CN111334677A

CN111334677A - Rolling process for improving corrosion resistance of surface of 6061 aluminum alloy

Info

Publication number: CN111334677A
Application number: CN202010116966.7A
Authority: CN
Inventors: 陈金生; 祖立成; 张立鑫; 杜凤彪; 张冉
Original assignee: Tianjin Zhongwang Aluminium Industry Co ltd
Current assignee: Tianjin Zhongwang Aluminium Industry Co ltd
Priority date: 2020-02-25
Filing date: 2020-02-25
Publication date: 2020-06-26
Anticipated expiration: 2040-02-25
Also published as: CN111334677B

Abstract

The invention belongs to the technical field of aluminum alloy manufacturing, and relates to a rolling process for improving the corrosion resistance of a 6061 aluminum alloy surface, wherein aluminum alloy raw materials are mixed according to the weight percentage: si: 0.50-0.65%, Fe is less than or equal to 0.2%, Cu: 0.25-0.35%, Mn is less than or equal to 0.10%, Mg: 0.9-1.1%, Cr: 0.13-0.26%, Ni is less than or equal to 0.05%, Zn is less than or equal to 0.04%, Ti is less than or equal to 0.15%, single impurities are less than or equal to 0.05%, the total is less than or equal to 0.15%, and the balance is Al.

Description

Rolling process for improving corrosion resistance of surface of 6061 aluminum alloy

Technical Field

The invention belongs to the technical field of aluminum alloy manufacturing, relates to a rolling process for improving the corrosion resistance of a 6061 aluminum alloy surface, and particularly relates to a rolling process for a 6061-T651 aluminum alloy thick plate with excellent corrosion resistance in an acid environment.

Background

The aluminum alloy has the comprehensive characteristics of small density, high specific strength, good machinability, good corrosion resistance and the like, and is widely applied to the fields of aerospace, ship transportation, part manufacturing and the like. The 6xxx aluminum alloy has lower strength after solution heat treatment, is suitable for processing parts with higher requirements on dimensional accuracy, and can reach higher strength and good corrosion resistance after subsequent treatment. Mechanical parts in the traditional semiconductor industry are mostly made of stainless steel, and under the development trend of light weight and energy conservation, aluminum alloy (such as 6061) is undoubtedly a good choice to replace stainless steel, so that the weight of a moving part can be greatly reduced, the energy consumed by the movement of the moving part in the working process is reduced, and the aim of reducing the production cost is fulfilled. However, the corrosion resistance of the common 6061 alloy produced by the traditional process after hard oxidation is still not ideal enough, and the common 6061 alloy cannot meet the requirement standard of semiconductor part application and cannot replace stainless steel materials.

Disclosure of Invention

In view of the above, the invention provides a rolling process for improving corrosion resistance of a 6061-T651 alloy thick plate, which aims to solve the problems that corrosion resistance of the 6061-T651 alloy thick plate prepared by the existing production process cannot meet application requirements of semiconductor parts and cannot replace stainless steel materials, greatly improves corrosion resistance of the 6061-T651 alloy thick plate in an acid environment, improves reliability and service life of parts processed by the 6061-T651 alloy thick plate, and provides powerful support for replacing stainless steel materials by aluminum alloys in the field of semiconductor part preparation.

In order to achieve the purpose, the invention provides a rolling process for improving the corrosion resistance of the surface of a 6061 aluminum alloy, which comprises the following steps:

A. preparing materials: the aluminum alloy raw materials for preparing the aluminum alloy medium plate are proportioned according to the weight percentage, namely: si: 0.50-0.65%, Fe is less than or equal to 0.2%, Cu: 0.25-0.35%, Mn is less than or equal to 0.10%, Mg: 0.9-1.1%, Cr: 0.13-0.26%, Ni is less than or equal to 0.05%, Zn is less than or equal to 0.04%, Ti is less than or equal to 0.15%, single impurities are less than or equal to 0.05%, the total is less than or equal to 0.15%, and the balance is Al;

