CN117957340A

CN117957340A - Method for manufacturing extrusion porous pipe

Info

Publication number: CN117957340A
Application number: CN202280063203.8A
Authority: CN
Inventors: 鈴木太一; 东森稜
Original assignee: UACJ Corp
Current assignee: UACJ Corp
Priority date: 2021-10-20
Filing date: 2022-10-13
Publication date: 2024-04-30
Also published as: JP2023061741A; WO2023068166A1

Abstract

In a method for producing an extruded porous tube (1), an ingot is produced, said ingot having the following chemical composition: contains Si:2.0 mass% or less, fe:0.6 mass% or less, cu:0.6 mass% or less, mn:2.0 mass% or less, mg:0.4 mass% or less, cr:0.1 mass% or less, zn:1.5 mass% or less of Ti:0.1 mass% or less and B:0.1 mass% or less of one or two or more elements, the remainder comprising Al and unavoidable impurities, the total of Si content and Mn content being 3.2 mass% or less, si content being smaller than Mn content. The ingot is kept at 550-650 ℃ for more than 2 hours, and after the first homogenization treatment, the ingot is kept at 450-540 ℃ for more than 3 hours, and the second homogenization treatment is carried out. The ingot is then hot extruded.

Description

Method for manufacturing extrusion porous pipe

Technical Field

The present invention relates to a method for manufacturing an extruded porous tube.

Background

The extrusion perforated pipe has an outer wall portion constituting an outer peripheral portion thereof and partition wall portions partitioning a space surrounded by the outer wall portion, and is configured so that a fluid can flow through passages surrounded by the outer wall portion and the partition wall portions. In order to form a complicated cross-sectional shape having such a microstructure by extrusion processing, many extrusion porous pipes are made of an aluminum alloy having a small content of alloy elements and excellent extrudability.

For example, patent document 1 describes an extruded flat porous tube for heat exchangers having excellent corrosion resistance, which contains, in mass%, si:0.01 to 0.3%, 0.01 to 0.3% Fe, 0.05 to 0.4% Cu, 0.05 to 0.3% Mn, 0.05 to 0.25% Zr, 0 to 0.15% Ti, 0.3% or less total of Zr and Ti, the balance comprising an aluminum alloy containing Al and unavoidable impurities, wherein the area of particles dispersed in the matrix is 1.0 [ mu ] m ² or more, and the area ratio occupied by the AlFeSi stable phase is 0.1% or more and less than 0.5%.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2009-46702

Disclosure of Invention

Technical problem to be solved by the invention

In recent years, due to the increase in environmental awareness, the importance of a technique for recycling aluminum scrap as a casting raw material has increased. But the aluminum scrap contains various elements other than aluminum. In addition, the aluminum scrap may contain a metal material other than aluminum such as iron, as the case may be. Therefore, when the aluminum scrap is reused as a casting raw material, the content of elements other than aluminum increases, and various problems such as an increase in deformation resistance and a decrease in extrusion speed during hot extrusion occur. Therefore, in the conventional art, it is considered that it is difficult to manufacture an extruded porous tube having a complicated cross-sectional shape when aluminum scrap is used as a casting material.

The present invention has been made in view of the above-described background, and an object thereof is to provide a method for producing an extruded porous pipe capable of easily performing hot extrusion even when the content of an element other than aluminum is large.

Technical scheme for solving technical problems

One embodiment of the present invention is a method for producing an extruded porous tube, wherein an ingot is produced, the ingot having the following chemical composition: contains a material selected from the group consisting of Si (silicon): 2.00 mass% or less, fe (iron): 0.60 mass% or less, cu (copper): 0.60 mass% or less, mn (manganese): 2.00 mass% or less, mg (magnesium): 0.40 mass% or less of Cr (chromium): 0.10 mass% or less, zn (zinc): 1.50 mass% or less of Ti (titanium): 0.10 mass% or less and B (boron): 0.10 mass% or less of one or two or more elements, the remainder comprising Al (aluminum) and unavoidable impurities, the total of Si content and Mn content being 3.20 mass% or less, si content being smaller than Mn content,

Maintaining the ingot at 550 ℃ to 650 ℃ for more than 2 hours, carrying out first homogenization treatment,

Then, the ingot is kept at a temperature of 450 ℃ or more and 540 ℃ or less for 3 hours or more, and a second homogenization treatment is performed,

Then, the cast ingot was hot extruded to produce an extruded porous tube.

