CN101333614B - Structural material piece of magnesium-containing silumin and method for preparing same - Google Patents

Abstract

Disclosed is a structure material part containing magnesium and high-silicon aluminum alloy, which comprises a profile, a rod, a plate and a forged part. The structure material part is characterized in that an ingot is prepared by the method of semi-continuous casting, then phase particles of eutectic silicon are discretized by preheating treatment, and then the ultimate form and the microstructure are obtained by hot-deforming processing and heating treatment; the structure material part contains 0.2 to 2.0 weight percent of magnesium, and 8 to 18 weight percent of silicon; and the structure material part has even and refined microstructure, for the structure of aluminum matrix is of equiaxed grains whose average size is less than 6 microns, and the silicon and other second phase particles are dispersively distributed, and the average size of the second phase particles is less than 5 microns. The structure material part containing magnesium and high-silicon deformed aluminum alloy, which has good plasticity and higher strength, can be manufactured with low cost on the premise that no modifier is added in the casting process.

Description

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

technical field

The invention relates to an aluminum alloy and its preparation technology, and in particular provides a structural material piece of a magnesium-containing high-silicon aluminum alloy and a preparation method thereof.

Background technique

Al-Si alloys, especially Al-Si alloys with high silicon content, are widely used in the automotive industry and aerospace industry due to their low density, high wear resistance, high corrosion resistance and low thermal expansion coefficient. However, for the aluminum-silicon alloy prepared by the common solidification method, there are coarse massive Si particles and lath-like eutectic structure in the ingot, which makes the alloy extremely brittle, and it is difficult to further improve the solidification structure and manufacture through plastic processing. High-performance materials with various cross-sectional shapes, thus limiting the application range of alloys. Traditionally, aluminum-silicon alloys have been classified as cast aluminum alloys. Aiming at the problem of poor deformation ability of common solidified aluminum-silicon alloys, people seek a rapid solidification method. However, only very small (<10 mm) blocks can be obtained using the rapid solidification method, and further processing is required to manufacture large-sized parts. 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 wrought aluminum alloys, the semi-continuous casting method (Direct Chill Casting, referred to as DC casting) has been widely used. People mainly focus on how to reduce alloy composition segregation, reduce grain size, and improve surface quality. The technology of preparing high-silicon aluminum alloy ingots with large specifications and without any modifiers (such as P, Na, Sr) by semi-continuous casting method has been applied by one of the inventors of the present invention and obtained Chinese patent authorization (Patent No. ZL200510119550 .6). Further research by the inventors found that using the above-mentioned invention technology, the lower limit content of Si is relaxed (to 8% by weight), the upper limit content of Si is reduced (to 18% by weight), and the content of Mg and other alloying elements is adjusted. Through thermoplasticity Processing and subsequent heat treatment can obtain a structural material piece of magnesium-containing high-silicon aluminum alloy with good plasticity and high strength.

Contents of the invention

The object of the present invention is to provide a structural material piece of magnesium-containing high-silicon aluminum alloy and its preparation method, which can be produced at low cost through thermoplastic processing and heat treatment without adding any modifier in the casting process. Plastic, high-strength magnesium-containing and high-silicon deformed aluminum alloy structural material parts.

The present invention specifically provides a structural material piece of magnesium-containing high-silicon aluminum alloy, including profiles, rods, plates, and forgings, which are characterized in that:

The structural material piece adopts the semi-continuous casting method to prepare the ingot, and then the particles of the eutectic silicon phase are dispersed through pre-heat treatment, and then the product with the final shape and microstructure is obtained through thermoplastic processing and heat treatment. The strengthening mechanism is the fineness of the aluminum matrix. Grain strengthening, particle strengthening of silicon particles and precipitation strengthening of second phase particles;

The content of Mg in the structural material piece is 0.2-2.0% by weight, and the content of Si is 8-18% by weight; it has a uniform and refined microstructure, the aluminum matrix structure is equiaxed grains, the average size is <6 μm, and Si It is dispersedly distributed with other second phase particles and the average size is <5 μm;

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

The present invention also provides a method for preparing the structural material of the above-mentioned magnesium-containing high-silicon aluminum alloy, which is characterized in that:

——The semi-continuous casting method is used to prepare the ingot, and the process parameters are:

Casting temperature: 150-300°C above the liquidus temperature of the corresponding alloy;

Casting speed: 100～200mm/min;

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

No modifiers are added;

——The eutectic silicon phase particles are discretized by pre-heating the above-mentioned ingot, and the process parameters are:

Heating speed: 10～30℃/min;

Heating temperature: 450～520℃;

Holding time: 1～3hr;

——Carry out thermoplastic processing on the above-mentioned pre-heat-treated ingot, and the process parameters are:

Deformation temperature: 400～520℃;

Cooling method: natural cooling or forced cooling;

- Heat treatment of the above-mentioned structural material pieces after thermoplastic processing.

