WO2023195480A1 - Method for inhibiting hydrogen embrittlement of aluminum alloy material, and hydrogen embrittlement inhibitor - Google Patents

Method for inhibiting hydrogen embrittlement of aluminum alloy material, and hydrogen embrittlement inhibitor Download PDF

Info

Publication number
WO2023195480A1
WO2023195480A1 PCT/JP2023/014043 JP2023014043W WO2023195480A1 WO 2023195480 A1 WO2023195480 A1 WO 2023195480A1 JP 2023014043 W JP2023014043 W JP 2023014043W WO 2023195480 A1 WO2023195480 A1 WO 2023195480A1
Authority
WO
WIPO (PCT)
Prior art keywords
aluminum alloy
phase
hydrogen embrittlement
alloy material
hydrogen
Prior art date
Application number
PCT/JP2023/014043
Other languages
French (fr)
Japanese (ja)
Inventor
一行 清水
裕之 戸田
正剛 山口
Original Assignee
国立大学法人岩手大学
国立大学法人九州大学
国立研究開発法人日本原子力研究開発機構
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 国立大学法人岩手大学, 国立大学法人九州大学, 国立研究開発法人日本原子力研究開発機構 filed Critical 国立大学法人岩手大学
Publication of WO2023195480A1 publication Critical patent/WO2023195480A1/en

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C21/00—Alloys based on aluminium
    • C22C21/10—Alloys based on aluminium with zinc as the next major constituent
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon

Definitions

  • the present invention relates to a method for preventing hydrogen embrittlement of aluminum alloy materials and an agent for preventing hydrogen embrittlement of aluminum alloy materials.
  • Patent Document 1 describes that Zn contains 5.0 to 7.0%, Mg 1.0 to 3.0%, Cu 1.0 to 3.0%, and Cr 0.05 to 0.3%, Zr 0.05 to 0.25%, Mn 0.05-0.40%, Sc 0.05-0.35%, and one or more selected from them within a total amount of 0.05-0.5%.
  • the impurities are regulated to 0.25% or less and Fe to 0.25% or less, with the remainder being Al and other unavoidable impurities.
  • the average cooling rate to at least 400°C is 100°C/hr or more.
  • hot rolling is performed to a thickness of 50 mm or more at a temperature within the range of 300 to 440 degrees Celsius, followed by solution treatment, quenching, and artificial aging treatment to prevent intermetallic compounds with a circular equivalent diameter exceeding 5 ⁇ m.
  • a method for manufacturing an aluminum alloy thick plate with excellent strength and ductility is described, which produces a thick plate with a total area ratio of 2% or less.
  • Patent Document 2 contains 4.5 to 8.5 wt% of Zn, 1.5 to 3.5 wt% of Mg, and 0.8 to 2.6 wt% of Cu, and further contains at least 1 of Mn, Cr, Zr, V, and Ti.
  • the Fe content in the alloy must be restricted to 0.15 wt% or less to prevent corrosion cracking.
  • Patent Document 3 states that Zn5-8% by weight, Mg1.2-4.0% by weight, Cu more than 1.5% by weight and 4.0% by weight or less, Ag0.03-1.0% by weight, and Fe0.01-4% by weight. Contains 1.0% by weight, 0.005 to 0.2% by weight of Ti, 0.01 to 0.2% by weight of V, and 0.01 to 1.5% by weight of Mn, and 0.01 to 0.6% by weight of Cr. , Zr0.01-0.25% by weight, B0.0001-0.08% by weight, Mo0.03-0.5% by weight, and the remainder consists of aluminum and inevitable impurities. A high-strength aluminum alloy for welded structural materials with excellent stress corrosion cracking resistance is described.
  • Patent Document 4 describes a hydrogen embrittlement inhibitor for aluminum alloy materials that can prevent hydrogen embrittlement of aluminum alloy materials and is made of Al 7 Cu 2 Fe particles. Patent Document 4 focuses on the fact that hydrogen embrittlement cracking is dominated by local hydrogen distribution behavior and accumulation behavior in aluminum alloy materials, and suggests that a second phase with higher hydrogen trapping energy than the semi-coherent precipitate interface By adding particles (Al 7 Cu 2 Fe particles), hydrogen embrittlement caused by hydrogen trapped at the precipitate interface was prevented.
  • the problem to be solved by the present invention is to provide a method for preventing hydrogen embrittlement of aluminum alloy materials, which can effectively prevent or suppress hydrogen embrittlement by a method other than using Al 7 Cu 2 Fe particles or the like. .
  • a method for preventing hydrogen embrittlement of an aluminum alloy material including a step of forming a T phase in the aluminum alloy material.
  • the raw material composition containing aluminum and other metal additives is a low Zn/Mg composition containing Zn and Mg as metal additives at a Zn/Mg atomic ratio of 1.5 or less,
  • [4] Including the step of aging a raw material composition containing aluminum and other metal additives, The method for preventing hydrogen embrittlement of an aluminum alloy material according to [1] or [2], wherein the step of forming the T phase is a step of performing aging treatment at a temperature higher than 120°C.
  • a hydrogen embrittlement inhibitor for aluminum alloy materials that can prevent hydrogen embrittlement of aluminum alloy materials and is used to form particles inside the aluminum alloy materials, A hydrogen embrittlement inhibitor for aluminum alloy materials whose particles are in T phase.
  • FIG. 1 is a schematic diagram of hydrogen concentration in an aluminum alloy material in which a T phase is formed.
  • FIG. 2 is a schematic diagram of hydrogen concentration in an aluminum alloy material in which an ⁇ phase is formed.
  • FIG. 3 is a flowchart illustrating an example of the method for preventing hydrogen embrittlement of an aluminum alloy material of the present invention, together with a hydrogen embrittlement test method and a tensile test method.
  • FIG. 4 is a schematic diagram of an example of the crystal structure of Mg 32 (Al, Zn) 49 particles (an example of T phase) and its hydrogen trap sites.
  • FIG. 5 is a calculated graph of the relationship between the number of hydrogen atoms and hydrogen trap energy in an example of Mg 32 (Al, Zn) 49 particles.
  • FIG. 1 is a schematic diagram of hydrogen concentration in an aluminum alloy material in which a T phase is formed.
  • FIG. 2 is a schematic diagram of hydrogen concentration in an aluminum alloy material in which an ⁇ phase is formed.
  • FIG. 3 is a
  • FIG. 6(A) is a TEM image obtained by morphological analysis of the LT material of Comparative Example 1.
  • FIG. 6(B) is a TEM image of the diffraction pattern of the ⁇ phase ( ⁇ ' phase) of the LT material of Comparative Example 1.
  • FIG. 6(C) is a TEM image obtained by morphological analysis of the HT material of Example 1.
  • FIG. 6(D) is a TEM image of the diffraction patterns of the ⁇ phase ( ⁇ ' phase) and T phase of the HT material of Example 1.
  • FIG. 7 is a graph showing the relationship between strain and stress of the aluminum alloy materials of Example 1 (HT) and Comparative Example 1 (LT).
  • FIG. 8 is a graph showing the area of intergranular cracks on the fracture surfaces of the aluminum alloy materials of Example 1 (HT) and Comparative Example 1 (LT).
  • FIG. 9-1(A) is a graph showing the relationship between strain and fracture area ratio of the aluminum alloy materials of Example 1 (HT) and Comparative Example 1 (LT).
  • FIG. 9-1(B) is a graph showing the relationship between strain and crack length (unit: ⁇ m) of the aluminum alloy materials of Example 1 (HT) and Comparative Example 1 (LT).
  • Figures 9-2 (C) to (E) are 3D renderings of intergranular crack fracture of the aluminum alloy material of Comparative Example 1 (LT) with strains of 8.9%, 14.0%, and 17.8%, respectively. It is.
  • FIG. 9-1(A) is a graph showing the relationship between strain and fracture area ratio of the aluminum alloy materials of Example 1 (HT) and Comparative Example 1 (LT).
  • FIG. 9-1(B) is a graph showing the relationship between strain and crack length (unit: ⁇ m) of the
  • FIG. 9-2 (F) is a SEM image obtained by morphological analysis of the fracture surface of the aluminum alloy material of Comparative Example 1 (LT).
  • Figures 9-3 (G) to (I) are 3D renderings of intergranular crack fracture of the aluminum alloy material of Example 1 (HT) with strains of 8.9%, 14.0%, and 17.8%, respectively. It is.
  • FIG. 9-3 (J) is a SEM image obtained by morphological analysis of the fracture surface of the aluminum alloy material of Example 1 (HT).
  • Figure 10(A) shows the trapped hydrogen concentration C H ( atom/m 3 ).
  • Figure 10(B) shows the hydrogen distribution ratio Occupancy trapped at each trap site in the aluminum alloy material of Example 1 (HT) at the crack tip before the tensile test (underformed) and after the tensile test.
  • This is a graph.
  • 11(A) to (D) show dislocations, grain boundaries (GB), vacancies, and ⁇ phase for the aluminum alloy materials of Example 1 (HT) and Comparative Example 1 (LT), respectively. It is a graph showing the hydrogen distribution ratio Occupancy trapped in ( ⁇ ' phase).
  • the method for preventing hydrogen embrittlement of an aluminum alloy material of the present invention includes a step of forming a T phase in the aluminum alloy material. With this configuration, the method for preventing hydrogen embrittlement of an aluminum alloy material of the present invention can effectively prevent or suppress hydrogen embrittlement by a method other than using Al 7 Cu 2 Fe particles or the like. Although the T phase is sometimes included in existing aluminum alloy materials, it was not known that it functions as a hydrogen embrittlement inhibitor for aluminum alloy materials.
  • T phase shows a schematic diagram of hydrogen concentration in an aluminum alloy material in which a T phase is formed.
  • the T phase (or T'phase; in this specification, the term T phase includes both T phase and T' phase without distinguishing between them) is dispersed in the aluminum base (aluminum base material). Therefore, hydrogen is concentrated inside the T phase.
  • Methods to prevent hydrogen embrittlement include (i) making the distribution of precipitates on grain boundaries less dense and coarse, (ii) reducing the grain boundary tilt angle (torsion angle) (creating a non-recrystallized structure), ( iii) Three types of structure control methods have been proposed to refine the crystal grains (for example, Goro Ito, Takehiko Eto, Yoshimitsu Miyagi, Mikihiro Kanno, "Al-Zn-Mg alloy", light metals, 38 ( (1988), p. 818-839). However, the effectiveness of these methods was unknown, and the specific mechanism was also unknown.
  • the present invention focuses on the fact that hydrogen embrittlement cracking is dominated by local distribution behavior and accumulation behavior of hydrogen within an aluminum alloy material.
  • the dominant factor causing hydrogen embrittlement is hydrogen trapped in precipitates (see Engineering Fracture Mechanics 216 (2019) 106503). Then, by determining the bonding energy between each microstructure of aluminum and hydrogen and calculating the hydrogen distribution within the aluminum alloy material, they quantitatively determined the amount of hydrogen at hydrogen trap sites that cause hydrogen embrittlement.
  • Nanoparticles that cause hydrogen embrittlement in aluminum alloys are ⁇ phase (or ⁇ ' phase.
  • ⁇ phase includes both ⁇ phase and ⁇ ' phase without distinguishing between them). They are dispersed in the alloy on the order of several to tens of nanometers.
  • FIG. 2 shows a schematic diagram of hydrogen concentration in an aluminum alloy material in which an ⁇ phase is formed.
  • the ⁇ phase is dispersed in the aluminum base (aluminum base material), and hydrogen is concentrated at the coherent or semi-coherent interface of the ⁇ phase.
  • the ⁇ phase has a particle composition of MgZn 2 , and the particle interface is between 0.35 eV/atom (coherent interface) and 0.56 eV/atom (semi-coherent interface). It has a hydrogen trap energy of .
  • Hydrogen embrittlement occurs in aluminum alloy materials due to the concentration of hydrogen in the ⁇ phase.
  • interfacial hydrogen removes the ⁇ phase, which is the source of hydrogen embrittlement, from the material and forms a T phase that can absorb hydrogen inside the material, thereby maintaining high strength and maintaining aluminum alloy materials (especially Al- It can fundamentally solve the hydrogen embrittlement of Zn-Mg alloy).
  • JP 2021-1881027 A describes that hydrogen embrittlement is prevented by preferentially distributing hydrogen inside coarse particles (second phase particles) while allowing the presence of the ⁇ phase. ing.
  • Hydrogen embrittlement cracking includes intergranular cracking and pseudo-cleavage cracking. In the present invention, it is preferable that intergranular crack fracture can be effectively prevented or suppressed, and it is more preferable that intergranular crack fracture and pseudo-cleavage cracking can be effectively prevented or suppressed. Preferred embodiments of the present invention will be described below.
  • An aluminum alloy material can be produced by a known process such as heat treatment, rolling, forging and/or casting, and aging treatment of a raw material composition (which may be a raw material mixture of aluminum and metal additives).
  • a raw material composition which may be a raw material mixture of aluminum and metal additives.
  • FIG. 3 is a flowchart illustrating an example of the method for preventing hydrogen embrittlement of an aluminum alloy material of the present invention, together with a hydrogen embrittlement test method and a tensile test method.
  • the melted or melted raw material composition is placed in a mold of a desired shape and cast.
  • the raw material composition that has a desired shape is homogenized.
  • the homogenized raw material composition is hot rolled (also referred to as hot rolling).
  • the hot rolled composition is subjected to thermal cycling (TC) and then electrical discharge machining (EDM).
  • the electrical discharge machined composition is polished and then subjected to solution treatment (ST). After solution treatment, aging treatment is performed at a desired temperature to obtain an aluminum alloy material.
  • the step of forming the T phase in the aluminum alloy material is not particularly limited, and the T phase can be formed by a known method.
  • a known method for example, J. JILM, 67, (2017) 5, 162-167 and J. of Materials Sci. & Tech. Examples include the method described in 85 (2021) 106-117.
