CN107190219A - The heat treatment method of the Casting Al-Li Alloy containing magnesium - Google Patents

The heat treatment method of the Casting Al-Li Alloy containing magnesium Download PDF

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CN107190219A
CN107190219A CN201710225042.9A CN201710225042A CN107190219A CN 107190219 A CN107190219 A CN 107190219A CN 201710225042 A CN201710225042 A CN 201710225042A CN 107190219 A CN107190219 A CN 107190219A
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alloy
magnesium
casting
heat treatment
treatment
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CN107190219B (en
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张小龙
张亮
吴国华
史春昌
陈安涛
陶佳申
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Shanghai Jiaotong University
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    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22FCHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/04Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22FCHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/04Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
    • C22F1/057Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon of alloys with copper as the next major constituent

Abstract

The invention provides a kind of heat treatment method of Casting Al-Li Alloy containing magnesium, the step of the step of its three-stage solution for including carrying out successively is handled and slow heating Ageing Treatment.The present invention is by reasonably optimizing aging treatment process, by being heated slowly to aging temp this method, the main hardening constituent (Al of control alloy3Li, Al2CuLi and Al2Cu volume fraction, size and distribution), more traditional aging treatment process can promote Al3The uniform of Li is grown up and Al2The precipitation of Cu (θ ') phase, promotion, S (Al2) and T1 (Al CuMg2CuLi) the heterogeneous forming core of phase and grow up;This slow heating aging technique greatly improves the plasticity of the Casting Al-Li Alloy containing magnesium while Casting Al-Li Alloy intensity is improved.

Description

The heat treatment method of the Casting Al-Li Alloy containing magnesium
Technical field
The present invention relates to a kind of heat treatment method of Casting Al-Li Alloy containing magnesium, belong to field of aluminum alloy heat treatment technology.
Background technology
Aluminium lithium alloy material is a kind of advanced lightweight structure material, is developed particularly in aerospace material in recent years Rapidly, with density is low, specific strength and specific stiffness are high, modulus of elasticity is high, fatigue crack growth rate is low, cryogenic property is preferable, Many excellent combination properties such as good corrosion resistance and the superplastic forming performance of brilliance.The high intensity aluminium of routine is replaced with it Alloy can make architecture quality mitigate 10~20%, and rigidity improves 15~20%.
Lithium (Li) is metallic element most light in nature, and density is only 0.534g/cm3, research shows:In aluminium alloy The Li that often addition mass fraction is 1%, can make alloy density reduce by 3%, modulus of elasticity is improved 6%.Li is in Al solid solutions There is a kind of metallic element of higher solubility in body, maximum (4.2%), as temperature is reduced, Li's are reached at 603 DEG C Solid solubility reduces therewith, is then reduced to less than 1% at room temperature, ageing strengthening effect is obvious.During fixation rates, Al3Li phases (δ ' phases) are separated out from supersaturated solid solution, the Al in subsequent timeliness3Li, which meets, progressively to grow up, and has to strength enhancing Very big contribution.But Al3Li phases are easily cut through by dislocation, and planar slip and strain can be caused to concentrate, when Li contents are higher, at heat Manage technological requirement it is very strict because Li elements can near crystal boundary segregation, while Al3A large amount of precipitations of Li phases can cause alloy Plasticity be greatly reduced, especially in deformation aluminium lithium alloy, dislocation density is high, it is easier to occurs planar slip and produces texture, Material anisotropy is serious, thus deformed in practical application the Li contents of aluminium lithium alloy it is relatively low (<1.5wt.%).
And in Casting Al-Li Alloy, the limitation for Li contents can suitably be relaxed, reason is dislocation density compared to deformation Alloy is substantially reduced, and planar slip tails off.But on Casting Al-Li Alloy composition design and Technology for Heating Processing exploration also In the presence of very big blank.Han Jiande of Shandong University et al. have studied the tissue and performance of casting Al-Li-Cu alloys, heat treatment The tensile strength of alloy reaches 350MPa afterwards, but elongation percentage is only 0.4%;Russia researcher find by add Cd and Be elements, can improve the plasticity of Casting Al-Li Alloy, but Cd and Be are toxic elements.Many studies have shown that Mg elements are becoming There are many advantageous effects in shape aluminium lithium alloy, in terms of mainly having three below:1. Mg elements can reduce Li consolidating in Al matrixes Solubility, so as to promote Al in ageing impact toughness3The precipitation of Li phases (δ ') coherence strengthening phase;2. Mg can also play solution strengthening work With especially by Mg, Cu simultaneously addition aluminium lithium alloy, when forming Al-Li-Cu-Mg systems, Mg can form Mg- together with Cu Cu- rooms cluster, promotes Al2A large amount of precipitations of Cu phases (θ '), can also form the S-phase (Al of lath-shaped2CuMg), its solid matter face Al matrixes are not parallel to, dislocation can only bypass S-phase, so as to form dislocation ring at S-phase, effectively disperse planar slip, reduce nothing The width in Precipitation area, improves intensity and plasticity;3. low-alloyed density can also further drop in Mg addition.And China Former magnesium resource enrich, be alloy element with low cost, have good actual application value in aluminium lithium alloy.
