JP2012188723A - Aluminum corrugated tube for automobile cooling water tube and method for production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum corrugated tube for an automobile cooling water tube satisfactory in both flexibility and corrosion resistance and to provide a method for the production thereof.SOLUTION: The aluminum corrugated tube for an automobile cooling water tube has two layers comprising a core material and a sacrifice material on one side of the core material. The core material is an aluminum alloy comprising 0.05-0.9% Si, 0.2-0.5% Fe, 0.1-0.7% Cu, 0.5-1.8% Mn, and 0.05-0.2% Ti, with the balance comprising Al and unavoidable impurities. The sacrifice material comprises 0.2-5% Zn and 0.2-0.5% Fe, with the balance comprising Al and unavoidable impurities.

Description

  The present invention relates to an aluminum corrugated tube for automobile cooling water piping excellent in corrosion resistance and flexibility, and a manufacturing method thereof.

  In current automobiles, rubber hoses are generally used for cooling water pipes that connect the radiator and engine. However, rubber hoses are crushed by the piping arrangement, and cooling water cannot be circulated efficiently. In some cases, and when used for a high-power engine, the engine room becomes hot, so deterioration of the rubber hose may be a problem, and an aluminum hose may be used instead of the rubber hose.

  As such an aluminum hose, it was common to use a clad pipe having a sacrificial anticorrosive layer as disclosed in Patent Document 1, but since it does not have flexibility, it is piped according to the shape in the engine room. After bending, the radiator and engine had to be connected, resulting in low productivity.

  As an aluminum hose having flexibility, one having a corrugated pipe structure as in Patent Document 2 is known, but it does not have corrosion resistance and cannot be used for the purpose of circulating cooling water. It was.

JP 11-44497 A JP 2004-156672 A

  This invention is made | formed in view of the said problem, and it aims at providing the aluminum corrugated tube for automotive cooling water piping which made the flexibility and corrosion resistance compatible, and its manufacturing method.

In order to achieve the above object, an aluminum corrugated tube for automobile cooling water piping according to the first aspect of the present invention,
Contains Si 0.05% or more, 0.9% or less, Fe 0.2% or more, 0.5% or less, Cu 0.1% or more, 0.7% or less, Mn 0.5% or more, 1.8% or less, Ti 0.05% or more, 0.2% or less In addition, the aluminum alloy core material layer is composed of Al and inevitable impurities, and one side of the core material layer contains Zn of 0.2% to 5%, Fe content of 0.2% to 0.5%, and the balance of Al. And a sacrificial material layer made of inevitable impurities.

The ratio of the minimum diameter to the maximum diameter is preferably 0.5 to 0.9.
The thickness of the corrugated tube material is preferably 0.2 mm or more and 1.0 mm or less, and the thickness of the sacrificial material is preferably 3 to 30% of the total thickness.

The manufacturing method of the aluminum corrugated tube for automobile cooling water piping according to the second aspect of the present invention,
Contains Si 0.05% or more, 0.9% or less, Fe 0.2% or more, 0.5% or less, Cu 0.1% or more, 0.7% or less, Mn 0.5% or more, 1.8% or less, Ti 0.05% or more, 0.2% or less In addition, the aluminum alloy core material layer is composed of Al and inevitable impurities, and one side of the core material layer contains Zn of 0.2% to 5%, Fe content of 0.2% to 0.5%, and the balance of Al. And an aluminum alloy clad plate consisting of two layers of sacrificial material layers consisting of unavoidable impurities and having a total thickness of 0.2 mm or more and 1.0 mm or less. A spiral ridge is formed in the longitudinal direction by processing.

  According to the present invention, aluminum for automobile cooling water piping that has flexibility and can determine the shape according to the shape in the engine room at the time of installation without determining the piping shape in advance, and has high corrosion resistance. A corrugated tube and a manufacturing method thereof can be provided.

