CN104634727A - Method for optimizing corrosion resistant composition of ultrahigh-strength Al-Zn-Mg-Cu alloy - Google Patents

Abstract

The invention relates to a method for optimizing the corrosion resistant composition of ultrahigh-strength Al-Zn-Mg-Cu alloy, belonging to the technical field of metal alloy. The method comprises the following steps: designing a plurality of groups of ingredient combinations in a matrix form; dosing and smelting according to the designed alloy ingredients, thereby acquiring aluminum alloy with different compositions; carrying out homogenization treatment on a cast ingot, that is, performing the optimized first heat preservation at 400 DEG C for 4h and the second heat preservation at 460-475 DEG C for 30h respectively; directly performing solution treatment with heat preservation at 465-475 DEG C for 3h; performing double-order overaging treatment, that is, carrying out the first order ageing treatment with heat preservation at 110 DEG C for 2h, and the second order ageing treatment with heat preservation at 160 DEG C for 10h; and finally, carrying out electrochemical corrosion resistance testing, thereby acquiring the alloy composition with good electrochemical corrosion resistance. According to the method, the transformation link of the alloy is omitted, the cost and the time of optimized alloy are saved, and the acquired result can provide guidance for the follow-up alloy production.

Description

The optimization method of the strong Al-Zn-Mg-Cu alloy resistant component of a kind of superelevation

Technical field

The invention belongs to field of metal alloy technology, be specifically related to the optimization method of the strong Al-Zn-Mg-Cu alloy resistant component of a kind of superelevation.

Background technology

The strong Al-Zn-Mg-Cu alloy of superelevation has specific strength and hardness is high, ductility and hot-working character is good, the advantage such as welding performance and good-toughness, being widely used in the heavily stressed welding structural element that the structural member of various aircraft is high with other desired strengths, is indispensable important feature material in current many dual-use aircrafts, transport facility.But this alloy is very sensitive to local corrosion, easily there is intercrystalline corrosion, Peeling Corrosion and stress corrosion crack, significantly limit its application.

In recent years along with the develop rapidly of modern industry, the demand of alloy combination property is day by day urgent, solves its corrosion proof problem and also becomes more and more important.Early stage, existing some patents were studied discussion for the obdurability of ultra-high-strength aluminum alloy and Technology for Heating Processing etc., but technological process conventional is at present generally that the alloy of frozen composition is carried out a series of flow processs such as melting, casting, homogenising, distortion, solid solution, timeliness, the last test carrying out aspect of performance again, the R&D cycle needed for the alloy obtaining desired properties is longer.The some compositions changed within the specific limits that first the present invention designs matrix form divide combination, afterwards according to the hereditary effect of material structure to performance, omit the distortion link of material, sample after homogenising is directly carried out fixation rates, then electrochemical property test is carried out, undertaken analyzing by this simulated experiment and obtain the anti-corrosion Al-Zn-Mg-Cu alloy composition optimized, can be used for the manufacture instructing follow-up alloy material.

Summary of the invention

The object of the invention is to overcome the deficiency that the ultra-high-strength aluminum alloy design cycle is long now, go out the excellent Al-Zn-Mg-Cu alloy composition of corrosion resisting property by the analysis optimization of simulated experiment, producing for follow-up alloy industry provides guidance.

For achieving the above object, the present invention takes following design proposal.

An optimization method for the strong Al-Zn-Mg-Cu alloy resistant component of superelevation, is characterized in that, comprise the following steps:

(1) design matrix form, at first row with wherein a kind of composition for variable becomes large from top to bottom gradually, other components are the most quantitative; Another kind of composition is variable in a second column, and except the variable composition in these row, other compositions be quantitatively, the like until all the components is as a variable, each alloy compositions in matrix is as testing composition.Some composition part combinations that alloying component can change among a small circle.The incremental range of variable or the quantity increased progressively can regulate as required.