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

——The solid solution treatment parameters are:

Heating speed: 10～30℃/min;

Solution treatment temperature: 500～540℃;

Solution treatment time: 0.5～3hr;

——The artificial aging parameters are:

Aging temperature: 160～200℃;

Aging time: 1~10hr.

In the preparation method of the magnesium-containing high-silicon aluminum alloy structural material parts provided by the present invention, for the structural material parts that are forced to cool after thermoplastic processing, the heat treatment adopts artificial aging or natural aging process:

——The artificial aging parameters are:

Aging temperature: 160～200℃;

Aging time: 1~10hr.

In the preparation method of the magnesium-containing high-silicon aluminum alloy structural material provided by the present invention, when the thermoplastic processing adopts the rolling process, the total rolling reduction is preferably greater than 40%.

In the preparation method of the magnesium-containing high-silicon aluminum alloy structural material provided by the present invention, when the extrusion process is used for thermoplastic processing, the extrusion ratio is preferably greater than 15.

In the preparation method of the magnesium-containing high-silicon aluminum alloy structural material provided by the present invention, when the thermoplastic processing adopts a forging process, the forging ratio is greater than 40%.

The key of the present invention is to overcome the traditional technical prejudice. On the premise of not adding any modifier, the traditional semi-continuous casting method is used for the preparation of magnesium-containing high-silicon aluminum alloy, combined with thermoplastic processing and heat treatment, an unexpected The technical effect is to obtain a new type of aluminum alloy processing material with fine dispersed silicon particles and the second phase distributed on the equiaxed grain aluminum matrix, with good plasticity and high strength.

Table 1 illustrates 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-15.5 The mechanical properties of Si-0.7Mg-0.27Fe) in the state of extrusion and heat treatment were compared with the mechanical properties of the extruded 6063 alloy in the Chinese national standard in the state of T5 and T6.

The mechanical property comparison of the alloy prepared by the present invention and Chinese national standard 6063 alloy in table 1

alloy state Yield strength (MPa) Tensile strength (MPa) Elongation (%) Al-8.5Si-1.8Mg-0.27Fe T1 175 252 13 Al-8.5Si-1.8Mg-0.27Fe T6 296 344 7.2 Al-15.5Si-0.7Mg-0.27Fe T1 120 232 11 Al-15.5Si-0.7Mg-0.27Fe T6 280 325 7.5 Al-12.7Si-0.7Mg-1.5Cu-0.3Ni-0.3Ti-0.3Fe T1 112 190 15 Al-12.7Si-0.7Mg-1.5Cu-0.3Ni-0.3Ti-0.3Fe T6 268 347 9 6063Al-(0.2-0.6)Si-(0.4-0.9)Mg T5 110 160 8 6063Al-(0.2-0.6)Si-(0.4-0.9)Mg T6 180 205 8

It can be seen that the yield of Al-15.5Si-0.7Mg-0.27Fe, Al-12.7Si-0.7Mg-1.5Cu-0.3Ni-0.3Ti-0.3Fe and Al-8.5Si-1.8Mg-0.27Fe alloys in the T6 state The strength and tensile strength are higher than the national standard of the 6063 alloy T6 state; the mechanical properties of the alloy in the extrusion state (T1), especially the elongation, are higher than the national standard of the 6060 alloy T5 state. 6063 alloy is the most common extruded profile alloy. It is widely used in construction, vehicles, decoration and other fields at home and abroad, and has a broad market demand. Once the 6063 alloy is partially replaced with magnesium-containing high-silicon aluminum alloy, it will definitely bring huge economic benefits. In addition, the addition of silicon will greatly save aluminum resources.