  • a raw material composition containing aluminum and other metal additives contains Zn and Mg as metal additives at a Zn/Mg atomic ratio of 1.5 or less (preferably 1.2 or less, more preferably 1.2 or less). It is preferable that the process of forming the T phase is a process of rolling and aging the low Zn/Mg composition. When using a low Zn/Mg composition, there are no particular restrictions on the temperature and time of the aging treatment.
  • the step of forming the T phase includes a step of aging a raw material composition containing aluminum and other metal additives; Preference is given to processes carried out at temperatures higher than 120°C.
  • the aging treatment temperature is more preferably 130°C or higher, particularly preferably 150°C or higher.
  • the time of the aging treatment performed at a temperature higher than 120 ° C. is preferably 1 hour or more, more preferably 5 hours or more, and particularly 10 hours or more, from the viewpoint of facilitating the formation of the T phase. preferable.
  • the temperature and time of the aging treatment may be set within these preferable ranges from the viewpoint of making it easier to form the T phase.
  • timing of aging treatment performed at a temperature higher than 120°C is not particular restriction on the timing of aging treatment performed at a temperature higher than 120°C, but it is preferably performed after rolling and after solution treatment.
  • Step of aging treatment of low Zn/Mg composition A preferred embodiment when the step of forming the T phase is a step of aging the low Zn/Mg composition will be described.
  • the raw material composition (low Zn/Mg composition) containing aluminum and other metal additives contains Zn and Mg as metal additives, and the Zn/Mg atomic ratio is 0.2 to 0.8. It is particularly preferably 0.4 to 0.6, and even more preferably 0.4 to 0.6.
  • T phase is a type of dispersed phase in aluminum alloys, and the ratio of the constituent elements of Mg 32 (Al, Zn, Cu) 49 or Mg 32 (Al, Zn) 49 is chemically It refers to a composition that deviates within 30% from the stoichiometric composition.
  • the dispersed phase with the above composition is called T phase in aluminum alloy materials containing at least Zn and Mg (Al-Mg-Zn alloy materials), but in aluminum alloy materials whose parent phase has other compositions, it is called T phase. It may be referred to by its name, and any dispersed phase (preferably a precipitated phase, but other phases such as coarse particles may also be used) having the above composition is included in the T phase in this specification.
  • the T phase is a dispersed phase in aluminum with a wide range of component compositions, including Mg 22.4-41.6 (Al, Zn, Cu) 34.3-63.7 or Mg 22.4-41.6 ( (Al, Zn) 34.3 to 63.7 , Mg 27.2 to 36.8 (Al, Zn, Cu) 41.7 to 56.4 or Mg 27.2 to 36.8 (Al , Zn) 41.7 to 56.4 , and particularly preferably Mg 32 (Al, Zn, Cu) 49 or Mg 32 (Al, Zn) 49 .
  • the T phase is required to have a higher hydrogen trapping energy than the coherent precipitate interface.
  • the hydrogen trap energy of the T phase needs to be higher than at least 0.35 eV/atom of the coherent precipitate interface.
  • First-principles calculation refers to representing electronic states theoretically by mathematically solving the Schrödinger equation (without using experimental data or empirical parameters).
  • the distribution of hydrogen at each trap site can be calculated from the density of other hydrogen trap sites, such as grain boundaries, precipitates, and interstitials, and the bonding energy with hydrogen.
  • 3D mapping is possible.
  • the hydrogen trap energy of the T phase is preferably 0.40 eV/atom or more, more preferably 0.45 eV/atom or more, particularly preferably 0.50 eV/atom or more, and semi-coherent precipitates. It is particularly preferably higher than 0.55 eV/atom at the interface, most preferably from 0.55 to 0.56 eV/atom. The higher the hydrogen trapping energy of the T phase, the more hydrogen can be trapped inside the T phase, making it easier to prevent or suppress hydrogen embrittlement of the aluminum alloy material.
  • the trap site density of the T phase in the obtained aluminum alloy material is preferably 1.0 site/nm 3 or more, more preferably 5.0 site/nm 3 or more, and 7.0 site/nm 3 or more. It is particularly preferable that there be.
  • the dispersing phase By dispersing the T phase in the aluminum alloy, hydrogen embrittlement can be prevented or suppressed. Although it is sufficient that the dispersed phase (precipitated phase) contains the T phase, it is preferable to disperse the T phase alone in the aluminum alloy from the viewpoint of easily controlling hydrogen embrittlement of the aluminum alloy material. However, this does not prevent multiple types of dispersed phases (precipitated phases (precipitates)) from being dispersed in the aluminum alloy.
  • the shape of the T phase includes various shapes such as spherical, ellipsoidal, prismatic, cylindrical, cubic, rectangular parallelepiped, and scale-like, and is preferably spherical or ellipsoidal.
  • the average particle diameter of the T phase is preferably 0.1 to 50 nm.
  • the upper limit of the average particle diameter of the T phase is more preferably 20 nm or less, more preferably 10 nm or less, and particularly preferably 5.0 nm or less. It is more preferable that the lower limit of the average particle diameter of the T phase is 0.5 nm or more.
  • the average particle diameter of the T phase can be calculated as an arithmetic mean by observing the structure using a transmission electron microscope, for example.
  • the alloy composition of the aluminum alloy material obtained by applying the method for preventing hydrogen embrittlement of an aluminum alloy material of the present invention to the raw material aluminum alloy material has aluminum as the main component, and contains 50% by mass of aluminum. It is preferable to include the above.
  • the aluminum alloy material may be a new aluminum alloy material or an existing aluminum alloy material.
  • the hydrogen embrittlement preventive agent for aluminum alloy materials of the present invention conforms to JIS standards (for example, JIS H 4000:2014 for rolled plates; for cast materials, extruded materials, forged materials, etc., refer to the respective JIS standards). It is preferable to be able to prevent hydrogen embrittlement of aluminum alloy materials of existing alloys and/or new alloys that do not meet JIS standards.
  • the aluminum alloy material has aluminum as a main component, and preferably contains 50% by mass or more of aluminum.
  • a preferred embodiment of the aluminum alloy material is a pure aluminum alloy with a purity of 99.0% or more.
  • Examples of pure aluminum alloys include 1000 series alloys such as A1050, A1100, and A1200. Another preferred embodiment of the aluminum alloy material preferably contains at least Cu. Examples of the Al-Cu alloy include 2000 series alloys such as A2017 and A2024. Another preferred embodiment of the aluminum alloy material preferably contains at least Mn. Examples of the Al-Mn alloy include 3000 series alloys such as A3003, A3004, and A3005. Another preferred embodiment of the aluminum alloy material preferably contains at least Si. Examples of the Al--Si alloy include 4000 series alloys such as A4042, A4043, and A4343. Another preferred embodiment of the aluminum alloy material preferably contains at least Mg.
  • Al-Mg alloy examples include 5000 series alloys such as A5005, A5052, A5083, and A5182. Another preferred embodiment of the aluminum alloy material preferably contains at least Mg and Si. Examples of Al-Mg-Si alloys include 6000 series alloys such as A6061 and A6063. In one preferable embodiment of the aluminum alloy material, it is preferable that the aluminum alloy material contains at least Zn and Mg. Examples of the Al-Zn-Mg alloy include 7000 series alloys such as A7075 and A7050 alloys.
  • the aluminum alloy material contains at least Zn and Mg (it is an Al-Zn-Mg based alloy).
  • Al-Zn-Mg alloy is the highest strength alloy among practical aluminum alloy wrought materials, and is used in transportation equipment such as Shinkansen trains and aircraft. This is because the strength of this alloy system is currently rate-limited by hydrogen embrittlement.
  • a more preferred embodiment is a 7000 series alloy specified in JIS H 4000:2014 for rolled plates.
  • Another more preferable embodiment of the Al-Zn-Mg based alloy is an embodiment in which the aluminum alloy material contains Zn and Mg at a Zn/Mg atomic ratio of 1.5 or less.
  • the Zn/Mg atomic ratio is more preferably 1.2 or less, particularly preferably 1 or less, even more preferably 0.2 to 0.8, and 0.4 to 0. Even more particularly preferred is .6.
  • the aluminum alloy material may include Zn and Mg in an atomic ratio of Zn/Mg of more than 1 (or more than 1.2, or more than 1.5).
  • the hydrogen embrittlement inhibitor for aluminum alloy materials of the present invention is a hydrogen embrittlement inhibitor for aluminum alloy materials that can prevent hydrogen embrittlement of aluminum alloy materials and is used to form particles inside the aluminum alloy materials. , the particles are in T phase. Note that the particles of the dispersed phase (for example, the precipitated phase (precipitate)) contained in the aluminum alloy material may include other particles (such as the ⁇ phase) in addition to the T phase. Preferred embodiments of the hydrogen embrittlement inhibitor for other aluminum alloy materials are the same as the preferred embodiments of the method for preventing hydrogen embrittlement of aluminum alloy materials.
  • the aluminum alloy material obtained by using the method for preventing hydrogen embrittlement of an aluminum alloy material of the present invention has a T phase formed inside.
  • the shape of the aluminum alloy material is not particularly limited.
  • the aluminum alloy material may be in the form of a lump or particulate, and is preferably in the form of a lump.
  • the aluminum alloy material can be made into various known shapes such as a rolled plate, a cast material, an extruded material, and a forged material.
  • Method for manufacturing aluminum alloy material There are no particular restrictions on the method for producing the aluminum alloy material. It can be manufactured by the method for preventing hydrogen embrittlement of an aluminum alloy material of the present invention described above. A preferred embodiment of the method for producing an aluminum alloy material is the same as a preferred embodiment of the method for preventing hydrogen embrittlement of an aluminum alloy material.
  • Example 1 ⁇ Analysis of hydrogen distribution state> The reported crystal structure of Mg 32 (Al, Zn, Cu) 49 or Mg 32 (Al, Zn) 49 particles (T phase) (see Bergman et al., Acta Cryst., 10 (1957), 254) Based on this, a computational model was constructed and a first-principles calculation was used to search for sites where hydrogen can be trapped inside the T phase. As a result, it was discovered that there was a hydrogen trap site of 0.555 eV/atom.
  • FIG. 5 shows a calculated graph of the relationship between the number of hydrogen atoms and hydrogen trap energy in an example of Mg 32 (Al, Zn) 49 particles.
  • the T phase was a strong trap site with high density. Further, from FIGS. 4 and 5, it can be confirmed that there is a hydrogen trap site of 0.555 eV/atom inside the T phase (Mg 32 (Al, Zn) 49 ). From the above, it was found that the T phase has the effect of trapping hydrogen atoms more efficiently than coarse particles (second phase particles such as Al 6 Mn particles, Al 7 Cu 2 Fe particles, and Al 11 Mn 3 Zn 2 particles). Ta.
  • Example 1 and Comparative Example 1 Aluminum alloy materials satisfying the chemical composition of Al-5.6Zn-2.5Mg-1.6Cu (mass%) were prepared using the following two aging treatment temperatures. This aluminum alloy material is also an Al-Zn-Mg alloy containing 50% by mass or more of Al as a main component. A method for preventing hydrogen embrittlement of an aluminum alloy material was carried out using the method shown in FIG. 3 on a material for casting an aluminum alloy material of Al-5.6Zn-2.5Mg-1.6Cu (mass%). Specifically, homogenization was performed at 460°C for 6 hours, then the temperature was raised to 465°C for 24 hours, and hot rolling was performed at 400°C. Thickness was reduced by 87.5%.
  • Example 1 From 18mm to 2 .25mm), heating at 500°C for 30 minutes followed by 8 cycles of air cooling, electrical discharge machining (EDM), polishing, and solution treatment in a salt bath at 470°C for 1 hour. Solution treatment) was performed. Thereafter, the HT material of Example 1 was subjected to aging treatment at a high temperature of 150° C. for 16 hours in oil as a step of forming a T phase in the aluminum alloy material. On the other hand, the LT material of Comparative Example 1 was subjected to low-temperature aging treatment in oil at 120° C. for 4 hours as a step of forming the ⁇ phase. The obtained aluminum alloy material was subjected to humid environment aging in steam at 120°C for 1 hour to prepare test pieces with increased hydrogen concentration. And so.
  • FIG. 6(A), FIG. 6(B), FIG. 6(C), and FIG. 6(D) The aluminum alloy materials of each Example and Comparative Example 1 were observed using a TEM (transmission electron microscope). The obtained results are shown in FIG. 6(A), FIG. 6(B), FIG. 6(C), and FIG. 6(D).
  • FIG. 6(A) is a TEM image obtained by morphology analysis of the LT material of Comparative Example 1
  • FIG. 6(B) is a TEM image of the diffraction pattern of the ⁇ phase ( ⁇ ' phase) of the LT material of Comparative Example 1.
  • FIG. 6(C) is a TEM image obtained by morphology analysis of the HT material of Example 1
  • FIG. 6(D) is a TEM image of the diffraction patterns of the ⁇ phase ( ⁇ ' phase) and T phase of the HT material of Example 1. It is.
  • the diffraction pattern in Figure 6(D) was obtained by fast Fourier transform (FFT) of the high-resolution TEM image of the T phase marked by the arrow. Note that all images were taken along the [110] Al zone axis. From FIG. 6(C) and FIG. 6(D), it was found that in Example 1, an aluminum alloy material in which a T phase was formed inside was obtained. Note that in the HT material of Example 1, in addition to the T phase, an ⁇ phase was also observed.
  • FIG. 6(A) and FIG. 6(B) when aging treatment is performed at low temperature, that is, when the step of forming T phase in the aluminum alloy material is not performed, T phase is not formed inside. , it was found that only the ⁇ phase was formed.
  • FIG. 7 is a graph showing the relationship between strain and stress of the aluminum alloy materials of Example 1 (HT) and Comparative Example 1 (LT).
  • FIG. 8 is a graph showing the area of intergranular crack (hydrogen embrittlement) on the fracture surfaces of the aluminum alloy materials of Example 1 (HT) and Comparative Example 1 (LT). Note that the hydrogen embrittlement fracture surface ratio is preferably as small as possible.
  • FIG. 9-1(A) is a graph showing the relationship between strain and fracture area ratio of the aluminum alloy materials of Example 1 (HT) and Comparative Example 1 (LT).
