91 alloy with better refiner and performance.

Contents of the invention

In view of the above objectives, the present invention discloses a magnesium-aluminum alloy ingot. By adding a refiner, the crystal grains of the prepared alloy are refined, the microstructure is adjusted, and its overall mechanical properties are improved and strengthened.

In order to achieve the above object, the technical solution adopted by the present invention is: a magnesium-aluminum alloy ingot, comprising the following raw materials in mass percentage: Al 8.5-9.5%, Zn 0.45-0.9%, Mn 0.17-0.4%, Al-Ti- B master alloy 0.18-0.2%, Al-Ti-C master alloy 0.19-0.21%, the total amount of impurity elements Si, Cu, Ni and Fe is less than 0.1%, and the balance is magnesium.

The Al-Ti-B master alloy is Al-4Ti-B master alloy.

The Al-Ti-C master alloy is an Al-5Ti-0.8C master alloy.

The preparation method of the above-mentioned magnesium-aluminum alloy ingot includes a smelting process and a heat treatment process; wherein, the smelting process is carried out under the protection condition of a mixed gas of N ₂ , CO ₂ and SF ₆ , and the steps are as follows:

(1) Weighing and drying materials: according to the mass percentage of raw materials, respectively weigh magnesium ingots, aluminum ingots, zinc ingots, magnesium-manganese master alloys, Al-Ti-B master alloys and Al-Ti-C master alloys; The raw materials are preheated in a preheating furnace at 200-220°C for 4-6 hours;

(2) Melting: Put the preheated magnesium ingot in a melting furnace and heat it to 690-700°C until the magnesium ingot is completely melted, then raise the temperature to 740-760°C, add the preheated aluminum ingot into the molten magnesium liquid and zinc ingot, stir until completely melted, then add the preheated magnesium-manganese master alloy, Al-Ti-B master alloy and Al-Ti-C master alloy when the melt temperature rises to 740-760°C, stir until completely Melted to obtain a mixed alloy melt;

(3) Refining and standing: Cool the mixed alloy melt obtained in step (2) to 700-720°C, skim off the surface scum, then stir and mix evenly, keep it warm for 10-15min, and refine at this temperature for 3-5min After refining, skim off the scum on the surface, raise the temperature to 740°C, and let it stand for 15-20 minutes;

(4) Casting: after standing still, when the mixed alloy melt cools down to 680-690°C, pour it into a preheated steel mold to obtain an alloy ingot;

Described heat treatment process is:

The smelted alloy ingot was subjected to solution treatment at a temperature of 420° C. for 8 hours, and then to an aging treatment at a temperature of 200° C. for 10 hours.

The volume ratio of the mixed gas N ₂ , CO ₂ and SF ₆ in the smelting process is 50:50:0.3.

The preheating temperature of the steel mold is 280-300°C.

The purpose of adding a refiner is to refine the grains of the previous alloy. The average grain size of the basic AZ91 alloy is refined from 75 μm to 39 μm, and the microstructure is adjusted uniformly. The compact and uniform alloy structure results in The castability and mechanical properties of the alloy have been improved; while the AZ91 alloy grains before refinement are usually relatively large, although its casting performance is good, but the overall mechanical properties such as hardness and tensile strength are not ideal.

Beneficial effects of the present invention: on the basis of the basic AZ91 alloy, the present invention adds an alloy refiner, and adopts a reasonable thermal process to improve the alloy added with the refiner, so that the crystal grains of the basic AZ91 alloy are refined and the microstructure is improved. The structural adjustment is more uniform, so that the comprehensive performance of the alloy is further strengthened.

Description of drawings

Fig. 1 is the grain size figure of the whole magnesium-aluminum alloy that only adds refining agent Al-4Ti-B master alloy in embodiment 1;

Fig. 2 is the grain size figure of the whole magnesium-aluminum alloy that only adds refining agent Al-5Ti-0.8C master alloy in embodiment 2;

Fig. 3 is a graph of the grain size of the overall magnesium-aluminum alloy in Example 3 with the addition of refining agents Al-4Ti-B master alloy and Al-5Ti-0.8C master alloy at the same time.

Detailed ways

Specific embodiments of the present invention will be described in detail below. It should be understood that the specific embodiments described here are only used to illustrate and explain the present invention, and are not intended to limit the present invention. In the embodiment, various raw materials are Marco Polo net products.

