阅读说明：本技术 一种铝合金除铁方法 (Iron removing method for aluminum alloy ) 是由 周成双 张�林 李晓 韩勇 董学民 于 2020-04-29 设计创作，主要内容包括：本发明提供了一种铝合金除铁方法,在除铁过程中加入的铬进行变质处理,由于铬与铁原子大小相近,能够替代(AlFeSi)相与(AlFe)相中的铁元素,对β-Fe相的生长有抑制作用,且能使针状β-Fe相产生断裂、分解；钴能使富铁相朝球形方向生长,有利于钛与铁反应产生FeTi(Fe2Ti)化合物的沉淀；镁反应时放出大量的热,对钛与铁元素的反应起到催化作用。钛与杂质铁反应生成高熔点、高密度的FeTi(Fe2Ti)化合物,这些富铁相在重力作用下沉降到坩埚底部,从而达到除铁效果,该方法克服了目前除铁方法单一、操作困难、存在污染等问题,以及克服除铁过程不易控制反应和不适用于工业生产的问题等。(The invention provides an aluminum alloy iron removal method, wherein chromium added in the iron removal process is modified, and the chromium and iron atoms are similar in size, so that the iron element in an (AlFeSi) phase and an (AlFe) phase can be replaced, the growth of a beta-Fe phase is inhibited, and a needle-shaped beta-Fe phase can be broken and decomposed; cobalt can enable an iron-rich phase to grow towards a spherical direction, and is beneficial to the reaction of titanium and iron to generate the precipitation of FeTi (Fe2Ti) compounds; the magnesium emits a large amount of heat during the reaction and plays a catalytic role in the reaction of titanium and iron elements. The titanium reacts with impurity iron to generate FeTi (Fe2Ti) compounds with high melting point and high density, and the iron-rich phases sink to the bottom of the crucible under the action of gravity, so that the iron removal effect is achieved.)

1. An iron removal method for aluminum alloy is characterized by comprising the following steps:

the method comprises the following steps: weighing an aluminum block with the mass of W and a refining agent with the mass of 0.2-0.35% of W, die-casting the refining agent into a refining agent block, putting the refining agent block into an oven, heating the oven to 250-350 ℃, and keeping the temperature for 60-90 min;

step two: weighing an aluminum-chromium intermediate alloy modifier with the mass of 0.4-0.6% W, putting the aluminum-chromium intermediate alloy modifier into an oven, heating the oven to 200-300 ℃, and preserving heat for 40-70 min;

step three: weighing 1.5-2.5 wt% of iron-removing agent, placing the iron-removing agent into an oven, heating the oven to 250-350 ℃, and keeping the temperature for 60-80 min;

step four: heating the aluminum liquid to 690-720 ℃, pressing the refining agent into the aluminum liquid by using a bell jar, preserving heat for 25-35 min, and slagging off;

step five: keeping the temperature of the aluminum liquid at 710-730 ℃, adding an aluminum-chromium intermediate alloy modifier into the aluminum liquid, and keeping the temperature for 20-40 min;

step six: and (3) keeping the temperature of the aluminum liquid at 710-740 ℃, adding a deironing agent into the aluminum liquid, keeping the temperature for 30-70 min, and finally air-cooling.

2. The method for removing iron from aluminum alloy as recited in claim 1, wherein said refining agent is AlF₃、Na₂SO₄、Na₂AlF₆、C₂Cl₆And C powder comprises (2.75-7.25) by mass, (7-8) by mass, (6.5-8.5) by mass, (3.25-4.25) by mass and (1-1.5) by mass.

3. The method for removing iron from aluminum alloy as recited in claim 1, wherein said modifier for aluminum-chromium master alloy contains chromium in an amount of 9% to 11%.

4. The method of claim 1, wherein the iron removing agent comprises Mg powder, Al-Co intermediate alloy and Al-Ti intermediate alloy in a weight ratio of (1-1.31): (2-2.54): 3.85-4.69).

