WO2009003365A1

WO2009003365A1 - A structural material part of a high-si mg-containing al alloy and the manufacture method thereof

Info

Publication number: WO2009003365A1
Application number: PCT/CN2008/001246
Authority: WO
Inventors: Liang Zuo; Fuxiao Yu; Gang Zhao; Xiang Zhao; Yongliang Yang; Yan Li
Original assignee: Northeastern University
Priority date: 2007-06-29
Filing date: 2008-06-30
Publication date: 2009-01-08
Also published as: CN101333614A; KR20100018048A; CN101333614B; RU2009149092A; EP2172572A1; EP2172572A4; JP2010531388A; RU2463371C2; CA2689332A1; US20100126639A1; EP2172572B1

Abstract

A structural material part of a high-Si Mg-containing Al alloy, which includes sectional material, bar, sheet and forged part, is characterized in that the structural material part is manufactured by: casting an ingot by semi-casting process, pre-heat-treating to disperse eutectic Si phase particles, thermal-plastic working and heat-treating to obtain eventual shape and microstructure. The structural part comprises 0.2-2.0wt% Mg and 8-18wt% Si, and has homogeneous and fine microstructure which comprises Al matrix of equiaxial crystals with an average grain size of < 6μm and dispersing Si particles and other second-phase particles with anaverage grain size of < 5μm. A structural material part of high-Si Mg-containing wrought Al alloy with good plasticity and high strength can be manufactured by the method at a low cost without adding any modifier during casting.

Description

Structural material piece containing magnesium high silicon aluminum alloy and preparation method thereof

The invention relates to an aluminum alloy and a preparation technique thereof, in particular to a magnesium containing high

Structure material and preparation method thereof. Background technique

Aluminum-silicon alloys, especially high-silicon-aluminum-silicon alloys, have a wide range of applications in the automotive industry and the aerospace industry due to their low density, high wear resistance, high corrosion resistance and low coefficient of thermal expansion. However, for the aluminum-silicon alloy prepared by the ordinary solidification method, there are coarse block-like precipitated Si particles and lath-like eutectic structure in the ingot, which makes the alloy brittle, and it is difficult to further improve the solidification structure and manufacture by plastic processing. High-performance materials in various cross-section shapes, thus limiting the range of applications of the alloy. Traditionally, aluminum-silicon alloys have been classified as cast aluminum alloys. In view of the problem of poor deformability of ordinary solidified aluminum-silicon alloys, people have sought a method of rapid solidification. However, with the rapid solidification method, only small-sized (< 10mm) blocks can be obtained, and further steps are required if large-sized parts are manufactured. A typical example is the preparation by powder metallurgy, but its production cost and process complexity are high.

In the production of industrial pure aluminum and deformed aluminum alloys, Direct Chill Casting (DC casting) has been widely used. People mainly focus on how to reduce alloy composition segregation, reduce grain size and improve surface quality. A technique for preparing a high-silicon aluminum alloy ingot of a large-size specification without any modifier (such as P, Na, Sr) by a semi-continuous casting method has been applied for by one of the inventors of the present invention and obtained a Chinese patent authorization (Patent No. ZL200510119550) .6). According to further research by the inventors, it was found that by using the above-mentioned invention technology, the lower limit content of Si (to 8% by weight) is relaxed, the upper limit content of Si (to 18% by weight) is lowered, the content of Mg and the content of other alloying elements are adjusted, and thermoplasticity is obtained. After processing and subsequent heat treatment, structural materials of magnesium-containing high-silicon aluminum alloy having good plasticity and high strength can be obtained. Disclosure of invention

The object of the present invention is to provide a structural material part containing magnesium high-silicon aluminum alloy and a preparation method thereof, which can be manufactured at low cost by thermoplastic processing and heat treatment without adding any modifier on the casting process. Plastic, high-strength magnesium-containing high-silicon deformation aluminum alloy structural material.

