CN104862551A

CN104862551A - Al-Mg-Cu-Zn series aluminum alloy and preparation method of aluminum alloy sheet

Info

Publication number: CN104862551A
Application number: CN201510263049.0A
Authority: CN
Inventors: 张迪; 曹城; 张济山; 庄林忠
Original assignee: University of Science and Technology Beijing USTB
Current assignee: University of Science and Technology Beijing USTB
Priority date: 2015-05-21
Filing date: 2015-05-21
Publication date: 2015-08-26
Anticipated expiration: 2035-05-21
Also published as: CN104862551B

Abstract

The invention discloses an Al-Mg-Cu-Zn series aluminum alloy and a preparation method of an aluminum alloy sheet. On the basis of AA5182 and AA5023 alloys, the content of Cu in the alloy is increased, Zn is added simultaneously, precipitation strength of a transition phase of an S phase in Al-Mg-Cu series and a transition phase of a T phase in Al-Mg-Zn series is sufficiently utilized. Cu and Zn are precipitated simultaneously in an artificial ageing process through solid solution and preageing processing, and cooperative strengthening is realized; by the aid of Cu and Zn which are added simultaneously, the alloy has remarkable natural ageing; according to the preageing processing, the natural ageing can be inhibited, the baked paint softening caused by the natural ageing is avoided, and the strength of the alloy can be remarkably improved after high-temperature ageing processing, especially in the short-term artificial ageing process of 180 DEG C/30 min. The alloy is not only applicable to preparation of inner panels of an automobile, but also is applicable to other related fields of the aluminum alloy.

Description

Al-Mg-Cu-Zn line aluminium alloy and aluminium alloy plate material, preparation method

Technical field

The invention belongs to aluminium alloy and preparation field thereof, particularly relate to a kind of can the Al-Mg-Cu-Zn line aluminium alloy of industrial applications and the preparation method of aluminum alloy plate materials.

Background technology

In order to solve the environment and energy problem that China Automobile Industry brings, automotive light weight technology more and more comes into one's own.Aluminium alloy becomes the best materials of automotive light weight technology with a series of good characteristics such as its high specific tenacity, good erosion resistance, surperficial easy coloring, excellent plasticity and good reproducibilities.

Typical aluminium alloys for automobile has 2xxx, 5xxx and 6xxx system alloy.Wherein 5xxx line aluminium alloy is widely used in car inner plate with its excellent plasticity.But the AA5182 alloy being widely used in car inner plate belongs to the alloy that thermal treatment can not be strengthened, the AA5023 alloy in the existing trade mark is lower due to Cu content, also cannot meet the requirement of the baking hardenability that should have as auto sheet and high anti-indenture.And due to PLC effect, 5xxx line aluminium alloy can form PLC deformation bands in stamping process, the surface smoothness of stamping parts is declined, brings difficulty to the baking vanish of automobile.

At present, in patent CN103255323, researchist improves intensity after the baking vanish of Al-Mg system alloy by adding a small amount of Cu and Zn element, but baking vanish intensity increment is not high; And the stress relief annealing technique of carrying out 240 DEG C ~ 300 DEG C after the aligning proposed in patent can cause Cu, Zn atom of solid solution to be separated out fast forms thick second-phase, strengthening effect can be caused greatly to reduce, the precipitation strength effect of Cu, Zn element cannot be made full use of; Moreover in alloy component range in that patent, Zn atom is difficult to the MgZn described in patent ₂form separate out.Therefore practical application is very limited.

Summary of the invention

The present invention is in order to the problem of the bake hardening that solves existing 5xxx line aluminium alloy and exist in auto sheet application process and anti-indenture deficiency.Separate out while newly-designed alloying constituent and preparation technology thereof take full advantage of Cu and Zn and reach strengthening effect, the timber intensity after baking vanish is greatly improved.

The first object of the present invention is to propose a kind of Al-Mg-Cu-Zn line aluminium alloy composition and composition range thereof, is respectively:

Mg 4.0～6.0wt％；

Cu 0.30～1.0wt％；

Zn 1.0～3.5wt％；

Mn≤0.4wt％；

Fe≤0.4wt％；

Si≤0.4wt％、

Cr≤0.2wt％；

Ti≤0.1wt％；

Surplus is Al and inevitable impurity.