Effects of the invention

In the method for producing an extruded porous tube, the first homogenization treatment and the second homogenization treatment are performed on an ingot having a chemical composition within the specific range. By performing the homogenization treatment in two stages in this manner, and setting the holding temperature and holding time of the homogenization treatment in each stage to the above-described specific ranges, it is possible to suppress an increase in deformation resistance during hot extrusion even when the content of the element other than aluminum is large.

As described above, according to the above-described aspect, a method for manufacturing an extruded porous pipe can be provided that can easily perform hot extrusion even when the content of elements other than aluminum is large.

Drawings

FIG. 1 is a perspective view of an extruded porous tube of example 1.

Detailed Description

In the method for producing an extruded porous tube, first, an ingot having the specific chemical composition is produced. The ingot contains one or more elements selected from Si, fe, cu, mn, mg, cr, zn, ti and B. These elements are contained in casting materials such as aluminum ingot, aluminum scrap, and master alloy. In the case of using aluminum scrap as a casting raw material, the above elements may also be mainly derived from aluminum scrap.

Si:2.00 mass% or less

The ingot may contain Si in an amount exceeding 0 mass% and 2.00 mass% or less. Si is an element contained in an aluminum ingot, an aluminum alloy (for example, 4000-series alloy, 6000-series alloy, and the like) containing Si in aluminum scrap, a master alloy, and the like. Si has the effect of increasing the strength of the extruded porous tube. The Si content is preferably 0.20 mass% or more, more preferably 0.40 mass% or more, further preferably 0.60 mass% or more, particularly preferably 0.70 mass% or more, and most preferably 0.80 mass% or more, from the viewpoint of further improving the strength of the extruded porous tube.

On the other hand, if the Si content is too large, there is a possibility that the deformation resistance of the ingot at the time of hot extrusion increases and the extrudability decreases. The content of Si is 2.00 mass% or less, preferably 1.50 mass% or less, more preferably 1.40 mass% or less, and even more preferably 1.30 mass% or less, whereby the strength of the extruded porous tube can be improved while suppressing an increase in deformation resistance of the ingot during hot extrusion.

Mn:2.00 mass% or less

The ingot may contain Mn exceeding 0 mass% and 2.00 mass% or less. Mn is an element contained in an aluminum ingot, an aluminum alloy (for example, 3000-series alloy) containing Mn in aluminum scrap, or a master alloy. Mn has the effect of increasing the strength of extruded porous tubes. The Mn content is preferably 0.40 mass% or more, more preferably 0.60 mass% or more, still more preferably 0.80 mass% or more, particularly preferably 0.90 mass% or more, and most preferably 1.00 mass% or more, from the viewpoint of further improving the strength of the extruded porous tube.

On the other hand, if the Mn content is too large, there is a possibility that the deformation resistance of the ingot at the time of hot extrusion increases and the extrudability decreases. When the Mn content is 2.00 mass% or less, preferably 1.80 mass% or less, more preferably 1.70 mass% or less, the strength of the extruded porous tube can be improved while suppressing an increase in deformation resistance of the ingot during hot extrusion.

The total of the Si content and the Mn content in the ingot is 3.20 mass% or less, and the Si content is smaller than the Mn content. In addition to the above specific ranges for the Si and Mn contents in the chemical components of the ingot, the Si content and the Mn content satisfy the above relation, whereby the increase in the deformation resistance of the ingot during hot extrusion can be more effectively suppressed, and an extrusion porous pipe having a complicated cross-sectional shape can be easily produced. From the viewpoint of further improving the above-described action, the total of the Si content and the Mn content is preferably 3.00 mass% or less.

When the total of the Si content and the Mn content exceeds 3.20 mass%, there is a possibility that the extrudability at the time of hot extrusion is lowered. In addition, when the Si content is equal to or higher than the Mn content, it is difficult to precipitate fine AlMnSi intermetallic compounds in the ingot, and there is a possibility that the extrudability may be deteriorated. In this case, the extrusion limit speed may be easily reduced, and the productivity of extruding the porous pipe may be reduced. When the total amount of Mn contained in the aluminum ingot and aluminum scrap is equal to or less than the total amount of Si in producing the ingot, the chemical composition can be adjusted by a method such as adding a master alloy containing Mn.