But, the addition of Mg elements may separate out Al in process of setting2CuMg, Al2MgLi and other low melting points Non-equilibrium second phase, can further increase the heat treatment difficulty of alloy again.How to make the abundant solid solution of alloying element and do not occur Obvious roughening does not occur yet for burning, crystal grain, is the key for solving the practical application of Casting Al-Li Alloy containing magnesium.Both at home and abroad for containing magnesium The design of Casting Al-Li Alloy and the research of Technology for Heating Processing are seldom, therefore necessary progress exploration sex work.Can be for reference Aluminium lithium alloy Technology for Heating Processing all be for deforming alloy design, deforming alloy heat treatment usually first carry out single-stage or Two-step homogenization, is then rolled or crimp processing, high temperature, short time solid solution is carried out afterwards, artificial aging is then carried out (T6 processing) or predeformation add artificial aging to handle (T8 processing).Typical deformation Al-Li-Cu-Mg deformation aluminium lithium alloys Technology for Heating Processing example has:
⑴AA2195(Al-4Cu-1Li-0.4Ag-0.4Mg-0.11Zr):450 DEG C × 24h+500 DEG C × 6h is carried out first Alloy, is then preheating at 420 DEG C and carries out hot rolling by two-step homogenization processing, and then thin plate is carried out at 504 DEG C × 1h solid solutions Reason, quenching-in water is after carrying out artificial aging at 180 DEG C;
⑵Al-2.13Li-1.28Cu-1.13Mg-0.2Zr:It is uniform that 450 DEG C × 16h+510 DEG C × 10h twin-stages are carried out first Change is handled, and crimp is then carried out at 450 DEG C, and then bar is carried out in 530 DEG C × 1h high temperature, short time solution treatment, water Quenching is after carrying out artificial aging at 190 DEG C;
⑶AA2099(Al-2.74Cu-1.77Li-0.32Mg-0.72Zn-0.34Mn-0.11Zr):510 DEG C are carried out first The processing of × 12h+530 DEG C × 36h two-step homogenizations, then carries out crimp at 470 DEG C, then carries out 540 DEG C to bar × 1h high temperature, short time solution treatment, quenching-in water carries out artificial aging after 160 DEG C.
Actual to prove, aluminium lithium alloy is very sensitive to Technology for Heating Processing, the Technology for Heating Processing phase of the aluminium lithium alloy of heterogeneity It is poor substantially, the Homogenization Treatments in deforming alloy are to dissolve non-equilibrium second phase in part, improve deformability, high temperature, short time Solid solution causes the second phase solid solution near crystal boundary to enter matrix;Casting Al-Li Alloy is different, and solution treatment need to cause as far as possible Non-equilibrium second mutually dissolves in matrix, and otherwise the plasticity of alloy can be very poor, especially after timeliness, therefore at the heat of deforming alloy Science and engineering skill can only be used as reference.In the heat treatment of Casting Al-Li Alloy, the abundant solid solution of alloying element, non-equilibrium second should be ensured Mutually eliminate as much as, excessive grain can not be made to grow up again.The addition of Mg elements, may separate out Al in process of setting2CuMg, Al2MgLi and non-equilibrium second phase of other low melting points, can further increase the heat treatment difficulty of alloy again.
The content of the invention
The purpose of the present invention is to overcome the heat treatment difficulty of Casting Al-Li Alloy containing magnesium, and the low shortcoming of plasticity contains for new There is provided a kind of heat treatment method of Casting Al-Li Alloy for magnesium Casting Al-Li Alloy exploitation new multistage Technology for Heating Processing.Pass through The Casting Al-Li Alloy containing magnesium of this PROCESS FOR TREATMENT, can give full play to the potentiality of alloy, obtain high intensity while, keep compared with High plasticity, realizes Strengthening and Toughening.Be conducive to the application and development of high-strength casting aluminium lithium alloy in promoting.
The present invention is achieved by the following technical solutions:
The invention provides a kind of heat treatment method of Casting Al-Li Alloy containing magnesium, it includes the three-stage solution carried out successively The step of the step of processing and slow heating Ageing Treatment.
