JP2013116479A - Method for manufacturing aluminum forging material in which corrosion resistance and stress corrosion cracking resistance are improved - Google Patents

Abstract

Provided is a forging method for a forging material in which corrosion resistance and stress corrosion cracking resistance are improved while a covering material is exuded and bonded to an aluminum material.
In a method for producing an aluminum forging material using a forging die, a covering material is disposed between an outer surface of the aluminum material and an inner surface of the forging die, and the aluminum forging material is generated in the aluminum material relative to the total mass of the aluminum material. Forging while joining the aluminum material and the coating material at a temperature at which the liquid phase mass ratio is 5 to 35%, and when the Mg content of the aluminum material is less than 2.0 mass%, the flux is applied to the joint In a non-oxidizing atmosphere, when the Mg content is 2.0 mass% or more, forging is performed while joining in a vacuum, a non-oxidizing atmosphere or in the air without applying a flux to the joint. A method for producing aluminum forgings.
[Selection] Figure 1

Description

  The present invention relates to a method for producing an aluminum forged material that is an aluminum forged material mainly used for undercarriage parts such as automobiles, and is formed by joining dissimilar alloys having excellent corrosion resistance and stress corrosion cracking resistance.

  In recent years, various parts used in facilities such as automobiles have been promoted to reduce the recyclability and weight of constituent materials in consideration of environmental issues. In particular, automobiles have the purpose of reducing the weight increase due to incidental facilities such as safety devices, and weight reduction of materials has become an important issue, and aluminum alloys are used for body seats and underbody parts.

  In vehicles such as automobiles, aluminum alloy is frequently used for undercarriage parts because the weight reduction under the floor is particularly effective for fuel economy. It is necessary for the undercarriage parts that strength and workability as well as strength reduction due to corrosion do not occur.

  As the undercarriage component, a high-strength forged product mainly using a 2000 (= Al—Cu) -based aluminum alloy or a 7000 (= Al—Zn—Mg (—Cu))-based aluminum alloy is used. In consideration of necessary strength and forgeability, a 6000 (Al—Mg—Si) -based aluminum alloy may be used.

  Forged materials are often formed from ingots or extruded rods. Forging of high-strength materials, processing by hot forging or warm forging is common, and in some cases, necessary properties are obtained by performing heat treatment after finish forging.

  By the way, in a metal material, a material structure | tissue changes by distortion provision or heat processing. Depending on the conditions, it becomes a fibrous structure or a recrystallized structure, and the precipitation state of the precipitate also changes.

  In addition to strength, corrosion resistance and stress corrosion cracking resistance are required as characteristics required for high-strength materials such as forgings, especially automobile undercarriage parts. These are mainly performed by organization control. For example, it is known that when a non-precipitated layer is formed at a grain boundary in an Al—Cu-based alloy, the progress of corrosion is accelerated, and the formation of a non-precipitated layer is prevented by controlling the structure.

Patent Document 1, the strength and toughness, i.e. high strength and Charpy impact value 20 J / cm ² or more Al-Mg-Si system excellent in corrosion resistance to be used as a vehicle structural member to obtain a high toughness than 350MPa at Strength An aluminum alloy forging is described. Addition of Mn and Zr with specific contents of Mg, Si, Cu, and a forging material manufacturing method (forging conditions, heat treatment conditions for forgings), the center of the cross-sectional thickness of the forging material The grain boundary corrosion is prevented by limiting the average grain size and the occupation ratio of the subgrain structure in.

Patent Document 2 discloses an Al-Mg-Si system having excellent corrosion resistance and strength and toughness, that is, a high strength of 400 MPa or more and a high toughness of Charpy impact value of 25 J / cm ² or more. An aluminum alloy forging is described. Similar to Patent Document 1, adding Mn, Cr, and Zr with specific contents of Mg, Si, and Cu, and forging production method (forging conditions, area reduction rate, heat treatment conditions for forgings) ) And limiting the average crystal grain size and occupancy ratio of the subgrain structure at the center of the cross-sectional thickness of the forged material to prevent intergranular corrosion.

  However, for the forged material, the more complicated the final shape by forging, the more the forging ratio and the metal flow differ depending on the part, so that it becomes difficult to control the subcrystalline structure and the crystalline structure. As a result, the intergranular corrosion cannot be sufficiently prevented, and the corrosion resistance and the stress corrosion cracking resistance are lowered, resulting in a quality defect.