The invention specifically provides a structural material part containing magnesium high silicon aluminum alloy, including profiles, bars, plates and forgings, characterized in that:

The structural material member is prepared by a semi-continuous casting method, and then pre-heat treated The particles of the eutectic silicon phase are dispersed, and the final shape and microstructure are obtained by thermoplastic processing and heat treatment, and the strengthening mechanism is fine grain strengthening of the aluminum matrix, particle strengthening of the silicon particles, and precipitation strengthening of the second phase particles;

The structural material has a Mg content of 0.2 to 2.0% by weight and a Si content of 8 to 18% by weight; a uniformly refined microstructure, an aluminum matrix structure of equiaxed grains, and an average size of <6 μ πι , Si and other second phase particles are dispersed and the average size is <5 μ πι _;

The structural material of the magnesium-containing high-silicon aluminum alloy provided by the present invention may further contain one or more of Cu, Zn, Ni, Ti, Fe, and the total content is less than 2% by weight.

The invention further provides a method for preparing a structural material member of the above magnesium-containing high-silicon aluminum alloy, characterized in that:

——Preparation of ingot by semi-continuous casting method, the process parameters are:

Casting temperature: corresponding to the liquidus temperature of the alloy above 150~300 °C _;

Casting speed: 100~200mm/min;

The amount of cooling water around the solidified billet: 5~15g/mm-s;

No added modifiers;

—— Discretizing the eutectic silicon phase by pre-heat treatment of the above ingot, the process parameters are:

Heating rate: 10~30 °C / min _;

Heating temperature: 450~520 °C _;

Holding time: l~3hr _;

——The above-mentioned pre-heat treated ingot is subjected to thermoplastic processing, and the process parameters are: deformation temperature: 400~520 ° C;

Cooling method: natural cooling or forced cooling;

- heat treating the above-mentioned thermoplastically processed structural material.

In the preparation method of the structural material part containing the magnesium high-silicon aluminum alloy provided by the invention, for the structural material part which is naturally cooled after the thermoplastic processing, the heat treatment adopts a solution treatment + an artificial aging process:

——The solution treatment parameters are:

Heating rate: 10~30 ° C / min;

Solution treatment temperature: 500~540 °C _;

Solution treatment time: 0.5~3hr;

——The artificial aging parameters are:

Aging temperature: 160~200 °C;

Aging time: l~10hr.

In the preparation method of the structural material part of the magnesium-containing high-silicon aluminum alloy provided by the invention, for the structural material piece forced cooling after the thermoplastic processing, the heat treatment adopts artificial aging or natural aging process: ——The artificial aging parameters are:

Aging temperature: 160~200 °C _;

Aging time: l~10hr.

In the method for preparing a structural material member containing a magnesium high silicon aluminum alloy provided by the present invention, when the thermoplastic processing is carried out by a rolling process, the total rolling reduction is preferably greater than 40%.

In the method for preparing a structural material member containing a magnesium high silicon aluminum alloy provided by the present invention, when the thermoplastic processing is carried out by an extrusion process, the extrusion ratio is preferably more than 15.

In the method for preparing a structural material member containing a magnesium high silicon aluminum alloy provided by the present invention, when the thermoplastic processing is performed by a forging process, the forging ratio is more than 40%.

The key to the invention is to overcome the traditional technical prejudice, and use the traditional semi-continuous casting method for the preparation of magnesium-containing high-silicon aluminum alloy without adding any modifier, and combine the thermoplastic processing and heat treatment to obtain unexpected The technical effect is that a new aluminum alloy processing material having fine dispersed silicon particles and a second phase distributed on an equiaxed grain aluminum substrate with good plasticity and high strength is obtained.

Table 1 exemplifies the extruded silicon aluminum alloy (Al-8.5Si-1.8Mg-0.27Fe, Al-12.7Si-0.7Mg-1.5Cu-0.3Ni-0.3Ti-0.3Fe and Al- prepared by the present invention). 15.5Si-0.7Mg-0.27Fe) Mechanical properties under extrusion and heat treatment, and compared with the mechanical properties of extruded 6063 alloy in Chinese national standard under T5 and Τ6 conditions. Table 1 Comparison of mechanical properties of alloys prepared by the present invention and Chinese national standard 6063 alloy

Yield strength tensile strength elongation state

(MPa) (MPa) (%)