Fe:0.60 mass% or less

The ingot may contain Fe in an amount exceeding 0 mass% and not more than 0.60 mass%. Fe is an element contained in aluminum ingots, aluminum scraps, and the like. In particular, when an aluminum scrap containing an Fe-based alloy is used as a casting material, the content of Fe in an ingot tends to be large in some cases. The content of Fe is preferably 0.10 mass% or more, more preferably 0.15 mass% or more, still more preferably 0.20 mass% or more, and particularly preferably 0.25 mass% or more, whereby the ratio of the aluminum scrap to the casting material can be more easily increased.

On the other hand, if the content of Fe is too large, coarse AlFe-based intermetallic compounds are easily formed in the ingot. Coarse AlFe-based intermetallic compounds in the ingot are not preferable because they may deteriorate the surface properties of the extruded porous tube, such as an increase in surface roughness. The deterioration of the surface properties can be avoided by setting the Fe content to 0.60 mass% or less, preferably 0.50 mass% or less.

Cu:0.60 mass% or less

The ingot may contain Cu in an amount exceeding 0 mass% and not more than 0.60 mass%. Cu is an element contained in aluminum ingots, aluminum scraps, and the like. In particular, in some cases, the aluminum scrap contains a component containing an aluminum alloy (for example, 2000-series alloy) containing a large amount of Cu, and when such aluminum scrap is used as a casting material, the Cu content in the ingot tends to be large. Cu has the effect of improving the natural potential of the extruded porous tube and improving the corrosion resistance of the extruded porous tube. The Cu content is preferably 0.05 mass% or more, more preferably 0.10 mass% or more, further preferably 0.15 mass% or more, and particularly preferably 0.20 mass% or more, from the viewpoint of further improving the corrosion resistance of the extruded porous tube. In addition, in this case, the ratio of the aluminum scrap occupied in the casting raw material can be made more easily increased.

On the other hand, if the Cu content is too large, the amount of Cu dissolved in the ingot increases, which may lead to an increase in deformation resistance and a decrease in extrudability of the ingot during hot extrusion. When the Cu content is 0.60 mass% or less, preferably 0.40 mass% or less, the increase in deformation resistance of the ingot during hot extrusion can be suppressed, and the corrosion resistance of the extrusion porous pipe can be improved.

Mg:0.40 mass% or less

Mg may be contained in the ingot in an amount exceeding 0 mass% and 0.40 mass% or less. Mg is an element contained in aluminum ingots, aluminum scraps, and the like. In particular, in some cases, the aluminum scrap contains a component containing an aluminum alloy (for example, 5000-series alloy, 6000-series alloy, or the like) containing a large amount of Mg, and when such aluminum scrap is used as a casting material, the Mg content in the ingot tends to be large. Mg has the effect of increasing the strength of the extruded porous tube. The Mg content is preferably 0.03 mass% or more, more preferably 0.05 mass% or more, and even more preferably 0.07 mass% or more, from the viewpoint of further improving the strength of the extruded porous tube. In addition, in this case, the ratio of the aluminum scrap occupied in the casting raw material can be made more easily increased.

On the other hand, if the Mg content is too large, the amount of Mg dissolved in the ingot increases, which may lead to an increase in deformation resistance and a decrease in extrudability of the ingot during hot extrusion. By setting the Mg content to 0.40 mass% or less, preferably 0.30 mass% or less, the increase in deformation resistance of the ingot during hot extrusion can be suppressed.

Cr:0.10 mass% or less

The ingot may contain Cr in an amount exceeding 0 mass% and not more than 0.10 mass%. Cr is an element contained in aluminum ingots, aluminum scraps, and the like. In particular, in some cases, the aluminum scrap contains a component containing an aluminum alloy (for example, 5000-series alloy, 7000-series alloy, etc.) containing a large amount of Cr, and when such an aluminum scrap is used as a casting material, the content of Cr in the ingot tends to be large. The content of Cr is preferably 0.01 mass% or more, more preferably 0.02 mass% or more, and still more preferably 0.03 mass% or more, whereby the ratio of the aluminum scrap to the casting material can be more easily increased.