B. casting: placing the prepared aluminum alloy raw material into a smelting furnace to be smelted into liquid aluminum alloy, and casting the liquid aluminum alloy into aluminum alloy cast ingots after slagging-off and filtering;

C. homogenizing: carrying out homogenization heat treatment on the aluminum alloy cast ingot in a heating furnace, wherein the homogenization heat treatment process comprises the following steps: heating the aluminum alloy ingot to 530-565 ℃, and preserving heat for 20-24 h;

D. sawing and milling the surface: cooling the aluminum alloy cast ingot subjected to the homogenization heat treatment in a cooling chamber, cutting off the head and the tail of the aluminum alloy cast ingot, and milling off a shell layer on the surface of the aluminum alloy cast ingot;

E. ingot casting and heating: placing the aluminum alloy ingot after saw cutting and surface milling in a heating furnace for heating, wherein the temperature of the heating furnace is 480-530 ℃, and the heat preservation time is 2-4 h;

F. hot rolling: discharging the aluminum alloy ingot after heating and heat preservation for hot rolling, wherein the rolling pass is 15-25, the large deformation amount of 3-5 passes is rolled at the middle and rear parts of the rolling, the single-pass deformation amount is not less than 50mm, then the small deformation amount is turned for temperature control rolling, the single-pass deformation amount is not more than 15mm, the emulsion spraying mode is adjusted in real time according to the rolling condition and plate temperature feedback, and the final rolling temperature of the control plate is 200-230 ℃;

G. solution quenching: carrying out solution treatment on the hot-rolled aluminum alloy plate, wherein the solution temperature is 525-545 ℃, the heat preservation time is 15-40 min, and quenching and discharging after the heat preservation;

H. stretching and straightening: carrying out water cooling on the aluminum alloy plate subjected to solution quenching to room temperature, and then carrying out stretching straightening, wherein the stretching rate is 1.5-2.5%;

I. aging: and (3) carrying out aging treatment on the aluminum alloy plate after stretching and straightening, wherein the aging temperature is 160-180 ℃, the heat preservation time is 12-14 h, and the aged plate is subjected to hard anodic oxidation to obtain a 6061-T651 finished product.

And further, step B, sequentially putting the prepared aluminum alloy raw materials into a smelting furnace for smelting, refining and covering by using a flux, stirring after the materials are put into the smelting furnace when molten aluminum appears in the furnace, smelting into liquid aluminum alloy after the materials are uniformly stirred, wherein the smelting temperature is 730-750 ℃, the smelted aluminum alloy melt is poured into a refining furnace for refining, the refining temperature is 720-740 ℃, the refining time is 20min, the refined aluminum alloy melt stands for 20min at 720 +/-5 ℃, high-purity argon is introduced into the refined aluminum alloy melt and the melt is stirred to remove impurity gases in the aluminum alloy melt, and then the degassed aluminum alloy melt is filtered by a foamed ceramic filter plate with the aperture being more than or equal to 50ppi, and the filtering temperature is 720 +/-5 ℃.

Further, the heating furnace in the step C and the step E is a pusher-type heating furnace.

And further, in the step F, rolling with large deformation is carried out in 10 th to 12 th passes, and temperature control rolling is carried out after turning to small deformation in 13 th pass.

And step G, placing the cold-rolled aluminum alloy plate in a roller hearth furnace for solution quenching treatment.

And further, the quenching mode in the step G is water cooling, and the water cooling quenching speed is 10-40 ℃/s.

The invention has the beneficial effects that:

1. the rolling process for improving the corrosion resistance of the surface of the 6061 aluminum alloy disclosed by the invention mainly controls the lower content of Fe element, the proper content of Mg and Si elements and part of Cr element in the composition. The corrosion resistance of the plate is reduced due to the fact that the Fe-rich phase is normally precipitated at the position of a grain boundary, and therefore the corrosion resistance of the alloy can be effectively improved by further controlling the amount of the Fe-attached phase in the finished plate through controlling the addition of a low Fe element. Mg and Si are main alloy elements in the 6xxx series aluminum alloy, and the added amount determines the mechanical property of the finished plate. The addition of Cr element is helpful for refining crystal grains and improving the mechanical and corrosion resistance of the alloy.