Description of drawings

Fig. 1 is the structural representation of semi-continuous casting equipment;

Fig. 2 is a semi-continuous casting (casting temperature 730°C, casting speed 180mm/min, cooling water flow rate 8g/mm s) ingot of Al-12.7Si-0.7Mg-0.3Fe alloy (#3) in typical Example 1 The as-cast microstructure of the slab;

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

Fig. 4 is the microstructural shape of the semi-continuously cast Al-12.7Si-0.7Mg-0.3Fe alloy (#3) in Example 2 after pre-heat treatment at 500°C for 2 hours and hot extrusion at 470°C (extrusion ratio 15). appearance;

Fig. 5 is the T6 state (solid state) after the semi-continuous casting Al-12.7Si-0.7Mg-0.3Fe alloy (#3) in the typical embodiment 3 is pre-heated at 500 ° C for 2 hours, and hot extruded at 470 ° C (extrusion ratio 15). Melting temperature 540°C, time 1hr; artificial aging temperature 200°C, time 3hr) microstructure morphology;

Fig. 6 is the semi-continuous casting (casting temperature 800 ℃, casting speed 140mm/min, cooling water flow rate 10gmm s) billet of Al-15.5Si-0.7Mg-0.27Fe alloy (#5) in typical embodiment 1 As-cast microstructure morphology;

Figure 7 is a semi-continuous casting (casting temperature 800°C, casting speed 140mm/min, cooling water flow rate 10g/mm s) ingot of Al-15.5Si-0.7Mg-0.27Fe alloy (#5) in typical Example 1 High-magnification as-cast microstructure of billet;

Figure 8 shows the microstructure of the semi-continuously cast Al-15.5Si-0.7Mg-0.27Fe alloy (#5) in Example 2 after heat treatment at 500°C for 2 hours and hot extrusion at 470°C (extrusion ratio 45). appearance;

Fig. 9 is a semi-continuously cast Al-15.5Si-0.7Mg-0.27Fe alloy (#5) rectangular cast slab in typical embodiment 2 after pre-heat treatment at 500°C for 1hr and hot rolling at 500°C (reduction 60%) Microstructure morphology;

Fig. 10 is the T6 state (solid state) after the semi-continuous casting Al-15.5Si-0.7Mg-0.27Fe alloy (#5) in the typical embodiment 3 is pre-heated at 500°C for 2 hours and hot extruded at 470°C (extrusion ratio 45). Melting temperature 520°C, time 2hr; artificial aging temperature 180°C, time 4hr) microstructure morphology;

Figure 11 shows T6 of the semi-continuously cast Al-15.5Si-0.7Mg-0.27Fe alloy (#5) rectangular billet in Example 3, which was pre-heated at 500°C for 1 hr and hot rolled at 500°C (reduction 60%) State (solution temperature 520°C, time 3hr; artificial aging temperature 200°C, time 4hr) microstructure morphology;

Fig. 12 is the T6 state (solid state) after the semi-continuous casting Al-15.5Si-0.7Mg-0.27Fe alloy (#5) in the typical embodiment 3 is pre-heated at 500°C for 2 hours and hot extruded at 470°C (extrusion ratio 45). Melting temperature 520°C, time 2hr; artificial aging temperature 180°C, time 4hr) high-magnification microstructure morphology;

Fig. 13 is the semi-continuous casting of Al-17.5Si-0.7Mg-1.0Cu-0.27Fe alloy (#7) in typical embodiment 1 (casting temperature 850 ℃, casting speed 120mm/min, cooling water flow rate 10g/mm. s) As-cast microstructure morphology of the ingot.

Detailed ways

The preparation of embodiment 1 semi-continuous casting billet

The selected equipment 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-metal liquid. The chemical composition of the alloy is shown in Table 2, and the casting process parameters are shown in Table 3.

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

Alloy No. Si Mg Cu Zn Ni Ti Fe Al #1 8.5 0.7 0.5 0.3 0.3 0.27 Bal. #2 8.5 1.8 0.27 Bal. #3 12.7 0.7 0.3 Bal.

Alloy No. Si Mg Cu Zn Ni Ti Fe Al #4 12.7 1.2 1.5 0.3 0.3 0.3 0.3 Bal. #5 15.5 0.7 0.27 Bal. #6 15.5 1.8 0.8 0.5 0.3 0.27 Bal. #7 17.5 0.7 1.0 0.27 Bal. #8 17.5 1.0 1.0 0.27 Bal.