(2) with high-purity Al, high-purity Mg, technical pure Zn and Al-5.03Cu, Al-4.50Zr intermediate alloy for raw material, the all alloy components designed by step (1) add raw material respectively, alloy molten solution is melting at 720-780 DEG C of temperature, cast temperature is 700-720 DEG C, is cast as the alloy pig of heterogeneity;

(3) for the alloy pig of all alloy compositions of step (2), respectively homogenizing annealing is carried out to it, adopt two-step homogenization annealing process, the first order is 400 DEG C of insulations 4 hours, the second level is 460-475 DEG C of insulation 30 hours, and the second level process of each alloy composition is respectively through multiple temperature; Choose best one group of each composition effect after above-mentioned homogenizing annealing and carry out subsequent experimental;

(4) ingot casting after the homogenizing annealing selected for step (3), directly carry out solution treatment, technique is 465-475 DEG C of insulation 3 hours, room temperature shrend immediately afterwards, quenching shift time is no more than 20 seconds, the ingot casting of each composition is respectively through the solution treatment of different temperatures, and what optimum solution treatment effect chosen by the ingot casting of each composition carries out subsequent experimental;

(5) ingot casting of the solution treatment obtained step (4) chosen carries out twin-stage Wetted constructures, and its technique is that first order timeliness was 110 DEG C of insulations 2 hours; Second level timeliness was 160 DEG C of insulations 10 hours;

(6) alloy of Ageing Treatment is carried out electrochemical property test, evaluation and test alloy electrochemical corrosion resistant performance, and then in the alloy of all the components, optimize the alloying component that corrosion resisting property is optimization preferably.

By matrix form design alloying component, alloying component can be finely tuned within the specific limits.In alloy treatment process, after solution hardening process, directly carry out twin-stage Wetted constructures, and without deformation process, thus shorten alloy designs flow process.For the alloy of heterogeneity, take optimum homogenising and solid solution aging technique respectively, make alloy structure reach optimum.Carry out electro-chemical test, quantitatively calculate the evaluation corrosion electric current density of alloy according to the Tafel curve obtained, characterize the corrosion resisting property of alloy by this value, namely finally obtain the alloying component of electrochemical corrosion resistant better performances.

Method of the present invention eliminates the distortion link of alloy by design simulation experiment, and save cost and the time of preferred alloy, result is more accurate, and the result of acquisition can be follow-up alloy production provides guidance.

Accompanying drawing explanation

Fig. 1 is 9 groups of design of alloy figure of matrix form.

Fig. 2 is that example 1 alloy cast ingot carries out 400 DEG C/4h+475 DEG C/30h respectively, 400 DEG C/4h+471 DEG C/30h, 400 DEG C/4h+467 DEG C/30h, the microstructure after 400 DEG C/4h+463 DEG C/30h tetra-kinds of Homogenization Treatments.

Fig. 3 be example 1 alloy can obtain sample Tafel curve by electro-chemical test.

Fig. 4 is the corrosion electric current density of alloy.

Embodiment

Have research and design alloying component according to the strong Al-Zn-Mg-Cu alloy of current superelevation, Zn composition as shown in Figure 1, is decided to be 10wt.% by Composition Design figure, and Zr is 0.12wt.%, obtains nine groups of samples with concentration gradient by the content adjusting Mg and Cu among a small circle.

Embodiment 1:(1) alloy preparation scheme is: 10%Zn, 2.0Mg, 1.2Cu, 0.12Zr, Al surplus (namely in accompanying drawing 1 corresponding 1., as alloy 1), with rafifinal (Al99.70), high-purity Mg (Mg9995), technical pure Zn (Zn≤98.7wt.%) and Al-5.03Cu, Al-4.50Zr intermediate alloy for raw material, prepare burden by above-mentioned chemical composition requirement.First aluminium ingot is loaded the resistance furnace of 780 DEG C, after aluminium ingot fusing, add pure zinc, aluminum bronze intermediate alloy, aluminium zirconium hardener in order.After metal and intermediate alloy all melt, take the scum silica frost of bath surface off, when melt temperature reaches 715-735 DEG C, add pure magnesium.For making alloying elements distribution even, stir melt, carry out refining afterwards, refining leaves standstill 20-35 minute at 710-730 DEG C, takes the scum silica frost on surface subsequently off, then is cast as alloy ingot blank after leaving standstill cast temperature 700-720 DEG C.

(2) respectively Homogenization Treatments as shown in table 1 is carried out to the alloy of example 1 step (1)

Table 1 homogenising heat-treat condition

Microstructure after 4 kinds of homogenising is shown in Fig. 1, the alloy structure any surface finish of 400 DEG C/4h+467 DEG C/30h homogenising heat treating regime can be found, without burn-off phenomenon, and not residual a large amount of residual eutectic phase and T-phase, be the optimal uniform metallization processes corresponding to example 1 alloy.

(3) to example 1 step (2) 400 DEG C/4h+467 DEG C/heat treated alloy of 30h homogenising, carry out the solution treatment of 465-475 DEG C/3h respectively, test the alloy of discovery through 470 DEG C/3h solution treatment without obvious residual phase, be decided to be the optimum solid solution craft of example 1 alloy.