Preferably, the step of three-stage solution is handled specifically includes following operation:
Magnesium Casting Al-Li Alloy will be contained successively at 445~465 DEG C, at 515~535 DEG C and at 540~550 DEG C to be consolidated Molten insulation.
Preferably, the Casting Al-Li Alloy containing magnesium at 445~465 DEG C, at 515~535 DEG C and 540~ Soaking time at 550 DEG C is respectively 16~24h, 20~32h, 2~12h.
Preferably, in the three-stage solution processing, the heating rate of temperature-rise period is no more than 4 DEG C/min, control Furnace temperature precision is ± 5 DEG C.
Preferably, the step of slow heating Ageing Treatment specifically includes following operation:
Casting Al-Li Alloy containing magnesium after three-stage solution is handled is warming up to 150~170 DEG C with 6~10 DEG C/h speed Under, timeliness is incubated 8~32h.
Preferably, the step of slow heating Ageing Treatment is the salt bath furnace in controllable heating rate or oil bath Carried out in stove, it is ± 3 DEG C to control furnace temperature precision.
Preferably, the Casting Al-Li Alloy containing magnesium includes each element of following mass percent:Li、1.7 ~2.3wt.%, Cu, 1.5~2.5wt.%, Mg, 0.4~2.5wt.%, surplus are Al and inevitable impurity.
Preferably, also include in the Casting Al-Li Alloy containing magnesium in following element by mass percentage It is at least one:Zr, 0.11~0.25wt.%, Yb, 0.1~0.3wt.%, Sc, 0.05~0.15wt.%, Ag, 0.1~ 0.6wt.%.
Many for the second phase species in Casting Al-Li Alloy containing magnesium, fusing point height is different, and single solution treatment is difficult, it is difficult to Non-equilibrium second phase being enriched with crystal boundary is eliminated, the situation for causing alloy plasticity toughness very poor, the inventive method is solid using three-level Molten processing, first order solid solution at 445~465 DEG C is incubated 16~24h, it is ensured that the mutually fully solid solution of low melting point containing magnesium second;Second Level is warming up to solid solution at 515~535 DEG C and is incubated 20~32h, according to the relative height of content of magnesium specific to a temperature in interval Spend near nodal insulation;Finally it is warming up at 540~550 DEG C solid solution and is incubated 2~12h, high temperature, short time solution treatment, by indissoluble the Two-phase is dissolved as far as possible, while avoiding burning and grain coarsening.The purpose of slow heating Ageing Treatment is to allow described in claim 1 Al in temperature-rise period3The crystal defects such as accumulation of vacancies that Li phases are grown up discharged formation dislocation ring, in subsequent slow heating and In timeliness insulating process, these defects can be Al2Cu phases (θ ') and S-phase (Al2CuMg) forming core and power of growing up are provided, enters one While step improves the intensity of alloy, disperse sliding, reduce stress concentration, greatly improve the plasticity of alloy, using being heat-treated work Skill realizes the Strengthening and Toughening of alloy, gives full play to the potentiality of alloy.
Compared with prior art, the present invention has following beneficial effect:
1st, the present invention considers different non-equilibrium second phase (AlLi, Al in Casting Al-Li Alloy containing magnesium3Li、Al2Cu, Al2CuMg, Al2MgLi and Al2CuLi solidus temperature), Interest frequency solid solubility temperature and soaking time, makes eutectic containing magnesium Point second carries out abundant solid solution under the relatively low solid solubility temperature of the first order, it is to avoid occurred in subsequent high temperature solution treatment Burn, the second level causes the second main phase Al2Cu and Al2CuLi etc. is dissolved at relatively high temperatures, and short time high temperature is finally imposed again and is consolidated Molten processing ensures the abundant solid solution of the phase of indissoluble second;High-temperature holding time is shortened, it is upper to greatest extent to solve non-equilibrium second phase Dissolving and crystallite dimension increase between contradiction.In optimized temperature range, content of magnesium is relatively higher, and the classification that need to be used is consolidated Molten temperature is relatively higher, and the temperature of corresponding artificial aging is relatively lower.Higher solid solubility temperature ensures that alloying element is abundant Dissolving, lower aging temp is to prevent Al3Li particles are largely separated out and rapid roughening.Compared with traditional solution handling process, Be enriched near the crystal boundary of Casting Al-Li Alloy containing magnesium second is set mutually to be greatly decreased, alloying element is able to abundant solid solution, avoids simultaneously Crystallite dimension rises appreciably, and greatly improves alloy in solid solution state and the elongation percentage of aging state, solves prior heat treatment process The inductile problem of the insurmountable Casting Al-Li Alloy containing magnesium, the Strengthening and Toughening of alloy is realized by heat treatment;
2nd, the present invention is by reasonably optimizing aging treatment process, by being heated slowly to aging temp this method, control Main hardening constituent (the Al of alloy3Li, Al2CuLi and Al2Cu volume fraction, size and distribution), more traditional Ageing Treatment work Skill, can promote Al3The uniform of Li is grown up and Al2The precipitation of Cu (θ ') phase, promotion, S (Al2) and T CuMg1(Al2CuLi) phase Heterogeneous forming core and grow up;This slow heating aging technique is greatly improved containing magnesium casting while Casting Al-Li Alloy intensity is improved Make the plasticity of aluminium lithium alloy.