Table 3 Casting process parameters of different alloys

Alloy No. Billet section size (mm) Casting temperature (℃) Casting speed (mm/min) Cooling water volume (g/mm s) #1 Φ100 780 120 8 #1 600×50 780 180 8 #2 Φ100 780 120 8 #2 600×50 780 180 8 #3 Φ100 730 180 10 #3 600×50 730 180 10 #4 Φ100 730 140 8 #4 600×50 730 180 8 #5 Φ100 800 140 10 #5 600×50 850 180 10 #6 Φ100 800 160 12 #7 Φ60 850 120 10

Alloy No. Billet section size (mm) Casting temperature (℃) Casting speed (mm/min) Cooling water volume (g/mm s) #8 Φ60 850 180 14 #8 Φ100 850 180 14

Pre-heat treatment and extrusion, rolling, forging of embodiment 2 cast alloy ingot billet

The pre-heat treatment is heated in the heat treatment furnace according to the set heating rate, and after reaching the set temperature, it is kept for the set time. Plastic deformation is then done using extruders, hot rolling mills and forging machines. 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

Alloy No. Pretreatment heating rate (℃/min) Pretreatment temperature (℃) Preprocessing time (hr) Extrusion temperature (℃) extrusion ratio cooling method Alloy number after deformation #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

Alloy No. Pretreatment heating rate (℃/min) Pretreatment temperature (℃) Preprocessing time (hr) Rolling temperature (℃) Rolling reduction (%) cooling method Alloy number after deformation #1 20 450 3 450 50 nature 1B #2 20 520 1 520 70 nature 2B

Alloy No. Pretreatment heating rate (℃/min) Pretreatment temperature (℃) Preprocessing time (hr) Rolling temperature (℃) Rolling reduction (%) cooling method Alloy number after deformation #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 nature 5B2

Table 6 Pre-heat treatment and forging process parameters of different alloys

Alloy No. Pretreatment heating rate (℃/min) Pretreatment temperature (℃) Preprocessing time (hr) Forging temperature (℃) Forging ratio (%) cooling method Alloy number after deformation #2 25 500 2 500 65 nature 2C #3 20 520 1 520 65 nature 3C #5 15 500 2 500 50 nature 5C #6 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 nature 8C

Heat treatment after embodiment 3 alloy deformation (extrusion, rolling, forging)

The extruded, rolled, and forged workpieces are heat treated 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 states are given in Table 10.

Table 7 Heat treatment process parameters of different alloy extrusion products

Alloy number after deformation Alloy No. Heat treatment state Solid solution temperature (℃) Solid solution time (hr) Artificial aging temperature (℃) Artificial aging time (hr) Alloy number after heat treatment 1A #1 T6 520 2 180 3 1AT6 3A #3 T6 540 0.5 200 3 3AT6 4A #4 T5 180 3 4AT5 5A #5 T1 5AT1 5A #5 T6 520 2 180 2 5AT6 7A #7 T5 180 6 7AT5 8A #8 T5 170 8 8AT5

Table 8 Heat treatment process parameters of different alloy rolled products

Alloy number after deformation Alloy No. Heat treatment status Solid solution temperature (℃) Solid solution time (hr) Artificial aging temperature (℃) Artificial aging time (hr) Alloy number after heat treatment 1B #1 T6 500 3 160 8 1BT6 2B #2 T5 180 3 2BT1 2B #2 T6 520 2 160 10 2BT6 4B #4 T6 540 0.5 200 8 4BT6 5B #5 T6 520 1 200 4 5BT6 5B2 #5 T6 520 1 200 6 5B2T6

Table 9 Heat Treatment Process Parameters of Different Alloy Forged Products

Alloy number after deformation Alloy No. Heat treatment state Solid solution temperature (℃) Solid solution time (hr) Artificial aging temperature (℃) Artificial aging time (hr) Alloy number after heat treatment 2C #2 T6 520 3 180 6 2CT6

Alloy number after deformation Alloy No. Heat treatment state Solid solution temperature (℃) Solid solution time (hr) Artificial aging temperature (℃) Artificial aging time (hr) Alloy number after heat treatment 5C #5 T6 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 of some alloys under different deformation and heat treatment states