(4) to the alloy of example 1 step (3) through 470 DEG C/3h solution treatment, carry out twin-stage Wetted constructures, its technique is that first order timeliness was 110 DEG C of insulations 2 hours; Second level timeliness was 160 DEG C of insulations 10 hours.The alloy of twin-stage Wetted constructures is carried out the test of electrochemical corrosion resistant performance reproducibility.Equipment therefor is standard three-electrode system, and platinum electrode is auxiliary electrode, and saturated calomel electrode is contrast electrode, and adopt saturated sodium-chloride salt bridge to connect, electrolyte solution is 3.5wt.%NaCl solution.Sample Tafel curve can be obtained as shown in Figure 2 by electro-chemical test.Usually corrosion potential E can be passed through _corrjudge that the driving force size of corrosion occurs alloy, by average corrosion current density i _corrjudge the corrosion rate of alloy, average corrosion current density i _corrlarger then corrosion speed is faster.Namely decay resistance for alloy of the present invention uses i _corrcharacterize.Example 1 is through the average corrosion current density i measured by step (1) (2) (3) (4) _corrbe 0.889 μ A/cm ².

As shown in Figure 1, its founding is identical with example 1 for the design of alloy of alloy 2-9.Homogenising selected by alloy 2-9 is identical with (3) with example 1 step (2) with the method for solid solubility temperature, and the heat treatment process parameter of institute's optimization lists in table 2.

Table 2 heat treatment process parameter

Corrosion electric current density measured by alloy 1-9 all lists in table 3, table 3 is mapped as shown in Figure 4, obviously can find out that the alloy corrosion current density of example 1 and 6 is relatively little, have better decay resistance, therefore the alloying component of optimization is Al-10Zn-2.0Mg-1.2Cu-0.12Zr and Al-10Zn-2.2Mg-1.2Cu-0.12Zr.By the simulated experiment that the method is carried out, obtain the alloying component of electrochemical corrosion resistant better performances.

The average corrosion current density of table 3 alloy

Alloy	i corr(μA/cm 2)
		1	0.889
2	2.79
		3	2.53
4	1.77
		5	1.52
6	1.07
		7	1.60
8	1.42
		9	2.60

Claims (2)

1. an optimization method for the strong Al-Zn-Mg-Cu alloy resistant component of superelevation, is characterized in that, comprise the following steps:

(1) design matrix form, at first row with wherein a kind of composition for variable becomes large from top to bottom gradually, other components are the most quantitative; Another kind of composition is variable in a second column, and except the variable composition in these row, other compositions be quantitatively, the like until all the components is as a variable, each alloy compositions in matrix is as testing composition;

(2) with high-purity Al, high-purity Mg, technical pure Zn and Al-5.03Cu, Al-4.50Zr intermediate alloy for raw material, the all alloy components designed by step (1) add raw material respectively, alloy molten solution is melting at 720-780 DEG C of temperature, cast temperature is 700-720 DEG C, is cast as the alloy pig of heterogeneity;

(3) for the alloy pig of all alloy compositions of step (2), respectively homogenizing annealing is carried out to it, adopt two-step homogenization annealing process, the first order is 400 DEG C of insulations 4 hours, the second level is 460-475 DEG C of insulation 30 hours, and the second level process of each alloy composition is respectively through multiple temperature; Choose best one group of each composition effect after above-mentioned homogenizing annealing and carry out subsequent experimental;

(4) ingot casting after the homogenizing annealing selected for step (3), directly carry out solution treatment, technique is 465-475 DEG C of insulation 3 hours, room temperature shrend immediately afterwards, quenching shift time is no more than 20 seconds, the ingot casting of each composition is respectively through the solution treatment of different temperatures, and what optimum solution treatment effect chosen by the ingot casting of each composition carries out subsequent experimental;

(5) ingot casting of the solution treatment obtained step (4) chosen carries out twin-stage Wetted constructures, and its technique is that first order timeliness was 110 DEG C of insulations 2 hours; Second level timeliness was 160 DEG C of insulations 10 hours;

(6) alloy of Ageing Treatment is carried out electrochemical property test, evaluation and test alloy electrochemical corrosion resistant performance, and then in the alloy of all the components, optimize the alloying component that corrosion resisting property is optimization preferably.

2. according to the method for claim 1, it is characterized in that, the Tafel curve that step (6) obtains quantitatively calculates the evaluation corrosion electric current density of alloy, characterizes the corrosion resisting property of alloy by this value.