  • FIG. 9-1(B) is a graph showing the relationship between strain and crack length (unit: ⁇ m) of the aluminum alloy materials of Example 1 (HT) and Comparative Example 1 (LT).
  • FIG. 9-2 (C) to (E) are 3D renderings of intergranular crack fracture of the aluminum alloy material of Comparative Example 1 (LT) with strains of 8.9%, 14.0%, and 17.8%, respectively. It is.
  • FIG. 9-2 (F) is a SEM image obtained by morphological analysis of the fracture surface of the aluminum alloy material of Comparative Example 1 (LT).
  • FIG. 9-3 (G) to (I) are 3D renderings of intergranular crack fracture of the aluminum alloy material of Example 1 (HT) with strains of 8.9%, 14.0%, and 17.8%, respectively. It is.
  • FIG. 9-3 (J) is a SEM image obtained by morphological analysis of the fracture surface of the aluminum alloy material of Example 1 (HT).
  • Example 1 (HT) has the same strength as Comparative Example 1 (LT), which was aged at a low temperature, and is more elongated than Comparative Example 1 (LT). (The elongation at break (strain at break) was large). This is because in Example 1 (HT), the T phase suppresses the occurrence and propagation of intergranular crack (hydrogen embrittlement). That is, the method for preventing hydrogen embrittlement of an aluminum alloy material of the present invention effectively prevents hydrogen embrittlement by forming a T phase in an aluminum alloy material by a method other than using Al 7 Cu 2 Fe particles or the like. It was found that this is an extremely effective method for preventing hydrogen embrittlement of aluminum alloy materials.
  • FIGS. 10(A) and (B) show the obtained results.
  • Figure 10(A) shows the trapped hydrogen concentration C H ( atom/m 3 ).
  • Figure 10(B) shows the hydrogen distribution ratio Occupancy trapped at each trap site in the aluminum alloy material of Example 1 (HT) at the crack tip before the tensile test (underformed) and after the tensile test. This is a graph. From FIGS. 10A and 10B, it was found that in the aluminum alloy material of Example 1 (HT), hydrogen was preferentially distributed to the T phase. This result was the same whether it was before the tensile test (before deformation) or at the crack tip after the tensile test (after deformation).
  • Example 1 (LT) the hydrogen distribution state of the aluminum alloy material of Comparative Example 1 (LT) was similarly analyzed and compared with Example 1 (HT). The obtained results are shown in FIGS. 11(A) to (D). 11(A) to (D) show dislocations, grain boundaries (GB), vacancies, and ⁇ phase for the aluminum alloy materials of Example 1 (HT) and Comparative Example 1 (LT), respectively. It is a graph showing the hydrogen distribution ratio Occupancy trapped in ( ⁇ ' phase). 11(A) to (D), especially FIG. 11(D), it is clear that less hydrogen was trapped in the ⁇ phase ( ⁇ ' phase) in Example 1 (HT) than in Comparative Example 1 (LT). Understood.

Abstract

The present invention provides a method for inhibiting hydrogen embrittlement of an aluminum alloy material, the method comprising a step for forming a T phase in the aluminum alloy material. This method for inhibiting hydrogen embrittlement of an aluminum alloy material is capable of effectively inhibiting or suppressing hydrogen embrittlement by a means other than usage of Al7Cu2Fe particles and the like.

Description

アルミニウム合金材の水素脆化防止方法および水素脆化防止剤Hydrogen embrittlement prevention method and hydrogen embrittlement inhibitor for aluminum alloy materials
　本発明は、アルミニウム合金材の水素脆化防止方法およびアルミニウム合金材の水素脆化防止剤に関する。 The present invention relates to a method for preventing hydrogen embrittlement of aluminum alloy materials and an agent for preventing hydrogen embrittlement of aluminum alloy materials.
　広範な用途を有するアルミニウム合金材は、水素脆化割れが生じる問題があり、この問題を解消することが提案されてきている（特許文献１～３、非特許文献１参照）。 Aluminum alloy materials, which have a wide range of uses, have the problem of hydrogen embrittlement cracking, and proposals have been made to solve this problem (see Patent Documents 1 to 3 and Non-Patent Document 1).
　特許文献１には、Ｚｎ５．０～７．０％、Ｍｇ１．０～３．０％、Ｃｕ１．０～３．０％を含有し、かつＣｒ０．０５～０．３％、Ｚｒ０．０５～０．２５％、Ｍｎ０．０５～０．４０％、Ｓｃ０．０５～０．３５％のうちから選ばれた１種もしくは２種以上を合計量が０．０５～０．５％の範囲内で含有し、さらに不純物としてＳｉを０．２５％以下、Ｆｅを０．２５％以下に規制し、残部がＡｌおよびその他の不可避的不純物としたＡｌ－Ｚｎ－Ｍｇ－Ｃｕ系アルミニウム合金を用い、その鋳塊に、４５０～５２０℃の範囲内の温度で１時間以上保持する均質化処理を行なった後、鋳塊を冷却する過程において、少なくとも４００℃までの平均冷却速度を１００℃／ｈｒ以上に規制し、その後３００～４４０℃の範囲内の温度で５０ｍｍ以上の板厚まで熱間圧延を行なった後、溶体化処理・焼入れおよび人工時効処理を施し、円相当径で５μｍを越える金属間化合物の総面積率を２％以下とした厚板を得る、強度および延性に優れたアルミニウム合金厚板の製造方法が記載されている。 Patent Document 1 describes that Zn contains 5.0 to 7.0%, Mg 1.0 to 3.0%, Cu 1.0 to 3.0%, and Cr 0.05 to 0.3%, Zr 0.05 to 0.25%, Mn 0.05-0.40%, Sc 0.05-0.35%, and one or more selected from them within a total amount of 0.05-0.5%. Using an Al-Zn-Mg-Cu based aluminum alloy, the impurities are regulated to 0.25% or less and Fe to 0.25% or less, with the remainder being Al and other unavoidable impurities. After homogenizing the ingot by holding it at a temperature within the range of 450 to 520°C for 1 hour or more, in the process of cooling the ingot, the average cooling rate to at least 400°C is 100°C/hr or more. After that, hot rolling is performed to a thickness of 50 mm or more at a temperature within the range of 300 to 440 degrees Celsius, followed by solution treatment, quenching, and artificial aging treatment to prevent intermetallic compounds with a circular equivalent diameter exceeding 5 μm. A method for manufacturing an aluminum alloy thick plate with excellent strength and ductility is described, which produces a thick plate with a total area ratio of 2% or less.
　特許文献２には、Ｚｎ４．５～８．５ｗｔ％、Ｍｇ１．５～３．５ｗｔ％、Ｃｕ０．８～２．６ｗｔ％を含有し、さらに、Ｍｎ、Ｃｒ、Ｚｒ、Ｖ、Ｔｉを少なくとも１種類含有し、残部Ａｌおよび不純物からなるアルミニウム合金を鍛造によりＨセクションを有する鍛造材に成型するに際し、合金中のＦｅ含有量を０．１５ｗｔ％以下に規制するなどする、対応力腐食割れ性に優れた高強度Ａｌ－Ｚｎ－Ｍｇ系アルミニウム合金鍛造材の製造方法が記載されている。 Patent Document 2 contains 4.5 to 8.5 wt% of Zn, 1.5 to 3.5 wt% of Mg, and 0.8 to 2.6 wt% of Cu, and further contains at least 1 of Mn, Cr, Zr, V, and Ti. When forging an aluminum alloy consisting of Al and other impurities into a forged material having an H section, the Fe content in the alloy must be restricted to 0.15 wt% or less to prevent corrosion cracking. A method for producing an excellent high-strength Al-Zn-Mg aluminum alloy forged material is described.
　特許文献３には、Ｚｎ５～８重量％、Ｍｇ１．２～４．０重量％、Ｃｕ１．５重量％を越え４．０重量％以下、Ａｇ０．０３～１．０重量％、Ｆｅ０．０１～１．０重量％、Ｔｉ０．００５～０．２重量％、Ｖ０．０１～０．２重量％を含有し、かつ、Ｍｎ０．０１～１．５重量％、Ｃｒ０．０１～０．６重量％、Ｚｒ０．０１～０．２５重量％、Ｂ０．０００１～０．０８重量％、Ｍｏ０．０３～０．５重量％のうちの少なくとも１種または２種以上を含み、残りアルミニウム及び不可避不純物からなる耐応力腐食割れ性に優れた溶接構造材用高力アルミニウム合金が記載されている。 Patent Document 3 states that Zn5-8% by weight, Mg1.2-4.0% by weight, Cu more than 1.5% by weight and 4.0% by weight or less, Ag0.03-1.0% by weight, and Fe0.01-4% by weight. Contains 1.0% by weight, 0.005 to 0.2% by weight of Ti, 0.01 to 0.2% by weight of V, and 0.01 to 1.5% by weight of Mn, and 0.01 to 0.6% by weight of Cr. , Zr0.01-0.25% by weight, B0.0001-0.08% by weight, Mo0.03-0.5% by weight, and the remainder consists of aluminum and inevitable impurities. A high-strength aluminum alloy for welded structural materials with excellent stress corrosion cracking resistance is described.
特開２０１１－０５８０４７号公報Japanese Patent Application Publication No. 2011-058047 特公平１－０２５３８６号公報Special Publication No. 1-025386 特許第２９１５４８７号Patent No. 2915487 特開２０２１－１８８１０２７号公報JP 2021-1881027 Publication
　このように近年まで、水素脆化を十分に効果的に防止ないし抑制できるアルミニウム合金材の水素脆化防止方法は知られていなかった。
　一方、近年、特許文献４には、アルミニウム合金材の水素脆化を防止でき、Ａｌ７Ｃｕ２Ｆｅ粒子からなる、アルミニウム合金材の水素脆化防止剤が記載されている。特許文献４では、アルミニウム合金材の中の局所的な水素の分配挙動と集積挙動が水素脆化割れを支配することに注目し、半整合析出物界面よりも高い水素トラップエネルギーを有する第二相粒子（Ａｌ７Ｃｕ２Ｆｅ粒子）を添加することで、析出物界面にトラップされた水素に起因する水素脆化を防止していた。しかし、水素脆化防止のためにＡｌ７Ｃｕ２Ｆｅ粒子等の粒子形成のための特殊な金属添加物の添加が必要であり、またそれらがアルミニウムの機械的性質を劣化させる可能性もある点でさらなる改善が求められるものであった。
　本発明が解決しようとする課題は、Ａｌ７Ｃｕ２Ｆｅ粒子等を用いる以外の方法で水素脆化を効果的に防止ないし抑制できる、アルミニウム合金材の水素脆化防止方法を提供することである。 As described above, until recently, a method for preventing hydrogen embrittlement of aluminum alloy materials that can sufficiently effectively prevent or suppress hydrogen embrittlement has not been known.
On the other hand, in recent years, Patent Document 4 describes a hydrogen embrittlement inhibitor for aluminum alloy materials that can prevent hydrogen embrittlement of aluminum alloy materials and is made of Al 7 Cu 2 Fe particles. Patent Document 4 focuses on the fact that hydrogen embrittlement cracking is dominated by local hydrogen distribution behavior and accumulation behavior in aluminum alloy materials, and suggests that a second phase with higher hydrogen trapping energy than the semi-coherent precipitate interface By adding particles (Al 7 Cu 2 Fe particles), hydrogen embrittlement caused by hydrogen trapped at the precipitate interface was prevented. However, to prevent hydrogen embrittlement, it is necessary to add special metal additives to form particles such as Al 7 Cu 2 Fe particles, and they may also deteriorate the mechanical properties of aluminum. Further improvements were required.
The problem to be solved by the present invention is to provide a method for preventing hydrogen embrittlement of aluminum alloy materials, which can effectively prevent or suppress hydrogen embrittlement by a method other than using Al 7 Cu 2 Fe particles or the like. .
　本発明によれば、アルミニウム合金材に分散相の一種であるＴ相を形成させることにより、Ａｌ７Ｃｕ２Ｆｅ粒子等を用いる以外の方法で水素脆化を効果的に防止ないし抑制できることを見出し、上記課題を解決した。
　上記課題を解決するための具体的な手段である本発明の構成と、本発明の好ましい構成を以下に記載する。 According to the present invention, it has been discovered that by forming a T phase, which is a type of dispersed phase, in an aluminum alloy material, hydrogen embrittlement can be effectively prevented or suppressed by a method other than using Al 7 Cu 2 Fe particles etc. , the above problem was solved.
The configuration of the present invention, which is a specific means for solving the above problems, and the preferred configuration of the present invention will be described below.
［１］　アルミニウム合金材にＴ相を形成させる工程を含む、アルミニウム合金材の水素脆化防止方法。
［２］　アルミニウム合金材がＺｎおよびＭｇを少なくとも含む、［１］に記載のアルミニウム合金材の水素脆化防止方法。
［３］　アルミニウムおよびその他の金属添加剤を含む原料組成物が、金属添加剤としてＺｎおよびＭｇをＺｎ／Ｍｇの原子比が１．５以下で含む低Ｚｎ／Ｍｇ組成物であり、
　Ｔ相を形成させる工程が、低Ｚｎ／Ｍｇ組成物を時効処理する工程である、［１］または［２］に記載のアルミニウム合金材の水素脆化防止方法。
［４］　アルミニウムおよびその他の金属添加剤を含む原料組成物を時効処理する工程を含み、
　Ｔ相を形成させる工程が時効処理を１２０℃より高い温度で行う工程である、［１］または［２］に記載のアルミニウム合金材の水素脆化防止方法。
［５］　Ｔ相がＭｇ３２（Ａｌ，Ｚｎ，Ｃｕ）４９またはＭｇ３２（Ａｌ，Ｚｎ）４９である、［１］または［２］に記載のアルミニウム合金材の水素脆化防止方法。
［６］　Ｔ相の平均粒子径が１～５０ｎｍである、［１］または［２］に記載のアルミニウム合金材の水素脆化防止方法。
［７］　アルミニウム合金材の水素脆化を防止でき、アルミニウム合金材の内部に粒子として形成させる用途であるアルミニウム合金材の水素脆化防止剤であって、
　粒子がＴ相である、アルミニウム合金材の水素脆化防止剤。 [1] A method for preventing hydrogen embrittlement of an aluminum alloy material, including a step of forming a T phase in the aluminum alloy material.
