A kind of heat resisting low expansion silumin and preparation method thereof
Technical field
The invention belongs to nonferrous materials and preparation shaping field thereof, relate to the cast Al-Si alloy material that a kind of high temperature uses, i.e. high silicon cast aluminium alloy of heat resisting low expansion and preparation method thereof.
Background technology
The design of motor car engine at present develops towards high-speed, less energy-consumption direction, motor speed and temperature raise, thereby the corresponding raising that requires to engine piston material, cylinder block material etc., mainly concentrate on and require thermotolerance, wear resistance, good corrosion resistance, thermal expansion is little, light weight etc., therefore selects for use suitable material just to seem particularly important.A lot of automobiles all adopt aluminum alloy materials on parts such as piston, scatterer, oil pan, cylinder body and the cylinder cap of engine, crankcase, purifier.Used so far aluminium piston material roughly has four classes: Al-Cu-(Ni)-Mg system in automotive industry, Al-Cu-Si system, cocrystallizing type Al-Si-Cu system and hypereutectic type Al-Si-Cu-Mg system, preceding two classes are because linear expansivity is big, density is big, the unsettled shortcoming of volume is eliminated already.The aluminium alloy of all the other two series still uses in the production of component such as current domestic and international middle low power engine cylinder-body or piston in a large number, as China aluminium alloy trade mark ZL109 (Si<13%), ZL108 (Si<13%) or Japanese ADC12 (Si<13%), U.S. A390 (Si<18%) etc.
For motor car engine and peripheral part thereof, adopting the outstanding advantage of aluminium alloy is that density is little, can significantly reduce the quality and the reciprocating inertia of piston, and the vibration damping of high-speed engine and the specific mass of reduction engine are had great significance.And the aluminium alloy of the trades mark such as the ZL109 of current use, A390 more and more is difficult to satisfy the engine use properties requirement that improves constantly, and is badly in need of the development of new aluminum alloy materials and the technology that forms a complete production network.The transcocrystallized Al-Si alloy of high silicon content (18~26%) than conventional piston with aluminum alloy materials have that linear expansivity is lower, resistance to abrasion and the better advantage of volume stability, be high performance heat resistant low bulk piston material or other antiwear heat resisting part comparatively ideal select.
Abroad the research of hypereutectic type Al-Si alloy is used early, except that the A390 alloy of widespread use, still there are many research workers continually developing various novel hypereutectic aluminum alloy materials, United States Patent (USP) (US5851320) discloses a kind of wear-resistant aluminum alloy as the aluminium piston, its composition is 13~15.5%, 0.8~1.8%Cu, 0.8~1.3%Mg etc. adopt P rotten.The same with A390, it is still on the low side to contain silicone content in this class aluminum silicon alloy, and high-temperature behavior and thermal expansivity can not satisfy higher requirement.Therefore, the research aspect the aluminum silicon alloy of having carried out many higher silicon contents in the recent period, the use aspect expands on the antiwear heat resisting component of automobile from motorcycle piston or cylinder body.For example, external certain company's pilot development in 2005 go out the all-aluminium engine cylinder body of Al-20%Si alloy, by casting forming, have cancelled Cast iron liner, and the table temperature reduces by 30 ℃ in the cylinder body, and oil consumption reduces by 2 times.
The key that influences the intensity of silumin is that alloy microscopic structure exists a large amount of thick en plaque primary silicon and minute hand shape Eutectic Silicon in Al-Si Cast Alloys to isolate matrix, and alloy rigidity and fragility are improved greatly, is difficult to machining.Therefore, made number of research projects with regard to refinement primary silicon and rotten Eutectic Silicon in Al-Si Cast Alloys both at home and abroad.At present, show: Na, Sr, Sb, Te, Ba, Bi, RE and S etc. have the refinement metamorphism to Eutectic Silicon in Al-Si Cast Alloys, and P, S, As have the refinement metamorphism to primary silicon, but for the aluminium alloy of high silicon content, the alterant that is added requires to have the dual metamorphism effect to primary silicon and Eutectic Silicon in Al-Si Cast Alloys.The Wu Shu of the Central China University of Science and Technology is gloomy wait invention " double inoculant of casting high-silicon aluminium-silicon alloy " (ZL00131196.4), the compound modifier that contains P, Sr by interpolation reaches refinement primary crystal Si and eutectic Si simultaneously, thereby effectively improves the purpose of alloy comprehensive mechanical property and machining property.A kind of hypereutectic Al-Si alloy of Japanese Patent (08-170136) invention, main component is 12.0-25.0%Si, 0.5-5.0%Cu, 0.1-2.0%Mg carries out modifying-refining primary crystal Si by adding P and Be.And " a kind of silumin material and the production method thereof " of Xue Yuanliang invention (ZL200310105905.7), and its silicon content is 10~12%, has then adopted Zr as the alloy modification processing element.