On the other hand, if the Cr content is too large, coarse AlCr-based intermetallic compounds are easily formed in the ingot. If coarse AlCr-based intermetallic compounds are present in the ingot, cracks may be easily generated during hot extrusion or secondary working after hot extrusion, which is not preferable. By setting the Cr content to 0.10 mass% or less, the formation of coarse AlCr-based intermetallic compounds can be avoided.

Zn:1.50 mass% or less

The ingot may contain Zn in an amount of more than 0 mass% and 1.50 mass% or less. Zn is an element contained in aluminum ingots, aluminum scraps, and the like. In particular, in some cases, the aluminum scrap contains a component containing an aluminum alloy (for example, 7000-series alloy) containing a large amount of Zn, and when such an aluminum scrap is used as a casting material, the Zn content in the ingot tends to be large. Zn has the effect of weakening the surface oxide film of the extruded porous tube and dispersing the occurrence of pitting corrosion, thereby improving corrosion resistance. From the viewpoint of further improving the above-described effect, the Zn content is preferably 0.05 mass% or more, more preferably 0.10 mass% or more, and still more preferably 0.15 mass% or more. In addition, in this case, the ratio of the aluminum scrap occupied in the casting raw material can be made more easily increased.

On the other hand, if the Zn content is too large, the solidus temperature of the aluminum alloy decreases, and therefore, there is a possibility that partial melting of the ingot or extruded porous pipe is likely to occur during the homogenization treatment or hot extrusion. By setting the Zn content to 1.50 mass% or less, preferably 1.00 mass% or less, partial melting of the ingot or the extruded porous tube can be avoided, and the effect due to Zn can be obtained.

Ti:0.10 mass% or less

The ingot may contain more than 0 mass% and 0.10 mass% or less of Ti. Ti has an effect of refining crystal grains in a metal structure of an ingot. From the viewpoint of further improving the above effect, the Ti content is preferably 0.005 mass% or more, more preferably 0.007 mass% or more, and even more preferably 0.010 mass% or more.

On the other hand, if the Ti content is too large, coarse AlTi-based intermetallic compounds are easily formed in the ingot. If coarse AlTi-based intermetallic compounds are present in the ingot, cracks may be easily generated during hot extrusion or secondary working after hot extrusion, which is not preferable. By setting the Ti content to 0.10 mass% or less, the formation of coarse AlTi-based intermetallic compounds can be avoided, and crystal grains in the microstructure of the ingot can be sufficiently refined.

B:0.10 mass% or less

The ingot may contain B in an amount of more than 0 mass% and not more than 0.10 mass%. By setting the content of B in the extrusion porous tube to the above-described specific range, crystal grains in the metallic structure of the extrusion porous tube can be sufficiently miniaturized. From the viewpoint of more reliably obtaining the above-described effects, the content of B in the ingot is preferably 0.005 mass% or more and 0.10 mass% or less.

Other elements

The ingot may contain elements other than the above elements as unavoidable impurities. Examples of the element include Zr (zirconium) and V (vanadium). The content of the element as an unavoidable impurity may be, for example, 0.05 mass% or less for each element. The total content of the elements as unavoidable impurities may be 0.50 mass% or less.

From the viewpoint of more reliably obtaining the effect of improving extrudability, the ingot preferably has the following chemical composition: contains Si:0.60 mass% or more and 1.40 mass% or less and Mn:0.80 mass% or more and 1.80 mass% or less, the remainder including Al and unavoidable impurities, the total of Si content and Mn content being 3.20 mass% or less, si content being smaller than Mn content. In this case, the ingot may further comprise a metal selected from the group consisting of Fe:0.10 mass% or more and 0.50 mass% or less, cu:0.05 mass% or more and 0.40 mass% or less, mg:0.05 mass% or more and 0.30 mass% or less, cr:0.01 mass% or more and 0.10 mass% or less, zn:0.10 mass% or more and 1.00 mass% or less, ti:0.005 mass% or more and 0.10 mass% or less and B:0.005 mass% or more and 0.10 mass% or less of one or two or more elements as an optional component.