[2] The method for preventing hydrogen embrittlement of an aluminum alloy material according to [1], wherein the aluminum alloy material contains at least Zn and Mg.
[3] The raw material composition containing aluminum and other metal additives is a low Zn/Mg composition containing Zn and Mg as metal additives at a Zn/Mg atomic ratio of 1.5 or less,
The method for preventing hydrogen embrittlement of an aluminum alloy material according to [1] or [2], wherein the step of forming the T phase is a step of aging the low Zn/Mg composition.
[4] Including the step of aging a raw material composition containing aluminum and other metal additives,
The method for preventing hydrogen embrittlement of an aluminum alloy material according to [1] or [2], wherein the step of forming the T phase is a step of performing aging treatment at a temperature higher than 120°C.
[5] The method for preventing hydrogen embrittlement of an aluminum alloy material according to [1] or [2], wherein the T phase is Mg 32 (Al, Zn, Cu) 49 or Mg 32 (Al, Zn) 49 .
[6] The method for preventing hydrogen embrittlement of an aluminum alloy material according to [1] or [2], wherein the average particle size of the T phase is 1 to 50 nm.
[7] A hydrogen embrittlement inhibitor for aluminum alloy materials that can prevent hydrogen embrittlement of aluminum alloy materials and is used to form particles inside the aluminum alloy materials,
A hydrogen embrittlement inhibitor for aluminum alloy materials whose particles are in T phase.
　本発明によれば、Ａｌ７Ｃｕ２Ｆｅ粒子等を用いる以外の方法で水素脆化を効果的に防止ないし抑制できるアルミニウム合金材の水素脆化防止方法を提供することができる。 According to the present invention, it is possible to provide a method for preventing hydrogen embrittlement of an aluminum alloy material, which can effectively prevent or suppress hydrogen embrittlement by a method other than using Al 7 Cu 2 Fe particles or the like.
図１は、Ｔ相が形成されたアルミニウム合金材における水素の濃化の模式図である。FIG. 1 is a schematic diagram of hydrogen concentration in an aluminum alloy material in which a T phase is formed. 図２は、η相が形成されたアルミニウム合金材における水素の濃化の模式図である。FIG. 2 is a schematic diagram of hydrogen concentration in an aluminum alloy material in which an η phase is formed. 図３は、本発明のアルミニウム合金材の水素脆化防止方法の一例を、水素脆化試験の方法および引張試験の方法とあわせて記載したフローチャートである。FIG. 3 is a flowchart illustrating an example of the method for preventing hydrogen embrittlement of an aluminum alloy material of the present invention, together with a hydrogen embrittlement test method and a tensile test method. 図４は、Ｍｇ３２（Ａｌ，Ｚｎ）４９粒子（Ｔ相の一例）の結晶構造の一例とその水素トラップサイトの模式図である。FIG. 4 is a schematic diagram of an example of the crystal structure of Mg 32 (Al, Zn) 49 particles (an example of T phase) and its hydrogen trap sites. 図５は、Ｍｇ３２（Ａｌ，Ｚｎ）４９粒子の一例における水素原子の数と、水素トラップエネルギーとの関係を計算したグラフである。FIG. 5 is a calculated graph of the relationship between the number of hydrogen atoms and hydrogen trap energy in an example of Mg 32 (Al, Zn) 49 particles. 図６（Ａ）は比較例１のＬＴ材のモルフォロジー解析によるＴＥＭ画像である。図６（Ｂ）は比較例１のＬＴ材のη相（η’相）の回折パターンのＴＥＭ画像である。図６（Ｃ）は実施例１のＨＴ材のモルフォロジー解析によるＴＥＭ画像である。図６（Ｄ）は実施例１のＨＴ材のη相（η’相）およびＴ相の回折パターンのＴＥＭ画像である。FIG. 6(A) is a TEM image obtained by morphological analysis of the LT material of Comparative Example 1. FIG. 6(B) is a TEM image of the diffraction pattern of the η phase (η' phase) of the LT material of Comparative Example 1. FIG. 6(C) is a TEM image obtained by morphological analysis of the HT material of Example 1. FIG. 6(D) is a TEM image of the diffraction patterns of the η phase (η' phase) and T phase of the HT material of Example 1. 図７は、実施例１（ＨＴ）および比較例１（ＬＴ）のアルミニウム合金材のひずみと応力との関係を示したグラフである。FIG. 7 is a graph showing the relationship between strain and stress of the aluminum alloy materials of Example 1 (HT) and Comparative Example 1 (LT). 図８は、実施例１（ＨＴ）および比較例１（ＬＴ）のアルミニウム合金材の破断面における粒界亀裂破壊（Ｉｎｔｅｒｇｒａｎｕｌａｒ　ｃｒａｃｋ）の面積を示したグラフである。FIG. 8 is a graph showing the area of intergranular cracks on the fracture surfaces of the aluminum alloy materials of Example 1 (HT) and Comparative Example 1 (LT). 図９－１（Ａ）は実施例１（ＨＴ）および比較例１（ＬＴ）のアルミニウム合金材のひずみと破壊面積率との関係を示したグラフである。図９－１（Ｂ）は、実施例１（ＨＴ）および比較例１（ＬＴ）のアルミニウム合金材のひずみとクラック長さ（単位：μｍ）との関係を示したグラフである。FIG. 9-1(A) is a graph showing the relationship between strain and fracture area ratio of the aluminum alloy materials of Example 1 (HT) and Comparative Example 1 (LT). FIG. 9-1(B) is a graph showing the relationship between strain and crack length (unit: μm) of the aluminum alloy materials of Example 1 (HT) and Comparative Example 1 (LT). 図９－２（Ｃ）～（Ｅ）は、それぞれ、ひずみが８．９％、１４．０％、１７．８％の比較例１（ＬＴ）のアルミニウム合金材の粒界亀裂破壊の３Ｄレンダリングである。図９－２（Ｆ）は、比較例１（ＬＴ）のアルミニウム合金材の破断面におけるモルフォロジー解析によるＳＥＭ画像である。Figures 9-2 (C) to (E) are 3D renderings of intergranular crack fracture of the aluminum alloy material of Comparative Example 1 (LT) with strains of 8.9%, 14.0%, and 17.8%, respectively. It is. FIG. 9-2 (F) is a SEM image obtained by morphological analysis of the fracture surface of the aluminum alloy material of Comparative Example 1 (LT). 図９－３（Ｇ）～（Ｉ）は、それぞれ、ひずみが８．９％、１４．０％、１７．８％の実施例１（ＨＴ）のアルミニウム合金材の粒界亀裂破壊の３Ｄレンダリングである。図９－３（Ｊ）は、実施例１（ＨＴ）のアルミニウム合金材の破断面におけるモルフォロジー解析によるＳＥＭ画像である。Figures 9-3 (G) to (I) are 3D renderings of intergranular crack fracture of the aluminum alloy material of Example 1 (HT) with strains of 8.9%, 14.0%, and 17.8%, respectively. It is. FIG. 9-3 (J) is a SEM image obtained by morphological analysis of the fracture surface of the aluminum alloy material of Example 1 (HT). 図１０（Ａ）は、引張試験前（ｕｎｄｅｒｆｏｍｅｄ）と引張試験後の亀裂先端（Ｃｒａｃｋ　ｔｉｐ）の実施例１（ＨＴ）のアルミニウム合金材において、各トラップサイトでのトラップされた水素濃度ＣＨ（ａｔｏｍ／ｍ３）を示したグラフである。図１０（Ｂ）は、引張試験前（ｕｎｄｅｒｆｏｍｅｄ）と引張試験後の亀裂先端（Ｃｒａｃｋ　ｔｉｐ）の実施例１（ＨＴ）のアルミニウム合金材において、各トラップサイトでトラップされた水素分配割合Ｏｃｃｕｐａｎｃｙを示したグラフである。Figure 10(A) shows the trapped hydrogen concentration C H ( atom/m 3 ). Figure 10(B) shows the hydrogen distribution ratio Occupancy trapped at each trap site in the aluminum alloy material of Example 1 (HT) at the crack tip before the tensile test (underformed) and after the tensile test. This is a graph. 図１１（Ａ）～（Ｄ）は、実施例１（ＨＴ）と比較例１（ＬＴ）のアルミニウム合金材について、それぞれ転位（Ｄｉｓｌｏｃａｔｉｏｎ）、粒界（ＧＢ）、空孔（Ｖａｃａｎｃｙ）、η相（η’相）でトラップされた水素分配割合Ｏｃｃｕｐａｎｃｙを示したグラフである。11(A) to (D) show dislocations, grain boundaries (GB), vacancies, and η phase for the aluminum alloy materials of Example 1 (HT) and Comparative Example 1 (LT), respectively. It is a graph showing the hydrogen distribution ratio Occupancy trapped in (η' phase).
　以下において、本発明について詳細に説明する。以下に記載する構成要件の説明は、代表的な実施形態や具体例に基づいてなされることがあるが、本発明はそのような実施形態に限定されるものではない。なお、本明細書において「～」を用いて表される数値範囲は「～」前後に記載される数値を下限値および上限値として含む範囲を意味する。 The present invention will be explained in detail below. Although the constituent elements described below may be explained based on typical embodiments and specific examples, the present invention is not limited to such embodiments. In this specification, a numerical range expressed using "~" means a range that includes the numerical values written before and after the "~" as lower and upper limits.
［アルミニウム合金材の水素脆化防止方法］
　本発明のアルミニウム合金材の水素脆化防止方法は、アルミニウム合金材にＴ相を形成させる工程を含む。
　この構成により、本発明のアルミニウム合金材の水素脆化防止方法はＡｌ７Ｃｕ２Ｆｅ粒子等を用いる以外の方法で水素脆化を効果的に防止ないし抑制できる。Ｔ相は、既存のアルミニウム合金材にも含まれていることがあるが、アルミニウム合金材の水素脆化防止剤として機能することは知られていなかった。
　なお、「Ａｌ７Ｃｕ２Ｆｅ粒子等を用いる以外の方法で水素脆化を効果的に防止ないし抑制できる」とは、本発明ではＡｌ７Ｃｕ２Ｆｅ粒子等を用いる方法とは異なるメカニズム（Ｔ相が水素脆化防止剤として機能すること）により水素脆化を効果的に防止ないし抑制できることを意味する。そのため、本発明ではＡｌ７Ｃｕ２Ｆｅ粒子等を用いるか否かは任意に選択できる。したがって、本発明のアルミニウム合金材の水素脆化防止方法を使用して得られるアルミニウム合金材にＡｌ７Ｃｕ２Ｆｅ粒子等が含まれていてもよい。原料組成物の組成によっては、アルミニウム合金材にＡｌ７Ｃｕ２Ｆｅ粒子等が不可避に生成して含まれることがある。
　図１にＴ相が形成されたアルミニウム合金材における水素の濃化の模式図を示す。図１では、アルミニウム基地（アルミニウム母材）に、Ｔ相（またはＴ’相。本明細書中、Ｔ相と言う場合はＴ相とＴ’相を区別せずに両方を含む）が分散しており、Ｔ相の内部に水素が濃化している。 [Method for preventing hydrogen embrittlement of aluminum alloy materials]
The method for preventing hydrogen embrittlement of an aluminum alloy material of the present invention includes a step of forming a T phase in the aluminum alloy material.
With this configuration, the method for preventing hydrogen embrittlement of an aluminum alloy material of the present invention can effectively prevent or suppress hydrogen embrittlement by a method other than using Al 7 Cu 2 Fe particles or the like. Although the T phase is sometimes included in existing aluminum alloy materials, it was not known that it functions as a hydrogen embrittlement inhibitor for aluminum alloy materials.
Note that "hydrogen embrittlement can be effectively prevented or suppressed by a method other than using Al 7 Cu 2 Fe particles, etc." in the present invention refers to a different mechanism ( T This means that hydrogen embrittlement can be effectively prevented or suppressed by the phase functioning as a hydrogen embrittlement inhibitor. Therefore, in the present invention, it can be arbitrarily selected whether or not to use Al 7 Cu 2 Fe particles or the like. Therefore, the aluminum alloy material obtained using the method for preventing hydrogen embrittlement of an aluminum alloy material of the present invention may contain Al 7 Cu 2 Fe particles and the like. Depending on the composition of the raw material composition, Al 7 Cu 2 Fe particles and the like may inevitably be generated and included in the aluminum alloy material.
FIG. 1 shows a schematic diagram of hydrogen concentration in an aluminum alloy material in which a T phase is formed. In FIG. 1, the T phase (or T'phase; in this specification, the term T phase includes both T phase and T' phase without distinguishing between them) is dispersed in the aluminum base (aluminum base material). Therefore, hydrogen is concentrated inside the T phase.