  For the purpose of improving the corrosion resistance and the stress corrosion cracking resistance, for example, a method in which a clad layer is provided in advance as a material excellent in corrosion resistance and stress corrosion cracking resistance in a cast material or an extruded material can be mentioned. However, this method not only makes the clad layer non-uniform due to deformation during forging, but an appropriate metal flow cannot be obtained depending on the shape after forging. As a result, a portion that is not covered with the cladding layer may be exposed. In such a case, even if a cladding layer is provided in order to improve the corrosion resistance and stress corrosion cracking resistance, the effect is greatly impaired.

  As another method, there is a method of providing a coating layer on the surface of the forging material as a means for protecting the forging material. However, in this method, it is necessary not only to provide a new coating process in addition to the forging process, but also the coating may be cracked or peeled off, and a stable quality as a product cannot be obtained.

  As for the joining method of different metals, Patent Document 3 describes the diffusion joining method. A means for forming a melt phase by a eutectic reaction on the contact surface and discharging the melt layer to the outside is shown. However, the diffusion bonding method has a drawback that it takes a long time for bonding.

JP 2007-169699 A JP 2007-177308 A JP 54-133450 A

  In view of such circumstances, as a result of intensive studies, the present inventors have found a method for producing an aluminum forged material excellent in corrosion resistance and stress corrosion cracking resistance regardless of the composition and structure of the aluminum material. It came to complete.

  The present invention is a forging material using, for example, an Al-Cu-based or Al-Zn-Mg- (Cu) -based alloy, which is mainly used for parts with high loads such as undercarriage parts such as automobiles, In order to prevent the occurrence of stress corrosion cracking, an object is to provide a method for producing an aluminum forging material in which a coating material is joined to an aluminum material to improve corrosion resistance and stress corrosion cracking resistance.

  The basic idea of the present invention is to provide a coating material between the aluminum material and the usage environment so that the surface is shielded from the usage environment and hardly affected by the usage environment. The forging material which consists of aluminum material excellent in the cracking property is manufactured. Then, the aluminum material and the covering material are exuded and joined by a joining method. Here, bleed-out joining is a method in which joining is performed by using a liquid phase that is produced by a liquid phase rate of 5 to 35% in a semi-molten state and does not flow greatly due to melting. Say.

  Specifically, in the method for producing an aluminum forging material using a forging die according to claim 1, the present invention provides a coating material between the outer surface of the aluminum material and the inner surface of the forging die, Forging while joining the aluminum material and the covering material at a temperature at which the ratio of the mass of the liquid phase generated in the aluminum material to the total mass is 5 to 35%, and the Mg content of the aluminum material is less than 2.0 mass% Is bonded in a non-oxidizing atmosphere or in a non-oxidizing atmosphere or in a non-oxidizing atmosphere in a non-oxidizing atmosphere with a flux applied to the joint, and in a state where the flux is not applied to the joint if the Mg content is 2.0 mass% or more. Thus, a method for producing an aluminum forged material characterized in that forging is performed.

  The present invention according to claim 2 is the coating material according to claim 1, wherein the ratio of the mass of the liquid phase generated in the aluminum material to the total mass of the aluminum material is 5 to 35% at a temperature corresponding to the total mass of the coating material. The ratio of the mass of the liquid phase produced inside was less than 5%.

  According to a third aspect of the present invention, in the first or second aspect, the thickness of the covering material is 1 to 10 mm.

  By the manufacturing method according to the present invention, a forging material with improved corrosion resistance and stress corrosion cracking resistance can be obtained by extruding a coating material to an aluminum material and joining it by joining.

It is a flowchart which shows one embodiment of the manufacturing method of the aluminum forge material which concerns on this invention. It is a front view which shows one embodiment of the shape of the forging material used by this invention. It is explanatory drawing of a measurement of a raw material deformation | transformation.

  Below, the manufacturing method of the aluminum forging material which concerns on this invention is explained in full detail. In the method according to the present invention, an aluminum forged material excellent in corrosion resistance and stress corrosion cracking resistance is produced by covering the surface of the aluminum material with a coating material.

A. Aluminum Material As the aluminum material, an Al—Cu alloy, an Al—Zn—Mg alloy, and an Al—Zn—Mg—Cu alloy are preferably used. These alloy compositions are described in detail below.