The various compositions of embodiment 1-3 are as follows:

The preparation method of the above-mentioned magnesium-aluminum alloy ingot includes a melting process and a heat treatment process, and the specific steps are as follows:

The smelting process is carried out under the protection condition of N ₂ , CO ₂ and SF ₆ mixed gas, and the steps are as follows:

(1) Weighing and drying materials: according to the mass percentage of raw materials, respectively weigh magnesium ingots, aluminum ingots, zinc ingots, magnesium-manganese master alloys, Al-4Ti-B master alloys and Al-5Ti-0.8C master alloys; and Various raw materials are preheated in a preheating furnace at 200°C for 4 hours;

(2) Melting: heat the preheated magnesium ingot to 690°C in a melting furnace until the magnesium ingot is completely melted, then raise the temperature to 740°C, add preheated aluminum and zinc ingots to the molten magnesium, Stir until it is completely melted, then add the preheated magnesium-manganese master alloy, Al-4Ti-B master alloy and Al-5Ti-0.8C master alloy when the melt temperature rises to 740°C, stir until it is completely melted to obtain a mixed alloy melt;

(3) Refining and standing: Cool the mixed alloy melt obtained in step (2) to 710°C, skim off the surface scum, then stir and mix evenly, keep it warm for 15 minutes, refine at this temperature for 5 minutes, and skim after refining Remove the scum on the surface, raise the temperature to 740°C, and let stand for 15 minutes;

(4) Casting: after standing still, when the mixed alloy melt is cooled to 680°C, it is poured into a steel mold preheated to 300°C to obtain an alloy ingot;

Described heat treatment process is:

The smelted alloy ingot was subjected to solution treatment at a temperature of 420° C. for 8 hours, and then to an aging treatment at a temperature of 200° C. for 10 hours.

In the preparation step of Example 1, only the refining agent Al-4Ti-B master alloy is added; in the preparation step of Example 2, only the refining agent Al-5Ti-0.8C master alloy is added; in the preparation step of Example 3, the refining agent is added at the same time Al-4Ti-B master alloy and Al-5Ti-0.8C master alloy.

The magnesium-aluminum alloy ingot prepared in the above-mentioned examples 1-3 is detected, and the technical parameters obtained are as follows:

It can be seen from the table that, on the basis of the original AZ91 alloy, the alloy refiner added and the heat treatment process improved further strengthen the comprehensive properties of the alloy.

Claims (6)

1. a kind of magnesium alloy ingot casting, it is characterised in that include the raw material of following mass percent：Al 8.5-9.5%, Zn 0.45-0.9%, Mn 0.17-0.4%, Al-Ti-B intermediate alloy 0.18-0.2%, Al-Ti-C intermediate alloy 0.19- 0.21%, impurity element S i, Cu, Ni and Fe total amount are less than 0.1%, and surplus is magnesium.

A kind of 2. magnesium alloy ingot casting according to claim 1, it is characterised in that：The Al-Ti-B intermediate alloys are Al- 4Ti-B intermediate alloys.

A kind of 3. magnesium alloy ingot casting according to claim 1, it is characterised in that：The Al-Ti-C intermediate alloys are Al- 5Ti-0.8C intermediate alloys.

A kind of 4. magnesium alloy ingot casting according to claim 1, it is characterised in that the preparation method of the magnesium alloy ingot casting Including smelting technology and Technology for Heating Processing；Wherein, the smelting technology is in N₂、CO₂And SF₆Carried out under the conditions of mixed gas protected, Step is as follows：

(1) weighing and baking material：By material quality percentage, magnesium ingot, aluminium ingot, zinc ingot metal, magnesium manganese intermediate alloy, Al-Ti- are weighed respectively B intermediate alloys and Al-Ti-C intermediate alloys；And various raw materials are placed in 200-220 DEG C of preheating furnace and preheat 4-6h；

(2) melting：Magnesium ingot after preheating is placed in melting furnace and is heated to 690-700 DEG C and is completely melt to magnesium ingot, is then heated up To 740-760 DEG C, preheated aluminium ingot and zinc ingot metal are added into the magnesium liquid of fusing, stirring is to being completely melt, then by melt temperature Preheated magnesium manganese intermediate alloy, Al-Ti-B intermediate alloys and Al-Ti-C intermediate alloys are added when ging up to 740-760 DEG C, is stirred Mix to being completely melt, obtain hybrid alloys melt；

(3) refine and stand：Hybrid alloys melt obtained by step (2) is cooled to 700-720 DEG C, skims surface scum, so After be uniformly mixed after be incubated 10-15min, refine 3-5min at this temperature, skim surface scum after the completion of refining again, return Temperature is risen to 740 DEG C, stands 15-20min；

(4) cast：When standing terminates rear alloy melt to be mixed and is cooled to 680-690 DEG C, to the steel die heated in advance In poured into a mould, obtain alloy cast ingot；

Described Technology for Heating Processing is：

The alloy cast ingot that melting obtains is carried out to 8h solution treatment at a temperature of 420 DEG C, then carried out in 200 DEG C of temperature 10h Ageing Treatment.

A kind of 5. magnesium alloy ingot casting according to claim 4, it is characterised in that：Mixed gas N in the smelting technology₂、 CO₂And SF₆Volume ratio be 50:50:0.3.

A kind of 6. magnesium alloy ingot casting according to claim 4, it is characterised in that：The preheating temperature of the steel die is 280-300℃。