A kind of efficient alterant and preparation method for A356.2 aluminium alloysTechnical field
The invention belongs to aluminum alloy materials melting and manufacture field, more particularly to a kind of preparation method of alterant, and itsApplication method in A356.2 aluminium alloys.
Background technology
Aluminium alloy is due to being considered as that current automobile is realized gently the advantages of its material is light, intensity is high, expansion and contraction high resiliency is goodThe important raw and processed materials of quantization.Wherein, A356.2 aluminium alloys are one of common materials in automotive casting product.A356.2 aluminium alloysMiddle Si mass content is 6.5%-7.5%, it is ensured that material possesses higher intensity and mobility, is conducive to enhancing to castThe mold-filling capacity of journey aluminium liquid, reduces the problem of feeding deficiency is brought.Because Si contents are increased, A356.2 aluminium alloys typically must be throughCross Metamorphism treatment to reach Eutectic Silicon Refinement effect, the refinement of Eutectic Silicon in Al-Si Cast Alloys is to the intensity of auto parts and components product, elongation percentage, fatigueThere is important influence etc. performance.
At present, alterant the most commonly used in A356.2 aluminium alloys is Al-Sr intermediate alloys.This kind of alloy modification effectThe obvious and sustainable time is longer.But during actual casting, the modification effect of Al-Sr alterants is more sensitive to cooling rate,When cooling rate is relatively low, metamorphism weakens, such as wheel rim is from spoke position because cooling rate is different in casting wheel, and rotten difference canEnergy can be larger.In addition, the Sr contents in the easy scaling loss of Sr elements, aluminium liquid are difficult quantitative control, moreover, the easy air-breathing of Sr elements,If aluminium liquid stop is long, easily the defects such as shrinkage cavity are brought in casting process.
Fine degenerate effect of the rare earth element (Re) in aluminium alloy is always study hotspot, and many rare earth elements possess carefullyChange metamorphism, but effect is uneven, current Eu metamorphism is the most obvious, but expensive price limit its closed in aluminiumExtensive use in gold.China is the maximum country of rare earth yield, with flourishing for rare-earth trade, lanthanum containing LREE(La), the byproduct bulk deposition such as cerium (Ce), causes the cost of these rare-earth products drastically to decline, and is expected to be widely used in aluminiumIn alloy material.For at present, the fine degenerate effect of these light rare earths member is still undesirable, strengthens these rare earth elementsFine degenerate effect turns into the key solved the problems, such as.
The content of the invention
It is therefore an object of the present invention to a kind of alterant and method of refining be provided, so as to substantially strengthen rare earth element pairEutectic Silicon in Al-Si Cast Alloys size is obviously reduced after the modification effect of A356.2 aluminium alloys, ingot casting, and form is threadiness and graininess, hence it is evident that excellentIn the modification effect for the Al-RE (RE is selected from La, Ce, Y, Yb, Eu) that this method is not used.In order to realize the goal of the invention of the above,The invention provides a kind of preparation method of intermediate alloy, it is characterised in that：During casting ARW intermediate alloys, accelerate itCooling procedure, makes RE abundant solid solutions in Al, and the phase containing RE separated out is tiny, uniformly.
There is provided a kind of method for the alterant for preparing A356.2 aluminium alloys, described side in one aspect of the inventionMethod includes：(1) Al-RE alloys are provided；(2) described Al-RE alloys are melted, and be incubated at 700-750 DEG C, during insulationBetween cannot be less than 5 minutes；(3) nitrogen degasification is passed through into melt body；And melt body chilling is obtained intermediate alloy by (4).
In currently preferred aspect, in step (1), described RE is selected from La, Ce, Y, Yb and Eu.
In currently preferred aspect, the RE containing 7-10 parts by weight in the Al-RE alloys of 100 parts by weight.
In currently preferred aspect, in step (2), before alloy is melted, mould is incubated 2 hours in 300 DEG CMore than.
In currently preferred aspect, in step (2), the temperature kept is 735 degrees Celsius.
In currently preferred aspect, in step (2), addition alloy gross weight in Al-RE alloy melt bodies is additionally included inThe step of 0.2% slag-cleaning agent.
In currently preferred aspect, in step (3), nitrogen degasification 10min, gas flow 1L/min.
In currently preferred aspect, in step (4), work as melt temperature>At 637 DEG C, cooling velocity must not be less than 60DEG C/s, when melt temperature is between 637 DEG C and 350 DEG C, cooling velocity must not be less than 30 DEG C/s.
In other aspects of the present invention, the fining agent prepared according to previously described method is additionally provided.
The method in A356.2 aluminium alloys is refined using previously described alterant, described method includes step：(1)After A356.2 aluminum alloy meltings, keeping temperature is in 725-745 DEG C；(2) added in 100 parts of A356.2 aluminium alloys by weight withThe alterant of 0.1-0.2 parts of weight meter, and stir.