Preferably, Mg 4.2 ~ 5.5wt% is comprised;

Preferably, Cu 0.4 ~ 0.9wt% is comprised;

Preferably, Zn 1.2 ~ 3.0wt% is comprised;

Preferably, Mn 0.1 ~ 0.3wt% is comprised;

The second object of the present invention is to propose a kind of Al-Mg-Cu-Zn line aluminium alloy preparation of plates technique, and this preparation technology comprises the following steps:

A above-mentioned al alloy component is carried out founding by ();

B () is by the annealing of step (a) gained ingot homogenization, hot rolling, cold rolling, solution hardening, ageing treatment.

Homogenizing annealing in described step (b) be by founding after aluminium alloy with the temperature rise rate of 20 ~ 40 DEG C/h start from room temperature be raised to 440 ~ 470 DEG C insulation 6 ~ 12h, and then be warmed up to 470 ~ 490 DEG C of insulation 5 ~ 10h with the temperature rise rate of 20 ~ 40 DEG C/h, and then be warmed up to 500 ~ 540 DEG C of insulation 6 ~ 12h, afterwards with the rate of temperature fall cool to room temperature of 20 ~ 40 DEG C/h with the temperature rise rate of 20 ~ 40 DEG C/h.

Hot-rolled temperature in described step (b) is 460 ~ 510 DEG C, hot rolling total reduction >=90%; Cold rolling total reduction >=80%.

Preferably, cold rolling in described step (b) comprises: first carry out draft be 40% ~ 60% first cold rolling, then carry out process annealing at 350 DEG C ~ 450 DEG C insulation 0.5 ~ 2h, carry out again afterwards draft be 50% ~ 70% second cold rolling.

In described step (b), solid solubility temperature is 520 DEG C ~ 540 DEG C, and solid solution soaking time is 5 ~ 12min, and quenching mode is direct-water-quenching.

In described step (b) ageing treatment be by Water Quenching after alloy transfer in 3 ~ 6min in aging oven and carry out preageing, pre-age temperature is 60 DEG C ~ 100 DEG C, and preageing soaking time is 8 ~ 16h.

C () stamping, japanning and paint baking.

The present invention is on the basis of AA5182 and AA5023 alloy, by improving the content of Cu and Zn in alloy, and introduce Pre-aging treatment, this Pre-aging treatment can not only suppress alloy depositing the natural aging in transportation, and the stationary atom cluster that formed of preageing can become the Precipitation forming core point in baking vanish process subsequently, sheet material intensity increment in the baking vanish process of short period of time is made to reach 50MPa, relative to intensity after the baking vanish of AA5182 and AA5023, after the baking vanish of novel alloy, intensity best result does not improve 140MPa and 100MPa nearly, reach bake hardening effect significantly.The bake hardening of aluminium alloy automobile plate and anti-indenture can be met.This invention alloy is not only applicable to auto sheet, is also applicable to other association areas of aluminium alloy.

Accompanying drawing explanation

The natural aging hardening curve of Figure 11 #, 2#, 5#, 6# alloy quenching state.

Figure 26 # alloy T4 state, the age hardening curves of T4P state at 180 DEG C, and the natural aging hardening curve after 6# alloy quenching state and Pre-aging treatment.

Embodiment

Below in conjunction with concrete case study on implementation the present invention further supplemented and illustrate.

The present invention's ingot casting used adopts common fine aluminium, technical pure Mg, technical pure Zn, and master alloy Al-20wt%Si, Al-50wt%Cu, Al-20wt%Fe, Al-10wt%Mn, Al-10wt%Ti, Al-5wt%Cr founding forms.Case study on implementation alloy specific chemical composition is in table 1.Wherein 1#, 2#, 3#, 4# are with reference to alloy, 5#, 6#, 7# alloying constituent designed by the present invention.