Alloy number after heat treatment Yield strength σ₀₂(MPa) Tensile strength σ_b(MPa) Elongation (%) 1AT6 293 378 14.6 2AT6 302 378 12.5 2BT6 294 360 11.7 4AT5 290 375 10.4 4AT6 305 380 9.2 5AT1 120 232 10 5AT6 280 325 7.5 5BT6 300 366 7.6 6C2T6 260 343 6 7AT5 240 265 1.8 7CT6 285 327 2.5 8C2T6 296 339 2.8

Claims (8)

1. structural wood materials and parts that contain the magnesium silumin comprise section bar, bar, sheet material, forging, it is characterized in that:

Described structural wood materials and parts adopt semi-continuous casting method to prepare ingot blank, carry out the particle discretize of Eutectic Silicon in Al-Si Cast Alloys phase then by thermal treatment in advance, Al-alloy products by thermoplasticity processing and thermal treatment acquisition net shape and microtexture again, its strengthening mechanism are the particle strengthening and second precipitation strength of particle mutually of refined crystalline strengthening, the silicon grain of aluminum substrate;

The content of Mg is 0.2～2.0% weight in the described structural wood materials and parts, and the content of Si is 8～18% weight; Have the heterogeneous microstructure of even refinement, aluminum substrate is organized as equi-axed crystal, mean sizes＜6 μ m, the Si particle with other second mutually particle be disperse distribution and mean sizes＜5 μ m.

2. according to the described structural wood materials and parts that contain the magnesium silumin of claim 1, it is characterized in that can containing in the described alloy one or more of Cu, Zn, Ni, Ti, Fe, total content is lower than 2% weight.

3. described preparation method who contains the structural wood materials and parts of magnesium silumin of claim 1 is characterized in that:

---adopt semi-continuous casting method to prepare ingot blank, processing parameter is:

Pouring temperature: above 150～300 ℃ of corresponding alloy liquid phase line temperature;

Casting speed: 100～200mm/min;

Solidify peripheral cooling water inflow: the 5～15g/mms of base;

Do not add any alterant;

---above-mentioned ingot blank is carried out the particle discretize of Eutectic Silicon in Al-Si Cast Alloys phase by thermal treatment in advance, and processing parameter is:

Rate of heating: 10～30 ℃/min;

Heating temperature: 450～520 ℃;

Soaking time: 1～3hr;

---above-mentioned ingot blank after thermal treatment is in advance carried out thermoplasticity processing, and processing parameter is:

Texturing temperature: 400～520 ℃;

The type of cooling: naturally cooling or pressure cooling;

---above-mentioned structural wood materials and parts after thermoplasticity processing are heat-treated.

4. according to the described preparation method who contains the structural wood materials and parts of magnesium silumin of claim 3, the structural wood materials and parts for thermoplasticity processing back naturally cooling adopt solution treatment+artificially aged thermal treatment process, it is characterized in that:

---the solution treatment parameter is:

Rate of heating: 10～30 ℃/min;

Solid solution temperature: 500～540 ℃;

The solution treatment time: 0.5～3hr;

---the artificial aging parameter is:

Aging temp: 160～200 ℃;

Aging time: 1～10hr.

5. according to the described preparation method who contains the structural wood materials and parts of magnesium silumin of claim 3, force refrigerative structural wood materials and parts, adopt the thermal treatment process of artificial aging or natural aging, it is characterized in that for thermoplasticity processing back:

---the artificial aging parameter is:

Aging temp: 160～200 ℃;

Aging time: 1～10hr.

6. according to the described preparation method who contains the structural wood materials and parts of magnesium silumin of claim 3, when rolling technology was adopted in processing for thermoplasticity, it is characterized in that: rolling total reduction was greater than 40%.

7. according to the described preparation method who contains the structural wood materials and parts of magnesium silumin of claim 3, when extrusion process was adopted in processing for thermoplasticity, it is characterized in that: extrusion ratio was greater than 15.

8. according to the described preparation method who contains the structural wood materials and parts of magnesium silumin of claim 3, when forging process was adopted in processing for thermoplasticity, it is characterized in that: forging ratio was greater than 40%.

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