For the production of superstrength hypereutectic Al-Si alloy, successful method is quench solidification powder metallurgic method or spray deposition at present, and its principle all is to make the Al-Si alloy liquid droplet 10
3~10
6℃/solidify under the cooling of the high speed of s, make structure refinement, primary crystal Si can refine to 2 μ m~10 μ m, and the intensity of material can be up to 400MPa." a kind of method of spraying and depositing high silicon aluminium alloy " of people such as University of Science ﹠ Technology, Beijing Zhang Ji mountain invention (ZL00124660.7), when adopting spray deposition technique to prepare Al-(16~45%) Si alloy, add Fe, Mn element, the advantage of cooled and solidified has been avoided the appearance of the rich Fe intermetallic compound of needle-like fast, has improved the thermostability of alloy.But this method needs quench solidification equipment, powder metallurgy or cold-extrusion shaping, and the shape and the size of part are restricted, and complex process, cost height.A kind of explained hereafter hypereutectic Al-Si alloy of United States Patent (USP) (US6669792) invention is promptly controlled Si:Mg ratio (15-35) and Cu:Mg ratio (4-15) improves performance.Utilize the Al-Si alloy material silicon content of spray pulverization or extrusion casting method preparation can reach 50%~70% in addition." a kind of preparation method of low bulk ultra high silicon aluminium alloy " of people's inventions such as the military Gao Hui of Harbin Institute of Technology (ZL200410043855.9), adopt the extrusion casting preparation method of matrix material, 60%~70% silica flour is made prefabricated component, prefabricated component is infiltrated in the extruding of aluminium liquid to form, this class material is mainly used in the Electronic Packaging field, should belong to matrix material or functional materials.And adopt liquid be shaped or the silicon content as the component of structured material of semi-solid-state shaping method manufacturing generally should be lower than 26%.
As a focus of new metallic substance research field, all there are many achievements in research to make known publicly both at home and abroad about silumin.The transcocrystallized Al-Si alloy that the existing part of western developed countries such as U.S., moral, Russia, day, method has standard brand is applied to industrial production.And at home, it is more still to be in achievement in research, the situation that practical application is less.The aluminium alloy of domestic widely used A390, the trades mark such as ZL108, ZL109 more and more is difficult to adapt to the demand of Modern Traffic carrier development at present, presses for exploitation new aluminum alloy materials and corresponding production technique.Main purpose of the present invention is exactly the aluminium alloy and the technology of preparing of exploitation heat resisting low expansion, main application is automobile, motorcycle and other transportation means, and the aerospace industry, the novel material of exploitation has a very important role to improving complete machine performance, reduction oil consumption and discharging etc.
Summary of the invention
The object of the present invention is to provide a kind of heat resisting low expansion silumin, this aluminium alloy had both had good wear resistance, had kept mechanical property preferably again, had good comprehensive performances; The present invention also provides the preparation method of this aluminium alloy.
Heat resisting low expansion silumin provided by the invention, its alloying element is formed and mass percent is:
Si 18~25, and Cu 1.0~2.5, and Ni 0.5~2.5, and Mn 0.3~0.6, and Mg 0.2~0.8, and RE 0.3~1.0, and wherein, the mass percent of Ce is greater than 40% among the RE, and P 0.006~0.04, and surplus is Al.
The preparation method of above-mentioned heat resisting low expansion silumin at first prepares raw material in proportion, wherein, increases the consumption of P, is 0.04~0.1% of raw material gross weight, carries out following process then:
The 1st step was molten into the aluminum silicon alloy melt with copper, nickel, silicon, aluminum feedstock;
The 2nd step added the manganese raw material again with aluminum silicon alloy melt overheat to 850~870 ℃, obtained blend melt after the fusion evenly; Afterwards, again the temperature of blend melt is transferred to 780~800 ℃ and is added magnesium;
The 3rd step added rare earths material in above-mentioned blend melt, and be incubated 10~15 minutes and be warming up to 820~840 ℃ afterwards,
The 4th step refining;
The 5th step was warming up to 830~850 ℃ with the blend melt of refining, and added phosphorus processings of go bad, was incubated 15~20 minutes after rotten the processing, poured into a mould again, and teeming temperature is 790~830 ℃, obtains the heat resisting low expansion silumin foundry goods.
The present invention combines composition design and conventional cast method, and the choose reasonable of the rotten treatment process by starting material selection, melting technology, melt, pouring technology, thermal treatment process etc. has improved the over-all properties of silumin material effectively.This material can be used for making engine periphery part, as piston, or other antiwear heat resisting part.Have, the present invention has following characteristics:
(1) heat resisting low expansion silumin of the present invention, si content are 18%~25%, have both guaranteed the wear resistance that material is good, are unlikely to again to cause the mechanical property of alloy to descend significantly because of silicone content is too high.
