CN102758108A

CN102758108A - Al-Si-Mg-Sm rare earth cast aluminum alloy and preparation method thereof

Info

Publication number: CN102758108A
Application number: CN201210202669XA
Authority: CN
Inventors: 闫洪; 邱鸿旭; 胡志
Original assignee: Nanchang University
Current assignee: Jiangxi Bell Non Ferrous Metal Processing Co Ltd
Priority date: 2012-06-19
Filing date: 2012-06-19
Publication date: 2012-10-31
Anticipated expiration: 2032-06-19
Also published as: CN102758108B

Abstract

The invention discloses an Al-Si-Mg-Sm rare earth cast aluminum alloy and a preparation method of the aluminum alloy; the Al-Si-Mg-Sm alloy comprises the components by weight percent: 6.5-7.0% of Si, 0.3-0.45% of Mg, 0.1-0.9% of Sm and the balance of Al. The preparation method comprises the steps of: firstly, adding an Al-Si-Mg alloy into a graphite crucible, heating the graphite crucible in a resistance furnace until the Al-Si-Mg alloy is melted, and then adding an Al-Sm intermediate alloy; carrying out heat preservation on the alloy melt within the temperature range of 710-750 DEG C for 20-30minutes, and then stirring for 3-5minutes at the speed of 40-50r/min; then, carrying out heat preservation again for 20-30minutes; and finally, degassing and refining the alloy melt, then casting when the temperature of the melt is reduced to 700-710 DEG C, and taking out the sample. The alloy and the preparation method thereof disclosed by the invention have the technical effects that rare earth Sm is added into the alloy, so that the shape and the distribution of eutectic silicon can be effectively improved, spheroidized crystalline grains are refined, a strengthening phase is added, and the alloy strength and elongation can be greatly improved. The rare earth cast aluminum alloy is simple in preparation method, low in cost, easy in control for adding quantity and free from three-waste pollution.

Description

A kind of Al-Si-Mg-Sm rare earth casting aluminium alloy and preparation method thereof

Technical field

The present invention relates to a kind of duraluminum preparation method, be specifically related to a kind of Al-Si-Mg-Sm rare earth casting aluminium alloy and preparation method thereof.

Background technology

Duraluminum has HS, low density, high fracture toughness as typical light material in the metallic substance, and good characteristic such as high anti-stress-corrosion ability, is able to widespread use in machinery, chemical industry, automobile, building, Aeronautics and Astronautics field.Concerning aluminium alloy cast ingot, crystal grain thinning can make its interior tissue even, reduces segregation, improves plasticity and tensile strength, prevents defectives such as crackle and shrinkage cavity.

ZL101 alloy physical strength (GB/T1173-1995): as cast condition σ _b=155MPa, δ=2%; T6 attitude: σ _b=225MPa, δ=1%

Obviously, the ZL 101 alloy mechanical property is low, has deficiency, has satisfied not the request for utilization of high load; Simultaneously; Be limited to material composition characteristics and technical matters characteristics; Also there is weak point; As being prone to exist various impurity, thick needle-like Eutectic Silicon in Al-Si Cast Alloys and iron containing compounds, aluminum substrate to organize problems such as thick in the tissue, the mechanical property that influences cast product improves, and it is necessary carrying out RE alloyed to ZL 101 alloy.

REE has particular configurations of electronic shell and physicochemical property, and unique 4f electronic structure, big magnetic moment of atom, very strong spin coupling characteristic are arranged, and is also quite unique to the influence of duraluminum.The metamorphism of REE has long-lasting and the stable characteristics of remelting, and is better than other alterants, and has deoxidation preferably and sweetening power.

Increasing to the research of rare earth aluminium alloy both at home and abroad, but the influence to the microstructure and property of Al-Si-Mg y alloy y does not also appear in the newspapers as a kind of alloy element for rare-earth Sm, therefore has bigger researching value.

Summary of the invention

The object of the present invention is to provide a kind of Al-Si-Mg-Sm rare earth casting aluminium alloy and preparation method thereof, Sm joins in the Al-Si-Mg alloy with appropriate vol, can effectively improve the form and the distribution of Eutectic Silicon in Al-Si Cast Alloys, to improve the mechanical property of alloy.

Al-Si-Mg-Sm rare earth casting aluminium alloy provided by the present invention; It is characterized in that: in the Al-Si-Mg alloy, added the rare earth casting aluminium alloy weight percent and be 0.1 ~ 0.9% Sm; The weight percent of Si is 6.3 ~ 6.5% in the described Al-Si-Mg alloy; The weight percent of Mg is 0.7 ~ 0.8%, and surplus is Al.

The present invention realizes that like this preparation method is: the Al-Si-Mg alloy is joined in the plumbago crucible, in resistance furnace, be heated to fusing after, add the Al-Sm master alloy, wherein REE Sm accounts for 0.1 ~ 0.9% of alloy gross weight.In 710 ~ 750 ℃ of TRs, with above-mentioned alloy melt insulation after-applied stirring in 20 ~ 30 minutes, churning time is 3 ~ 5 minutes, and stirring velocity is 40 ~ 50 rev/mins, and then is incubated 20 ~ 30 minutes.Last above-mentioned alloy melt is cast when melt temperature is reduced to 700 ~ 710 ℃ after the degasification refining and is taken a sample.