The grain structure is controlled to be fine and uniform in the aspect of structure, so that the uniform and compact oxide layer can be favorably controlled to grow in the subsequent hard oxidation process of the alloy, and the corrosion resistance of the alloy is improved. The purpose of regulating and controlling the grain structure is achieved mainly by controlling the hot rolling process, and particularly, the process combining large-deformation rolling and small-deformation temperature-controlled rolling is adopted in the hot rolling process. The large-deformation rolling can promote the crushing of the Fe-attached phase, reduce the proportion of the large-size Fe-attached phase, be beneficial to improving the uniformity of crystal grains and be beneficial to improving the corrosion resistance of the alloy; the small-deformation temperature-control rolling can control the rolled plate to retain larger distortion energy, and is beneficial to promoting the recrystallization of crystal grains in the subsequent solid solution process, so that the crystal grain structure is fine.

2. The invention discloses a rolling process for improving corrosion resistance of a 6061 aluminum alloy surface, which optimizes the components of the traditional 6061 alloy, adopts a hot rolling process combining large-deformation rolling and small-deformation temperature-control rolling, prepares a 6061-T651 alloy thick plate with excellent corrosion resistance, has fine and uniform plate crystal grain structure, greatly improves the corrosion resistance of the plate in an acid environment under the condition of not losing mechanical properties, prolongs the service life of parts processed by the plate, and provides powerful support for replacing stainless steel materials by aluminum alloys in the field of semiconductor part preparation.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the means of the instrumentalities and combinations particularly pointed out hereinafter.

Drawings

For the purposes of promoting a better understanding of the objects, aspects and advantages of the invention, reference will now be made to the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a metallographic image of an aluminum alloy sheet produced in example 1 of the present invention along each cross section;

FIG. 2 is a metallographic image of an aluminum alloy sheet produced in example 2 of the present invention along each cross section;

FIG. 3 is a gold phase diagram of an aluminum alloy sheet produced by a comparative example of the present invention along each section.

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.

Example 1

A rolling process for improving the corrosion resistance of the surface of 6061 aluminum alloy comprises the following steps:

A. preparing materials: calculating the using amount of each aluminum alloy raw material and preparing the aluminum alloy raw material according to the mixture ratio, wherein the 6061 aluminum alloy raw material comprises the following elements in percentage by mass:

	Si	Fe	Cu	Mn	Mg	Cr	Ni	Zn	Ti	impurities	Al
												Content (wt.)	0.58	0.14	0.28	0.07	0.96	0.21	0.003	0.007	0.02	0.06	Balance of

B. Casting: the method comprises the following steps of putting prepared aluminum alloy raw materials into a smelting furnace in sequence for smelting, refining and covering by using a flux, stirring after the materials are put until aluminum water appears in the furnace, smelting the aluminum alloy into liquid aluminum alloy after the materials are uniformly stirred, wherein the smelting temperature is 730 ℃, the smelted aluminum alloy melt is poured into a refining furnace for refining, the refining temperature is 720 ℃, the refining time is 20min, the refined aluminum alloy melt is kept stand for 20min at 720 ℃, high-purity argon is introduced into the refined aluminum alloy melt, the melt is stirred, impurity gases in the aluminum alloy melt are removed, then the degassed aluminum alloy melt is filtered by a foamed ceramic filter plate with the aperture being more than or equal to 50ppi, and the filtering temperature is 720 ℃;

C. homogenizing: carrying out homogenization heat treatment on the aluminum alloy cast ingot in a push type heating furnace, wherein the homogenization heat treatment process comprises the following steps: heating the aluminum alloy ingot to 565 ℃, and preserving heat for 24 hours;

E. ingot casting and heating: placing the aluminum alloy cast ingot with the sawed and milled surface in a push type heating furnace for heating, wherein the temperature of the heating furnace is 480 ℃, and the heat preservation time is 2 hours;