It is a figure which shows an example of the aluminum corrugated tube for motor vehicle cooling water piping of this invention. It is a figure for demonstrating joining of an aluminum alloy clad board | plate material. It is a figure which shows the aspect of the aluminum corrugated tube material in a tensile strength measurement. It is a figure which shows the aspect of the aluminum corrugated tube material in bending workability evaluation.

  Hereinafter, the present invention will be described in detail.

  The aluminum corrugated tube for automobile cooling water piping according to the present invention comprises two layers of a core material (layer) and a sacrificial material (layer) on one side of the core material.

(Sacrificial material)
In the sacrificial material, Zn is added in an amount of 0.2% to 5.0%. By adding Zn, it acts to lower the natural potential of the sacrificial anode material than the core material, and the corrosion resistance of the clad material is improved by the sacrificial anticorrosive effect. If Zn is less than 0.2%, the sacrificial anticorrosive effect becomes difficult to function, and the corrosion resistance decreases. On the other hand, when Zn exceeds 5.0%, the self-corrosion resistance of the sacrificial material is lowered, so that the corrosion resistance is lowered, Zn concentration becomes remarkable at the fusion weld portion of the aluminum corrugated tube, and preferential corrosion occurs.

  In the sacrificial material, Fe is added in an amount of 0.2% to 0.5%. Fe exists as an Al—Fe based compound or an Al—Fe—Si based compound, and has an effect of improving strength. If Fe is less than 0.2%, the strength is insufficient because these compounds are few. On the other hand, if the Fe content exceeds 0.5%, these compounds increase, and therefore the cathode sites increase and the self-corrosion resistance decreases. From the viewpoint of strength and corrosion resistance, Fe is preferably 0.2% or more and 0.5% or less.

(Heartwood)
In the core material, Si is added to 0.05% or more and 0.9% or less. If the Si content of the core material is less than 0.05 wt%, there is no effect in terms of strength improvement, and if it exceeds 0.9 wt%, deep pitting corrosion may occur due to single Si. More preferably, Si is 0.3 to 0.6 wt%.

  In the core material, Fe is added in an amount of 0.2% to 0.5%. When Fe is added to the core, it exists as an Al—Fe compound or Al—Fe—Si compound, and has the effect of improving strength. If Fe is less than 0.2%, the strength is insufficient because these compounds are few. On the other hand, if Fe exceeds 0.5%, these compounds increase, so that the cathode sites increase and the corrosion resistance of the core material decreases. From the viewpoint of strength and corrosion resistance, Fe is more preferably 0.1% or more and 0.5% or less.

  In the core material, Cu is added 0.1% or more and 0.7% or less. Cu is an element that improves the strength of the core material. If it is less than 0.1%, the strength of the core material cannot be improved. On the other hand, if it exceeds 0.7%, the intergranular corrosion sensitivity increases and the corrosion resistance decreases.

  In the core material, Mn is added to 0.5% or more and 1.8% or less. Mn is an element that improves the strength of the core material. If Mn is less than 0.5%, the strength of the core material cannot be improved. On the other hand, if Mn exceeds 1.8%, a coarse intermetallic compound is produced, so that workability and corrosion resistance are lowered.

  In the core material, Ti is added to 0.05% or more and 0.2% or less. Ti is an element that improves the corrosion resistance of the core material. When Ti is contained in the core material, it has an effect of preventing the pitting corrosion from proceeding in the depth direction by depositing into the core material in layers. If Ti is less than 0.05%, the corrosion resistance is not affected. On the other hand, if Ti exceeds 0.2%, a coarse intermetallic compound is generated, so that workability and corrosion resistance are deteriorated.

  The sacrificial material is clad with a thickness of 3% or more and 30% or less. If the thickness of the sacrificial material is less than 3%, the thickness difference from the core material is extremely large, so that clad after rolling becomes difficult. On the other hand, if the thickness of the sacrificial material exceeds 30%, the sacrificial material itself is low in strength, so the inner sacrificial material ratio increases, causing the corrugated tube material itself to be weakened and cracked when bent, It becomes easy to destroy.

