CN108728707A - A kind of crushing failure at high speed high-strength wrought magnesium alloys and preparation method thereof - Google Patents

Abstract

The invention discloses a rapidly extruded high-strength deformed magnesium alloy, which is composed of the following components by mass percentage: industrial pure tin: 5%~7%; industrial pure aluminum: 1%~2%; copper: 0.1%~ 3%; the rest is industrial pure magnesium and trace impurity elements; the invention also provides a preparation method of high-strength wrought magnesium alloy, which adopts a rapid extrusion method, is simple and convenient to operate, and is convenient for popularization and application. The Mg-Sn-Al-Cu deformed magnesium alloy prepared by the rapid extrusion method in the present invention has high strength while still maintaining a good elongation, which solves the problem that cannot be solved in the existing magnesium alloy extrusion processing preparation method. The use of rapid extrusion technology, many defects in the profile, etc., improve the processing efficiency and yield.

Description

A rapid extrusion high-strength deformed magnesium alloy and its preparation method

technical field

The invention relates to the field of metal materials, in particular to a rare-earth-free high-strength wrought magnesium alloy containing copper and a preparation method thereof.

Background technique

Magnesium alloy has a series of advantages such as low density, high specific stiffness and specific strength, superior shock absorption performance, good mechanical properties, etc., and is one of the promising lightweight structural materials. Alloying elements of magnesium alloys widely used at present include aluminum, zinc, rare earth and so on. While the comprehensive properties of these alloys are improved, they also have certain limitations. Among them, the high-temperature application of Mg-Al alloy is limited, and Mg-Zn-RE alloy has excellent mechanical properties and good high-temperature service ability, but the high price and increasingly scarce reserves of rare earth elements limit its large-scale application in the civil field. and promotion. Therefore, in order to promote the application of magnesium alloy materials, the demand for research and development of new lightweight high-strength magnesium alloys that do not contain rare earths is increasing. In this context, Mg-Sn alloys have attracted more and more attention from researchers. In addition, in view of the disadvantage that the currently widely used Mg-Al series extrusion alloy cannot adopt the rapid extrusion process, the Mg ₂ Sn phase in the Mg-Sn series wrought magnesium alloy has a relatively high melting point, and is not formed during the high-speed extrusion process. There will be no second phase dissolution to cause deformation and cracking of the alloy profile.

Contents of the invention

In view of the above-mentioned deficiencies, the present invention provides rapid extruding high-strength deformed magnesium alloys and a preparation method thereof, and the present invention is achieved through the following technical solutions:

A rapidly extruded high-strength deformed magnesium alloy, the alloy is a Mg-Sn-Al-Cu deformed magnesium alloy, and the raw material components and mass percentages are as follows:

Industrial pure tin: 5%~7%; industrial pure aluminum: 1%~2%; copper (measured by the mass fraction of copper): 0.1%~3%; the balance is industrial pure magnesium and trace impurity elements; The purity of industrial pure magnesium, industrial pure aluminum and industrial pure tin is above 99%.

Preferably, copper is measured by the mass fraction of copper, and is added in the form of Mg-30wt.%Cu master alloy.

The preparation method of a kind of rapid extrusion high-strength deformed magnesium alloy described above is carried out according to the following steps:

(1) Clean up the alloying crucible, preheat it to 250°C-300°C, preheat the raw materials used to 80°C-100°C, pass in protective gas, put industrial pure magnesium and industrial pure tin into the alloying crucible Melt into alloy liquid within the temperature range of 710°C-730°C;

(2) According to the ratio of raw materials, industrial pure aluminum and magnesium-copper master alloy are added to the alloy liquid obtained in step (1), and the alloy liquid is melted in the temperature range of 710°C-730°C;

(3) Let the alloy liquid obtained in step (2) stand at 700°C-720°C for 30-40 minutes, and fully stir for 1-3 minutes to remove the scum and scale on the surface to obtain the alloy liquid;