Table 1 embodiment alloy specific chemical composition (mass percent, wt%)

	Mg	Cu	Zn	Mn	Cr	Ti	Fe	Si	Al
										1#	5.2	0	0	0.2	0.05	0.02	0.2	0.1	Surplus
2#	5.18	0.42	0	0.2	0.05	0.02	0.2	0.1	Surplus
										3#	5.19	0	2.0	0.2	0.05	0.02	0.2	0.1	Surplus
4#	5.45	0.44	0.58	0.2	0.05	0.02	0.2	0.1	Surplus
										5#	5.25	0.42	1.19	0.2	0.05	0.02	0.2	0.1	Surplus
6#	5.0	0.44	1.93	0.2	0.05	0.02	0.2	0.1	Surplus
										7#	4.41	0.8	1.2	0.2	0.05	0.02	0.2	0.1	Surplus

。

Alloy cast ingot of the present invention carries out Homogenization Treatments in recirculated air stove, then carries out milling face, hot rolling, cold rolling, process annealing, cold rolling, quenching, Pre-aging treatment.Specific embodiments is as follows:

Homogenization Treatments is carried out to 1#, 2#, 3#, 4#, 5#, 6#, 7# ingot casting, concrete technology is: the alloy after founding is raised to 460 DEG C of insulation 10h with the temperature rise rate of 30 DEG C/h from room temperature, and then be warmed up to 480 DEG C of insulation 5h with the temperature rise rate of 30 DEG C/h, and then be warmed up to 520 DEG C of insulation 10h with the temperature rise rate of 30 DEG C/h, and then with the rate of temperature fall cool to room temperature of 30 DEG C/h.After the ingot mill surface after Homogenization Treatments, then carry out hot rolling, hot-rolled temperature is 500 DEG C, and hot rolling total reduction >=90% obtains 6mm hot-rolled sheet.Carry out first cold rolling again, cold rolling total reduction is 50%, obtains 3mm cold-reduced sheet, then at 450 DEG C, be incubated 1h carry out process annealing, carry out second cold rolling afterwards, cold rolling total reduction is 67%, finally obtains the 1mm cold-reduced sheet of 1#, 2#, 3#, 4#, 5#, 6#, 7# alloy.

Comparative example

The 1mm cold-reduced sheet of 1#, 2#, 3#, 4# alloy obtained with aforesaid method is carried out in salt bath furnace 525 DEG C insulation 10min solution treatment after direct-water-quenching.Cold-reduced sheet after quenching is divided into two groups, puts into the Pre-aging treatment that aging oven carries out 80 DEG C of insulation 12h in 6min after one group of quenching, then place in room temperature and obtain T4P state in 7 days; Be placed directly in room temperature after other one group of quenching and obtain T4 state in 7 days.Finally carry out 180 DEG C/30min (simulation baking vanish) artificial aging process to T4P state and T4 state alloy, measure the intensity increment before and after alloy baking vanish, concrete outcome is in table 2.Be placed on the natural aging hardening curve of room temperature after making 1# and 2# alloy quenching, concrete outcome is shown in Fig. 1 simultaneously.Stamping, mopping and paint baking are the production stages of typical automobile component reality, present case is in order to verify that new constituent and novel process are to the precipitation strength effect of Al-Mg system alloy, so eliminate this step stamping, this is in order to avoid the deformation in punching course is on the impact of baking vanish strengthening increment.Actual baking vanish process is also simulated in aging oven.

Embodiment 1

The 1mm cold-reduced sheet of the 5# alloy obtained with aforesaid method is carried out in salt bath furnace 525 DEG C insulation 10min solution treatment after direct-water-quenching.Cold-reduced sheet after quenching is divided into two groups, puts into the Pre-aging treatment that aging oven carries out 80 DEG C of insulation 12h in 6min after one group of quenching, then place in room temperature and obtain T4P state in 7 days; Be placed directly in room temperature after other one group of quenching and obtain T4 state in 7 days.Finally carry out 180 DEG C/30min (simulation baking vanish) artificial aging process to T4P state and T4 state alloy, measure the intensity increment before and after alloy baking vanish, concrete outcome is in table 2.Be placed on the natural aging hardening curve of room temperature after making the process of 5# alloy solid solution, concrete outcome is shown in Fig. 1 simultaneously.