F. hot rolling: and (3) discharging the aluminum alloy ingot after heating and heat preservation, hot rolling, wherein the rolling pass is 22, and rolling is carried out on the aluminum alloy ingot in the 10 th to 12 th passes with large deformation, and the single-pass deformation is not less than 50 mm. Starting to convert the 13 th pass into the small-deformation-amount pass rolling, wherein the single-pass rolling deformation is not higher than 15mm, and adjusting the emulsion spraying mode in real time according to the rolling condition and the plate temperature feedback to control the final rolling temperature of the plate to be 202 ℃; wherein the aluminum alloy ingot hot rolling pass table 1 is:

G. solution quenching: putting the hot-rolled aluminum alloy plate into a roller hearth furnace for solution treatment, wherein the solution temperature is 530 ℃, the heat preservation time is 15min, and quenching and discharging after the heat preservation;

H. stretching and straightening: cooling the aluminum alloy plate subjected to solution quenching to room temperature by water, and then carrying out stretching straightening, wherein the stretching rate is 2.0%;

I. aging: and (3) carrying out aging treatment on the aluminum alloy plate after stretching and straightening, wherein the aging temperature is 170 ℃, the heat preservation time is 12h, and the aged plate is subjected to hard anodic oxidation to obtain a 6061-T651 finished product. The grain structure of the 6061-T651 plate in example 1 is shown in FIG. 1.

Example 2

The difference between the embodiment 2 and the embodiment 1 is that the rolling pass of the step F is 19, and the large deformation amount of 3 passes is introduced in the 10 th to 12 th passes for rolling, so that the single-pass deformation amount is not less than 50 mm. Before the 13 th pass, the temperature of the plate is measured, the temperature is 472 ℃, the rolling is suspended, and the temperature is reduced to 370 ℃ by spraying the emulsion. And then, converting into small-deformation pass rolling, controlling the temperature of the plate and the final rolling temperature of the plate to be 205 ℃ according to the rolling condition and the real-time emulsion spraying mode of the plate feedback temperature. Wherein the aluminum alloy ingot hot rolling pass table 2 is:

the grain structure of the 6061-T651 plate in example 2 is shown in FIG. 2.

Comparative example

The difference between the comparative example and the example 1 is that the 6061 aluminum alloy raw material in the step A comprises the following elements in percentage by mass:

	Si	Fe	Cu	Mn	Mg	Cr	Ni	Zn	Ti	impurities	Al
												Content (wt.)	0.62	0.34	0.27	0.08	0.97	0.10	0.006	0.002	0.02	0.06	Balance of

And F, rolling at 22 passes, continuously rolling according to the pass sequence by adopting a conventional product rolling pass table in the hot rolling process, wherein the maximum single-pass deformation is not higher than 25mm, the plate belongs to the production of the traditional process, and the final rolling temperature of the plate is 358 ℃. Wherein the aluminum alloy ingot hot rolling pass table 3 is:

the grain structure of the 6061-T651 plate in the comparative example is shown in FIG. 3.

Comparing the grain structures of the sheets of examples 1 and 2 and the comparative example, it can be found that: the grain appearance of the 6061-T651 thick plate produced by the traditional process (comparative example) has obvious elongation trend along the rolling direction, the grain size difference of the L-T, L-S, T-S surface is obvious, and the grain size is far larger than 200 mu m. The 6061-T651 thick plate crystal grains produced by the process (examples 1 and 2) disclosed by the patent basically eliminate the directionality of crystal grain distribution, the crystal grain sizes on three surfaces are generally small and uniformly distributed, and the average crystal grain size is about 60 mu m. The grain distribution characteristic is beneficial to controlling the alloy to grow a uniform and compact oxide layer in the subsequent hard oxidation process, and the corrosion resistance of the alloy is improved.