  The appropriate corrugated tube thickness is 0.2 mm or more and 1.0 mm or less. If the thickness of the corrugated tube is less than 0.2 mm, when the molded corrugated tube material is bent, the tube cross section at the bent portion is extremely deformed. On the other hand, when the thickness of the corrugated tube exceeds 1.0 mm, it becomes difficult to bend and deform and it becomes difficult to perform construction on site.

  Further, in the corrugated tube, clad with a brazing material layer on the outer surface for joining with other members such as a connector has no practical problem and does not impair the function of the present invention. When brazing is performed, it is mainly applied to brazing using a fluoride-based flux. For joining with connectors, construction by torch brazing is also an object.

  The ingot of the sacrificial material and the core material is cast by a DC casting method, a continuous casting method, or the like. In the ingot of the sacrificial material and the brazing material, hot rolling is performed to a predetermined thickness after chamfering. The ingot for the core material can be manufactured by a conventional method by combining the sacrificial material plate and the brazing material plate after performing homogenization treatment and chamfering.

  The plate material having a predetermined thickness after rolling is bent into a cylindrical shape, and the bent butt plate ends are joined in the longitudinal direction by welding or electro-sewing as shown in FIG. . An aluminum corrugated tube for automobile cooling water piping as shown in FIG. 1 is manufactured by forming the joined continuous cylindrical material into a shape in which the cross-sectional diameter is bent into a corrugated shape at regular intervals. The corrugated bent shape molded in this rolling process has an appropriate ratio of the maximum diameter to the minimum diameter of 0.5 to 0.9. If it is less than 0.5, when the molded corrugated tube material is bent, the deformation is concentrated in the trough deformation having a limited corrugated shape, and a large stress accumulates and is easily broken. If it exceeds 0.9, the tube cross-section will be deformed when bent, making it difficult to secure the tube cross-section.

  Hereinafter, examples of the present invention will be described in comparison with comparative examples.

(Example)
DC casting was performed on each of the sacrificial anode material within the component composition range of the present invention shown in alloy codes A1 to A10 in Table 1 and the core material within the component composition range of the present invention shown in alloy codes B1 to B13 of Table 2, respectively. Was made.

  The sacrificial material was subjected to chamfering and then rolled into a plate shape by hot rolling at 500 ° C. The ingot for core material was homogenized for 6 hours at 520 ° C. and faced to a thickness of 40 mm. The sacrificial material plate and the core material ingot are stacked in this order in the combinations shown in Tables 5 to 11 and hot-rolled at 480 ° C. to form a two-layer clad material having a thickness of 3.5 mm. After cold rolling to 6 mm and then annealing at 360 ° C. for 3 hours, cold rolling was performed to a predetermined plate thickness to obtain a clad material.

  The clad material was bent into a cylindrical shape, and the bent butt plate ends were joined in the longitudinal direction by TIG welding. The joined continuous cylindrical material was rolled into a corrugated shape having a cross-sectional diameter at regular intervals at the dimensional ratios shown in Tables 5 to 11, and an evaluation corrugated tube material was produced.

(Comparative example)
Sacrificial materials shown in alloy codes A11 to A17 in Table 1, core materials shown in alloy codes B14 to B23 in Table 2, and clad materials having combinations shown in Tables 12 to 15 were produced in the same manner as in the examples.

  Also, the sacrificial material shown in alloy code C1 in Table 3 and the core material shown in alloy code D1 in Table 4 are melted and cast to form a cylindrical core material hollow billet (outer diameter 400 mm, inner diameter 90 mm, length 990 mm) of the core material alloy Was cut to obtain a core billet hollow billet of 150 mmφ at room temperature, and a sacrificial alloy extruded tube (room temperature: outer diameter 150 mm, inner diameter set to a predetermined clad configuration, length 990 mm) was obtained as a sacrificial material hollow billet. After the core material hollow billet was heated to 500 ° C., the sacrificial material hollow billet at room temperature was inserted into the inner diameter portion of the core material hollow billet and cooled to perform shrink fitting. The hollow billet of the two-layer clad that has been shrink-fitted is indirectly extruded at 450 ° C. to obtain an extruded tube having an outer diameter of 47 mm and a wall thickness of 3.5 mm. Was obtained as a combination shown in Table 15.