(4) Then take out the alloy liquid and cool it to 700°C, and pour the alloy liquid obtained in step (3) into an iron mold preheated to 150°C-200°C under the condition of gas protection to prepare an ingot;

(5) Homogenization treatment: evenly spray paint on the surface of the ingot prepared in step (4), keep it warm for 8-10 hours at 300°C-330°C, heat it up to 450°C-500°C in 1 hour, and keep it warm for 12 -14 hours, then quenched in water to obtain a homogenized sample;

(6) Extrusion: cast the magnesium alloy ingot obtained after the homogenization treatment in step (5), put it into a resistance furnace after the car body, and preheat it at 300°C~350°C for 2 hours, and coat the mold cavity and ejector pin Cover it with lubricant, put it into an extruder at 300~400°C for extrusion molding, and then you can get a high-strength deformed magnesium alloy.

Preferably, the protective gas introduced during the smelting process is a mixed gas of SF ₆ and CO ₂ with a volume ratio of 1:100.

Preferably, the paint sprayed on the surface of the ingot is a mixed powder of magnesium oxide and aluminum oxide with a mass ratio of 3:1, mixed with absolute ethanol, and 45-50 ml of absolute ethanol is used for every 10 g of the mixed powder.

Preferably, the lubricant coated on the mold cavity and ejector pin is polyethylene wax.

Preferably, the direct heating rapid extrusion process is adopted, the extrusion ratio is 30:1, and the extrusion speed is 6-10m/min.

Description of drawings

Figure 1: Metallographic diagram of the extruded alloy prepared in Example 2.

Figure 2: Metallographic diagram of the extruded alloy prepared in Comparative Example 1.

Fig. 3: A picture of the surface macroscopic appearance of the pre-extruded ingot car skin prepared in Comparative Example 3.

Beneficial effect

1. The Mg-Sn-Al-Cu alloy proposed by the present invention is a novel rare earth-free copper-magnesium alloy, and the alloying elements used are all cheap metals. In the Mg-Sn-Al ternary system, there are only three phases of Mg ₁₇ Al ₁₂ , Mg ₂ Sn and α-Mg, and Mg-Cu phase and Al-Cu phase are also formed after adding Cu, so the addition of alloying elements has a great influence on The alloy plays a dual role of solid solution strengthening and second phase strengthening. After hot extrusion, a magnesium alloy profile with high strength is prepared.

2. The present invention adopts a relatively simple rapid extrusion processing technology, and realizes rapid extrusion processing with a large extrusion ratio by reasonably adjusting the preheating temperature and extrusion temperature. The extrusion speed can reach up to 10m/min, and the average extrusion The ratio is 30:1, the surface of the extruded profile is smooth and clean, without obvious defects and cracks, and the density is high. The strength of the extruded alloy obtained exceeds most of the AZ series wrought magnesium alloys, and is comparable to the commercial rare earth wrought magnesium alloy WE54.

Detailed ways

The embodiments of the present invention are described in detail below. This embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating procedures are provided, but the protection scope of the present invention is not limited to the following implementation example.

Example 1

(1) Weigh the alloy raw materials according to the mass percentage: Sn: 6%; Al: 1%; Cu: 0.5% (measured by the mass fraction of pure copper, added in the form of Mg-30wt.%Cu master alloy); the balance is Mg.

(2) Clean up the alloyed crucible, preheat it to 250°C-300°C, and preheat the raw materials to 80°C-100°C, under the protection of a mixed gas of SF ₆ and CO ₂ with a volume ratio of 1:100, first Melt industrial pure magnesium and industrial pure tin at a temperature range of 710°C-730°C. After they are completely melted, add industrial pure aluminum and magnesium-copper master alloy. After the raw materials are completely melted, let the melt stand at 720°C 35 minutes, and fully stir for 1-3 minutes to remove the scum and scale on the surface. Then take out the melt and cool it to 700°C, pour it into an iron mold preheated to 150°C-200°C under the condition of gas protection, and prepare an ingot.