From the same point of view, the ingot preferably has the following chemical composition: it must contain Si:0.70 mass% or more and 1.30 mass% or less, fe:0.10 mass% or more and 0.50 mass% or less, cu:0.05 mass% or more and 0.40 mass% or less, mn:0.90 mass% or more and 1.70 mass% or less, mg:0.05 mass% or more and 0.30 mass% or less, cr:0.01 mass% or more and 0.10 mass% or less, zn:0.10 mass% or more and 1.00 mass% or less, ti:0.005 mass% or more and 0.10 mass% or less and B:0.005 mass% or more and 0.10 mass% or less, the remainder including Al and unavoidable impurities, the total of Si content and Mn content being 3.00 mass% or less, si content being smaller than Mn content.

The ingot can be produced by a known casting method such as DC casting or CC casting. As a casting raw material for producing an ingot, for example, a new ingot of aluminum or aluminum scrap can be used.

In the above method for producing an extruded porous tube, at least a part of the casting raw material is preferably aluminum scrap. Here, the aluminum scrap includes an end material, chips, used aluminum products, aluminum parts separated from the used products, and the like, which are generated in the manufacturing process of the aluminum products.

As described above, when the aluminum scrap is reused as a casting raw material, the content of elements other than aluminum increases, which causes various problems such as an increase in deformation resistance and a decrease in extrusion speed during hot extrusion. Therefore, in the conventional art, when aluminum scrap is used as a casting material, it is considered that it is difficult to manufacture an extruded porous tube having a complicated cross-sectional shape.

In contrast, in the method for producing an extruded porous tube, the chemical composition of the ingot is set to the above-described specific range, and further a two-stage homogenization treatment described later is performed, whereby even when the content of an element other than aluminum is large, an increase in deformation resistance at the time of hot extrusion can be suppressed. Therefore, according to the manufacturing method of the above embodiment, even when at least a part of the casting raw material uses aluminum scrap and the content of the element other than aluminum is large, the extrusion porous pipe having a complicated cross-sectional shape can be easily manufactured.

In addition, by using aluminum scrap as at least a part of the casting raw material, the amount of new ingot of aluminum used can be reduced. As a result, the environmental load in the process of manufacturing the extruded porous tube can be further reduced, and the material cost of the extruded porous tube can be further reduced. From the viewpoint of further improving the above effect, the proportion of the aluminum scrap in the casting material is preferably 35 mass% or more, more preferably 45 mass% or more, and particularly preferably 60 mass% or more.

In the above method for producing an extruded porous tube, after producing an ingot, the ingot is held at a temperature of 550 ℃ or higher and 650 ℃ or lower for 2 hours or longer, and then subjected to a first homogenization treatment. By setting the holding temperature and holding time in the first homogenization treatment to the above specific ranges, coarse crystals in the ingot can be decomposed, granulated, or re-dissolved in the Al matrix.

The holding temperature in the first homogenization treatment is preferably 580 ℃ or higher and 620 ℃ or lower from the viewpoint of further promoting the decomposition of the crystal in the ingot or the like. From the same point of view, the holding time in the first homogenization treatment is preferably 10 hours or longer. In addition, from the viewpoint of productivity, the holding time in the first homogenization treatment is preferably 24 hours or less.

In the case where the holding temperature in the first homogenization treatment is less than 550 ℃, or in the case where the holding time is less than 2 hours, the decomposition of the crystal or the like may become insufficient. In the case where the holding temperature in the first homogenization treatment exceeds 650 ℃, the ingot may be partially melted.

In the method for producing an extruded porous tube, the ingot after the first homogenization treatment is subjected to the second homogenization treatment. The holding temperature in the second homogenization treatment is set to 450 ℃ or higher and 540 ℃ or lower, and the holding time is set to 3 hours or longer. As described above, the first homogenization treatment is mainly performed for the purpose of decomposition, granulation, and re-solution of coarse crystals crystallized in an ingot at the time of casting. However, when the holding temperature and holding time in the first homogenization treatment are within the above specific ranges, the dissolution, granulation, and re-dissolution of the crystal are promoted, and the dissolution of Mn and Si as solute elements in the Al matrix is also promoted. If the solute element is excessively dissolved in the Al matrix phase, the movement speed of dislocation in the matrix phase at the time of hot extrusion is lowered, and the deformation resistance is liable to rise.