　従来、金属組織と水素脆化との関係について、さまざまな議論があった。水素脆化を防止する手法として、（ｉ）粒界上析出物の分布を低密および粗大とする、（ｉｉ）粒界傾角（ねじれ角）を小さくする（非再結晶組織とする）、（ｉｉｉ）結晶粒を微細化する、の３通りの組織制御法が提案されていた（例えば、伊藤吾郎、江藤武比古、宮木美光、菅野幹宏、「Ａｌ－Ｚｎ－Ｍｇ系合金」、軽金属、３８（１９８８）、ｐ８１８～８３９参照）。しかし、これらの手法の有効性は不明であり、具体的な機構も不明であった。有効性は不十分であるが、水素脆化の防止法として実際に行われているジルコニウムやクロムなどの合金元素の添加は、上記（ｉｉ）または（ｉｉｉ）に基づくものであった。これに対し、本発明では、アルミニウム合金材の中の局所的な水素の分配挙動と集積挙動が、水素脆化割れを支配することに注目した。特に、水素脆化をもたらしている支配因子は、析出物にトラップされた水素であることに注目した（Ｅｎｇｉｎｅｅｒｉｎｇ　Ｆｒａｃｔｕｒｅ　Ｍｅｃｈａｎｉｃｓ　２１６　（２０１９）　１０６５０３参照）。そして、アルミニウムの各ミクロ組織と水素との間の結合エネルギーを求め、アルミニウム合金材の中の水素分配を計算することにより、水素脆化をもたらす水素トラップサイトの水素量を定量的に把握した。 In the past, there have been various discussions regarding the relationship between metal structure and hydrogen embrittlement. Methods to prevent hydrogen embrittlement include (i) making the distribution of precipitates on grain boundaries less dense and coarse, (ii) reducing the grain boundary tilt angle (torsion angle) (creating a non-recrystallized structure), ( iii) Three types of structure control methods have been proposed to refine the crystal grains (for example, Goro Ito, Takehiko Eto, Yoshimitsu Miyagi, Mikihiro Kanno, "Al-Zn-Mg alloy", light metals, 38 ( (1988), p. 818-839). However, the effectiveness of these methods was unknown, and the specific mechanism was also unknown. Although the effectiveness is insufficient, the addition of alloying elements such as zirconium and chromium, which is actually carried out as a method for preventing hydrogen embrittlement, is based on the above (ii) or (iii). In contrast, the present invention focuses on the fact that hydrogen embrittlement cracking is dominated by local distribution behavior and accumulation behavior of hydrogen within an aluminum alloy material. In particular, we focused on the fact that the dominant factor causing hydrogen embrittlement is hydrogen trapped in precipitates (see Engineering Fracture Mechanics 216 (2019) 106503). Then, by determining the bonding energy between each microstructure of aluminum and hydrogen and calculating the hydrogen distribution within the aluminum alloy material, they quantitatively determined the amount of hydrogen at hydrogen trap sites that cause hydrogen embrittlement.
　アルミニウム合金で水素脆化をもたらすナノ粒子は、η相（またはη’相。本明細書中、η相と言う場合は、η相とη’相を区別せずにこれらの両方を含む）と呼ばれ、数～数十ｎｍオーダーで合金中に分散している。図２にη相が形成されたアルミニウム合金材における水素の濃化の模式図を示す。図２では、アルミニウム基地（アルミニウム母材）に、η相が分散しており、η相の整合界面または半整合界面に水素が濃化している。例えば、Ａｌ－Ｚｎ－Ｍｇ系（７０００系）合金では、η相はＭｇＺｎ２の粒子組成をもち、この粒子界面は０．３５ｅＶ／ａｔｏｍ（整合界面）～０．５６ｅＶ／ａｔｏｍ（半整合界面）の水素トラップエネルギーを持つ。η相に水素が濃化することが原因となり、アルミニウム合金材の水素脆化は発現する。
　本発明では、界面水素が水素脆化の起源となるη相を材料から除去し、内部に水素吸蔵可能なＴ相を形成させることで、高い強度を維持したまま、アルミニウム合金材（特にＡｌ－Ｚｎ－Ｍｇ合金）の水素脆化を根本的に解決できる。
　なお、特開２０２１－１８８１０２７号公報では、η相の存在を許容したまま、水素を粗大粒子（第二相粒子）内部に優先的に分配させることで、水素脆化防止をすることが記載されている。本発明では、水素脆化をもたらすη相とは別の化学組成および結晶構造をもつＴ相を形成させることで、（場合によってはη相を減少または除去した上で、）Ｔ相に水素吸着させることができる。
　水素脆化割れには、粒界割れおよび擬へき開割れがある。本発明では粒界亀裂破壊を効果的に防止ないし抑制できることが好ましく、粒界亀裂破壊および擬へき開割れを効果的に防止ないし抑制できることがより好ましい。
　以下、本発明の好ましい態様を説明する。 Nanoparticles that cause hydrogen embrittlement in aluminum alloys are η phase (or η' phase. In this specification, η phase includes both η phase and η' phase without distinguishing between them). They are dispersed in the alloy on the order of several to tens of nanometers. FIG. 2 shows a schematic diagram of hydrogen concentration in an aluminum alloy material in which an η phase is formed. In FIG. 2, the η phase is dispersed in the aluminum base (aluminum base material), and hydrogen is concentrated at the coherent or semi-coherent interface of the η phase. For example, in the Al-Zn-Mg (7000 series) alloy, the η phase has a particle composition of MgZn 2 , and the particle interface is between 0.35 eV/atom (coherent interface) and 0.56 eV/atom (semi-coherent interface). It has a hydrogen trap energy of . Hydrogen embrittlement occurs in aluminum alloy materials due to the concentration of hydrogen in the η phase.
In the present invention, interfacial hydrogen removes the η phase, which is the source of hydrogen embrittlement, from the material and forms a T phase that can absorb hydrogen inside the material, thereby maintaining high strength and maintaining aluminum alloy materials (especially Al- It can fundamentally solve the hydrogen embrittlement of Zn-Mg alloy).
Furthermore, JP 2021-1881027 A describes that hydrogen embrittlement is prevented by preferentially distributing hydrogen inside coarse particles (second phase particles) while allowing the presence of the η phase. ing. In the present invention, by forming a T phase with a chemical composition and crystal structure different from the η phase that causes hydrogen embrittlement, hydrogen adsorption is achieved in the T phase (after reducing or removing the η phase in some cases). can be done.
Hydrogen embrittlement cracking includes intergranular cracking and pseudo-cleavage cracking. In the present invention, it is preferable that intergranular crack fracture can be effectively prevented or suppressed, and it is more preferable that intergranular crack fracture and pseudo-cleavage cracking can be effectively prevented or suppressed.
Preferred embodiments of the present invention will be described below.
＜アルミニウム合金材の製造工程の概要＞
　まず、アルミニウム合金材の製造工程の概要を説明する。
　原料組成物（アルミニウムと金属添加物の原料混合物であってもよい）を、熱処理、圧延、鍛造および／または鋳造、ならびに時効処理するなど公知の工程により、アルミニウム合金材を製造することができる。本発明では、原料のアルミニウム合金材を、時効処理して、アルミニウム合金材を製造することが、析出物への水素トラップの抑制、すなわち擬へき開破壊の抑制の観点から好ましい。
　図３は、本発明のアルミニウム合金材の水素脆化防止方法の一例を、水素脆化試験の方法および引張試験の方法とあわせて記載したフローチャートである。
　図３では、溶融または溶解させた原料組成物を、所望の形状の型に入れて鋳造（ｃａｓｔｉｎｇ）する。所望の形状となった原料組成物は、均質化（ｈｏｍｏｇｅｎｉｚａｔｉｏｎ）される。均質化された原料組成物は、熱圧延（ｈｏｔ　ｒｏｌｌｉｎｇ；熱間圧延ともいう）される。熱圧延された組成物は、熱サイクル（ｔｈｅｒｍａｌ　ｃｙｃｌｉｎｇ；ＴＣ）にかけられ、その後に放電加工（ＥＤＭ）される。放電加工された組成物は、研磨（ｐｏｌｉｓｈ）され、その後に溶体化処理（ｓｏｌｕｔｉｏｎ　ｔｒｅａｔｍｅｎｔ；ＳＴ）される。溶体化処理された後、所望の温度で時効処理をされ、アルミニウム合金材を得る。 <Overview of the manufacturing process of aluminum alloy materials>
First, an overview of the manufacturing process of aluminum alloy material will be explained.
An aluminum alloy material can be produced by a known process such as heat treatment, rolling, forging and/or casting, and aging treatment of a raw material composition (which may be a raw material mixture of aluminum and metal additives). In the present invention, it is preferable to produce an aluminum alloy material by subjecting the raw material aluminum alloy material to an aging treatment from the viewpoint of suppressing hydrogen trapping in precipitates, that is, suppressing pseudo-cleavage fracture.
FIG. 3 is a flowchart illustrating an example of the method for preventing hydrogen embrittlement of an aluminum alloy material of the present invention, together with a hydrogen embrittlement test method and a tensile test method.
In FIG. 3, the melted or melted raw material composition is placed in a mold of a desired shape and cast. The raw material composition that has a desired shape is homogenized. The homogenized raw material composition is hot rolled (also referred to as hot rolling). The hot rolled composition is subjected to thermal cycling (TC) and then electrical discharge machining (EDM). The electrical discharge machined composition is polished and then subjected to solution treatment (ST). After solution treatment, aging treatment is performed at a desired temperature to obtain an aluminum alloy material.
＜アルミニウム合金材にＴ相を形成させる工程＞
　アルミニウム合金材にＴ相を形成させる工程は、特に制限はなく、公知の方法でＴ相を形成させることができる。公知の方法としては、例えば、Ｊ．　ＪＩＬＭ，　６７，　（２０１７）５，　１６２－１６７やＪ．　ｏｆ　Ｍａｔｅｒｉａｌｓ　Ｓｃｉ．　＆　Ｔｅｃｈ．　８５（２０２１）１０６－１１７に記載の方法などを挙げることができる。 <Step of forming T phase in aluminum alloy material>
The step of forming the T phase in the aluminum alloy material is not particularly limited, and the T phase can be formed by a known method. As a known method, for example, J. JILM, 67, (2017) 5, 162-167 and J. of Materials Sci. & Tech. Examples include the method described in 85 (2021) 106-117.
　本発明の好ましい一態様として、アルミニウムおよびその他の金属添加剤を含む原料組成物が、金属添加剤としてＺｎおよびＭｇをＺｎ／Ｍｇの原子比が１．５以下（好ましくは１．２以下、より好ましくは１以下）で含む低Ｚｎ／Ｍｇ組成物であり、Ｔ相を形成させる工程が、低Ｚｎ／Ｍｇ組成物を圧延および時効処理する工程であることが好ましい。低Ｚｎ／Ｍｇ組成物を用いる場合、時効処理の温度および時間は特に制限はない。 In a preferred embodiment of the present invention, a raw material composition containing aluminum and other metal additives contains Zn and Mg as metal additives at a Zn/Mg atomic ratio of 1.5 or less (preferably 1.2 or less, more preferably 1.2 or less). It is preferable that the process of forming the T phase is a process of rolling and aging the low Zn/Mg composition. When using a low Zn/Mg composition, there are no particular restrictions on the temperature and time of the aging treatment.
　低Ｚｎ／Ｍｇ組成物を用いない場合、Ｔ相を形成させる工程としては、アルミニウムおよびその他の金属添加剤を含む原料組成物を時効処理する工程を含み、Ｔ相を形成させる工程が時効処理を１２０℃より高い温度で行う工程が好ましい。時効処理の温度が１３０℃以上であることがより好ましく、１５０℃以上であることが特に好ましい。
　１２０℃より高い温度で行う時効処理の時間は、Ｔ相を形成しやすくする観点から、１時間以上であることが好ましく、５時間以上であることがより好ましく、１０時間以上であることが特に好ましい。１２０℃より高い温度で行う時効処理の時間の上限は特に制限はないが、例えば３０時間以下とすることができる。
　なお、低Ｚｎ／Ｍｇ組成物を用いる場合も、よりＴ相を形成しやすくする観点から、時効処理の温度および時間をこれらの好ましい範囲としてもよい。 When a low Zn/Mg composition is not used, the step of forming the T phase includes a step of aging a raw material composition containing aluminum and other metal additives; Preference is given to processes carried out at temperatures higher than 120°C. The aging treatment temperature is more preferably 130°C or higher, particularly preferably 150°C or higher.
The time of the aging treatment performed at a temperature higher than 120 ° C. is preferably 1 hour or more, more preferably 5 hours or more, and particularly 10 hours or more, from the viewpoint of facilitating the formation of the T phase. preferable. There is no particular restriction on the upper limit of the time for the aging treatment performed at a temperature higher than 120°C, but it can be, for example, 30 hours or less.
In addition, even when using a low Zn/Mg composition, the temperature and time of the aging treatment may be set within these preferable ranges from the viewpoint of making it easier to form the T phase.
　１２０℃より高い温度で行う時効処理を行うタイミングは、特に制限はないが、圧延後、かつ溶体化処理の後に行うことが好ましい。 There is no particular restriction on the timing of aging treatment performed at a temperature higher than 120°C, but it is preferably performed after rolling and after solution treatment.
（低Ｚｎ／Ｍｇ組成物を時効処理する工程）
　Ｔ相を形成させる工程が、低Ｚｎ／Ｍｇ組成物を時効処理する工程である場合の好ましい態様を説明する。
　この場合、アルミニウムおよびその他の金属添加剤を含む原料組成物（低Ｚｎ／Ｍｇ組成物）が、金属添加剤としてＺｎおよびＭｇを含み、Ｚｎ／Ｍｇの原子比が０．２～０．８であることが特に好ましく、０．４～０．６であることがより特に好ましい。 (Step of aging treatment of low Zn/Mg composition)
A preferred embodiment when the step of forming the T phase is a step of aging the low Zn/Mg composition will be described.
In this case, the raw material composition (low Zn/Mg composition) containing aluminum and other metal additives contains Zn and Mg as metal additives, and the Zn/Mg atomic ratio is 0.2 to 0.8. It is particularly preferably 0.4 to 0.6, and even more preferably 0.4 to 0.6.
　その他の製造方法については、特開２００９－２２１５５６号公報の［００３４］～［００４２］、Ｊ．　ＪＩＬＭ，　６７，　（２０１７）５，　１６２－１６７およびＹａｎ　Ｚｏｕ　ｅｔａｌ，　Ｊ．　ｏｆ　Ｍａｔｅｒｉａｌｓ　Ｓｃｉ．　＆　Ｔｅｃｈ．　８５（２０２１）１０６－１１７に記載の方法を流用することができ、これらの文献の内容は参照して本明細書に組み込まれる。 For other manufacturing methods, see [0034] to [0042] of JP-A No. 2009-221556, J. JILM, 67, (2017) 5, 162-167 and Yan Zou etal, J. of Materials Sci. & Tech. 85 (2021) 106-117 can be used, and the contents of these documents are incorporated herein by reference.