(3) Evenly spray the surface of the prepared ingot with the mixed powder of magnesia and alumina mixed with anhydrous ethanol at a mass ratio of 3:1, heat it at 330°C for 10 hours, and then heat it up for 1 hour Heat at 450°C for 12 hours, then quench in water to obtain a homogenized sample;

(4) Preheat the homogenized ingot and wagon at 350°C for 2 hours, coat the mold cavity and ejector pin with polyethylene wax, and extrude at 400°C; the extrusion ratio is 30 : 1, the extrusion speed is 6m/min, and an extruded profile is prepared. The tensile strength of the alloy is 300.1MPa, and the elongation is 7.42%.

Example 2

(1) Weigh the alloy raw materials according to the mass percentage: Sn: 6%; Al: 1%; Cu: 1% (measured by the mass fraction of pure copper, added in the form of Mg-30wt.%Cu master alloy); the balance is Mg.

(2) Clean up the alloyed crucible, preheat it to 250°C-300°C, and preheat the raw materials to 80°C-100°C, under the protection of a mixed gas of SF ₆ and CO ₂ with a volume ratio of 1:100, first Melt industrial pure magnesium and industrial pure tin at a temperature range of 710°C-730°C. After they are completely melted, add industrial pure aluminum and magnesium-copper master alloy. After the raw materials are completely melted, let the melt stand at 720°C 35 minutes, and fully stir for 1-3 minutes to remove the scum and scale on the surface. Then take out the melt and cool it to 700°C, pour it into an iron mold preheated to 150°C-200°C under the condition of gas protection, and prepare an ingot.

(3) Evenly spray the surface of the prepared ingot with the mixed powder of magnesia and alumina mixed with absolute ethanol at a mass ratio of 3:1, keep it at 330°C for 10 hours, and then heat it up to 450°C, heat preservation for 12 hours, and then water quenching to obtain a homogenized sample;

(4) Preheat the homogenized ingot and wagon at 350°C for 2 hours, coat the mold cavity and ejector pin with polyethylene wax, and extrude at 400°C; the extrusion ratio is 30 : 1, the extrusion speed is 8m/min, and an extruded profile is prepared. The alloy has a tensile strength of 310MPa and an elongation of 6.60%.

Example 3

(1) Weigh the alloy raw materials according to the mass percentage: Sn: 6%; Al: 1%; Cu: 2% (measured by the mass fraction of pure copper, added in the form of Mg-30wt.%Cu master alloy); the balance is Mg.

(2) Clean up the alloyed crucible, preheat it to 250°C-300°C, and preheat the raw materials to 80°C-100°C, under the protection of a mixed gas of SF ₆ and CO ₂ with a volume ratio of 1:100, first Melt industrial pure magnesium and industrial pure tin at a temperature range of 710°C-730°C. After they are completely melted, add industrial pure aluminum and magnesium-copper master alloy. After the raw materials are completely melted, let the melt stand at 720°C 35 minutes, and fully stir for 1-3 minutes to remove the scum and scale on the surface. Then take out the melt and cool it to 700°C, pour it into an iron mold preheated to 150°C-200°C under the condition of gas protection, and prepare an ingot.

(3) Evenly spray the surface of the prepared ingot with the mixed powder of magnesia and alumina mixed with absolute ethanol at a mass ratio of 3:1, keep it at 330°C for 10 hours, and then heat it up to 480°C, heat preservation for 12 hours, and then water quenching to obtain a homogenized sample;

(4) Preheat the homogenized ingot and wagon at 350°C for 2 hours, coat the mold cavity and ejector pin with polyethylene wax, and extrude at 400°C; the extrusion ratio is 30 : 1, the extrusion speed is 8m/min, and an extruded profile is prepared. The alloy has a tensile strength of 282.6MPa and an elongation of 7.20%.

Example 4

(1) Weigh the alloy raw materials according to the mass percentage: Sn: 6%; Al: 1.5%; Cu: 1% (measured by the mass fraction of pure copper, added in the form of Mg-30wt.%Cu master alloy); the balance is Mg.