Brief description of the drawings
By reading the detailed description made with reference to the following drawings to non-limiting example, further feature of the invention, Objects and advantages will become more apparent upon:
Fig. 1 is the as-cast structure photo of the two kinds of alloys used in embodiment 1;
Fig. 2 be embodiment 1 in through technique sequence number 1-1 be heat-treated after alloy A and B metallographic structure photo;
Fig. 3 be embodiment 1 in through technique sequence number 1-1 be heat-treated after alloy A bright field image TEM photos;
Fig. 4 be embodiment 1 in through technique sequence number 1-1 be heat-treated after alloy B bright field image TEM photos;
Fig. 5 is grain size, tissue contrast metallographic group of the alloy under as cast condition in embodiment 2 containing magnesium alloy and without magnesium Knit photo;
What Fig. 6 contrasted to add the alloy of Sc microalloyings in embodiment 3 with alloy B in embodiment 1 in as cast condition and solid solution state Metallograph;
Fig. 7 is the metallographic structure contrast photo after different third level solution times processing in comparative example 5.
Embodiment
With reference to specific embodiment, the present invention is described in detail.Following examples will be helpful to the technology of this area Personnel further understand the present invention, but the invention is not limited in any way.It should be pointed out that to the ordinary skill of this area For personnel, without departing from the inventive concept of the premise, various modifications and improvements can be made.These belong to the present invention Protection domain.
Embodiment 1
The Casting Al-Li Alloy containing magnesium used in the present embodiment is voluntarily melting and is used obtained by metal mold gravity casting, Nominal chemical composition is by mass percentage:Li 2.0%, Cu 2.0%, Zr 0.20%, 0.4%Mg, remaining is Al, is designated as Alloy B, for advantageous effect of the display Mg elements in Casting Al-Li Alloy, same technique melts out the aluminium lithium alloy without magnesium Group as a comparison, the actual constituent for being designated as alloy A, alloy A and alloy B is as shown in table 1.As-cast structure is made up of dendrite, brilliant The as-cast structure metallograph that a and b in continuous second phase, Fig. 1 is respectively alloy A and alloy B in the present embodiment is enriched with boundary, Analyzed by XRD and EDS, second is mutually main by Al2Cu、Al2CuLi and Al3Li is constituted, a small amount of containing also existing in magnesium alloy Al2CuMg phases.The elongation percentage of alloy is all 0.6~1.0% or so under as cast condition.
Be heat-treated respectively using alloy A manufactured in the present embodiment and alloy B, only control first order solution treatment when Between it is different, obtain 6 samples, A-1, A-2, A-3 and B-1, B-2, B-3 be designated as respectively, wherein, sample A-1 and sample B-1 heat Processing method is as shown in the technique sequence number 1-1 in table 2:
Step one:It is first that fine sand is placed in the vessel, then be placed in heat-treatment furnace and be dried and heat up.Furnace temperature is stable at After 450 DEG C of the first order solid solubility temperature of setting, ready aluminium lithium alloy A and B is buried in dry fine sand.It is incubated 16 small Shi Hou, is warming up to 515 DEG C and is incubated 20 hours, is finally warming up at 540 DEG C and is incubated 2 hours.Insulation is transferred in warm water after terminating Quenching.
Step 2:Alloy after solid solution is transferred in oil bath furnace (or salt bath furnace) and is warming up to 170 DEG C, liter from room temperature with stove Warm speed is 8 DEG C/h, waits that being warming up to 170 DEG C is incubated 16 hours, soaking time terminates rear water quenching.
The technique sequence number 1-2 first order solution treatment time is 12h, technique sequence number 1-3 first order solution treatment time For 24h.
The actual constituent (mass percent/wt.%) of alloy is used in the embodiment 1 of table 1
Alloy Li Cu Mg Zr Fe Al
A (is free of magnesium) 1.96 1.95 0.014 0.21 0.13 Bal.
B (contains magnesium) 1.98 1.93 0.41 0.18 0.11 Bal.