(2) alloying action of elements such as the Cu that is added in the fusion process, Mg, Ni has guaranteed the room temperature and the mechanical behavior under high temperature of alloy material.Again owing on castmethod, adopted RE+P's. composite inoculating is handled, refinement when having realized hypereutectic aluminium alloy primary silicon and Eutectic Silicon in Al-Si Cast Alloys, and modification effect is better, as shown in Figure 1, thus the mechanical property height of alloy.Primary silicon mean sizes in the alloy of rotten back is at 20~30 μ m, and Eutectic Silicon in Al-Si Cast Alloys becomes granular or rod-short by the minute hand shape, and form has obtained very big improvement.Eutectic Silicon in Al-Si Cast Alloys spheroidizing and being uniformly distributed in α-Al matrix after T6 thermal treatment, this helps further to improve alloy mechanical property.This material can be used for making engine periphery part, as piston, or other antiwear heat resisting part.
(3) silumin foundry goods of the present invention is after T6 thermal treatment, and room temperature tensile strength can reach 260~290MPa, and 300 ℃ of tensile strength are 160~180MPa, 25~300 ℃ of thermal expansivity 17.0 * 10
-6~18.0 * 10
-6/ ℃, can satisfy the performance requriements of engine for automobile periphery material preferably.Table 1 is depicted as the silumin that alloying constituent is Al-20Si-2Cu-1Ni-0.4Mg-0.5Mn, through the RE+P composite inoculating, and cast
The standard tensile sample, through room temperature and the high temperature tensile strength after the T6 thermal treatment, and 25~300 ℃ of thermal expansivity.
The performance of table 1 silumin material
Sequence number |
Room temperature strength (MPa) |
300 ℃ of hot strengths (MPa) |
25~300 ℃ of thermal expansivity (1/ ℃) |
1 |
270 |
165 |
17.4×10
-6 |
2 |
275 |
164 |
17.2×10
-6 |
3 |
290 |
180 |
17.8×10
-6 |
Description of drawings
Fig. 1 is the metallographic structure figure of silumin as cast condition of the present invention;
Fig. 2 is silumin T6 thermal treatment metallographic structure figure of the present invention.
Embodiment
The present invention mainly studies, designs a kind of heat resisting low expansion silumin, and target is to have good room temperature and mechanical behavior under high temperature and lower thermal expansivity.On this basis, the method for this heat resisting low expansion silumin of research preparation comprises the rotten treatment process, pouring technology, thermal treatment process of starting material selection, melting technology, melt etc.
The alloying element of heat resisting low expansion silumin is formed and mass percent is:
Si 18~25, and Cu 1.0~2.5, and Ni 0.5~2.5, and Mn 0.3~0.6, and Mg 0.2~0.8, and RE 0.3~1.0, and wherein, the mass percent of Ce is greater than 40% among the RE, and P 0.006~0.04, and surplus is Al.
The preparation of above-mentioned heat resisting low expansion silumin comprises melting and two processes of rotten processing.The material of Si, Mn, RE, phosphoric adopts its middle alloy usually.Si adopts aluminium silicon master alloy usually, or the technical pure aluminium ingot adds silicon metal, Mn employing aluminium manganese master alloy, RE employing aluminium rare earth intermediate alloy, phosphoric employing phosphor bronze alloy.Before beginning preparation, prepare standby by above-mentioned mass percent raw material earlier.The processing owing to need to go bad in the preparation process, P can be by a large amount of scaling loss in the rotten treating processes, so want excess to add P, promptly the phosphorus add-on is 0.04~0.1% of a raw material gross weight, the actual content that so just can make P in the silumin for preparing is 0.006~0.04%.
In the above-mentioned preparation process, RE, P add as alterant, carry out double composite inoculating, play the purpose of rotten eutectic Si and primary crystal Si respectively.
Water the foundry goods that outpours and need heat-treat usually, suitable T6 thermal treatment process is: 510 ℃ of solution treatment were quenched after 6~10 hours, and through 190 ℃ of ageing treatment 8~14 hours, middle quenchant was 70~80 ℃ of water again.
Below by by embodiment the present invention being described in further detail, but following examples only are illustrative, and protection scope of the present invention is not subjected to the restriction of these embodiment.