(2) Clean up the alloyed crucible, preheat it to 250°C-300°C, and preheat the raw materials to 80°C-100°C, under the protection of a mixed gas of SF ₆ and CO ₂ with a volume ratio of 1:100, first Melt industrial pure magnesium and industrial pure tin at a temperature range of 710°C-730°C. After they are completely melted, add industrial pure aluminum and magnesium-copper master alloy. After the raw materials are completely melted, let the melt stand at 720°C 35 minutes, and fully stir for 1-3 minutes to remove the scum and scale on the surface. Then take out the melt and cool it to 700°C, pour it into an iron mold preheated to 150°C-200°C under the condition of gas protection, and prepare an ingot.

(3) Evenly spray the surface of the prepared ingot with the mixed powder of magnesia and alumina mixed with absolute ethanol at a mass ratio of 3:1, keep it at 330°C for 10 hours, and then heat it up to 480°C, heat preservation for 12 hours, and then water quenching to obtain a homogenized sample;

(4) Preheat the homogenized ingot and wagon at 350°C for 2 hours, coat the mold cavity and ejector pin with polyethylene wax, and extrude at 400°C; the extrusion ratio is 30 : 1, the extrusion speed is 10m/min, and an extruded profile is prepared. The alloy has a tensile strength of 298.5MPa and an elongation of 7.18%.

Example 5

(1) Weigh the alloy raw materials according to the mass percentage: Sn: 7%; Al: 2%; Cu: 1% (measured by the mass fraction of pure copper, added in the form of Mg-30wt.%Cu master alloy); the balance is Mg.

(2) Clean up the alloyed crucible, preheat it to 250°C-300°C, and preheat the raw materials to 80°C-100°C, under the protection of a mixed gas of SF ₆ and CO ₂ with a volume ratio of 1:100, first Melt industrial pure magnesium and industrial pure tin at a temperature range of 710°C-730°C. After they are completely melted, add industrial pure aluminum and magnesium-copper master alloy. After the raw materials are completely melted, let the melt stand at 720°C 35 minutes, and fully stir for 1-3 minutes to remove the scum and scale on the surface. Then take out the melt and cool it to 700°C, pour it into an iron mold preheated to 150°C-200°C under the condition of gas protection, and prepare an ingot.

(3) Evenly spray the surface of the prepared ingot with the mixed powder of magnesia and alumina mixed with absolute ethanol at a mass ratio of 3:1, keep it at 330°C for 10 hours, and then heat it up to 480°C, heat preservation for 12 hours, and then water quenching to obtain a homogenized sample;

(4) Preheat the homogenized ingot and wagon at 350°C for 2 hours, coat the mold cavity and ejector pin with polyethylene wax, and extrude at 400°C; the extrusion ratio is 30 : 1, the extrusion speed is 10m/min, and an extruded profile is prepared. The alloy has a tensile strength of 283.0MPa and an elongation of 6.88%.

Comparative example 1

Alloy raw materials are weighed according to mass percentage: Sn: 6%; Al: 1%; Cu: 1% (added in the form of pure copper); the balance is Mg.

The preparation method is the same as in Example 2.

The tensile strength of the prepared alloy is 255.3MPa, and the elongation is 5.30%.

Comparative example 2

According to the mass percentage: Sn: 2.7%, Al: 30.8%, Cu: 1.9% (measured by the mass fraction of pure copper, added in the form of Mg-30wt.%Cu master alloy); the balance is Mg;

The preparation method is the same as in Example 2.

The tensile strength of the prepared alloy is 193.7MPa, and the elongation is 3.50%.

Comparative example 3

In Example 2, the step "step (3) evenly spraying the surface of the prepared ingot with the mixed powder of magnesium oxide and aluminum oxide mixed with absolute ethanol at a mass ratio of 3:1" was removed, and the others were as in Example 2 The alloy is prepared according to the ratio of raw materials and its preparation method. The disadvantages of the prepared alloy are: a black oxide layer and deep pits of oxidized burning appear on the surface of the pre-extruded ingot, and the car body still partially remains when it reaches the corresponding size. , Slag inclusions and pores appear inside the extruded profile. Its tensile strength is 268.5MPa and its elongation is 4.36%.

Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and equivalent technologies thereof, the present invention also intends to include these modifications and variations.

Claims (7)

1. a kind of crushing failure at high speed high-strength wrought magnesium alloys, which is characterized in that the alloy is Mg-Sn-Al-Cu wrought magnesium alloys, Raw material components and mass percentage are as follows：

Industrial pure tin：5%~7%；Commercial-purity aluminium：1%~2%；Copper：0.1%~3%；Surplus is pure magnesium and micro impurity element；System Standby pure magnesium used, commercial-purity aluminium and industrial pure tin purity are all 99% or more.

2. a kind of crushing failure at high speed high-strength wrought magnesium alloys as described in claim 1, which is characterized in that copper is with Mg- The form of 30wt.%Cu intermediate alloys is added.

3. a kind of a kind of preparation method of crushing failure at high speed high-strength wrought magnesium alloys described in claim 1, which is characterized in that press It is carried out according to following step：

（1）Alloying crucible is cleaned out, is preheated to 250 DEG C -300 DEG C, 80 DEG C -100 DEG C are preheated to by raw materials used, is led to Enter protective gas, pure magnesium and industrial pure tin are put into alloying crucible to be melted within the temperature range of 710 DEG C -730 DEG C Alloy liquid；

（2）By raw material proportioning, in step（1）In commercial-purity aluminium and magnesium copper intermediate alloy is added in obtained alloy liquid, 710 It is melted into alloy liquid within the temperature range of DEG C -730 DEG C；

（3）It will be in step（2）In obtained alloy liquid, stand 30-40 minute at 700 DEG C -720 DEG C, and be sufficiently stirred 1-3 and divide Clock destroys the dross and oxide skin on surface, obtains alloy liquid；

（4）It then takes out alloy liquid and is cooled to 700 DEG C, by step under conditions of gas shield（3）In obtained aluminium alloy Body is poured into and is preheating in 150 DEG C -200 DEG C of swage, prepares ingot casting；

（5）Homogenization Treatments：By step（4）Prepared ingot casting surface even application coating, under conditions of 300 DEG C -330 DEG C Heat preservation 8-10 hours was warming up to 450 DEG C -500 DEG C through 1 hour, keeps the temperature 12-14 hours, then water quenching obtains Homogenization Treatments Sample；

（6）It squeezes：By step（5）The magnesium alloy ingot obtained after institute's Homogenization Treatments, railway carriage are put into resistance furnace 300 later DEG C ~ 350 DEG C at preheat 2 hours, mold cavity and mandril painting be covered with lubricant, be put at 300 ~ 400 DEG C extruder progress Extrusion forming；It can be obtained high-strength wrought magnesium alloys.

4. a kind of crushing failure at high speed high-strength wrought magnesium alloys preparation method as claimed in claim 3, which is characterized in that in melting The protection gas being passed through in the process is SF₆And CO₂Mixed gas, volume ratio 1:100.

5. a kind of crushing failure at high speed high-strength wrought magnesium alloys preparation method as claimed in claim 3, which is characterized in that ingot casting table The coating of face spraying is magnesia and alumina mixed powder, mass ratio 3:1, it is mixed using absolute ethyl alcohol, is mixed per 10g Powder adapted 45-50ml absolute ethyl alcohols.

6. a kind of crushing failure at high speed high-strength wrought magnesium alloys preparation method as claimed in claim 3, which is characterized in that mould type Lubricant coated by chamber and mandril is polyethylene wax.

7. a kind of crushing failure at high speed high-strength wrought magnesium alloys preparation method as claimed in claim 3, which is characterized in that using straight Connect heating crushing failure at high speed technique, extrusion ratio 30:1, extrusion speed is 6 ~ 10m/ min.