Embodiment 2

The 1mm cold-reduced sheet of the 6# alloy obtained with aforesaid method is carried out in salt bath furnace 525 DEG C insulation 10min solution treatment after direct-water-quenching.Cold-reduced sheet after quenching is divided into two groups, puts into the Pre-aging treatment that aging oven carries out 80 DEG C of insulation 12h in 6min after one group of quenching, then place in room temperature and obtain T4P state in 7 days; Be placed directly in room temperature after other one group of quenching and obtain T4 state in 7 days.Finally carry out 180 DEG C/30min (simulation baking vanish) artificial aging process to T4P state and T4 state alloy, measure the intensity increment before and after alloy baking vanish, concrete outcome is in table 2.Be placed on the natural aging hardening curve of room temperature after making 6# alloy quenching, concrete outcome is shown in Fig. 1 simultaneously.In order to compare Pre-aging treatment to the impact of 6# alloy in artificial aging process, make the natural aging hardening curve after 6# alloy solid solution state and Pre-aging treatment and T4 state and T4P state at artificial age-hardening's curve of 180 DEG C, concrete outcome is shown in Fig. 2 simultaneously.

Embodiment 3

The 1mm cold-reduced sheet of the 7# alloy obtained with aforesaid method is carried out in salt bath furnace 525 DEG C insulation 10min solution treatment after direct-water-quenching.Cold-reduced sheet after quenching is divided into two groups, puts into the Pre-aging treatment that aging oven carries out 80 DEG C of insulation 12h in 6min after one group of quenching, then place in room temperature and obtain T4P state in 7 days; Be placed directly in room temperature after other one group of quenching and obtain T4 state in 7 days.Finally carry out 180 DEG C/30min (simulation baking vanish) artificial aging process to T4P state and T4 state alloy, measure the intensity increment before and after alloy baking vanish, concrete outcome is in table 2.

Embodiment 4

The 1mm cold-reduced sheet of the 6# alloy obtained with aforesaid method is carried out in salt bath furnace 525 DEG C insulation 10min solution treatment after direct-water-quenching.The Pre-aging treatment that 70 DEG C are incubated 15h is carried out by putting into aging oven in the cold-reduced sheet 6min after quenching, then place in room temperature and within 7 days, obtain T4P (1) state, finally 180 DEG C/30min (simulation baking vanish) artificial aging process is carried out to T4P (1) state alloy, measure the intensity increment before and after alloy baking vanish, concrete outcome is in table 2.

Embodiment 5

The 1mm cold-reduced sheet of the 6# alloy obtained with aforesaid method is carried out in salt bath furnace 525 DEG C insulation 10min solution treatment after direct-water-quenching.The Pre-aging treatment that 90 DEG C are incubated 8h is carried out by putting into aging oven in the cold-reduced sheet 6min after quenching, then place in room temperature and within 7 days, obtain T4P (2) state, finally 180 DEG C/30min (simulation baking vanish) artificial aging process is carried out to T4P (2) state alloy, measure the intensity increment before and after alloy baking vanish, concrete outcome is in table 2.

The mechanical property of sheet alloy before and after 180 DEG C/30min process of table 2 different-alloy composition and state

As can be seen from Table 2, at 1# (AA5182), 2# (AA5023), 3#, the basis of 4# comparative alloy is added by the compound of Cu and Zn, and the content of Zn is greater than 1%, intensity and baking vanish increment after baking vanish, 5#, the T4 state of 7# alloy is better than the baking finish result of T4P state, and 6# alloy T4P state is better than T4 state baking finish result, especially relative to 1# (AA5182) and 2# (AA5023) alloy, after 6# alloy T4P state baking vanish, intensity improves 140Mpa and 100MPa nearly respectively, substantially the bake hardening of car inner plate and anti-indenture can be met.As can be seen from Figure 1, due to the interpolation of Zn, make 6# alloy phase for originally not having 1#, 2# alloy of natural aging effect to have natural aging very significantly.The strengthening that this natural aging causes is totally unfavorable for the stamping of auto sheet.And as can be seen from Figure 2, this natural aging also can cause the process having a lowered hardness in 180 DEG C of artificial aging processes in later stage, after making 180 DEG C/30min simulate baking vanish, intensity can decline.It can also be seen that from Fig. 2, the present invention is softening by what carry out to 6# alloy that Pre-aging treatment not only can avoid baking vanish process to occur, and significantly can accelerate 180 DEG C of artificial age-hardening's processes in later stage, significantly improves the bake hardening increment of novel alloy.And it can also be seen that from Fig. 2, the 6# alloy after Pre-aging treatment is in room temperature put procedure, and its performance is also very stable.In sum, the alloying constituent designed by the present invention and preparation technology well solve the problem of 5xxx aluminium alloy bake hardening deficiency, take full advantage of the Precipitation strengthening of Cu, Zn atom.And well avoided because Cu, Zn add the disadvantageous effect of caused natural aging for bake hardening simultaneously by Pre-aging treatment.Certainly, alloy of the present invention and technique are not only applicable to the manufacture of car inner plate, and are applicable to other association areas of aluminium alloy.