Comparative example 1
This comparative example is, in order to be contrasted, work to be heat-treated according to traditional aging to the alloy A and alloy B in embodiment 1 Skill is handled, and treatment conditions are as shown in comparative example 1 in table 2.
The multistage heat treatment process parameter of alloy in the embodiment 1 of table 2 and comparative example 1
Technique sequence number First order solid solution Second level solid solution Third level solid solution Timeliness heats up Timeliness
1-1 450℃×16h 515℃×20h 540℃×2h 8℃/h 170℃×16h
1-2 450℃×12h 515℃×20h 540℃×2h 8℃/h 170℃×16h
1-3 450℃×24h 515℃×20h 540℃×2h 8℃/h 170℃×16h
Comparative example 1 450℃×16h 515℃×20h 540℃×2h -- 170℃×16h
Fig. 2 a and 2b are respectively the metallographic structure of alloy A and alloy B after technique sequence number 1-1 solution treatment conditions in table 2 Photo, is mutually greatly reduced compared with being remained on as-cast structure crystal boundary.Fig. 3 is alloy A after technique sequence number 1-1 heat treatment conditions in table 2 Light field phase TEM photos, it can be seen that tiny Al is occurred in that after heat treatment3Li phases and Al3Li/Al3Zr compound particles and a small amount of T1Phase, Fig. 4 is the aging state bright field image TEM photos of alloy B after technique sequence number 1-1 heat treatment conditions in table 2, adds Mg elements Afterwards, alloy precipitated phase species, size and the distribution of aging state are varied considerably, Al2Cu (θ ') phases and T1Alloy mutually greatly improved Intensity and plasticity.
The mechanical experimental results of alloy A and B after method heat treatment in embodiment 1 and comparative example 1 are respectively such as table 3 With shown in table 4.
Mechanical experimental results in the embodiment 1 of table 3 and comparative example 1 after alloy A multistage heat treatment
Mechanical experimental results in the embodiment 1 of table 4 after alloy B multistage heat treatment
Embodiment 2
The Casting Al-Li Alloy containing magnesium used in the present embodiment is voluntarily melting and is used obtained by metal mold gravity casting, Nominal chemical composition is by mass percentage:Li 2.0%, Cu 2.0%, Zr 0.20%, 2.5%Mg, remaining is Al.Adding Plus high level Mg elements when, the as-cast structure of alloy is made up of dendrite, and continuous second be enriched with crystal boundary is mutually more, brilliant Grain has a slight refinement compared to the control group for being not added with Mg elements, and reason is the constitutional supercooling that causes of segregation of Mg elements to as cast condition group Certain refining effect is woven with, as shown in figure 5, the cast alloy containing 2.5Mg has than the crystal grain of the cast alloy (0Mg) without Mg A certain degree of refinement.Analyzed by XRD and EDS, second be enriched near crystal boundary is mainly mutually Al2Cu、Al2CuLi、Al3Li And Al2CuMg phases.The tensile strength of the alloy containing 2.5Mg is 200MPa under as cast condition, and elongation percentage is 0.8%.
Be heat-treated using Casting Al-Li Alloy containing magnesium manufactured in the present embodiment, only control first order solution treatment when Between it is different, obtain 3 samples, sample 2-1,2-3 and 2-3 be designated as respectively, wherein, sample 2-1 heat treatment method is as in table 5 Shown in technique sequence number 2-1:
Step one:It is first that fine sand is placed in the vessel, then be placed in heat-treatment furnace and be dried and heat up.Furnace temperature is stable at After 465 DEG C of the first order solid solubility temperature of setting, ready aluminium lithium alloy is buried in dry fine sand.Insulation 24 hours Afterwards, 535 DEG C are warming up to and is incubated 20 hours, is finally warming up at 550 DEG C and is incubated 4 hours.Insulation is transferred in warm water after terminating quenches Fire.
Step 2:Alloy after solid solution is transferred in oil bath furnace (or salt bath furnace) and is warming up to 150 DEG C, liter from room temperature with stove Warm speed is 6 DEG C/h, waits that being warming up to 150 DEG C is incubated 12 hours, soaking time terminates rear water quenching.Add after Mg elements, aging state Alloy precipitated phase species, size and distribution vary considerably, Al2Cu (θ ') phases and T1Phase and S (Al2CuMg a large amount of precipitations), The intensity and plasticity of alloy greatly improved.
The sample 2-2 first order solution treatment time is 12h, and the sample 2-3 first order solution treatment time is 30h.
Comparative example 2
This comparative example be in order to be contrasted, to the alloy in embodiment 2 according to traditional aging Technology for Heating Processing at Reason, treatment conditions are as shown in comparative example 2 in table 5.