5. The method for removing iron from aluminum alloy as recited in claim 4, wherein the cobalt content in said aluminum-cobalt intermediate alloy is 8% -11%; the content of titanium in the aluminum-titanium intermediate alloy is 1 to 2 percent.

Technical Field

The invention relates to the field of alloy iron removal, in particular to an aluminum alloy iron removal method.

Background

Industrial pure aluminum is a casting alloy material containing aluminum as a main component, and generally contains less than about 0.2% of Fe. However, in actual industrial production, the components of cast aluminum alloy inevitably contain a certain amount of impurity Fe, and the service performance of the material is reduced.

The impurity Fe comes from the raw material firstly, and secondly because the crucible, the melting tool, the mold, and the like used in the melting and casting process are mostly Fe-based, so that Fe is taken into the Al liquid. In addition, the content of Fe in the aluminum alloy is increased every time the foundry returns are remelted, and the content of Fe in the alloy is gradually increased after repeated recycling, so that the method is particularly prominent in metal mold casting and pressure casting. And the solid solubility of Fe in the aluminum alloy is very low, when the content of Fe exceeds 0.6%, a small amount of Fe is combined with other elements in the aluminum alloy to form a needle-shaped Fe phase, the matrix is cut, stress concentration is generated, cracks are germinated, and pores are easily generated on the intersection interface of the matrix and brittle precipitation in the deformation processing process. When the Fe content exceeds 0.7%, a large amount of coarse beta-Fe phase will be present. Besides the influence on the material performance, the Fe phase can also obstruct the flow of molten metal during solidification, thereby increasing defects such as shrinkage cavity and porosity of the cast ingot. The needle-shaped Fe phase has higher hardness, and a cutter is abraded in the machining process, so that the precision of parts cannot be guaranteed.

In order to reduce the harm of needle-shaped Fe phase, the current research methods mainly include two types: the first is to change the shape of Fe phase by modification treatment, adding chemical elements or adopting a special process to convert a coarse needle-like beta-Fe phase into a less harmful alpha-Fe phase; the other method adopts a physical method, utilizes different physical and chemical properties between the iron-rich phase and the melt, and further achieves the aim of removing iron, and comprises a gravity settling method, a centrifugal separation method, electromagnetic separation, electroslag refining, filtering and the like. The centrifugal separation increases the production process, and the operation is complicated, so the method is not suitable for industrial production. The electromagnetic separation has higher requirement on the shape of the Fe phase, the magnetic permeability in pure aluminum is weaker, and the iron removal effect is not obvious, so that the iron removal rate is reduced.

Disclosure of Invention

The invention aims to design an aluminum alloy iron removal method, which solves the problems of singleness, difficult operation, pollution and the like of the existing iron removal method and solves the problems that the reaction is not easy to control and the iron removal process is not suitable for industrial production.

In order to achieve the purpose, the invention provides an iron removal method for an aluminum alloy, which comprises the following steps:

the method comprises the following steps: weighing an aluminum block with the mass of W and a refining agent with the mass of 0.2-0.35% of W, die-casting the refining agent into a refining agent block, putting the refining agent block into an oven, heating the oven to 250-350 ℃, and keeping the temperature for 60-90 min;

step two: weighing an aluminum-chromium intermediate alloy modifier with the mass of 0.4-0.6% W, putting the aluminum-chromium intermediate alloy modifier into an oven, heating the oven to 200-300 ℃, and preserving heat for 40-70 min;

step three: weighing 1.5-2.5 wt% of iron-removing agent, placing the iron-removing agent into an oven, heating the oven to 250-350 ℃, and keeping the temperature for 60-80 min;

step four: heating the aluminum liquid to 690-720 ℃, pressing the refining agent into the aluminum liquid by using a bell jar, preserving heat for 25-35 min, and slagging off;

step five: keeping the temperature of the aluminum liquid at 710-730 ℃, adding an aluminum-chromium intermediate alloy modifier into the aluminum liquid, and keeping the temperature for 20-40 min;

step six: and (3) keeping the temperature of the aluminum liquid at 710-740 ℃, adding a deironing agent into the aluminum liquid, keeping the temperature for 30-70 min, and finally air-cooling.