＜Ｔ相＞
　Ｔ相とは、アルミニウム合金中の分散相の１種であり、Ｍｇ３２（Ａｌ，Ｚｎ，Ｃｕ）４９またはＭｇ３２（Ａｌ，Ｚｎ）４９、あるいは、これらのＴ相の構成元素の比率が化学量論組成から３０％以内でずれた組成のもののことを言う。上記の組成の分散相は、ＺｎおよびＭｇを少なくとも含むアルミニウム合金材（Ａｌ－Ｍｇ－Ｚｎ系合金材）ではＴ相と言われるが、母相がその他の組成のアルミニウム合金材ではＴ相以外の名称で言われてもよく、上記の組成の分散相（好ましくは析出相だが、粗大粒子などその他の相であってもよい）であれば本明細書のＴ相に含まれる。
　Ｔ相は、成分組成に幅を有するアルミニウム中の分散相であり、Ｍｇ２２．４～４１．６（Ａｌ，Ｚｎ，Ｃｕ）３４．３～６３．７またはＭｇ２２．４～４１．６（Ａｌ，Ｚｎ）３４．３～６３．７であることが好ましく、Ｍｇ２７．２～３６．８（Ａｌ，Ｚｎ，Ｃｕ）４１．７～５６．４またはＭｇ２７．２～３６．８（Ａｌ，Ｚｎ）４１．７～５６．４であることがより好ましく、Ｍｇ３２（Ａｌ，Ｚｎ，Ｃｕ）４９またはＭｇ３２（Ａｌ，Ｚｎ）４９であることが特に好ましい。
　Ｔ相は、整合析出物界面よりも高い水素トラップエネルギーを有することが必要である。すなわち、Ｔ相の水素トラップエネルギーは、少なくとも整合析出物界面の０．３５ｅＶ／ａｔｏｍより高いことが必要である。
　第一原理計算とは、シュレディンガー方程式を（実験データや経験パラメータを用いずに）数学的に解くことによって、理論的に電子状態を表すことをいう。結晶粒界や析出物、格子間など、その他の水素トラップサイトの密度や水素との結合エネルギーから、各トラップサイトにある水素の分布を計算することができる。なお、放射光トモグラフィーでアルミニウム合金材の変形過程の観察を行い、３Ｄまたは４Ｄ画像処理をすることにより、アルミニウム合金材の中に多数分散する第二相粒子を追跡して内部の塑性歪み分布を３Ｄマッピングできる。３Ｄ歪み分布から幾何学的に必要な転位および統計的に必要な転位、原子空孔の濃度分布を計算できる。
　Ｔ相の水素トラップエネルギーは、０．４０ｅＶ／ａｔｏｍ以上であることが好ましく、０．４５ｅＶ／ａｔｏｍ以上であることがより好ましく、０．５０ｅＶ／ａｔｏｍ以上であることが特に好ましく、半整合析出物界面の０．５５ｅＶ／ａｔｏｍよりも高いことがより特に好ましく、０．５５～０．５６ｅＶ／ａｔｏｍであることが最も好ましい。Ｔ相の水素トラップエネルギーが高くなるほど、Ｔ相の内部に水素をよりトラップすることができ、アルミニウム合金材の水素脆化をより防止ないし抑制しやすくなる。 <T phase>
The T phase is a type of dispersed phase in aluminum alloys, and the ratio of the constituent elements of Mg 32 (Al, Zn, Cu) 49 or Mg 32 (Al, Zn) 49 is chemically It refers to a composition that deviates within 30% from the stoichiometric composition. The dispersed phase with the above composition is called T phase in aluminum alloy materials containing at least Zn and Mg (Al-Mg-Zn alloy materials), but in aluminum alloy materials whose parent phase has other compositions, it is called T phase. It may be referred to by its name, and any dispersed phase (preferably a precipitated phase, but other phases such as coarse particles may also be used) having the above composition is included in the T phase in this specification.
The T phase is a dispersed phase in aluminum with a wide range of component compositions, including Mg 22.4-41.6 (Al, Zn, Cu) 34.3-63.7 or Mg 22.4-41.6 ( (Al, Zn) 34.3 to 63.7 , Mg 27.2 to 36.8 (Al, Zn, Cu) 41.7 to 56.4 or Mg 27.2 to 36.8 (Al , Zn) 41.7 to 56.4 , and particularly preferably Mg 32 (Al, Zn, Cu) 49 or Mg 32 (Al, Zn) 49 .
The T phase is required to have a higher hydrogen trapping energy than the coherent precipitate interface. That is, the hydrogen trap energy of the T phase needs to be higher than at least 0.35 eV/atom of the coherent precipitate interface.
First-principles calculation refers to representing electronic states theoretically by mathematically solving the Schrödinger equation (without using experimental data or empirical parameters). The distribution of hydrogen at each trap site can be calculated from the density of other hydrogen trap sites, such as grain boundaries, precipitates, and interstitials, and the bonding energy with hydrogen. In addition, by observing the deformation process of aluminum alloy materials using synchrotron radiation tomography and performing 3D or 4D image processing, we can track the large number of second phase particles dispersed within the aluminum alloy materials and understand the internal plastic strain distribution. 3D mapping is possible. Geometrically necessary dislocations, statistically necessary dislocations, and vacancy concentration distributions can be calculated from the 3D strain distribution.
The hydrogen trap energy of the T phase is preferably 0.40 eV/atom or more, more preferably 0.45 eV/atom or more, particularly preferably 0.50 eV/atom or more, and semi-coherent precipitates. It is particularly preferably higher than 0.55 eV/atom at the interface, most preferably from 0.55 to 0.56 eV/atom. The higher the hydrogen trapping energy of the T phase, the more hydrogen can be trapped inside the T phase, making it easier to prevent or suppress hydrogen embrittlement of the aluminum alloy material.
　得られたアルミニウム合金材におけるＴ相のトラップサイト密度は、１．０ｓｉｔｅ／ｎｍ３以上であることが好ましく、５．０ｓｉｔｅ／ｎｍ３以上であることがより好ましく、７．０ｓｉｔｅ／ｎｍ３以上であることが特に好ましい。得られたアルミニウム合金材におけるＴ相のトラップサイト密度は高いほど好ましく、上限値に制限はないが、上限値は例えば２０ｓｉｔｅ／ｎｍ３以下、１５ｓｉｔｅ／ｎｍ３以下、１０ｓｉｔｅ／ｎｍ３以下であってもよい。 The trap site density of the T phase in the obtained aluminum alloy material is preferably 1.0 site/nm 3 or more, more preferably 5.0 site/nm 3 or more, and 7.0 site/nm 3 or more. It is particularly preferable that there be. The higher the trap site density of the T phase in the obtained aluminum alloy material is, the more preferable it is, and there is no limit to the upper limit, but the upper limit is, for example, 20 sites/nm 3 or less, 15 sites/nm 3 or less, 10 sites/nm 3 or less, and Good too.
　さらに、本発明では、Ｔ相の構成元素の比率が化学量論組成から３０％以内でずれ、かつ、Ｔ相の構成元素として知られている元素以外に微量元素が固溶した粒子でも同様な効果が期待できる。Ｔ相の構成元素の比率が化学量論組成から３０％以内でずれ、かつ、Ｔ相の構成元素として知られている元素以外に微量元素が固溶した粒子も、本発明におけるＴ相に含まれる。 Furthermore, in the present invention, even particles in which the ratio of the constituent elements of the T phase deviates within 30% from the stoichiometric composition and in which trace elements are dissolved in solid solution in addition to the elements known as the constituent elements of the T phase can also be treated in the same manner. You can expect good results. Particles in which the ratio of the constituent elements of the T phase deviates within 30% from the stoichiometric composition and in which trace elements are dissolved in solid solution in addition to the elements known as constituent elements of the T phase are also included in the T phase in the present invention. It will be done.
　Ｔ相をアルミニウム合金中に分散させることにより、水素脆化を防止ないし抑制することができる。分散相（析出相）にはＴ相が含まれていればよいが、Ｔ相単独でアルミニウム合金中に分散させる方が、アルミニウム合金材の水素脆化を制御しやすい観点からは好ましい。ただし、複数種類の分散相（析出相（析出物））をアルミニウム合金中に分散させることを妨げるものではない。 By dispersing the T phase in the aluminum alloy, hydrogen embrittlement can be prevented or suppressed. Although it is sufficient that the dispersed phase (precipitated phase) contains the T phase, it is preferable to disperse the T phase alone in the aluminum alloy from the viewpoint of easily controlling hydrogen embrittlement of the aluminum alloy material. However, this does not prevent multiple types of dispersed phases (precipitated phases (precipitates)) from being dispersed in the aluminum alloy.
　Ｔ相の形状は、球状、楕円体状、角筒状、円筒状、立方体、直方体、鱗片状などの種々の形状が挙げられ、好ましくは球状または楕円体状である。 The shape of the T phase includes various shapes such as spherical, ellipsoidal, prismatic, cylindrical, cubic, rectangular parallelepiped, and scale-like, and is preferably spherical or ellipsoidal.
　Ｔ相の平均粒子径は０．１～５０ｎｍであることが好ましい。Ｔ相の平均粒子径の上限値は２０ｎｍ以下であることがより好ましく、１０ｎｍ以下であることがより好ましく、５．０ｎｍ以下であることが特に好ましい。Ｔ相の平均粒子径の下限値は０．５ｎｍ以上であることがより好ましい。Ｔ相の平均粒子径は、例えば透過電子顕微鏡を用いた組織観察により算術平均として算出することができる。 The average particle diameter of the T phase is preferably 0.1 to 50 nm. The upper limit of the average particle diameter of the T phase is more preferably 20 nm or less, more preferably 10 nm or less, and particularly preferably 5.0 nm or less. It is more preferable that the lower limit of the average particle diameter of the T phase is 0.5 nm or more. The average particle diameter of the T phase can be calculated as an arithmetic mean by observing the structure using a transmission electron microscope, for example.
＜合金組成＞
　原料のアルミニウム合金材に対して、本発明のアルミニウム合金材の水素脆化防止方法を適用して得られるアルミニウム合金材の合金組成は、アルミニウムを主成分とするものであり、アルミニウムを５０質量％以上含むことが好ましい。 <Alloy composition>
The alloy composition of the aluminum alloy material obtained by applying the method for preventing hydrogen embrittlement of an aluminum alloy material of the present invention to the raw material aluminum alloy material has aluminum as the main component, and contains 50% by mass of aluminum. It is preferable to include the above.
　アルミニウム合金材は、新規合金のアルミニウム合金材であっても、既存のアルミニウム合金材であってもよい。本発明のアルミニウム合金材の水素脆化防止剤は、ＪＩＳ規格（例えば、圧延板であればＪＩＳ　Ｈ　４０００：２０１４など。鋳造材、押し出し材、鍛造材などはそれぞれのＪＩＳ規格を参照）内の既存合金および／またはＪＩＳ規格外の新規合金のアルミニウム合金材の水素脆化を防止できることが好ましい。
　アルミニウム合金材は、アルミニウムを主成分とするものであり、アルミニウムを５０質量％以上含むことが好ましい。
　アルミニウム合金材の好ましい一態様は、純度９９．０％以上の純アルミニウム合金である。純アルミニウム合金としては、Ａ１０５０、Ａ１１００、Ａ１２００などの１０００系合金などを挙げることができる。
　アルミニウム合金材の別の好ましい一態様では、Ｃｕを少なくとも含むことが好ましい。Ａｌ－Ｃｕ系合金としては、例えばＡ２０１７、Ａ２０２４などの２０００系合金を挙げることができる。
　アルミニウム合金材の別の好ましい一態様では、Ｍｎを少なくとも含むことが好ましい。Ａｌ－Ｍｎ系合金としては、例えばＡ３００３、Ａ３００４、Ａ３００５などの３０００系合金を挙げることができる。
　アルミニウム合金材の別の好ましい一態様では、Ｓｉを少なくとも含むことが好ましい。Ａｌ－Ｓｉ系合金としては、例えばＡ４０４２、Ａ４０４３、Ａ４３４３などの４０００系合金を挙げることができる。
　アルミニウム合金材の別の好ましい一態様では、Ｍｇを少なくとも含むことが好ましい。Ａｌ－Ｍｇ系合金としては、例えばＡ５００５、Ａ５０５２、Ａ５０８３、Ａ５１８２などの５０００系合金を挙げることができる。
　アルミニウム合金材の別の好ましい一態様では、ＭｇおよびＳｉを少なくとも含むことが好ましい。Ａｌ－ＭｇーＳｉ系合金としては、例えばＡ６０６１、Ａ６０６３などの６０００系合金を挙げることができる。
　アルミニウム合金材の好ましい一態様では、ＺｎおよびＭｇを少なくとも含むことが好ましい。Ａｌ－Ｚｎ－Ｍｇ系合金としては、例えば、Ａ７０７５やＡ７０５０合金などの７０００系合金を挙げることができる。 The aluminum alloy material may be a new aluminum alloy material or an existing aluminum alloy material. The hydrogen embrittlement preventive agent for aluminum alloy materials of the present invention conforms to JIS standards (for example, JIS H 4000:2014 for rolled plates; for cast materials, extruded materials, forged materials, etc., refer to the respective JIS standards). It is preferable to be able to prevent hydrogen embrittlement of aluminum alloy materials of existing alloys and/or new alloys that do not meet JIS standards.
The aluminum alloy material has aluminum as a main component, and preferably contains 50% by mass or more of aluminum.
A preferred embodiment of the aluminum alloy material is a pure aluminum alloy with a purity of 99.0% or more. Examples of pure aluminum alloys include 1000 series alloys such as A1050, A1100, and A1200.
Another preferred embodiment of the aluminum alloy material preferably contains at least Cu. Examples of the Al-Cu alloy include 2000 series alloys such as A2017 and A2024.
Another preferred embodiment of the aluminum alloy material preferably contains at least Mn. Examples of the Al-Mn alloy include 3000 series alloys such as A3003, A3004, and A3005.
Another preferred embodiment of the aluminum alloy material preferably contains at least Si. Examples of the Al--Si alloy include 4000 series alloys such as A4042, A4043, and A4343.
Another preferred embodiment of the aluminum alloy material preferably contains at least Mg. Examples of the Al-Mg alloy include 5000 series alloys such as A5005, A5052, A5083, and A5182.
Another preferred embodiment of the aluminum alloy material preferably contains at least Mg and Si. Examples of Al-Mg-Si alloys include 6000 series alloys such as A6061 and A6063.