Al-8.5Si-l .8Mg-0.27Fe Tl 175 252 13

Al-8.5Si-l .8Mg-0.27Fe T6 296 344 7.2

Al-15.5Si-0.7Mg-0.27Fe Tl 120 232 1 1

Al-15.5Si-0.7Mg-0.27Fe T6 280 325 7.5

Al-12.7Si-0.7Mg-l .5Cu-0.3Ni-0.3Ti-0.3Fe Tl 1 12 190 15

Al-12.7Si-0.7Mg- 1.5Cu-0.3Ni-0.3Ti-0.3Fe T6 268 347 9

6063 Al-(0.2-0.6)Si-(0.4-0.9)Mg T5 1 10 160 8

6063 Al-(0.2-0.6)Si-(0.4-0.9)Mg T6 180 205 8 It can be seen that Al-15.5Si-0.7Mg-0.27Fe, Al-12.7Si-0.7Mg-l .5Cu-0.3Ni-0.3Ti-0.3Fe and Al- 8.5Si-1.8Mg-0.27Fe alloy in T6 state The yield strength and tensile strength are higher than the national standard of 6063 alloy Τ6 state; the alloy extrusion state (T1) mechanical properties, especially the elongation is higher than the national standard of 6060 alloy Τ5 state. 6063 alloy is the most versatile extruded profile alloy, which is widely used in construction, vehicles, decoration and other fields at home and abroad, and has broad market demand. Once the 6063 alloy is partially replaced with a magnesium-containing high-silicon aluminum alloy, it will bring huge economic benefits. In addition, the addition of silicon will save a lot of aluminum resources. BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a schematic structural view of a semi-continuous casting equipment;

2 is a semi-continuous casting of a typical Al-12.7Si-0.7Mg-0.3Fe alloy (#3) in Example 1 (casting temperature 730 ° C, casting speed 180 mm/min, cooling water flow rate 8 g/mrrrs) As-cast microstructure morphology;

Figure 3 is a semi-continuous casting of a typical Example 1 AI-12.7Si-0.7Mg-0.3Fe alloy (#3) (casting temperature 730 ° C, casting speed 180 mm / min, cooling water flow rate 8 g / mm, s) High-magnification microstructure of the ingot;

Figure 4 is a microscopic view of a semi-continuously cast Al-12.7Si-0.7Mg-0.3Fe alloy (#3) in Example 2 after preheating at 500 °C for 2 hr and 470 °C hot extrusion (extrusion ratio 15). Fig. 5 is a typical example 3 semi-continuous casting Al-12.7Si-0.7Mg-0.3Fe alloy (#3) preheated at 500 °C for 2 hr, hot extrusion at 470 °C (extrusion ratio 15 The microstructure of the post-T6 state (solution temperature 540V, time lhr; artificial aging temperature 200 ° C, time 3 hr);

Figure 6 is a semi-continuous casting of a typical Al-15.5Si-0.7Mg-0.27Fe alloy (# 5 ) in Example 1 (casting temperature 800 ° C, casting speed 140 mm / min, cooling water flow 10 g / mnrs ) ingot The as-cast microstructure morphology; - Figure 7 is a semi-continuous casting of a typical Al-15.5Si-0.7Mg-0.27Fe alloy (#5) in Example 1 (casting temperature 800 ° C, casting speed 140 mm / min, Cooling water flow rate lOg/mnvs) high-strength as-cast microstructure of the ingot;

Figure 8 is a diagram showing the microstructure of a semi-continuously cast Al-15.5Si-0.7Mg-0.27Fe alloy (#5) in a typical example 2 after 500 hr preheating for 2 hr and 470 °C hot extrusion (extrusion ratio 45). Figure 9 is a typical example 2 semi-continuous casting Al-15.5Si-0.7Mg-0.27Fe alloy (# 5) rectangular casting billet pre-heat treated at 500 ° C for 1 hr, 500 Ό hot rolling (compression amount 60%) Post-microscopic morphology;

Figure 10 is a typical example 3 semi-continuous casting Al-15.5Si-0.7Mg-0.27Fe alloy (# 5) preheated at 500 ° C for 2 hr, 470 ° C hot extrusion (extrusion ratio 45) after T6 state Microstructure morphology (solution temperature 520 ° C, time 2 hr; artificial aging temperature 180 ° C, time 4 hr); Figure 11 is a typical example 3 semi-continuous casting Al-15.5Si-0.7Mg-0.27Fe alloy (# 5) rectangular casting blank pre-heat treated at 500 ° C for 1 hr, 500 ° C hot rolling (60% reduction) The microstructure of the post-T6 state (solution temperature 520 ° C, time 3 hr _; artificial aging temperature 200 ° C, time 4 hr); Figure 12 is a typical example 3 semi-continuous casting Al-15.5Si-0.7Mg- 0.27Fe alloy (#5) high-microscopic microscopic micro-microscopic after 200 hr heat treatment for 2 hr, 470 Ό hot extrusion (extrusion ratio 45) and T6 state (solution temperature 520 ° C, time 2 hr; artificial aging temperature 180 ° C, time 4 hr) Fig. 13 is a semi-continuous casting of a typical Al-17.5Si-0.7Mg-l.0Cu-0.27Fe alloy (#7) in Example 1 (casting temperature 850 ° C, casting speed 120 mm/min, cooling) Water flow rate 10g/mnvs) The as-cast microstructure of the ingot. The best way to implement the invention