A-1. Al-Cu-based alloy As the Al-Cu-based alloy, it is preferable to include Cu: 3.0 to 6.0 mass%, with the balance being Al and inevitable impurities. Cu is an element that forms Al—Cu-based precipitates and contributes to strength. Moreover, the liquid phase rate in a forging material changes with Cu content and heating temperature, and has a big influence on joining. When the Cu content is less than 3.0 mass%, the strength and the bonding rate are lowered. On the other hand, when Cu content rate exceeds 6.0 mass%, workability, such as a fall of corrosion resistance and extrudability, will deteriorate. Therefore, the Cu content is preferably 3.0 to 6.0 mass%.

  Si, Mn, and Mg may be added to the Al—Cu alloy as elements other than Cu. Mg is an element that contributes to strength. If it is less than 0.1 mass%, its effect is small, and if it exceeds 2.0 mass%, extrudability and forgeability are poor. Therefore, Mg: 0.1 to 2.0 mass% is preferable. Si is an element that contributes to strength. If it is less than 0.2 mass%, its effect is small, and if it exceeds 0.8 mass%, extrudability and forgeability are poor. Therefore, the Si content is preferably 0.2 to 0.8 mass%. Mn is effective for refining crystal grains, but if it is less than 0.2 mass%, the effect is small, and if it exceeds 1.5 mass%, a compound is formed. Therefore, Mn: 0.2 to 1.5 mass% is preferable.

  Other elements such as Fe, Cr, Zn, Ti, and V may be contained within a range that does not affect the product. For example, Fe is 0.7 mass% or less, Cr is 0.1 mass% or less, Zn is 0.25 mass% or less, and V is 0.15 mass% or less. Cr refines the recrystallized grains of the alloy and exhibits the effect of improving strength and toughness. However, when the addition amount is too large, a coarse compound is formed, resulting in a decrease in strength and toughness. Although Zn contributes to strength improvement, it is necessary to limit the addition amount in order to make the potential lower.

  Ti and B are elements that refine the cast structure and improve the strength and toughness of the alloy. Without addition, these effects are not obtained, and the effect is exhibited by addition exceeding 0 mass%. However, if the amount added is too large, a coarse compound is formed, resulting in a decrease in strength and a decrease in toughness. Ti is preferably added in an amount of 0.15 mass% or less, and B is preferably added in an amount of 0.01 mass% or less.

  Ni addition forms a compound in the alloy and improves the chip breaking property. However, if the addition amount is too large, a coarse compound is easily formed, resulting in a decrease in strength and a decrease in toughness. preferable.

A-2. Al-Zn-Mg- (Cu) -based alloy As the Al-Zn-Mg-based alloy, Zn: 2.0-7.0 mass%, Mg: 0.5-3.0 mass%, with the balance being Al and Those consisting of inevitable impurities are preferred.

Zn forms MgZn ₂ which is a precipitate that contributes to strength in the aluminum matrix. If the Zn content is less than 2.0 mass%, the formation of MgZn ₂ may be insufficient and the strength may be poor. As will be described in detail later, this precipitate can be more effectively generated by heat treatment after bonding, and the strength of the bonded body can be increased. On the other hand, even if the Zn content exceeds 7.0 mass%, the precipitation amount does not increase and the contribution to strength is saturated. Therefore, the Zn content is preferably 2.0 to 7.0 mass%.

Mg forms MgZn ₂ which is a precipitate that contributes to the strength together with Zn. If the Mg content is less than 0.5 mass%, the strength may be reduced, and if it exceeds 3.0 mass%, the contribution to the strength is saturated. Therefore, the Mg content is preferably 0.5 to 3.0 mass%.

  As an Al-Zn-Mg alloy, in the above-described one, an alloy further containing Cu: 0.5 to 3.0 mass% may be used, and in addition to Cu, Cr is added to 0.05 to 0.3 mass%. May further be contained. The action of the Cu element is as described above. In this alloy, when the Cu content is less than 0.5 mass%, the strength and the bonding rate may be lowered. On the other hand, when the Cu content exceeds 3.0 mass%, workability such as a decrease in corrosion resistance and extrudability may be deteriorated. Therefore, the Cu content is preferably 0.5 to 3.0 mass%. Cr has the effect of refining crystal grains, but the effect is small at 0.05 mass%, and if it exceeds 0.3 mass%, a compound is formed and the performance is adversely affected. Therefore, the Cr content is preferably 0.05 to 0.3 mass%.