In one preferable embodiment of the aluminum alloy material, it is preferable that the aluminum alloy material contains at least Zn and Mg. Examples of the Al-Zn-Mg alloy include 7000 series alloys such as A7075 and A7050 alloys.
　これらの中でも、本発明ではアルミニウム合金材が、ＺｎおよびＭｇを少なくとも含む（Ａｌ－Ｚｎ－Ｍｇ系合金である）ことが好ましい。Ａｌ－Ｚｎ－Ｍｇ系合金は、実用アルミニウム合金展伸材で最も高強度な合金系であり、新幹線や航空機といった輸送機器等に実用されている。そして、この合金系の強度は、水素脆化により律速されているという現状があるためである。
　Ａｌ－Ｚｎ－Ｍｇ系合金の中でも、より好ましい一態様は、圧延板であればＪＩＳ　Ｈ　４０００：２０１４に規定される７０００系合金である。
　Ａｌ－Ｚｎ－Ｍｇ系合金の中における別のより好ましい一態様は、アルミニウム合金材がＺｎおよびＭｇをＺｎ／Ｍｇの原子比が１．５以下で含む態様である。この場合、Ｚｎ／Ｍｇの原子比が１．２以下であることがより好ましく、１以下であることが特に好ましく、０．２～０．８であることがより特に好ましく、０．４～０．６であることがさらにより特に好ましい。
　ただし、アルミニウム合金材はＺｎおよびＭｇをＺｎ／Ｍｇの原子比が１を超えて（または１．２を超えて、または１．５を超えて）含む態様であってもよい。 Among these, in the present invention, it is preferable that the aluminum alloy material contains at least Zn and Mg (it is an Al-Zn-Mg based alloy). Al-Zn-Mg alloy is the highest strength alloy among practical aluminum alloy wrought materials, and is used in transportation equipment such as Shinkansen trains and aircraft. This is because the strength of this alloy system is currently rate-limited by hydrogen embrittlement.
Among Al-Zn-Mg alloys, a more preferred embodiment is a 7000 series alloy specified in JIS H 4000:2014 for rolled plates.
Another more preferable embodiment of the Al-Zn-Mg based alloy is an embodiment in which the aluminum alloy material contains Zn and Mg at a Zn/Mg atomic ratio of 1.5 or less. In this case, the Zn/Mg atomic ratio is more preferably 1.2 or less, particularly preferably 1 or less, even more preferably 0.2 to 0.8, and 0.4 to 0. Even more particularly preferred is .6.
However, the aluminum alloy material may include Zn and Mg in an atomic ratio of Zn/Mg of more than 1 (or more than 1.2, or more than 1.5).
［アルミニウム合金材の水素脆化防止剤］
　本発明のアルミニウム合金材の水素脆化防止剤は、アルミニウム合金材の水素脆化を防止でき、アルミニウム合金材の内部に粒子として形成させる用途であるアルミニウム合金材の水素脆化防止剤であって、粒子がＴ相である。
　なお、アルミニウム合金材に含まれる分散相（例えば析出相（析出物））の粒子は、Ｔ相の他に、その他の粒子（η相など）を含んでいてもよい。
　その他のアルミニウム合金材の水素脆化防止剤の好ましい態様は、アルミニウム合金材の水素脆化防止方法の好ましい態様と同様である。 [Hydrogen embrittlement inhibitor for aluminum alloy materials]
The hydrogen embrittlement inhibitor for aluminum alloy materials of the present invention is a hydrogen embrittlement inhibitor for aluminum alloy materials that can prevent hydrogen embrittlement of aluminum alloy materials and is used to form particles inside the aluminum alloy materials. , the particles are in T phase.
Note that the particles of the dispersed phase (for example, the precipitated phase (precipitate)) contained in the aluminum alloy material may include other particles (such as the η phase) in addition to the T phase.
Preferred embodiments of the hydrogen embrittlement inhibitor for other aluminum alloy materials are the same as the preferred embodiments of the method for preventing hydrogen embrittlement of aluminum alloy materials.
［アルミニウム合金材］
　本発明のアルミニウム合金材の水素脆化防止方法を使用して得られるアルミニウム合金材は、内部にＴ相が形成している。 [Aluminum alloy material]
The aluminum alloy material obtained by using the method for preventing hydrogen embrittlement of an aluminum alloy material of the present invention has a T phase formed inside.
＜合金材の特性＞
　アルミニウム合金材の破断伸びおよび破断応力などの引張試験特性は、ＪＩＳ　Ｚ　２２４１に基づいてＪＩＳ　Ｈ　４０００：２０１４に規定される試験片について、測定される。 <Characteristics of alloy material>
Tensile test properties such as elongation at break and stress at break of an aluminum alloy material are measured on a test piece specified in JIS H 4000:2014 based on JIS Z 2241.
＜合金材の形状＞
　アルミニウム合金材の形状は、特に限定されない。アルミニウム合金材は、塊状であっても粒子状であってもよく、塊状であることが好ましい。アルミニウム合金材が塊状である場合、アルミニウム合金材を圧延板、鋳造材、押し出し材、鍛造材など公知の様々な形状とすることができる。 <Shape of alloy material>
The shape of the aluminum alloy material is not particularly limited. The aluminum alloy material may be in the form of a lump or particulate, and is preferably in the form of a lump. When the aluminum alloy material is in the form of a lump, the aluminum alloy material can be made into various known shapes such as a rolled plate, a cast material, an extruded material, and a forged material.
＜アルミニウム合金材の製造方法＞
　アルミニウム合金材の製造方法は、特に制限はない。上述した本発明のアルミニウム合金材の水素脆化防止方法により、製造することができる。アルミニウム合金材の製造方法の好ましい態様は、アルミニウム合金材の水素脆化防止方法の好ましい態様と同様である。 <Method for manufacturing aluminum alloy material>
There are no particular restrictions on the method for producing the aluminum alloy material. It can be manufactured by the method for preventing hydrogen embrittlement of an aluminum alloy material of the present invention described above. A preferred embodiment of the method for producing an aluminum alloy material is the same as a preferred embodiment of the method for preventing hydrogen embrittlement of an aluminum alloy material.
　以下に実施例と比較例を挙げて本発明をさらに具体的に説明する。以下の実施例に示す材料、使用量、割合、処理内容、処理手順等は、本発明の趣旨を逸脱しない限り適宜変更することができる。従って、本発明の範囲は以下に示す具体例により限定的に解釈されるべきものではない。 The present invention will be explained in more detail below with reference to Examples and Comparative Examples. The materials, usage amounts, proportions, processing details, processing procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the specific examples shown below.
［実施例１］
＜水素の分配状態の解析＞
　報告されているＭｇ３２（Ａｌ，Ｚｎ，Ｃｕ）４９またはＭｇ３２（Ａｌ，Ｚｎ）４９粒子（Ｔ相）の結晶構造（Ｂｅｒｇｍａｎ　ｅｔ　ａｌ．，　Ａｃｔａ　Ｃｒｙｓｔ．，　１０　（１９５７），　２５４参照）に基づいて計算モデルを構築し、第一原理計算によりＴ相内部で水素をトラップできるサイトを総当たりで探索した。
　その結果、０．５５５ｅＶ／ａｔｏｍの水素トラップサイトがあることが発見された。Ｍｇ３２（Ａｌ，Ｚｎ，Ｃｕ）４９またはＭｇ３２（Ａｌ，Ｚｎ）４９粒子（Ｔ相の一例）の結晶構造（ＢＣＣ構造，空間群Im-3m (229)）の一例とその水素トラップサイトの模式図を図４に示す。
　さらに、第一原理計算により、アルミニウム合金材中のＴ相（Ｍｇ３２（Ａｌ，Ｚｎ）４９）のトラップサイト密度を計算した。
　一方、η相の内部には水素トラップサイトはないことを別に確認した。
　参考として、Ａｌ６Ｍｎ粒子、Ａｌ７Ｃｕ２Ｆｅ粒子、Ａｌ１１Ｍｎ３Ｚｎ２粒子などの第２相粒子の水素トラップエネルギーおよびトラップサイト密度を計算した。得られた結果を表１に示した。また、Ｍｇ３２（Ａｌ，Ｚｎ）４９粒子の一例における水素原子の数と、水素トラップエネルギーとの関係を計算したグラフを図５に示す。 [Example 1]
<Analysis of hydrogen distribution state>
The reported crystal structure of Mg 32 (Al, Zn, Cu) 49 or Mg 32 (Al, Zn) 49 particles (T phase) (see Bergman et al., Acta Cryst., 10 (1957), 254) Based on this, a computational model was constructed and a first-principles calculation was used to search for sites where hydrogen can be trapped inside the T phase.
As a result, it was discovered that there was a hydrogen trap site of 0.555 eV/atom. An example of the crystal structure (BCC structure, space group Im-3m (229)) of Mg 32 (Al, Zn, Cu) 49 or Mg 32 (Al, Zn) 49 particles (an example of T phase) and its hydrogen trap site. A schematic diagram is shown in FIG.
Furthermore, the trap site density of the T phase (Mg 32 (Al, Zn) 49 ) in the aluminum alloy material was calculated by first principles calculation.
On the other hand, we separately confirmed that there are no hydrogen trap sites inside the η phase.
For reference, the hydrogen trap energy and trap site density of second phase particles such as Al 6 Mn particles, Al 7 Cu 2 Fe particles, and Al 11 Mn 3 Zn 2 particles were calculated. The results obtained are shown in Table 1. Further, FIG. 5 shows a calculated graph of the relationship between the number of hydrogen atoms and hydrogen trap energy in an example of Mg 32 (Al, Zn) 49 particles.
　上記表１より、Ｔ相は高密度な強いトラップサイトであることがわかった。また、図４および図５より、Ｔ相（Ｍｇ３２（Ａｌ，Ｚｎ）４９）の内部には、０．５５５ｅＶ／ａｔｏｍの水素トラップサイトがあることが確認できる。
　以上より、Ｔ相が粗大粒子（Ａｌ６Ｍｎ粒子、Ａｌ７Ｃｕ２Ｆｅ粒子、Ａｌ１１Ｍｎ３Ｚｎ２粒子などの第２相粒子）より効率的に水素原子をトラップする効果があることがわかった。 From Table 1 above, it was found that the T phase was a strong trap site with high density. Further, from FIGS. 4 and 5, it can be confirmed that there is a hydrogen trap site of 0.555 eV/atom inside the T phase (Mg 32 (Al, Zn) 49 ).
From the above, it was found that the T phase has the effect of trapping hydrogen atoms more efficiently than coarse particles (second phase particles such as Al 6 Mn particles, Al 7 Cu 2 Fe particles, and Al 11 Mn 3 Zn 2 particles). Ta.
［実施例１および比較例１］
　Ａｌ－５．６Ｚｎ－２．５Ｍｇ－１．６Ｃｕ（質量％）の化学組成を満たすアルミニウム合金材を、以下の２通りの時効処理の温度とする方法で準備した。このアルミニウム合金材は、Ａｌを主成分として５０質量％以上含む、Ａｌ－Ｚｎ－Ｍｇ合金でもある。
　Ａｌ－５．６Ｚｎ－２．５Ｍｇ－１．６Ｃｕ（質量％）のアルミニウム合金材を鋳造するための材料に対し、図３の方法でアルミニウム合金材の水素脆化防止方法を実施した。具体的には、４６０℃で６時間、その後に温度を上げて４６５℃で２４時間の均質化（Ｈｏｍｏｇｅｎｉｚａｔｉｏｎ）、４００℃での熱圧延（Ｈｏｔ　ｒｏｌｌｉｎｇ。８７．５％の厚み減少。１８ｍｍから２．２５ｍｍ）、５００℃、３０分間の加熱の後に空冷を８サイクルの熱サイクル（ｔｈｅｒｍａｌ　ｃｙｃｌｉｎｇ）、放電加工（ＥＤＭ）、研磨（ｐｏｌｉｓｈ）、４７０℃で１時間のｓａｌｔ　ｂａｔｈでの溶体化処理（Ｓｏｌｕｔｉｏｎ　ｔｒｅａｔｍｅｎｔ）を行った。
　その後、実施例１のＨＴ材では、アルミニウム合金材にＴ相を形成させる工程として、油中で１５０℃、１６時間の高温での時効処理を行った。一方、比較例１のＬＴ材では、η相を形成させる工程として、油中で１２０℃、４時間の低温での時効処理を行った。
　得られたアルミニウム合金材に対して、水蒸気中での１２０℃、１時間の湿潤環境時効を行い、水素濃度を増加させた試験片を作製し、それぞれ実施例１および比較例１のアルミニウム合金材とした。 [Example 1 and Comparative Example 1]
Aluminum alloy materials satisfying the chemical composition of Al-5.6Zn-2.5Mg-1.6Cu (mass%) were prepared using the following two aging treatment temperatures. This aluminum alloy material is also an Al-Zn-Mg alloy containing 50% by mass or more of Al as a main component.
A method for preventing hydrogen embrittlement of an aluminum alloy material was carried out using the method shown in FIG. 3 on a material for casting an aluminum alloy material of Al-5.6Zn-2.5Mg-1.6Cu (mass%). Specifically, homogenization was performed at 460°C for 6 hours, then the temperature was raised to 465°C for 24 hours, and hot rolling was performed at 400°C. Thickness was reduced by 87.5%. From 18mm to 2 .25mm), heating at 500°C for 30 minutes followed by 8 cycles of air cooling, electrical discharge machining (EDM), polishing, and solution treatment in a salt bath at 470°C for 1 hour. Solution treatment) was performed.
Thereafter, the HT material of Example 1 was subjected to aging treatment at a high temperature of 150° C. for 16 hours in oil as a step of forming a T phase in the aluminum alloy material. On the other hand, the LT material of Comparative Example 1 was subjected to low-temperature aging treatment in oil at 120° C. for 4 hours as a step of forming the η phase.
The obtained aluminum alloy material was subjected to humid environment aging in steam at 120°C for 1 hour to prepare test pieces with increased hydrogen concentration. And so.