Although write out case study on implementation of the present invention, just the preferred embodiment of the present invention.It should be pointed out that for the ordinary skill in the art, can make some amendments and modification under the premise without departing from the principles of the invention, these amendments and modification should be considered as protection scope of the present invention.

Claims

1. an Al-Mg-Cu-Zn line aluminium alloy, it is characterized in that, the chemical composition of this alloy and mass percent thereof are: Mg 4.0 ~ 6.0wt%, Cu 0.30 ~ 1.0wt%, Zn 1.0 ~ 3.5wt%, Mn≤0.4wt%, Fe≤0.4wt%, Si≤0.4wt%, Cr≤0.2wt%, Ti≤0.1wt%, and surplus is Al and inevitable impurity.

2. Al-Mg-Cu-Zn line aluminium alloy according to claim 1, is characterized in that, the chemical composition of Mg, Cu, Zn, Mn in this alloy is: Mg 4.2 ~ 5.5wt%, Cu 0.4 ~ 0.9wt%, Zn 1.2 ~ 3.0wt%, Mn 0.1 ~ 0.3wt%.

3. Al-Mg-Cu-Zn line aluminium alloy sheet material preparation method according to claim 1 or 2, is characterized in that, comprise the following steps:

A al alloy component described in claim 1 or 2 is carried out founding by ();

B step (a) gained ingot casting is carried out homogenizing annealing, hot rolling, cold rolling, solution hardening and ageing treatment by ().

4. Al-Mg-Cu-Zn line aluminium alloy sheet material preparation method according to claim 3, it is characterized in that, homogenizing annealing in described step (b) is three grades of homogenizing annealing process, specifically the aluminium alloy after founding is started to be raised to 440 ~ 470 DEG C of insulation 6 ~ 12h from room temperature with the temperature rise rate of 20 ~ 40 DEG C/h, and then be warmed up to 470 ~ 490 DEG C of insulation 5 ~ 10h with the temperature rise rate of 20 ~ 40 DEG C/h, and then with the temperature rise rate of 20 ~ 40 DEG C/h be warmed up to 500 ~ 540 DEG C insulation 6 ~ 12h, afterwards with the rate of temperature fall furnace cooling of 20 ~ 40 DEG C/h to room temperature.

5. Al-Mg-Cu-Zn line aluminium alloy sheet material preparation method according to claim 3, it is characterized in that, the hot-rolled temperature in described step (b) is 460 ~ 510 DEG C, hot rolling total reduction >=90%.

6. Al-Mg-Cu-Zn line aluminium alloy sheet material preparation method according to claim 3, is characterized in that, cold rolling total reduction >=80% in described step (b).

7. Al-Mg-Cu-Zn line aluminium alloy sheet material preparation method according to claim 6, it is characterized in that, cold rolling in described step (b) comprises: first carry out draft be 40% ~ 60% first cold rolling, then carry out process annealing at 350 DEG C ~ 450 DEG C insulation 0.5 ~ 2h, carry out again afterwards draft be 50% ~ 70% second cold rolling.

8. Al-Mg-Cu-Zn line aluminium alloy sheet material preparation method according to claim 3, is characterized in that, in described step (b), solid solubility temperature is 520 DEG C ~ 540 DEG C, and solid solution soaking time is 5 ~ 12min, and quenching mode is direct-water-quenching.

9. Al-Mg-Cu-Zn line aluminium alloy sheet material preparation method according to claim 3, it is characterized in that, in described step (b) ageing treatment be by Water Quenching after aluminium alloy transfer in 3 ~ 6min in aging oven and carry out preageing, pre-age temperature is 60 DEG C ~ 100 DEG C, and preageing soaking time is 8 ~ 16h.