阅读说明：本技术 一种提高Al-Mg系合金表面强度的处理方法 (Treatment method for improving surface strength of Al-Mg alloy ) 是由 刘清陈 王泽辉 杨林 王璐 乙姣姣 徐明沁 于 2020-05-15 设计创作，主要内容包括：本发明涉及一种提高Al-Mg系合金表面强度的处理方法,包括如下顺序步骤：(1)对Al-Mg系合金材料进行表面处理,清洗,烘干；(2)步骤(1)完成后,将所述Al-Mg系合金材料置于450℃～500℃的加热炉中保温30min～40min进行预热处理；(3)所述预热处理完成后立即进行搅拌摩擦加工处理；(4)最后进行轧制成型处理。本发明方法能够进一步细化表层晶粒,达到提高Al-Mg系合金材料表面强度的目的；还能延长搅拌头寿命,提高搅拌摩擦加工处理的生产效率,降低生产成本。(The invention relates to a treatment method for improving the surface strength of Al-Mg series alloy, which comprises the following steps in sequence: (1) carrying out surface treatment, cleaning and drying on the Al-Mg alloy material; (2) after the step (1) is finished, placing the Al-Mg alloy material in a heating furnace at 450-500 ℃ for heat preservation for 30-40 min for preheating treatment; (3) immediately carrying out stirring friction processing after the preheating processing is finished; (4) and finally, carrying out rolling forming treatment. The method can further refine surface layer crystal grains and achieve the purpose of improving the surface strength of the Al-Mg alloy material; the service life of the stirring head can be prolonged, the production efficiency of friction stir processing is improved, and the production cost is reduced.)

1. A treatment method for improving the surface strength of Al-Mg series alloy is characterized by comprising the following sequential steps:

(1) carrying out surface treatment, cleaning and drying on the Al-Mg alloy material;

(2) after the step (1) is finished, placing the Al-Mg alloy material in a heating furnace at 450-500 ℃ for heat preservation for 30-40 min for preheating treatment;

(3) immediately carrying out stirring friction processing after the preheating processing is finished;

(4) and finally, carrying out rolling forming treatment.

2. The treatment method for improving the surface strength of an Al-Mg-based alloy according to claim 1, wherein the surface treatment in the step (1) is: polishing and peeling the Al-Mg alloy material at room temperature, soaking in a sodium hydroxide solution, and then soaking in a nitric acid solution; the cleaning adopts alcohol cleaning.

3. The treatment method for improving the surface strength of the Al-Mg series alloy according to claim 2, wherein the concentration of the sodium hydroxide solution is 40g/L to 60g/L, and the soaking time is 2min to 3 min; the concentration of the nitric acid solution is 20 g/L-50 g/L, and the soaking time is 1 min-2 min.

4. The treatment method for improving the surface strength of the Al-Mg alloy as claimed in claim 1, wherein the stirring head inclination angle of the friction stir processing in the step (3) is 2 °, the stirring head rotation speed is 1200r/min to 1500r/min, the stirring head shaft shoulder reduction is 0.2mm to 0.5mm, and the feeding speed of the Al-Mg alloy is 50mm/min to 80 mm/min.

5. The treatment method for improving the surface strength of the Al-Mg series alloy according to claim 1, wherein the roll forming treatment in the step (4) is at least one rolling process, and the reduction per pass is 20-50%.

6. The treatment method for improving the surface strength of the Al-Mg series alloy according to claim 1 or 5, wherein the roll forming treatment in the step (4) is cold rolling and/or hot rolling.

7. The treatment method for improving the surface strength of the Al-Mg series alloy according to claim 6, wherein the temperature of the hot rolling is 300 to 400 ℃.

Technical Field

The invention relates to the technical field of alloy material processing, in particular to a treatment method for improving the surface strength of Al-Mg alloy.

Background

Magnesium is an important alloying element because magnesium can form a high strength alloy with metals such as aluminum, copper, and zinc. Particularly in the aspect of aluminum alloy application, the metal magnesium is added into the aluminum alloy, so that the alloy is lighter and has higher specific strength. Metal magnesium is a main additive element in Al — Mg series alloys (5000 series aluminum alloys), Al — Mg — Si series alloys (6000 series aluminum alloys), and Al — Zn — Mg series alloys (7000 series aluminum alloys), and is added in a large amount. Other alloys such as Al — Cu-based alloys (2000-based aluminum alloys) and Al — Mn-based alloys (3000-based aluminum alloys) in which magnesium is not used as a main additive element are also added with a small amount of magnesium.

The main reason why magnesium is added to aluminum is that aluminum has a high solid solubility for magnesium, and solid solution hardening occurs to improve the strength of the aluminum alloy. The Al-Mg alloy has higher specific strength, corrosion resistance, good formability and weldability, and has wide application in the fields of modern buildings, transportation, aerospace, military manufacturing, machinery, power electronics, household appliances and the like. The addition amount of magnesium in the A5052 aluminum alloy is 2.2% -2.8%, the moderate-strength aluminum alloy has good corrosion resistance, and is mainly used in the fields of vehicles, buildings and the like; the magnesium addition amount in the A6061 aluminum alloy is 0.8-1.2%, and the A6061 aluminum alloy is mainly used in the fields of ships, vehicles, industrial sections, pressure containers and the like. However, in these industries, the requirements for the properties, especially the surface properties, of Al — Mg alloy materials are also increasing.