Embodiment 1
A00 number pure Al, the pure Ni of 99.9% (massfraction, together following), 99.99% pure Cu, Al-25.8%Si master alloy are dropped in the smelting furnace, make it be molten into the aluminum silicon alloy melt.Alloy melt is superheated to 850 ℃ again, adds the Al-10%Mn master alloy.Stir after the heating for dissolving then and obtain blend melt; Afterwards, melt temperature is transferred to 780 ℃ adds 99.9% pure Mg, resulting alloying constituent is Al-20Si-2Cu-1Ni-0.4Mg-0.5Mn-1.0RE-0.01P, and all the other are Al.Add the Al-15%RE master alloy after fusing finishes, the content of Ce is 50% among the RE, and making the final RE content of aluminium alloy is 1.0%, mainly plays eutectic Si metamorphism.With pure Ar gas melt is carried out refining in the time of 820 ℃, skim, leave standstill 10min.Add phosphor bronze alloy and carry out the rotten of primary crystal Si, the P add-on is a raw material gross weight 0.06%, and the final content that makes P is about 0.01%.The rotten back of handling is incubated 18 minutes.Alloy melt after rotten directly pours into the metal mold tension specimen mould through preheating; 820 ℃ of teeming temperatures.The foundry goods that cast is come out carries out T6 thermal treatment.Thermal treatment process is T6:510 ℃ of solid solution 7 hours, and 190 ℃ of ageing treatment are 10 hours after 70 ℃ of shrends.The mechanical property of this material can reach room temperature strength 280MPa, 300 ℃ of hot strength 170MPa; 25~300 ℃ of thermal expansivity reach 17.6 * 10
-6/ ℃.
Embodiment 2
A00 number pure Al, No. 1 silicon metal, the pure Ni of 99.9% (massfraction, together following), 99.99% pure Cu are dropped in the smelting furnace, make it be molten into the aluminum silicon alloy melt.Alloy melt is superheated to 870 ℃ again, adds the Al-10%Mn master alloy.Stir after the heating for dissolving then and obtain blend melt; Afterwards, melt temperature is transferred to 800 ℃ adds 99.9% pure Mg, carry out melting in crucible electrical resistance furnace, the alloyage composition is Al-25Si-2.5Cu-0.5Ni-0.8Mg-0.6Mn-0.8RE-0.04P, and all the other are Al.Add Al-10%RE after fusing finishes, the content of Ce is 65% among the RE, and making the final RE content of aluminium alloy is 0.8%, mainly plays eutectic Si metamorphism.With pure Ar gas melt is carried out refining in the time of 820 ℃, skim, leave standstill 10min.Add phosphor bronze alloy and carry out the rotten of primary crystal Si, the P add-on is a raw material gross weight 0.10%, and the final content that makes P is about 0.04%.The rotten back of handling is incubated 15 minutes, and the alloy melt after going bad directly pours into the metal mold tension specimen mould through preheating; 830 ℃ of teeming temperatures.The foundry goods that cast is come out carries out T6 thermal treatment.Thermal treatment process is T6:510 ℃ of solid solution 9 hours, and 190 ℃ of ageing treatment are 14 hours after 70 ℃ of shrends.The mechanical property of this material can reach room temperature strength 265MPa, 300 ℃ of hot strength 180MPa; 25~300 ℃ of thermal expansivity reach 17.0 * 10
-6/ ℃.
Embodiment 3
A00 number pure Al, No. 1 silicon metal, the pure Ni of 99.9% (massfraction, together following), 99.99% pure Cu are dropped in the smelting furnace, make it be molten into the aluminum silicon alloy melt.Alloy melt is superheated to 870 ℃ again, adds the Al-10%Mn master alloy.Stir after the heating for dissolving then and obtain blend melt; Afterwards, melt temperature is transferred to 800 ℃ adds 99.9% pure Mg, carry out melting in crucible electrical resistance furnace, the alloyage composition is Al-18Si-1.0Cu-2.5Ni-0.2Mg-0.3Mn-0.3RE-0.006P, and all the other are Al.Add Al-10%RE after fusing finishes, the content of Ce is 45% among the RE, and making the final RE content of aluminium alloy is 0.3%, mainly plays eutectic Si metamorphism.With pure Ar gas melt is carried out refining in the time of 820 ℃, skim, leave standstill 10min.Add phosphor bronze alloy and carry out the rotten of primary crystal Si, the P add-on is a raw material gross weight 0.04%, and the final content that makes P is about 0.006%.The rotten back of handling is incubated 20 minutes, and the alloy melt after going bad directly pours into the metal mold tension specimen mould through preheating; 790 ℃ of teeming temperatures.The foundry goods that cast is come out carries out T6 thermal treatment.Thermal treatment process is T6:510 ℃ of solid solution 8 hours, and 190 ℃ of ageing treatment are 12 hours after 70 ℃ of shrends.The mechanical property of this material can reach room temperature strength 300MPa, 300 ℃ of hot strength 155MPa; 25~300 ℃ of thermal expansivity reach 18.0 * 10
-6/ ℃.
The above is preferred embodiment of the present invention, but the present invention should not be confined to the disclosed content of the foregoing description.So everyly do not break away from the equivalence of finishing under the spirit disclosed in this invention or revise, all fall into the scope of protection of the invention.