  The Al—Zn—Mg (—Cu) -based alloy may also contain Si, Fe, Mn, Ti, Zr, and the like as long as the effects of the present invention are not impaired. For example, Si is 0.4 mass% or less, Fe is 0.5 mass% or less, Mn is 0.6 mass%, preferably 0.3 mass% or less, Ti is 0.2 mass% or less, and Ti + Zr ≦ 0.25 mass%. The explanation of the operation is as described above.

B. Covering material The use of the covering material is intended to shield the aluminum material surface from the usage environment and to give the aluminum material corrosion resistance and stress corrosion cracking resistance. For this purpose, the coating material needs to have corrosion resistance and stress corrosion cracking resistance. As such a covering material, an aluminum material having a purity of 95 mass% or more, a 1050 alloy, a 1070 alloy, or the like is preferably used.

  Moreover, a coating | covering material needs to be joined to an aluminum material, without fracture | rupture in a forge process. For this purpose, the thickness of the covering material is preferably 1 to 10 mm.

C. Forging process As shown in FIG. 1, for example, when a forging material is manufactured using a casting material or an extruded material, a die or a extruded rod is preheated and heated separately by a heater 1 for heating. 2 is placed in a preheated mold 3 and forged to obtain a forged material 4. In the second rough forging process, the forged material is made almost similar to the finished shape, and the forged material is combined with the forged material that has been reheated to generate the liquid phase necessary for joining, and the final shape is forged by passing through the finishing forging process. Item 7 is obtained. In addition, you may apply | coat the flux 6 to a junction part, when combining the coating | covering material 5 with a forging material. Usually, a forging process does not consist of a single process, but consists of a plurality of processes such as a rough forging process, a heating process, and a finishing forging process, and these processes may also have subdivided processes.
Here, as an example of the shape of the forged material 4, the one shown in FIG. 2 is used, but the shape of the forged material is not particularly defined. In FIG. 2, the unit of the numerical value is mm.

C-1. In the present invention, for example, in the final finishing process, which is the final stage of the finish forging process, or in the process immediately before, the aluminum material and the coating material are bonded by the bleeding bonding method. Specifically, the covering material is disposed between the mold and the aluminum material, and the aluminum material is forged and the covering material is joined at the same time.

  At the time of joining, it is necessary that a liquid phase is generated in at least one of the aluminum material and the covering material. In the present invention, a liquid phase is generated at least in the aluminum material. When the aluminum material is held at a liquid phase temperature, which is a temperature at which the liquid phase is generated, a part of the liquid phase generated in the aluminum material oozes out on the surface of the aluminum material, and the liquid phase fills the gap between the aluminum material and the coating material. Both are joined. As a result, the covering material covers the aluminum material, and the aluminum material is cut off from the use environment. Note that it is preferable that the coating material in contact with the mold does not generate a liquid phase as much as possible in order to avoid contact between the mold and the liquid phase.

  The liquid phase amount generated in the aluminum material is represented by the liquid phase rate. Here, the liquid phase ratio is defined as the ratio of the mass of the liquid phase generated in the aluminum material to the total mass of the aluminum material. The liquid phase ratio is determined by the composition and temperature of the aluminum material. Specifically, it is calculated by thermodynamic equilibrium calculation software such as Thermo-Calc. In the present invention, the semi-melting temperature at which the liquid phase ratio of the aluminum material is 3 to 35% is the liquid phase temperature. When the liquid phase ratio is less than 5%, the amount of liquid phase used for bonding is insufficient and an unbonded portion remains. If the liquid phase ratio exceeds 35%, the deformation of the aluminum material becomes remarkable and the required dimensional accuracy cannot be obtained. Therefore, the liquid phase ratio of the aluminum material needs to be 5 to 35%.