Technique effect of the present invention is: in duraluminum, add rare-earth Sm and can not improve production cost; And the adding of rare-earth Sm can obviously promote the refinement nodularization of primary phase α-Al; It is tiny fibrous that bulk, needle-like Eutectic Silicon in Al-Si Cast Alloys are become; And make distribution on crystal boundary by the gathering homodisperse that becomes, thereby increase substantially alloy strength and unit elongation.Rare earth casting aluminium alloy among the present invention, the preparation method is simple, and is with low cost, and add-on is easy to control and three-waste free pollution.

Description of drawings

Fig. 1 is the microscopic fibers tissue of Al-6.4Si-0.75Mg alloy;

Fig. 2 is the microscopic fibers tissue of Al-6.4Si-0.75Mg-0.9Sm alloy.

Embodiment

The present invention will be described further through embodiment once.

Embodiment 1: at first Al-6.4Si-0.75Mg (massfraction) alloy is joined in the plumbago crucible; Molten alloy in resistance furnace, smelting temperature is 750 ℃, treat that metal melts fully after; Be incubated 20 minutes, feed high pure nitrogen (purity is 99.999%) degasification, refining then.Be poured into after leaving standstill and make the Al-Si-Mg alloy cast ingot in the metal die, pouring temperature is 710 ℃.

Embodiment 2: at first Al-6.3Si-0.7Mg (massfraction) alloy is joined in the plumbago crucible, in resistance furnace, be heated to fusing after, add the Al-15%Sm master alloy, wherein REE Sm accounts for 0.3% of alloy gross weight.At 750 ℃, with above-mentioned alloy melt insulation after-applied stirring in 20 minutes, churning time is 3 minutes, and stirring velocity is 40 rev/mins, and then is incubated 20 minutes.Last above-mentioned alloy melt is cast when melt temperature is reduced to 700 ℃ after the degasification refining and is taken a sample.

Embodiment 3: at first Al-6.5Si-0.8Mg (massfraction) alloy is joined in the plumbago crucible, in resistance furnace, be heated to fusing after, add the Al-15%Sm master alloy, wherein REE Sm accounts for 0.6% of alloy gross weight.At 730 ℃, with above-mentioned alloy melt insulation after-applied stirring in 25 minutes, churning time is 5 minutes, and stirring velocity is 50 rev/mins, and then is incubated 25 minutes.Last above-mentioned alloy melt is cast when melt temperature is reduced to 710 ℃ after the degasification refining and is taken a sample.

Embodiment 4: at first Al-6.4Si-0.75Mg (massfraction) alloy is joined in the plumbago crucible, in resistance furnace, be heated to fusing after, add the Al-15%Sm master alloy, wherein REE Sm accounts for 0.9% of alloy gross weight.At 740 ℃, with above-mentioned alloy melt insulation after-applied stirring in 30 minutes, churning time is 5 minutes, and stirring velocity is 50 rev/mins, and then is incubated 30 minutes.Last above-mentioned alloy melt is cast when melt temperature is reduced to 700 ℃ after the degasification refining and is taken a sample.

The ingot casting that obtains in above-mentioned four embodiments is processed into tension specimen by GB/T228-2002 metallic substance tensile test at room temperature method, and the mechanical property of the different embodiment samples of test is as shown in table 1 on tensile testing machine.

Can find out that from table 1 along with the increase of Sm content, the mechanical property of cast alloy significantly increases; When the content of Sm is increased to 0.9%; Tensile strength of alloys reaches 232.91MPa, and when more not adding Sm, alloy substrate has improved 34%; Unit elongation reaches 4.6% simultaneously, and the alloy substrate that does not more add Sm has improved 142.1 %.

With the ingot casting sampling that embodiment 1 and embodiment 4 make, after polishing, polishing, corrosion, under opticmicroscope, observe alloy microscopic structure, shown in accompanying drawing 1 (embodiment 1) and accompanying drawing 2 (embodiment 4).From accompanying drawing, can find out; The adding of rare-earth Sm can obviously promote the refinement nodularization of primary phase α-Al; It is tiny fibrous that Eutectic Silicon in Al-Si Cast Alloys is changed into by block, needle-like, and make Eutectic Silicon in Al-Si Cast Alloys assemble the homodisperse that becomes at crystal boundary, thereby increase substantially alloy strength.And technology is simple, safe and reliable, easy to operate, and three-waste free pollution.

Table 1. Al-Si-Mg alloy adds the mechanical property under the as-cast condition of Sm front and back

Claims

1. Al-Si-Mg-Sm rare earth casting aluminium alloy; It is characterized in that: in the Al-Si-Mg alloy, added the rare earth casting aluminium alloy weight percent and be 0.1 ~ 0.9% Sm; The weight percent of Si is 6.3 ~ 6.5% in the described Al-Si-Mg alloy; The weight percent of Mg is 0.7 ~ 0.8%, and surplus is Al.

2. the preparation method of the described a kind of Al-Si-Mg-Sm rare earth casting aluminium alloy of claim 1 is characterized in that: the Al-Si-Mg alloy is joined in the plumbago crucible, in resistance furnace, be heated to fusing after; Add the Al-Sm master alloy; Wherein REE Sm accounts for 0.1 ~ 0.9% of alloy gross weight, in 710 ~ 750 ℃ of TRs, with above-mentioned alloy melt insulation after-applied stirring in 20 ~ 30 minutes; Churning time is 3 ~ 5 minutes; Stirring velocity is 40 ~ 50 rev/mins, and then is incubated 20 ~ 30 minutes, and last above-mentioned alloy melt is cast when melt temperature is reduced to 700 ~ 710 ℃ after the degasification refining and taken a sample.