Example 1 Preparation of semi-continuous casting ingot

The equipment used is self-made equipment, and its structural principle is shown in Figure 1. In the figure, 1 - cooling water; 2 - crystallizer; 3 - blank; 4 - hot top; 5 - graphite ring, 6 - molten metal. The chemical composition of the alloy is shown in Table 2. The casting process parameters are shown in Table 3.

Table 2 Chemical composition of semi-continuous casting magnesium-containing high-silicon aluminum alloy (wt.%)

Table 3 Casting process parameters of different alloys

a 3z. Casting section dimensions Casting temperature Casting speed Cooling water Quantity (mm) (°C) (mm/min)

Ηι Φ100 780 120 8 ηι 600X50 780 180 8

U2 Φ100 780 120 8

#2 600X50 780 180 8

' »3 Φ100 730 180 10

S3 600X50 730 180 10

M Φ100 730 140 8

«4 600X50 730 180 8 »5 Φ100 800 140 10

#5 600 50 850 180 10

#6 Φ100 800 160 12 m Φ60 850 120 10

U8 Φ60 850 180 14

U8 Φ100 850 180 14 Example 2 Pre-heat treatment of cast alloy ingots and extrusion, rolling and forging

The pre-heat treatment is heated in the heat treatment furnace at a set heating rate, and after reaching the set temperature, it is kept warm for the set time. The plastic deformation is then completed using an extruder, a hot rolling mill and a forging machine. The specific process parameters are given in Table 4, Table 5, and Table 6, respectively.

Table 4 Pre-heat treatment and extrusion process parameters of different alloys Pretreatment Pretreatment Pretreatment After deformation α5 Cooling

Heating rate temperature time 51 extrusion ratio

the way

(°C/min) (V) (hr)

# 1 25 450 3 450 36 Nature 1A

#2 20 450 3 450 36 Nature 2A

#3 15 500 2 470 15 Nature 3A

#4 15 500 2 470 15 Mandatory 4A

#5 15 500 2 470 45 Nature 5A

#7 10 500 4 480 30 Mandatory 7A

#8 10 500 4 480 30 Mandatory 8A Table 5 Pre-heat treatment and rolling process parameters of different alloys Pretreatment Pretreatment Pretreatment Rolling After rolling Deformation Alloy Cooling

Heating rate temperature time temperature reduction amount alloy numbering method

(°C/min) (°C) (hr) (.C) (%)

#1 20 450 3 450 50 Nature IB

#2 20 520 1 520 70 Nature 2B

#3 20 500 2 500 60 Nature 3B

#4 15 480 3 480 60 Nature 4B

#4 15 520 1 520 70 Nature 4B2

#5 15 500 3 500 60 Nature 5B

#5 15 520 1 520 70 Natural 5B2 Table 6 Pre-heat treatment and forging process parameters of different alloys Pretreatment Pretreatment Pretreatment Forging Deformation Alloy Forging ratio Cooling

Heating rate temperature time temperature alloy number (%) mode

(°C/min) (°C) (hr) CC)

#2 25 500 2 500 65 Nature 2C

#3 20 520 1 520 65 Nature 3C #5 15 500 2 500 50 Nature 5C

10 500 4 500 50 Nature 6C

#6 15 490 4 490 50 Nature 6C2

#7 10 500 4 500 50 Nature 7C

#8 10 500 4 500 50 Natural 8C Example 3 Heat treatment after alloy deformation (extrusion, rolling, forging)

After extrusion, rolling, and forging, the heat treatment is performed under the set heat treatment process parameters. The specific heat treatment process parameters are given in Table 7, Table 8, and Table 9, respectively. The mechanical properties of some alloys under different deformation modes and heat treatment conditions are given in Table 10. Table 7 Heat treatment process parameters of different alloy extruded products

Table 8 Heat treatment process parameters of different alloy rolled products

Table 9 Heat treatment process parameters of different alloy forged products After deformation, solid solution solid solution, artificial aging, artificial aging heat treatment

π ϋζ. Heat treatment

Alloy temperature time temperature time port fe

Number status

No. CC) (hr) (°C) (hr) No.