In currently preferred aspect, in step (1), before alloy is melted, mould is incubated 2 hours in 300 DEG CMore than.
In currently preferred aspect, in step (1), the temperature kept is 735 degrees Celsius.
In currently preferred aspect, in step (1), added in 100 parts of A356.2 aluminium alloys by weight with weightThe alterant of 0.2 part of gauge.
In currently preferred aspect, described method is additionally included in the step that nitrogen degasification 10min is passed through after step (2)Suddenly, gas flow 1L/min.
In currently preferred aspect, in the aluminium alloy that refining is finished, Mg in 100 parts of A356.2 aluminium alloys by weightContent must not be less than 0.3 part.
The present invention obtains tiny spheric eutectic silicon by adding a small amount of ARW alterants in A356.2 aluminium alloysGrain.Technical scheme provides the preparation method and its application method in A356 alloys of new and effective alterant, profitSignificant modification effect can be realized in A356 alloys with the alterant prepared by this method, Eutectic Silicon in Al-Si Cast Alloys is embodied in big absolutelyPart is threadiness and graininess.
Described alterant is consistent with the composition for preparing preceding material, is still Al-RE intermediate alloys, by quenchingAfterwards, tissue topography is changed, and rotten ability is significantly improved.Technical scheme provides new aluminum alloy modifierPreparation method and Modification Manners, using this method the alterant can be made to realize significant modification effect.
Brief description of the drawings
Hereinafter, embodiment of the present invention is described in detail with reference to accompanying drawing, metallographic observation uses ZEISS AxioObserver A1m metallographic microscopes, wherein：
Fig. 1：The metallograph for the ARW alloys that the method for embodiment 1 is obtained and raw material Al-10Ce metallograph；
Fig. 2：The metallograph of the as cast condition for the aluminium alloy ingots that the method for embodiment 2 is obtained；
Fig. 3：The metallograph of the as cast condition for the aluminium alloy ingots that the method for embodiment 3 is obtained；
Embodiment
Embodiment 1
The essential element of prepared intermediate alloy (being named as ARW) is still Al, RE, and contained RE phases are largely pointShape, graininess, rod-short, and be evenly distributed, as shown in Figure 1.Specifically：Directly observe raw material Al-10Ce microstructure of the alloy groupsKnit (see Fig. 1 a).Al-Ce alloy pigs are placed in iron crucible, iron crucible is put in graphite crucible stove, treat alloy melting and protectTemperature is held at 735 DEG C, the slag-cleaning agent of alloy gross weight 0.2% is added, while being passed through nitrogen degasification 10min, gas flow 1L/min.After the completion of refining, 715 DEG C of standing 5min are cooled to, iron crucible are directly placed into water, water temperature is 24 DEG C, after coolingAlloy takes out and observes metallographic structure (see Fig. 1 b).As can be seen that alloy microstructure there occurs after chilling from metallographRod-short, granular, fine microstructures is presented in significant change, the compound containing rare earth.Chemical combination containing rare earth in raw material rare earth alloyElongated rod shape is presented in thing, block, organizes thick.
Embodiment 2
A356.2 aluminium alloy ingots is melted in aluminium melting furnace, 735 DEG C are maintained the temperature at, alloy gross weight 0.2% is addedRaw material Al-10Ce, is stirring evenly and then adding into the slag-cleaning agent of alloy gross weight 0.2%, while being passed through nitrogen degasification 10min, gasBody flow 1L/min.After the completion of refining, 715 DEG C of standing 5min are cooled to, casting ingot-forming simultaneously observes metallographic structure (see Fig. 2), thisOuter is to avoid cooling rate from covering rotten result, and mold temperature is incubated more than 2 hours in 300 DEG C.It can be seen that from metallographIn the case where using raw material Al-10Ce as alterant, long needle-like, thick bar shape, block etc. is presented in Eutectic Silicon in Al-Si Cast Alloys, and this shows on a small quantityRaw material Al-10Ce almost without modification effect.
Embodiment 3
A356.2 aluminium alloy ingots is melted in aluminium melting furnace, 735 DEG C are maintained the temperature at, alloy gross weight 0.2% is addedARW alterants, are stirring evenly and then adding into the slag-cleaning agent of alloy gross weight 0.2%, while being passed through nitrogen degasification 10min, gas streamMeasure 1L/min.After the completion of refining, cool to 715 DEG C of standing 5min, casting ingot-forming simultaneously observes metallographic structure (see Fig. 3), in addition forCooling rate is avoided to cover rotten result, mold temperature is incubated more than 2 hours in 300 DEG C.As can be seen that making from metallographIn the case of with ARW alterants, threadiness is mainly presented in Eutectic Silicon in Al-Si Cast Alloys.This shows that the modification effect of ARW alterants is better than raw materialAl-10Ce。