On the other hand, if the ingot is heated under the above specific conditions in the second homogenization treatment, si and Mn dissolved in the Al matrix in the first homogenization treatment can be finely precipitated as AlMnSi intermetallic compounds. As a result, the amount of solute element in the Al matrix phase can be reduced, and the deformation resistance during hot extrusion can be reduced. Therefore, the extrusion property at the time of hot extrusion can be improved by heating the ingot after the first homogenization treatment under the above-described specific conditions and performing the second homogenization treatment.

From the viewpoint of further improving the effect of improving extrudability, the holding temperature in the second homogenization treatment is preferably 480 ℃ to 520 ℃. From the same point of view, the holding time in the second homogenization treatment is preferably 5 hours or more. In addition, from the viewpoint of productivity, the holding time in the second homogenization treatment is preferably 24 hours or less, more preferably 15 hours or less.

In the case where the holding temperature in the second homogenizing treatment is less than 450 ℃, or in the case where the holding time is less than 3 hours, the amount of the AlMnSi intermetallic compound deposited tends to be small, and there is a possibility that the extrudability may be deteriorated at the time of hot extrusion. If the holding temperature in the second homogenization treatment exceeds 540 ℃, si and Mn dissolved in the Al matrix phase are difficult to form intermetallic compounds, and there is a possibility that the extrudability in hot extrusion is deteriorated.

In the above manufacturing method, the first homogenization treatment and the second homogenization treatment can be performed continuously. Here, continuously performing the first homogenization treatment and the second homogenization treatment means that after the completion of the first homogenization treatment, the temperature of the ingot is reduced to the holding temperature in the second homogenization treatment, and the second homogenization treatment is started at a time when the temperature of the ingot reaches the holding temperature in the second homogenization treatment.

In the case where the first homogenization treatment and the second homogenization treatment are continuously performed, it is preferable that the ingot is cooled to the holding temperature in the second homogenization treatment at an average cooling rate of 20 ℃/hr or more and 60 ℃/hr or less after the completion of the first homogenization treatment.

In the above-described production method, after the completion of the first homogenization treatment, the ingot may be temporarily cooled to a temperature lower than the holding temperature in the second homogenization treatment, and then the second homogenization treatment may be performed. In this case, the temperature of the ingot at the time of completion of cooling can be set to, for example, 200 ℃. When the cooled ingot is heated to the holding temperature in the second homogenization treatment, the ingot is preferably heated to the holding temperature in the second homogenization treatment at an average temperature increase rate of 20 to 60 ℃.

In the method for producing an extruded porous tube, the extruded porous tube can be obtained by hot extrusion of the ingot after the second homogenization treatment. The temperature of the ingot at the start of extrusion in the hot extrusion, the temperature of the extrusion porous tube at the completion of extrusion, and the like may be appropriately set according to the chemical composition of the extrusion porous tube. For example, the temperature of the ingot at the start of extrusion can be appropriately set from a range of 450 ℃ to 550 ℃. The extruded porous tube thus obtained may be used as it is, or may be used after post-treatment such as corrective work or cutting for adjusting the size and shape, heat treatment for adjusting the strength, zinc plating for improving the corrosion resistance, and painting. These post treatments can be appropriately combined according to the use of the extruded porous tube, etc.

The extruded porous tube obtained by the above-described production method has an outer wall portion that partitions an outer space and an interior of the extruded porous tube, and a plurality of partition wall portions that partition an inner space of the outer wall portion. The extrusion porous pipe has a plurality of passages surrounded by an outer wall portion and a partition wall portion, and is configured so that liquid, gas, and the like can flow through the passages. The cross-sectional shape of the extrusion perforated pipe is not particularly limited, and various cross-sectional shapes such as an oblong shape and a rectangular shape can be used. The cross-sectional shape of the passage of the extrusion perforated pipe is not particularly limited, and various cross-sectional shapes such as a circle, triangle, and quadrangle can be used.