The Mechanics Performance Testing of alloy after being heat-treated through the present embodiment method is as shown in table 6.
The multistage heat treatment process parameter of alloy in the embodiment 2 of table 5
Technique sequence number First order solid solution Second level solid solution Third level solid solution Timeliness heats up Timeliness
2-1 465℃×24h 535℃×20h 550℃×4h 6℃/h 150℃×12h
2-2 465℃×12h 535℃×20h 550℃×4h 6℃/h 150℃×12h
2-3 465℃×30h 535℃×20h 550℃×4h 6℃/h 150℃×12h
Comparative example 2 465℃×16h 535℃×20h 550℃×4h -- 150℃×12h
Mechanical experimental results of the alloy after multistage heat treatment in the embodiment 2 of table 6
Embodiment 3
The Casting Al-Li Alloy containing magnesium used in the present embodiment is voluntarily melting and is used obtained by metal mold gravity casting, Nominal chemical composition is by mass percentage:Li 2.0%, Cu 2.0%, Zr 0.20%, 1.0%Mg, 0.11%Sc, remaining For Al.Sc elements are a kind of very effective fining agent in Al alloys, and compared to the alloy B in embodiment 1, crystallite dimension is big Width reduces, and with adding the contrast of the grain size before Sc as shown in figure 6 a and 6b, as-cast structure is changed into tiny from dendrite Equiax crystal.Continuous netted non-equilibrium second phase is still enriched near crystal boundary.The crystal grain significantly refined can not only improve alloy Intensity, while can also there is further lifting to plasticity.
Be heat-treated using Casting Al-Li Alloy containing magnesium manufactured in the present embodiment, only control first order solution treatment when Between it is different, obtain 3 samples, wherein, sample 3-1 heat treatment method is as shown in the technique sequence number 3-1 in table 7:
Step one:It is first that fine sand is placed in the vessel, then be placed in heat-treatment furnace and be dried and heat up.Furnace temperature is stable at After 450 DEG C of the first order solid solubility temperature of setting, ready aluminium lithium alloy is buried in dry fine sand.Insulation 16 hours Afterwards, 515 DEG C are warming up to and is incubated 24 hours, is finally warming up at 540 DEG C and is incubated 2 hours.Insulation is transferred in warm water after terminating quenches Fire.It is alloy in embodiment 1 in alloy B and the implementation case through in table 7 at the 3-1 solid solutions of technique sequence number that Fig. 6 c and 6d, which are respectively, Metallographic structure photo after reason, is mutually greatly reduced compared with being remained on as-cast structure crystal boundary, and the plasticity of alloy obtains carrying greatly very much compared with as cast condition It is high.
Step 2:Alloy after solid solution is transferred in oil bath furnace (or salt bath furnace) and is warming up to 170 DEG C, liter from room temperature with stove Warm speed is 8 DEG C/h, waits that being warming up to 170 DEG C is incubated 16 hours, soaking time terminates rear water quenching.What is used in the implementation case is more Level heat treatment process parameter is as shown in table 7.
The sample 3-2 first order solution treatment time is 12h, and the sample 3-3 first order solution treatment time is 24h.
Comparative example 3
This comparative example be in order to be contrasted, to the alloy in the present embodiment according to traditional aging Technology for Heating Processing at Reason, treatment conditions are shown in comparative example 3 in table 7.
The Mechanics Performance Testing of alloy after being heat-treated through the implementation case method is as shown in table 8.
The multistage heat treatment process parameter of alloy in the embodiment 3 of table 7
Technique sequence number First order solid solution Second level solid solution Third level solid solution Timeliness heats up Timeliness
3-1 450℃×16h 515℃×24h 540℃×2h 8℃/h 170℃×16h
3-2 450℃×12h 515℃×24h 540℃×2h 8℃/h 170℃×16h
3-3 450℃×24h 515℃×24h 540℃×2h 8℃/h 170℃×16h
Comparative example 3 450℃×16h 515℃×24h 540℃×2h -- 170℃×16h
Mechanical experimental results of the alloy after multistage heat treatment in the embodiment 3 of table 8
Comparative example 4
The composition of Casting Al-Li Alloy containing magnesium used in this comparative example is in the same manner as in Example 2, and difference is hot place Manage the details of technological parameter.
Comparative example 5
The composition of Casting Al-Li Alloy containing magnesium used in this comparative example is in the same manner as in Example 2, and difference is hot place Manage the details of technological parameter.
The specific contrast test heat treatment process parameter of comparative example 4~5 is as shown in table 9.