  In addition, a liquid phase may be generated in the covering material joined to the aluminum material, but the covering material joined to the aluminum material is in contact with the forging die, so that the liquid phase that exudes from the surface of the covering material is the die. If they come into contact with each other, there is a possibility that problems may occur during the forging process, such as joining them together. Therefore, it is preferable that a liquid phase is not generated as much as possible from the coating material. The liquid phase ratio may be appropriately selected depending on forging conditions and the like. Specifically, the liquid phase ratio is preferably less than 5%, and the liquid phase ratio is most preferably 0%. The liquid phase ratio of the coating material is also defined as the ratio of the mass of the liquid phase generated in the coating material to the total mass of the coating material, similarly to the aluminum material.

C-2. Presence or absence of use of flux When an aluminum material having an Mg content of less than 2.0 mass% is used as the aluminum material to be joined to the coating material, the joining is performed in a non-oxidizing atmosphere with the flux applied to the joint. Here, the non-oxidizing atmosphere refers to an atmosphere such as nitrogen gas or argon gas. As the flux, a fluoride flux is preferably used, but a chloride flux may be used. The flux removes the oxide film on the surface of the aluminum material and the coating material, and facilitates the joining of the aluminum material and the coating material.

  When using an aluminum material with Mg content of 2.0 mass% or more, the oxide film is destroyed by the action of the Mg itself evaporating from the aluminum material surface and destroying the oxide film on the material surface (getter effect) at the time of bonding heating. Therefore, it is not necessary to apply flux to the joint. In addition, when a flux is used when an aluminum material having an Mg content of 2.0 mass% or more is used, there is a risk that Mg and the flux react to cause defects such as insufficient oxide film destruction. In addition, when not using a flux, it joins in the said non-oxidizing atmosphere or air | atmosphere in a vacuum.

C-3. Forging Conditions In the present invention, since the aluminum material and the coating material in the mold are leached and joined during forging, the aluminum material to be forged is heated to a temperature at which a liquid phase is generated and forged in this state. The heating temperature in the forging process is within the range of the liquid phase temperature of the aluminum material, and forging is performed under normal hot forging conditions. As a pressurizing method, a conventionally used hammer method such as an air hammer or a spring hammer, or a press method such as a mechanical press or a hydraulic press is used. In addition, when joining a coating | covering material, about 3 minutes time may be required at the time of a press, and it is possible to change a press system by manufacture.

  As for the atmosphere in a forging process, it is preferable that oxygen concentration, a moisture content, etc. are controlled. For example, if oxygen or moisture is contained in the atmosphere, an oxide film formed on the bonding surface between the aluminum material and the coating material grows, and even when using a flux at the time of bonding or using the Mg getter effect It becomes difficult to destroy the oxide film. Therefore, it is desirable that the dew point of the atmosphere in the forging process is −30 ° C. or lower, and a non-oxidizing atmosphere such as nitrogen or argon is used as described above. In addition, in an aluminum material having a Mg content of 2.0 mass% or more, in order to effectively remove the oxide film by the Mg getter effect, a non-oxidizing atmosphere such as nitrogen or argon is used as described above, and thereafter More preferably, a reduced pressure atmosphere is used.

D. Heat treatment of the forging material The forging material of the aluminum material joined with the covering material is subjected to heat treatment for improving the strength as necessary. This is because the strength of Al—Cu, Al—Zn—Mg, and Al—Zn—Mg—Cu heat-treated alloys is improved by the heat treatment. These alloys usually improve strength by applying artificial aging after solution treatment and quenching. In the case of an Al—Cu alloy, solution treatment is usually performed at 495 to 505 ° C., followed by quenching by water cooling. Then, artificial aging is performed by being held at room temperature or a temperature of 150 ° C. or higher for several hours, and T6 treatment is performed. In the case of an Al—Zn—Mg alloy, solution treatment is usually performed at 460 to 500 ° C., followed by quenching by water cooling. Then, artificial aging is performed by being held at a temperature of 115 ° C. or higher for several hours, and T6 treatment is performed. In artificial aging, heat treatment may be performed in multiple stages, or overaging may be performed. In addition, although described about T6 process, what is necessary is just to heat-process according to required tempering regardless of T6 process.

  Cooling at the time of quenching preferably uses water at normal temperature to 70 ° C. or warm water. Quenching is usually rapid cooling, but excessive quenching is accompanied by deformation of the material. Therefore, quenching is performed at room temperature to 70 ° C. while observing the material characteristics and the deformation state of the material.

  Next, based on an Example, this invention is demonstrated in detail.