  In addition, each component composition value shown to Table 1, 2, 3, 4 here is the value measured from the sacrificial material and core material after casting with the emission spectroscopic analyzer.

(Evaluation)
About each obtained aluminum corrugated tube material, productivity, tensile strength, bending workability, and corrosion resistance were evaluated as follows. The results are shown in Tables 5-15.

(Manufacturability evaluation)
When the clad material was produced by superposing the sacrificial anode material and the core material, the case where a sound clad material was produced was marked with ◎, and the case where the clad rate could not be controlled was marked with x.

(Tensile strength measurement)
Each aluminum corrugated tube material was subjected to a tensile test in the manner shown in FIG. 3 to examine the tensile strength. The tensile strength of 170 MPa or more was rated as ◎, and 170 MPa or less was rated as x.

(Bending workability evaluation)
When bending was performed in the manner shown in FIG. 4 and cracks did not occur on the outside and inside of the bent portion, ◎ was indicated, and when it was generated, ×. In addition, the case where the tube cross section was not greatly deformed was marked with ◎, and the case where it was deformed was marked with ×.

(Corrosion resistance evaluation)
The inner tube member, the city water was added 10ppm of Cu 2 ⁺ ions as etchant, performs cycle circulation test 8hr at 16hr and 80 ° C. at room temperature, was measured pit depth of the inner surface cladding layer at 3 months . The flow rate of the corrosive liquid was 10 l / min. When the maximum pitting depth was less than 60 μm, ◎, less than 80 μm, and 100 μm or more were evaluated as x.

  As shown in Tables 5 to 15, as a result of various tests, in Examples 1 to 95 of the present invention, the aluminum corrugated tube material of the present invention is applied for manufacturability, tensile strength bending workability, and corrosion resistance. Although it was confirmed that it was suitable for use and environment, in Comparative Examples 96 to 132, as described below, an unreasonable result may be obtained in the use and environment in which the aluminum corrugated tube material of the present invention is used. found.

That is,
In the case of the comparative example 96, since the minimum diameter / maximum diameter ratio of the aluminum corrugated tube material was small, bending workability was lowered.
In the case of the comparative example 97, since the minimum diameter / maximum diameter ratio of the aluminum corrugated tube material was small, bending workability was lowered.
In the case of Comparative Example 98, the corrosion resistance was reduced because the amount of Zn in the sacrificial material was small.
In the case of Comparative Example 99, the corrosion resistance decreased because the amount of Zn in the sacrificial material was large.
In the case of Comparative Example 100, the strength was reduced because the amount of Fe in the sacrificial material was small.
In the case of Comparative Example 101, the corrosion resistance decreased because the amount of Fe in the sacrificial material was large.
In the case of the comparative example 102, since the minimum diameter / maximum diameter ratio of the aluminum corrugated tube material was small, bending workability was lowered.
In the case of Comparative Example 103, since the thickness of the sacrificial material was small, a sound clad material could not be manufactured.
In the case of the comparative example 104, since the thickness of the sacrificial material was large, a sound clad material could not be manufactured.
In the case of Comparative Example 105, the strength decreased because the amount of Si in the core material was small.
In the case of Comparative Example 106, the corrosion resistance decreased because the amount of Si in the core material was large.
In the case of Comparative Example 107, the strength decreased because the amount of Fe in the core material was small.
In the case of Comparative Example 108, the corrosion resistance decreased because the amount of Fe in the core material was large.
In the case of Comparative Example 109, the strength decreased because the amount of Mn in the core material was small.
In the case of Comparative Example 110, since the amount of Mn in the core material was large, it could not be produced.