The extruded porous tube may have a flat cross-sectional shape. In this case, the ratio of the width to the thickness of the extruded porous tube may be 2 or more and 50 or less, and preferably 3 or more and 30 or less. In general, when the extruded porous pipe has a flat shape, the higher the ratio of the width to the thickness is, the more difficult the extrusion processing is, and the higher the extrudability tends to be required. In the process of producing the extrusion porous pipe, the aluminum alloy ingot having the specific chemical composition is subjected to two-stage homogenization treatment, whereby the rise in deformation resistance during hot extrusion can be suppressed and the extrudability can be improved. Therefore, the extruded porous tube having a cross-sectional shape requiring such high extrudability can be easily obtained.

The extrusion porous tube has an outer wall portion that divides an outer space and an interior of the extrusion porous tube, and a plurality of partition wall portions that divide an interior space of the outer wall portion, and the thickness of the outer wall portion and the partition wall portions may be 0.10mm or more and 2.0mm or less, and preferably 0.15mm or more and 1.5mm or less. In the extrusion porous tube, as in the case of the ratio of the width to the thickness, the thinner the thickness of the outer wall portion and the partition wall portion is, the more difficult the extrusion processing is, and there is a tendency that high extrudability is required. In the process of producing the extrusion porous pipe, the extrusion property can be improved by performing a two-stage homogenization treatment on the aluminum alloy ingot having the specific chemical composition, thereby suppressing an increase in deformation resistance during hot extrusion. Therefore, the extruded porous tube having a cross-sectional shape requiring such high extrudability can be easily obtained.

Examples

An example of the method for producing the extruded porous tube is described below. In the method of manufacturing an extruded porous tube of the present embodiment, an ingot is produced, the ingot having the following chemical composition: contains Si selected from: 2.00 mass% or less, fe:0.60 mass% or less, cu:0.60 mass% or less, mn:2.00 mass% or less, mg:0.40 mass% or less, cr:0.10 mass% or less, zn:1.50 mass% or less of Ti:0.10 mass% or less and B:0.10 mass% or less of one or two or more elements, the remainder comprising Al and unavoidable impurities, the total of Si content and Mn content being 3.20 mass% or less, si content being smaller than Mn content. Then, the ingot is kept at a temperature of 550 ℃ or higher and 650 ℃ or lower for 2 hours or longer, and a first homogenization treatment is performed. After the completion of the first homogenization treatment, the ingot is held at a temperature of 450 ℃ or higher and 540 ℃ or lower for 3 hours or longer, and then a second homogenization treatment is performed. Then, the ingot after the second homogenization treatment is subjected to hot extrusion, whereby an extruded porous tube can be produced.

As shown in fig. 1, the extruded porous tube 1 of the present embodiment has a flat cross-sectional shape. More specifically, the extruded porous tube 1 has an oblong cross-sectional shape. The extruded perforated tube 1 has a width of, for example, 14.0mm and a thickness of, for example, 2.5mm.

The extrusion perforated tube 1 has an outer wall 11 dividing the outer space and the interior thereof, and partition walls 13 dividing the space surrounded by the outer wall 11 into 19 passages 12. The passageway 12 of the extruded porous tube 1 in this embodiment has a circular cross-sectional shape. The thickness of the thinnest part of the outer wall portion 11 and the partition wall portion 13 is, for example, 0.4mm.

Hereinafter, an example of the method for producing the extruded porous tube of the present embodiment will be described in more detail. First, cast ingots having chemical compositions (alloy marks A1 to A3) shown in table 1 were produced by DC casting using a casting raw material including aluminum scrap. In table 1, "bal." is a symbol indicating that the element is the remainder.

After the ingot was produced, the ingot was kept at 600 ℃ for 10 hours, and subjected to a first homogenization treatment. After the completion of the first homogenization treatment, the ingot was held at a temperature of 500 ℃ for 10 hours, and a second homogenization treatment was performed. The first homogenization treatment and the second homogenization treatment may be performed continuously, or the temperature of the ingot may be lower than the holding temperature of the second homogenization treatment during the period from the completion of the first homogenization treatment to the completion of the second homogenization treatment.