  Aluminum alloys having compositions shown in Tables 1 and 2 were used as aluminum materials. This was dissolved and a plate material of 2 mm (t) × 100 mm (L) × 20 mm (W) was produced as a primary evaluation sample by a conventional method. In addition, an extruded round bar of φ35 mm × 150 mm (L) was produced as a sample for secondary evaluation.

(1) Primary evaluation Using the above-mentioned aluminum alloy plate and a plate material made of 1050 alloy <2 mm (t) × 100 mm (L) × 20 mm (W)> as a covering material, these are simply fixed and exuded and joined. Went. The seepage joining was performed at a temperature at which the liquid phase ratio of the aluminum alloy plate was 3, 5, 35, and 38%. The liquid phase rate of the coating material was 5% or less. In addition, in the same liquid phase rate, joining using the flux and joining not using were performed. As the flux, a fluoride-based flux (KAlF ₄ ) was used. The possibility of joining and material deformation were evaluated as follows.

(Joinability)
The bonding cross section of the bonded sample cooled after the seepage bonding was observed with a 50 × optical microscope to evaluate the possibility of bonding. The case where the ratio of the length that can be joined to the total length of the joint portion is 90% or more was evaluated as “good”, and the case where it was less than 90% was regarded as “failed”.

(Material deformation)
As shown in FIG. 3, two tables were arranged at an interval of 80 mm, and a combination of the aluminum alloy plate and the cover plate before bonding was placed thereon, and exudation bonding was performed by heat treatment. The case where there was no change with respect to the original state at the center in the plate length direction was evaluated as “good”, and the case where there was a change of 1 mm or more with respect to the original state at the center in the plate length direction was determined as “failed”.

  The case where both the joining possibility and the deformation of the forged material are acceptable is the primary evaluation is a pass “◯”, and the case where at least one of them is a failure is the primary evaluation is a failure “×”. The results of the primary evaluation are shown in Tables 3-8.

(2) Secondary evaluation Next, primary evaluation was performed. In this evaluation, a forged material was manufactured and evaluated in the following steps with respect to an aluminum alloy having a liquid phase ratio of 35% that passed the primary evaluation.

  First, an extruded round bar manufactured using the aluminum alloy used for the primary evaluation is heated so that the liquid phase ratio is 35%, and is trained so as to be sandwiched between aluminum plates made of 1050 alloy having a thickness of 1 to 20 mm as a coating material. Upset forging with a ratio of about 75% was performed. At the time of pressing, the mold was preheated at about 250 ° C., and at the same time, the same Lux coating as that used in the primary evaluation was applied to an aluminum material having a Mg content of less than 2.0 mass%.

  This forged material was further quenched with hot water at 50 ° C. after solution treatment suitable for each alloy, further subjected to artificial aging treatment, and the material was set to T6. About the produced sample, it evaluated as follows about etching evaluation, a joining rate, the uniformity of a coating material, and a moldability.

(A) Etching evaluation It was confirmed by etching whether or not the aluminum alloy as a forging material protruded from the coating material after pressing. Since different alloys are observed in different structures by etching, such protrusions can be confirmed. If there was no protrusion, it was able to be cut off from the environment of use, which means that the aluminum alloy sheet was protected by the coating material of 1050 alloy having excellent corrosion resistance. Those that did not protrude were rated as “good”, and those that protruded were rated as “failed”.

(B) Joining rate The forged material was cut along the longitudinal direction and the vertical plane through the circular center, and the ratio of the lengths of the extruding round bar and the covering material that were exuded and joined was measured. The cross-sectional observation was performed with a 50 × optical microscope, and the case where the ratio of the lengths that can be joined accounted for 90% or more was judged as “good”, and the case where less than 90% was judged as “failed”.

(C) Uniformity of the covering material The forged material is cut on a circular surface, and the uniformity of the covering material and the state of surplus are confirmed by cross-sectional etching. And the case where the coating was non-uniform or there was a surplus was defined as a failure “x”.

  When all of the etching evaluation, the bonding rate, and the uniformity of the covering material are acceptable, the secondary evaluation is a pass “○”, and at least one of them is a failure, the secondary evaluation is a “fail” did. The results are shown in Tables 9-12. Here, the alloys A1 to A7 and B1 to B4 were subjected to solution treatment at 500 ° C. × 3 hr, then immersed in water at 30 ° C. and rapidly cooled, and subjected to artificial aging treatment or natural aging treatment at 180 ° C. × 10 hr. Alloys C1 to C10 and D1 to D6 were subjected to solution treatment at 470 ° C. × 3 hr, then immersed in water at 30 ° C. and rapidly cooled, and subjected to artificial aging at 120 ° C. × 25 hr.