In Comparative Examples 96-110, since the minimum diameter / maximum diameter ratio of the aluminum corrugated tube material was small, bending workability was lowered.
In the case of Comparative Example 111, since the minimum diameter / maximum diameter ratio of the aluminum corrugated tube material was large, bending workability was lowered.
In the case of the comparative example 112, since the minimum diameter / maximum diameter ratio of the aluminum corrugated tube material was large, bending workability was lowered.
In the case of Comparative Example 113, the corrosion resistance decreased because the amount of Zn in the sacrificial material was small.
In the case of Comparative Example 114, the corrosion resistance decreased because the amount of Zn in the sacrificial material was large.
In the case of Comparative Example 115, the strength decreased because the amount of Fe in the sacrificial material was small.
In the case of Comparative Example 116, the corrosion resistance decreased because the amount of Fe in the sacrificial material was large.
In the case of Comparative Example 117, bending workability deteriorated because the minimum diameter / maximum diameter ratio of the aluminum corrugated tube material was small.
In the case of Comparative Example 118, since the thickness of the sacrificial material was small, a sound clad material could not be manufactured.
In the case of Comparative Example 119, since the thickness of the sacrificial material was large, a sound clad material could not be manufactured.
In the case of Comparative Example 120, the strength decreased because the amount of Si in the core material was small.
In the case of Comparative Example 121, the corrosion resistance decreased because the amount of Si in the core material was large.
In the case of Comparative Example 122, the strength decreased because the Fe material contained in the core material was small.
In the case of Comparative Example 123, the corrosion resistance decreased because the amount of Fe in the core material was large.
In the case of Comparative Example 124, the strength decreased because the amount of Mn in the core material was small.
In the case of Comparative Example 125, since the Mn content of the core material was large, it could not be produced.

Since Comparative Example 111-125 had a large minimum diameter / maximum diameter ratio of the aluminum corrugated tube material, bending workability was lowered.
In the case of Comparative Example 126, the strength decreased because the amount of Cu in the core material was small.
In the case of Comparative Example 127, the corrosion resistance decreased because the amount of Cu in the core material was large.
In the case of Comparative Example 128, the corrosion resistance decreased because the amount of Ti in the core material was small.
In the case of Comparative Example 129, since the amount of Ti in the core material was large, it could not be produced.
In the case of the comparative example 130, since the total plate thickness of the aluminum corrugated tube material was thin, bending workability was lowered.
In the case of the comparative example 131, since the total plate thickness of the aluminum corrugated tube material was thick, the bending workability was lowered.
In the case of Comparative Example 132, since the minimum diameter / maximum diameter ratio of the extruded material was 1, bending workability was lowered.

Claims (4)

  Contains Si 0.05% or more, 0.9% or less, Fe 0.2% or more, 0.5% or less, Cu 0.1% or more, 0.7% or less, Mn 0.5% or more, 1.8% or less, Ti 0.05% or more, 0.2% or less In addition, the aluminum alloy core material layer is composed of Al and inevitable impurities, and one side of the core material layer contains Zn of 0.2% to 5%, Fe content of 0.2% to 0.5%, and the balance of Al. And an aluminum corrugated tube for automobile cooling water piping, comprising two layers of sacrificial material layers made of inevitable impurities.   The aluminum corrugated tube for automobile coolant piping according to claim 1, wherein the ratio of the minimum diameter to the maximum diameter is 0.5 to 0.9.   The corrugated tube has a thickness of 0.2 mm to 1.0 mm, and the sacrificial material has a thickness of 3 to 30% of the total thickness. tube.   Contains Si 0.05% or more, 0.9% or less, Fe 0.2% or more, 0.5% or less, Cu 0.1% or more, 0.7% or less, Mn 0.5% or more, 1.8% or less, Ti 0.05% or more, 0.2% or less In addition, the aluminum alloy core material layer is composed of Al and inevitable impurities, and one side of the core material layer contains Zn of 0.2% to 5%, Fe content of 0.2% to 0.5%, and the balance of Al. And an aluminum alloy clad plate consisting of two layers of sacrificial material layers consisting of unavoidable impurities and having a total thickness of 0.2 mm or more and 1.0 mm or less. A method for producing an aluminum corrugated tube for automobile cooling water piping, characterized in that a spiral protrusion is formed in the longitudinal direction by processing.