The multistage heat treatment process parameter of alloy in the comparative example 4 and 5 of table 9
Comparative example sequence number First order solid solution Second level solid solution Third level solid solution Timeliness heats up Timeliness
4 465℃×0h 535℃×20h 550℃×4h 6℃/h 150℃×12h
5 465℃×32h 535℃×20h 550℃×4h 6℃/h 150℃×12h
The Mechanics Performance Testing of the alloy after the technical parameter heat treatment of example 4~5 is as shown in table 10 by contrast.As a result table Bright, the first order low temperature solid solution of Casting Al-Li Alloy containing magnesium is essential, it is ensured that low melting point mutually fully dissolves containing magnesium second, no Can be in crystal boundary enrichment, so as to avoid it from turning into the formation of crack of brittle fracture in follow-up solid solution and timeliness.In view of temperature compared with The diffusion rate of solute atoms is relatively slow when low, and soaking time is relatively long;After ensureing that low melting point second mutually fully dissolves, then Extension first order solid solution soaking time does not have a significant effect to the performance of material, therefore considered for the energy is saved, without mistake Divide extension first order solid solution soaking time.
Mechanical experimental results of the alloy after multistage heat treatment in the embodiment 2 of table 10 and comparative example 4 and 5
Comparative example 6
The composition of Casting Al-Li Alloy containing magnesium used in this comparative example is in the same manner as in Example 1, and nominal chemical composition presses matter Measuring percentage is:Li 2.0%, Cu 2.0%, Zr 0.20%, 0.4%Mg, remaining is Al, and difference is to be heat-treated work The parameter detail of skill.
Comparative example 7
The composition of Casting Al-Li Alloy containing magnesium used in this comparative example is in the same manner as in Example 1, and nominal chemical composition presses matter Measuring percentage is:Li 2.0%, Cu 2.0%, Zr 0.20%, 0.4%Mg, remaining is Al, and difference is to be heat-treated work The parameter detail of skill.
The specific heat treatment process parameter of comparative example 6~7 is as shown in table 11.
The multistage heat treatment process parameter of alloy in the comparative example 6 and 7 of table 11
Sample sequence number First order solid solution Second level solid solution Third level solid solution Timeliness heats up Timeliness
Comparative example 6 450℃×16h 515℃×20h 540℃×0h 8℃/h 170℃×16h
Comparative example 7 450℃×16h 515℃×20h 540℃×4h 8℃/h 170℃×16h
Fig. 7 a are the metallographic structure photo of the alloy without third level solution treatment, it can be seen that still can be rich near crystal boundary Collection has non-equilibrium second phase in part, is distributed also uneven;Fig. 7 b are (comparative example 7) solid solution after the third level is handled through 540 DEG C × 4h State metallographic structure photo, only very small amount second are not dissolved in matrix mutually.Alloy after method is heat-treated in example 6 and 7 by contrast Mechanics Performance Testing it is as shown in table 12.Remaining not molten second meets adversely affects to the plasticity of alloy, near crystal boundary Thick second meet as potential formation of crack, material is occurred brittle fracture.But third level solution time is long also Crystal grain is caused to occur more obvious roughening, intensity, the plasticity of alloy can be in a slight decrease.Therefore, the abundant solid solution of alloy is being ensured On the premise of, the time of third level solution treatment should be as short as possible, it is ensured that intensity, the plasticity of material, while also saving energy consumption.
Mechanical experimental results of the alloy after multistage heat treatment in the comparative example 6 and 7 of table 12
Embodiment 4
The Casting Al-Li Alloy containing magnesium used in the present embodiment is voluntarily melting and is used obtained by metal mold gravity casting, Nominal chemical composition is by mass percentage:Li 2.0%, Cu 2.0%, Zr 0.20%, 1.5%Mg, 0.11%Yb, remaining For Al.Yb is also a kind of fining agent effective in Al alloys, can form Al in the alloy3Yb particles are used as heterogeneous forming core matter Point, the crystal grain of effective refining alloy.
The implementation purpose of the present embodiment is to prove influence of the timeliness heating rate to alloy aging state plasticity.Comparative example 8, Comparative example 9 is characterised by that timeliness heating rate is different with comparative example 10.
Specific contrast test heat treatment process parameter is as shown in table 13.
The multistage heat treatment process parameter of alloy in the embodiment 4 of table 13 and comparative example 8~10
The parameter of set contrast experiment is that, with 20 DEG C/h, 3 DEG C/min heating rate is warming up to 170 DEG C and is placed directly in 170 DEG C, compared to slow heating timeliness (embodiment 4), different heating rates have notable shadow to the plasticity of alloy after Ageing Treatment Ring, heating rate is slower, the crystal defect that the room motion aggregation in temperature-rise period is formed is more, promotes θ ' and S-phase Heterogeneous forming core and precipitation are grown up, and are conducive to scattered sliding, are reduced strain and are concentrated, while reducing δ ' (Al to a certain extent3Li) The volume fraction of phase, the plasticity to alloy is greatly improved, and the Ageing Treatment that shows to heat up slowly is a kind of Effective Regulation casting aluminium lithium The method of alloy microstructure, the effect in deforming alloy need specific research.