(3) Liquid phase rate of coating material and inner surface property of mold For some of the examples that passed the primary evaluation, the relationship between the liquid phase rate of the coating material and the inner surface property of the mold was examined. The results are shown in Table 13. When the liquid phase ratio of the coating material pressure-bonded to the inner surface of the mold was increased, adhesion of the liquid phase of the coating material to the inner surface of the mold was observed. This adhesion impairs the appearance of the surface of the forging material that is the product. The case where the inner surface properties of the mold were almost the same as before joining was indicated as “◯”, the case where small inconspicuous deposits were observed was indicated as “Δ”, and the case where conspicuous large deposits were observed was indicated as “x”. ○ and Δ were accepted, and x was rejected.

  In the primary evaluations shown in Tables 3 to 8, those having a liquid phase ratio of 3% failed to be joined. In addition, when the liquid phase ratio was 38%, the deformation of the forged material was unacceptable. When the liquid phase ratio is 5% or 35%, the alloys A6, B4, C2, C4, C5, C7 to C10, D2, D4, and D6 having an Mg content of 2.0 mass% or more are not bonded when flux is applied. Passed. In the alloys A1 to A5, A7, B1 to B3, C1, C3, C6, D1, D3, and D5 having an Mg content of less than 2.0 mass%, the bonding was passed by applying flux.

  In the secondary evaluation shown in Tables 9 to 12, when the plate thickness of the coating material was 0.5 mm, a portion where the forging material protruded from the coating material was found by etching evaluation, and the etching evaluation was unacceptable. In addition, when the plate thickness is 20 mm, there is a large surplus due to the plate thickness, and the time required for further trimming processes after finishing forging is increased, and the uniformity of the coating material is significantly impaired depending on the material. Sex was rejected. The bonding rate was acceptable in all cases. Thicknesses of 1 mm and 10 mm passed in the secondary evaluation, and it was found that the thickness of the covering material was appropriate to be 1 to 10 mm.

  As shown in Table 2, the liquid phase rate and the presence or absence of deposits such as aluminum on the forging die, that is, the inner surface properties of the die were confirmed. When the liquid phase ratio was 0 to 3%, metal did not adhere to the mold, but from 5%, the deposit became noticeable.

  Forging excellent in corrosion resistance and stress corrosion cracking resistance without being affected by the components of aluminum material, strain and heat treatment, and without lowering the strength when producing a forged aluminum material according to the present invention It becomes possible to provide the material.

  As a result, the forging method according to the present invention can be applied to parts that require corrosion resistance and stress corrosion cracking resistance such as automobile undercarriage parts, such as equipment using lightweight aluminum materials. The weight can be reduced, and the industrially significant effect is achieved.

1: Heating heater 2: Casting rod or extrusion rod 3: Die 4: Forging material 5: Coating material 6: Flux 7: Forging product (finished product)

Claims (3)

  In the method for producing an aluminum forging material using a forging die, a coating material is disposed between the outer surface of the aluminum material and the inner surface of the forging die, and the liquid phase generated in the aluminum material with respect to the total mass of the aluminum material. Forging while joining the aluminum material and the covering material at a temperature at which the mass ratio is 5 to 35%. When the Mg content of the aluminum material is less than 2.0 mass%, it is non-oxidizing in a state where the flux is applied to the joint portion. In the atmosphere, when the Mg content is 2.0 mass% or more, the aluminum forging is characterized by being forged while being bonded in a vacuum, in a non-oxidizing atmosphere or in the air without applying a flux to the joint. Production method.   At a temperature at which the ratio of the mass of the liquid phase generated in the aluminum material to the total mass of the aluminum material is 5 to 35%, the ratio of the mass of the liquid phase generated in the coating material to the total mass of the coating material is The manufacturing method of the aluminum forging material of Claim 1 which is less than 5%.   The manufacturing method of the aluminum forging material of Claim 1 or 2 whose thickness of the said coating | covering material is 1-10 mm.

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