Friction Stir Processing (FSP) was developed from Friction Stir Welding (FSW), and by using the vigorous stirring action of the stir head, severe plastic deformation, mixing, crushing and thermal exposure of the material in the processing region are caused, thereby realizing refinement, homogenization and densification of the microstructure of the material. But the surface of the part after the friction stir processing has obvious residual stress and microcracks, so that the Al-Mg alloy is easy to crack in the application process, and the application range of the alloy is reduced.

Disclosure of Invention

In order to solve the technical problem that the material is easy to crack due to obvious residual stress and microcracks existing on the surface of the Al-Mg alloy material after the stirring friction processing, the treatment method for improving the surface strength of the Al-Mg alloy is provided. The treatment method can improve the surface strength of the Al-Mg alloy material.

In order to achieve the purpose, the invention is realized by the following technical scheme:

a treatment method for improving the surface strength of Al-Mg series alloy comprises the following steps:

(1) carrying out surface treatment, cleaning and drying on the Al-Mg alloy material;

(2) after the step (1) is finished, placing the Al-Mg alloy material in a heating furnace at 450-500 ℃ for heat preservation for 30-40 min for preheating treatment; different from the solution treatment, along with the rise of the temperature, the alloy material has the phenomenon of softening with the reduction of the strength and the hardness, and the preheating can reduce the friction stir resistance of the alloy material;

(3) immediately carrying out stirring friction processing after the preheating processing is finished;

(4) and finally, carrying out rolling forming treatment.

Further, the surface treatment method in the step (1) is as follows: polishing and peeling the Al-Mg alloy material at room temperature, soaking in a sodium hydroxide solution, and then soaking in a nitric acid solution; the cleaning adopts alcohol cleaning. The purpose of the sodium hydroxide and the nitric acid treatment is to remove oxide scale Al on the surface of the Al-Zn alloy₂O₃The oxide skin can react with sodium hydroxide and nitric acid, after the oxide skin is firstly treated by the sodium hydroxide, excessive alkali is used for neutralizing by the nitric acid, meanwhile, the nitric acid further removes the oxide skin, and then the oxide skin is washed clean by alcohol.

Furthermore, the concentration of the sodium hydroxide solution is 40 g/L-60 g/L, and the soaking time is 2 min-3 min; the concentration of the nitric acid solution is 20 g/L-50 g/L, and the soaking time is 1 min-2 min.

Further, the inclination angle of the stirring head in the friction stir processing in the step (3) is 2 degrees, the rotation speed of the stirring head is 1200 r/min-1500 r/min, the reduction of the shaft shoulder of the stirring head is 0.2 mm-0.5 mm, and the feeding speed of the Al-Mg series alloy is 50 mm/min-80 mm/min.

Further, the rolling forming treatment in the step (4) is at least one-pass rolling process, and the reduction of each pass is 20-50%.

Further, the roll forming process in the step (4) is cold rolling and/or hot rolling.

Further, the temperature of the hot rolling is 300 ℃ to 400 ℃. When the cold rolling has no obvious effect on improving the material performance, hot rolling can be carried out.

The beneficial technical effects are as follows:

the processing method has the advantages that the operation process is easy to control, the Al-Mg alloy material is subjected to preheating treatment at 450-500 ℃ before the stirring friction processing, so that the interior of the Al-Mg alloy material is recrystallized, the existing microscopic defects of residual stress, shrinkage cavity, shrinkage porosity and the like are eliminated, and the plastic deformation capacity of the material is improved; the stirring friction processing treatment is carried out at the temperature, the surface layer crystal grains of the alloy material can be refined by the stirring friction, the surface hardness of the alloy material is improved, and the surface strength is improved; the friction stir processing method has the advantages that friction stir friction is performed after preheating processing, so that friction stir resistance of alloy materials can be reduced, acting force on a stirring head is reduced, the service life of the stirring head is prolonged, factors such as the inclination angle of the stirring head, the rotation speed of the stirring head, the shaft shoulder pressing amount of the stirring head and the like are comprehensively considered, the feeding speed of the materials is increased, the production efficiency of friction stir processing can be improved, and the production cost is reduced; and finally, rolling is carried out to make up for the defects of residual stress, microcracks and the like after the stirring friction processing, and surface crystal grains are further refined, so that the effect of improving the mechanical property of the Al-Mg alloy material is achieved.

Drawings

FIG. 1 is a sample object diagram after steps (3) and (4) in example 2; wherein a is a sample obtained after the stirring friction processing in the step (3); b is a sample after being rolled by 30 percent of the two-pass reduction in the step (4); c is a tensile specimen cut on b; d is the fracture state of the tensile sample at the stirring friction.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Unless specifically stated otherwise, the numerical values set forth in these examples do not limit the scope of the invention. Techniques, methods known to those of ordinary skill in the relevant art may not be discussed in detail, but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values.