After the completion of the second homogenization treatment, the ingot was hot-extruded at a temperature of 500 ℃ to thereby produce an extrusion porous tube 1. From the above, test materials S1 to S3 shown in table 2 were obtained. The test materials R1 to R4 shown in table 2 are test materials for comparison with the test materials S1 to S3. The production methods of the test materials R1 to R3 were the same as those of the test materials S1 to S3 except that the chemical compositions of the ingots were changed to the alloy marks A4 to A6 shown in table 1. The production method of the test material R4 was similar to the test materials S1 to S3 except that the chemical composition of the ingot was changed to the alloy mark A7 shown in table 1, and the second homogenization treatment was omitted.

The method for evaluating the extrudability of each test material is described below.

Extrusion Property

The extrudability can be evaluated based on the appearance of the test material. More specifically, the appearance of the test material was visually observed to evaluate the presence or absence of cracks and streak patterns along the extrusion direction. Table 2 shows the presence or absence of cracks and streak patterns at the ends of each test material.

TABLE 1

TABLE 2

As shown in tables 1 and 2, in the production process of the test materials S1 to S3, the first homogenization treatment and the second homogenization treatment were performed on the ingot having the above-described specific chemical composition under the above-described specific conditions, and therefore, the deformation resistance of the ingot at the time of hot extrusion could be reduced. Thus, the test materials S1 to S3 had good appearance.

On the other hand, since the Si content of the test material R1 is not less than the Mn content, the extrudability is inferior to those of the test materials S1 to S3, and a streak pattern is generated on the surface of the test material.

Since the total of the Si content and the Mn content of the test material R2 is too large, the extrudability is inferior to the test materials S1 to S3, cracks are generated at the ends of the test material in the width direction, and a striped pattern is generated on the surface of the test material.

Since the test material R3 has too much Mn content, the extrudability is inferior to the test materials S1 to S3, and a streak pattern is generated on the surface of the test material.

Since the test material R4 was not subjected to the second homogenization treatment during the production process, the extrudability was inferior to that of the test materials S1 to S3, and a streak pattern was generated on the surface of the test material.

The specific embodiment of the method for producing an extruded porous tube according to the present invention has been described above with reference to examples, but the specific embodiment of the method for producing an extruded porous tube according to the present invention is not limited to the embodiment, and the structure can be appropriately modified within a range that does not impair the gist of the present invention.

Claims

1. A method of manufacturing an extruded porous tube, characterized by producing an ingot having the following chemical composition: contains Si selected from: 2.00 mass% or less, fe:0.60 mass% or less, cu:0.60 mass% or less, mn:2.00 mass% or less, mg:0.40 mass% or less, cr:0.10 mass% or less, zn:1.50 mass% or less of Ti:0.10 mass% or less and B:0.10 mass% or less of one or two or more elements, the remainder comprising Al and unavoidable impurities, the total of Si content and Mn content being 3.20 mass% or less, si content being smaller than Mn content,

Then, the ingot was hot-extruded to produce an extruded porous tube.

2. The method for producing an extruded porous tube according to claim 1, wherein after the completion of the first homogenization treatment, the ingot is cooled to a holding temperature in the second homogenization treatment at an average cooling rate of 20 ℃/hr or more and 60 ℃/hr or less.

3. The method for producing an extruded porous tube according to claim 1, wherein after the completion of the first homogenization treatment, the ingot is cooled to a temperature lower than a treatment temperature in the second homogenization treatment, and then the ingot is heated to a holding temperature in the second homogenization treatment at an average temperature increase rate of 20 ℃/hr or more and 60 ℃/hr or less.

4. The method for producing an extruded porous tube according to any one of claims 1 to 3, wherein at least a part of the casting raw material is aluminum scrap at the time of producing the ingot.

5. The method for producing an extruded porous tube according to any one of claims 1 to 4, wherein the extruded porous tube having a flat cross-sectional shape and a ratio of width to thickness of 2 to 50 inclusive is produced by the hot extrusion.

6. The method for producing an extrusion porous tube according to any one of claims 1 to 5, wherein the extrusion porous tube is produced by the hot extrusion, and the extrusion porous tube has an outer wall portion that partitions an outer space and an interior of the extrusion porous tube, and a plurality of partition wall portions that partition an inner space of the outer wall portion, and the thickness of the outer wall portion and the partition wall portion is 0.10mm or more and 2.0mm or less.