2C #2 Τ6 520 3 180 6 2CT6

5C #5 Τ6 540 0.5 200 4 5CT6

5C #5 T1 5CT1 6C2 # 6 T6 510 4 170 10 6C2T6

7C # 7 T6 510 3 200 2 7CT6

8C2 # 8 T6 510 4 180 8 8C2T6 Table 10 Mechanical properties at room temperature under different deformation and heat treatment conditions

Industrial applicability

The structural material part of the magnesium-containing high-silicon aluminum alloy of the invention and the preparation method thereof can be manufactured with good plasticity and high strength at low cost by thermoplastic processing and heat treatment without adding any modifier on the casting process. Magnesium-containing high-silicon deformation aluminum alloy structural material.

Claims

Rights request

1. A structural material part comprising a magnesium high silicon aluminum alloy, comprising a profile, a bar, a plate, a forging, characterized in that:

The structural material part is prepared by a semi-continuous casting method, and then the particles of the eutectic silicon phase are discretized by pre-heat treatment, and then the final shape and microstructure of the aluminum alloy product are obtained by thermoplastic processing and heat treatment, and the strengthening mechanism is aluminum. Fine grain strengthening of the matrix, particle strengthening of the silicon particles, and precipitation strengthening of the second phase particles;

The content of Mg in the structural material is 0. 2~2. 0% by weight, the content of Si is 8~18% by weight; the microstructure is uniformly refined, the aluminum matrix is equiaxed, and the average size <6 μ m, the Si particles are dispersed with other second phase particles and have an average size of <5 μm.

2. The structural material member of the magnesium-containing high-silicon aluminum alloy according to claim 1, wherein the alloy may contain one or more of Cu, Zn, Ni, Ti, Fe, and the total content is less than 2%. weight.

3. A method of preparing a structural material member comprising a magnesium high silicon aluminum alloy according to claim 1, wherein:

^ "The ingot is prepared by semi-continuous casting method. The process parameters are:

Casting temperature: corresponding to the liquidus temperature of the alloy above 150~30 (TC _;

Casting speed: 100~200 let /min;

The amount of cooling water around the solidified billet: 5~15g/solid·s _;

No added modifiers;

Heating rate: 10~30 °C / min _;

Heating temperature: 450~520Ό _;

Holding time: l~3hr;

——The above-mentioned pre-heat treated ingot is subjected to thermoplastic processing, and the process parameters are: deformation temperature: 400~520 ° C _;

Cooling method: natural cooling or forced cooling;

A method for preparing a structural material member containing a magnesium high silicon aluminum alloy according to claim 3, wherein a solid solution treatment + artificial aging heat treatment process is used for the structural material member which is naturally cooled after the thermoplastic processing, and is characterized in that:

——The solution treatment parameters are:

Heating rate: 10~30 °C / min _;

Solution treatment temperature: 500~540 °C; Solution treatment time: 0. 5~3hr;

——The artificial aging parameters are:

Aging temperature: 160~200 °C;

Aging time: l~10hr.

The method for preparing a structural material member containing a magnesium high silicon aluminum alloy according to claim 3, wherein the structural material member for forced cooling after the thermoplastic processing is subjected to an artificial aging or natural aging heat treatment process, wherein:

—— artificial aging parameters are: - aging temperature: 160~200 °C _;

Aging time: l~10hr.

6. A method of preparing a structural material member comprising a magnesium high silicon aluminum alloy according to claim 3, wherein when the rolling process is employed for thermoplastic processing, the total rolling reduction is greater than 40%.

A method of preparing a structural material member containing a magnesium high silicon aluminum alloy according to claim 3, wherein when the extrusion process is employed for thermoplastic processing, the extrusion ratio is greater than 15.

8. A method of preparing a structural material member comprising a magnesium high silicon aluminum alloy according to claim 3, wherein when the forging process is employed for thermoplastic processing, the forging ratio is greater than 40%.