Mechanical experimental results of the alloy after multistage heat treatment in the embodiment 4 of table 14 and comparative example 8~10
In summary, the present invention considers different non-equilibrium second phase (AlLi, Al in Casting Al-Li Alloy containing magnesium3Li、 Al2Cu, Al2CuMg, Al2MgLi and Al2CuLi solidus temperature), Interest frequency solid solubility temperature and soaking time shorten High-temperature holding time, the contradiction between the upper dissolving for solving non-equilibrium second phase and crystallite dimension increase to greatest extent.Relatively pass System solid solution treatment process, greatly reduces the enrichment of non-equilibrium second phase near the crystal boundary of Casting Al-Li Alloy containing magnesium, alloying element Abundant solid solution is able to, while avoiding the roughening of crystal grain, alloy is greatly improved in solid solution state and the elongation percentage of aging state, solves The inductile problem of the insurmountable Casting Al-Li Alloy containing magnesium of prior heat treatment process, the strong of alloy is realized by heat treatment Toughening.
The present invention controls composition, the chi of the main hardening constituent of alloy by reasonably optimizing two-stage time effect temperature and soaking time Very little and distribution, distinguished is that three-stage solution processing is largely effective to Casting Al-Li Alloy solution treatment, and shortens solid solution Required time, being slowly warming up to the process that aging temp is incubated again has obvious positive role to alloy plasticity.Pass through heat treatment The reasonable application of technique realizes the Strengthening and Toughening of the Casting Al-Li Alloy containing magnesium.
The specific embodiment of the present invention is described above.It is to be appreciated that the invention is not limited in above-mentioned Particular implementation, those skilled in the art can make various deformations or amendments within the scope of the claims, this not shadow Ring the substantive content of the present invention.

Claims (8)

1. the heat treatment method of a kind of Casting Al-Li Alloy containing magnesium, it is characterised in that including the three-stage solution processing carried out successively The step of and the step of slow heating Ageing Treatment.
2. the heat treatment method of the Casting Al-Li Alloy as claimed in claim 1 containing magnesium, it is characterised in that at the three-stage solution The step of reason, specifically includes following operation:
Magnesium Casting Al-Li Alloy will be contained and carry out solid solution guarantor at 445~465 DEG C, at 515~535 DEG C and at 540~550 DEG C successively Temperature.
3. the heat treatment method of the Casting Al-Li Alloy as claimed in claim 2 containing magnesium, it is characterised in that described to cast aluminium containing magnesium Lithium alloy is at 445~465 DEG C, the soaking time at 515~535 DEG C and at 540~550 DEG C be respectively 16~24h, 20~ 32h, 2~12h.
4. the heat treatment method of the Casting Al-Li Alloy as claimed in claim 2 containing magnesium, it is characterised in that at the three-stage solution In reason, the heating rate of temperature-rise period is no more than 4 DEG C/min, and it is ± 5 DEG C to control furnace temperature precision.
5. the heat treatment method of the Casting Al-Li Alloy as claimed in claim 1 containing magnesium, it is characterised in that the slow heating timeliness The step of processing, specifically includes following operation:
Casting Al-Li Alloy containing magnesium after three-stage solution is handled is warming up at 150~170 DEG C with 6~10 DEG C/h speed, when 8~32h of effect insulation.
6. the heat treatment method of the Casting Al-Li Alloy as claimed in claim 5 containing magnesium, it is characterised in that the slow heating timeliness The step of processing, is carried out in the salt bath furnace or oil bath furnace of controllable heating rate, and it is ± 3 DEG C to control furnace temperature precision.
7. the heat treatment method of the Casting Al-Li Alloy as claimed in claim 1 containing magnesium, it is characterised in that described to cast aluminium containing magnesium Lithium alloy includes each element of following mass percent:Li, 1.7~2.3wt.%, Cu, 1.5~2.5wt.%, Mg, 0.4~ 2.5wt.%, surplus is Al and inevitable impurity.
8. the heat treatment method of the Casting Al-Li Alloy containing magnesium as described in claim 1 or 7, it is characterised in that described containing magnesium casting Make in aluminium lithium alloy also including at least one of following element by mass percentage:Zr, 0.11~0.25wt.%, Yb, 0.1~0.3wt.%, Sc, 0.05~0.15wt.%, Ag, 0.1~0.6wt.%.
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