In order to test the corrosion resistance of the plate in an acid environment, the adopted test method comprises the following steps: preparing a hydrochloric acid solution with the concentration of 5%, loading and taking the hydrochloric acid solution by using a large test tube, then tightly buckling the test tube on the surface of a sample, sealing the test tube by using a special means to prevent leakage, locally corroding the surface of the sample, observing whether bubbles appear on the surface of the sample, recording the time of the bubbles, and testing the corrosion resistance of the plate in an acid environment by using the time of keeping the surface of the product free of the bubbles. The hydrochloric acid corrosion resistant times for the 6061-T651 plates of examples 1, 2 and comparative example are shown in table 4 and it can be found that: the corrosion resistance time of the L-T, L-S, T-S surface of the 6061-T651 thick plate produced by the process (examples 1 and 2) disclosed by the patent can reach more than 220min, and is obviously higher than that of the 6061-T651 thick plate produced by the traditional process (comparative example). The production and use environment of mechanical parts in the field of semiconductors is often in an acid atmosphere, so that the first condition for applying aluminum alloy products in the field is to ensure that the aluminum alloy products cannot be corroded in the atmosphere within a certain time, and the corrosion resistance of the 6061-T651 thick plate in the acid condition is greatly improved by the process disclosed by the patent.

Table 4 shows the hydrochloric acid corrosion resistant time of 6061-T651 plates in examples 1 and 2 and comparative example

Table 4:

corrosion resistance time/min	Example 1	Example 2	Comparative example
				L-T surface	235	240	100
L-S face	240	230	80
				T-S surface	240	220	90

The mechanical properties of the finished 6061-T651 thick plates of examples 1 and 2 and the comparative example are tested according to GB/T3880-2012, and the results are shown in Table 5, and it can be found that: the mechanical properties of the 6061-T651 thick plate produced by the traditional process (comparative example) and the process (examples 1 and 2) disclosed by the patent all meet the requirements of GB/T3880-; the tensile strength and yield strength of the 6061-T651 thick plate produced by the process disclosed by the patent are close to those of the traditional process, and the elongation is slightly superior to that of the traditional process. The corrosion resistance of the product is improved, and meanwhile, the mechanical property of the product is not lost, even slightly improved, and the comprehensive performance is good.

Table 5 shows the mechanical properties of the samples of examples 1 and 2 and comparative example

TABLE 5

Finally, the above embodiments are only intended to illustrate the technical solutions of the present invention and not to limit the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it will be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions, and all of them should be covered by the claims of the present invention.

Claims

1. A rolling process for improving the corrosion resistance of the surface of 6061 aluminum alloy is characterized by comprising the following steps:

2. The rolling process for improving the corrosion resistance of the surface of 6061 aluminum alloy as claimed in claim 1, wherein the step B comprises the steps of putting prepared aluminum alloy raw materials into a smelting furnace in sequence for smelting, refining and covering by using a flux, stirring when molten aluminum appears in the furnace after the materials are put into the smelting furnace, smelting into liquid aluminum alloy after stirring uniformly, wherein the smelting temperature is 730-750 ℃, pouring the smelted aluminum alloy melt into a refining furnace for refining, the refining temperature is 720-740 ℃, the refining time is 20min, standing the refined aluminum alloy melt at 720 +/-5 ℃ for 20min, introducing high-purity argon into the refined aluminum alloy melt, stirring the melt, removing impurity gases in the aluminum alloy melt, filtering the degassed aluminum alloy melt by a foamed ceramic filter plate with the pore diameter of more than or equal to 50ppi, and filtering at the temperature of 720 +/-5 ℃.

3. The rolling process for improving the corrosion resistance of a surface of 6061 aluminum alloy as claimed in claim 2, wherein the heating furnace in step C and step E is a pusher furnace.

4. The rolling process for improving the corrosion resistance of the surface of 6061 aluminum alloy according to claim 3, wherein step F is performed by large-deformation rolling in 10 th to 12 th passes and is performed by small-deformation temperature-controlled rolling after 13 th pass.

5. The rolling process for improving the corrosion resistance of the surface of 6061 aluminum alloy as claimed in claim 4, wherein step G is carried out by putting the aluminum alloy plate after cold rolling into a roller hearth furnace for solution quenching treatment.

6. The rolling process for improving the corrosion resistance of the surface of 6061 aluminum alloy as claimed in claim 5, wherein the quenching manner in the step G is water cooling, and the water cooling quenching speed is 10-40 ℃/s.