Preferably, the refining agent is AlF₃、Na₂SO₄、Na₂AlF₆、C₂Cl₆And C powder comprises (2.75-7.25) by mass, (7-8) by mass, (6.5-8.5) by mass, (3.25-4.25) by mass and (1-1.5) by mass.

Preferably, the content of chromium in the aluminum-chromium intermediate alloy modifier is 9 to 11 percent.

Preferably, the iron removing agent consists of Mg powder, an aluminum-cobalt intermediate alloy and an aluminum-titanium intermediate alloy according to the mass part ratio of (1-1.31): (2-2.54): 3.85-4.69.

Preferably, the cobalt content in the aluminum-cobalt intermediate alloy is 8 to 11 percent; the content of titanium in the aluminum-titanium intermediate alloy is 1 to 2 percent.

The invention has the beneficial effects that:

(1) the method is simple to operate, low in cost and easy to control, and combines the refining agent, the modifier, the iron remover and the final filtration, so that the acicular iron phase in the aluminum alloy can be refined and captured and settled to the bottom of the crucible, the iron content in the aluminum alloy is obviously reduced, the tensile strength and the elongation percentage of the aluminum alloy are improved, and the corrosion resistance and the casting performance of the aluminum alloy are enhanced; the EDS energy spectrometer can be adopted for chemical component detection and analysis;

(2) the method is practical, produces less harmful gas and can effectively remove impurity iron element in the aluminum alloy. AlF in refining agent₃The surface energy of the aluminum liquid can be reduced, so that the reaction is fully performed; na (Na)₂SO₄A large amount of heat is generated during reaction, so that the refining temperature can be increased, and the viscosity of the surface of the aluminum liquid is reduced; na (Na)₂AlF₆Can adsorb and melt Al₂O₃Impurities, so that the reaction is more thorough; c₂Cl₆Decomposition to give C₂Cl₄And Cl₂，C₂Cl₄High-temperature volatilization can remove oxide inclusions and H in the molten liquid₂The functions of degassing and deslagging are achieved; the C powder can adsorb the surface of impurities, so that the slag skimming efficiency is improved;

(3) in the process of removing iron, chromium is added for modification treatment, and because the chromium and the iron atoms are similar in size, the iron element in the (AlFeSi) phase and the (AlFe) phase can be replaced, the growth of the beta-Fe phase is inhibited, and the acicular beta-Fe phase can be broken and decomposed; cobalt can enable an iron-rich phase to grow towards a spherical direction, and is beneficial to the reaction of titanium and iron to generate the precipitation of FeTi (Fe2Ti) compounds; a large amount of heat is released during the reaction of magnesium, and the reaction of titanium and iron elements is catalyzed; the titanium reacts with impurity iron to generate FeTi (Fe2Ti) compounds with high melting point and high density, and the iron-rich phases sink to the bottom of the crucible under the action of gravity, thereby achieving the iron removal effect.

In conclusion, the method has the advantages of simple operation, low cost, easy control, no pollution and the like, and is particularly suitable for the field of alloy iron removal.

Drawings

FIG. 1 is a process flow diagram of the present invention;

FIG. 2 is a metallographic microscopic comparison chart before and after an experiment in the first embodiment of the present invention;

FIG. 3 is a metallographic phase microscopic map before and after an experiment in example two of the present invention;

FIG. 4 is a metallographic microscopic comparison chart before and after an experiment in the third example of the present invention;

FIG. 5 is a metallographic microscopic comparison chart before and after the experiment in the fourth example of the present invention;

FIG. 6 is a metallographic microscopic comparison chart before and after the experiment in the fifth example of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in 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. 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.

In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the equipment or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.