［評価］
＜ＴＥＭ観察＞
　各実施例、各比較例１のアルミニウム合金材をＴＥＭ（透過型電子顕微鏡）観察を行った。得られた結果を図６（Ａ）、図６（Ｂ）、図６（Ｃ）、図６（Ｄ）に示した。
　図６（Ａ）は比較例１のＬＴ材のモルフォロジー解析によるＴＥＭ画像であり、図６（Ｂ）は比較例１のＬＴ材のη相（η’相）の回折パターンのＴＥＭ画像である。図６（Ｃ）は実施例１のＨＴ材のモルフォロジー解析によるＴＥＭ画像であり、図６（Ｄ）は実施例１のＨＴ材のη相（η’相）およびＴ相の回折パターンのＴＥＭ画像である。図６（Ｄ）の回折パターンは、矢印でマークされたＴ相の高分解能ＴＥＭ画像の高速フーリエ変換（ＦＦＴ）によって得られた。なお、すべての画像は［１１０］Ａｌ晶帯軸（ｚｏｎｅ　ａｘｉｓ）に沿って撮影された。
　図６（Ｃ）および図６（Ｄ）より、実施例１では内部にＴ相が形成されたアルミニウム合金材を得られたことがわかった。なお、実施例１のＨＴ材は、Ｔ相に加えて、η相も観察された。
　一方、図６（Ａ）および図６（Ｂ）より、低温での時効処理を行った場合、すなわちアルミニウム合金材にＴ相を形成させる工程を行わなかった場合、内部にＴ相が形成されず、η相のみが形成されたことがわかった。 [evaluation]
<TEM observation>
The aluminum alloy materials of each Example and Comparative Example 1 were observed using a TEM (transmission electron microscope). The obtained results are shown in FIG. 6(A), FIG. 6(B), FIG. 6(C), and FIG. 6(D).
FIG. 6(A) is a TEM image obtained by morphology analysis of the LT material of Comparative Example 1, and FIG. 6(B) is a TEM image of the diffraction pattern of the η phase (η' phase) of the LT material of Comparative Example 1. FIG. 6(C) is a TEM image obtained by morphology analysis of the HT material of Example 1, and FIG. 6(D) is a TEM image of the diffraction patterns of the η phase (η' phase) and T phase of the HT material of Example 1. It is. The diffraction pattern in Figure 6(D) was obtained by fast Fourier transform (FFT) of the high-resolution TEM image of the T phase marked by the arrow. Note that all images were taken along the [110] Al zone axis.
From FIG. 6(C) and FIG. 6(D), it was found that in Example 1, an aluminum alloy material in which a T phase was formed inside was obtained. Note that in the HT material of Example 1, in addition to the T phase, an η phase was also observed.
On the other hand, from FIG. 6(A) and FIG. 6(B), when aging treatment is performed at low temperature, that is, when the step of forming T phase in the aluminum alloy material is not performed, T phase is not formed inside. , it was found that only the η phase was formed.
＜引張試験＞
　Ｅｎｇｉｎｅｅｒｉｎｇ　Ｆｒａｃｔｕｒｅ　Ｍｅｃｈａｎｉｃｓ　２１６　（２０１９）　１０６５０３に準じた方法により、評点間距離０．７ｍｍ、断面積０．６ｘ０．６ｍｍ２のトモグラフィー観察用微小試験片を用いて、実施例１および比較例１のアルミニウム合金材の試験片の引張試験を行った。図７は、実施例１（ＨＴ）および比較例１（ＬＴ）のアルミニウム合金材のひずみと応力との関係を示したグラフである。 <Tensile test>
Using a method according to Engineering Fracture Mechanics 216 (2019) 106503, the aluminum alloys of Example 1 and Comparative Example 1 were examined using a micro test piece for tomography observation with a distance between scores of 0.7 mm and a cross-sectional area of 0.6 x 0.6 mm2. A tensile test was conducted on a specimen of the material. FIG. 7 is a graph showing the relationship between strain and stress of the aluminum alloy materials of Example 1 (HT) and Comparative Example 1 (LT).
＜引張試験後の破断面上の水素脆化破面率＞
　引張試験後の実施例１（ＨＴ）および比較例１（ＬＴ）のアルミニウム合金材の破断面上における水素脆性破壊粒界亀裂破壊（Ｉｎｔｅｒｇｒａｎｕｌａｒ　ｃｒａｃｋ）の面積率を画像計測して求めた。得られた結果を図８に記載した。図８は、実施例１（ＨＴ）および比較例１（ＬＴ）のアルミニウム合金材の破断面における粒界亀裂破壊（Ｉｎｔｅｒｇｒａｎｕｌａｒ　ｃｒａｃｋ）（水素脆化）の面積を示したグラフである。なお、水素脆化破面率は少ないほど好ましい。図９－１（Ａ）は実施例１（ＨＴ）および比較例１（ＬＴ）のアルミニウム合金材のひずみと破壊面積率との関係を示したグラフである。図９－１（Ｂ）は、実施例１（ＨＴ）および比較例１（ＬＴ）のアルミニウム合金材のひずみとクラック長さ（単位：μｍ）との関係を示したグラフである。 <Hydrogen embrittlement fracture surface ratio on the fracture surface after tensile test>
The area ratio of hydrogen embrittlement fracture intergranular cracks on the fracture surfaces of the aluminum alloy materials of Example 1 (HT) and Comparative Example 1 (LT) after the tensile test was determined by image measurement. The obtained results are shown in FIG. FIG. 8 is a graph showing the area of intergranular crack (hydrogen embrittlement) on the fracture surfaces of the aluminum alloy materials of Example 1 (HT) and Comparative Example 1 (LT). Note that the hydrogen embrittlement fracture surface ratio is preferably as small as possible. FIG. 9-1(A) is a graph showing the relationship between strain and fracture area ratio of the aluminum alloy materials of Example 1 (HT) and Comparative Example 1 (LT). FIG. 9-1(B) is a graph showing the relationship between strain and crack length (unit: μm) of the aluminum alloy materials of Example 1 (HT) and Comparative Example 1 (LT).
＜引張試験後のトモグラフィー断層像＞
　引張試験後の実施例１（ＨＴ）および比較例１（ＬＴ）のアルミニウム合金材の試験片について、放射光ナノトモグラフィー断層像を撮影した。図９－２（Ｃ）～（Ｅ）は、それぞれ、ひずみが８．９％、１４．０％、１７．８％の比較例１（ＬＴ）のアルミニウム合金材の粒界亀裂破壊の３Ｄレンダリングである。図９－２（Ｆ）は、比較例１（ＬＴ）のアルミニウム合金材の破断面におけるモルフォロジー解析によるＳＥＭ画像である。
　図９－３（Ｇ）～（Ｉ）は、それぞれ、ひずみが８．９％、１４．０％、１７．８％の実施例１（ＨＴ）のアルミニウム合金材の粒界亀裂破壊の３Ｄレンダリングである。図９－３（Ｊ）は、実施例１（ＨＴ）のアルミニウム合金材の破断面におけるモルフォロジー解析によるＳＥＭ画像である。 <Tomography tomographic image after tensile test>
After the tensile test, synchrotron radiation nanotomography tomographic images were taken of the aluminum alloy test pieces of Example 1 (HT) and Comparative Example 1 (LT). Figures 9-2 (C) to (E) are 3D renderings of intergranular crack fracture of the aluminum alloy material of Comparative Example 1 (LT) with strains of 8.9%, 14.0%, and 17.8%, respectively. It is. FIG. 9-2 (F) is a SEM image obtained by morphological analysis of the fracture surface of the aluminum alloy material of Comparative Example 1 (LT).
Figures 9-3 (G) to (I) are 3D renderings of intergranular crack fracture of the aluminum alloy material of Example 1 (HT) with strains of 8.9%, 14.0%, and 17.8%, respectively. It is. FIG. 9-3 (J) is a SEM image obtained by morphological analysis of the fracture surface of the aluminum alloy material of Example 1 (HT).
　図７～図９－３より、実施例１（ＨＴ）では、低温での時効処理を行った比較例１（ＬＴ）と同程度の強度であり、比較例１（ＬＴ）よりも伸びている（破断伸び（破断時のひずみ）が大きい）ことがわかった。これは、実施例１（ＨＴ）では、Ｔ相により粒界亀裂破壊（Ｉｎｔｅｒｇｒａｎｕｌａｒ　ｃｒａｃｋ）（水素脆化）の発生と親展を抑えられていることに起因する。
　すなわち、本発明のアルミニウム合金材の水素脆化防止方法は、アルミニウム合金材にＴ相を形成させることにより、Ａｌ７Ｃｕ２Ｆｅ粒子等を用いる以外の方法で水素脆化を効果的に防止ないし抑制でき、アルミニウム合金材の水素脆化防止方法として極めて有効であることがわかった。 From Figures 7 to 9-3, Example 1 (HT) has the same strength as Comparative Example 1 (LT), which was aged at a low temperature, and is more elongated than Comparative Example 1 (LT). (The elongation at break (strain at break) was large). This is because in Example 1 (HT), the T phase suppresses the occurrence and propagation of intergranular crack (hydrogen embrittlement).
That is, the method for preventing hydrogen embrittlement of an aluminum alloy material of the present invention effectively prevents hydrogen embrittlement by forming a T phase in an aluminum alloy material by a method other than using Al 7 Cu 2 Fe particles or the like. It was found that this is an extremely effective method for preventing hydrogen embrittlement of aluminum alloy materials.
＜水素の分配状態の解析＞
　実施例１（ＨＴ）のアルミニウム合金材について、ミクロ組織、特に転位（Ｄｉｓｌｏｃａｔｉｏｎ；Ｄｉｓ．）、粒界（ＧＢ）、空孔（Ｖａｃａｎｃｙ；Ｖａｃ．）、Ｓ相（Ｓ）、η相（η’相）、Ｔ相、ポア（Ｐｏｒｅ）の水素量などを、計算プロセスにより求めた。
　下記の関係の式１～式３に基づき、第一原理計算で求めた水素トラップエネルギーを用いて、熱平衡状態下の水素の分配状態を計算した。具体的な計算は、Ｅｎｇｉｎｅｅｒｉｎｇ　Ｆｒａｃｔｕｒｅ　Ｍｅｃｈａｎｉｃｓ　２１６　（２０１９）　１０６５０３に準じた方法で行った。 <Analysis of hydrogen distribution state>
Regarding the aluminum alloy material of Example 1 (HT), the microstructure, especially dislocation (Dis.), grain boundary (GB), vacancy (Vac.), S phase (S), η phase (η' The amount of hydrogen in the phase), T phase, pore, etc. were determined by a calculation process.
Based on the following relationships Equations 1 to 3, the distribution state of hydrogen under a thermal equilibrium state was calculated using the hydrogen trap energy determined by first-principles calculation. The specific calculation was performed in accordance with Engineering Fracture Mechanics 216 (2019) 106503.
　得られた結果を図１０（Ａ）および（Ｂ）に示した。図１０（Ａ）は、引張試験前（ｕｎｄｅｒｆｏｍｅｄ）と引張試験後の亀裂先端（Ｃｒａｃｋ　ｔｉｐ）の実施例１（ＨＴ）のアルミニウム合金材において、各トラップサイトでのトラップされた水素濃度ＣＨ（ａｔｏｍ／ｍ３）を示したグラフである。図１０（Ｂ）は、引張試験前（ｕｎｄｅｒｆｏｍｅｄ）と引張試験後の亀裂先端（Ｃｒａｃｋ　ｔｉｐ）の実施例１（ＨＴ）のアルミニウム合金材において、各トラップサイトでトラップされた水素分配割合Ｏｃｃｕｐａｎｃｙを示したグラフである。図１０（Ａ）およおび（Ｂ）より、実施例１（ＨＴ）のアルミニウム合金材では、Ｔ相に優先的に水素分配されることがわかった。この結果は、引張試験前（変形前）であっても、引張試験後の亀裂先端（変形後）であっても同様であった。
　さらに、比較例１（ＬＴ）のアルミニウム合金材についても、同様に水素の分配状態の解析を行い、実施例１（ＨＴ）と比較した。得られた結果を図１１（Ａ）～（Ｄ）に示した。図１１（Ａ）～（Ｄ）は、実施例１（ＨＴ）と比較例１（ＬＴ）のアルミニウム合金材について、それぞれ転位（Ｄｉｓｌｏｃａｔｉｏｎ）、粒界（ＧＢ）、空孔（Ｖａｃａｎｃｙ）、η相（η’相）でトラップされた水素分配割合Ｏｃｃｕｐａｎｃｙを示したグラフである。図１１（Ａ）～（Ｄ）、特に図１１（Ｄ）より、実施例１（ＨＴ）では、比較例１（ＬＴ）よりもη相（η’相）でトラップされた水素が少ないことがわかった。 The obtained results are shown in FIGS. 10(A) and (B). Figure 10(A) shows the trapped hydrogen concentration C H ( atom/m 3 ). Figure 10(B) shows the hydrogen distribution ratio Occupancy trapped at each trap site in the aluminum alloy material of Example 1 (HT) at the crack tip before the tensile test (underformed) and after the tensile test. This is a graph. From FIGS. 10A and 10B, it was found that in the aluminum alloy material of Example 1 (HT), hydrogen was preferentially distributed to the T phase. This result was the same whether it was before the tensile test (before deformation) or at the crack tip after the tensile test (after deformation).
Furthermore, the hydrogen distribution state of the aluminum alloy material of Comparative Example 1 (LT) was similarly analyzed and compared with Example 1 (HT). The obtained results are shown in FIGS. 11(A) to (D). 11(A) to (D) show dislocations, grain boundaries (GB), vacancies, and η phase for the aluminum alloy materials of Example 1 (HT) and Comparative Example 1 (LT), respectively. It is a graph showing the hydrogen distribution ratio Occupancy trapped in (η' phase). 11(A) to (D), especially FIG. 11(D), it is clear that less hydrogen was trapped in the η phase (η' phase) in Example 1 (HT) than in Comparative Example 1 (LT). Understood.
ＨＴ　　実施例１のアルミニウム合金材
ＬＴ　　比較例１のアルミニウム合金材 HT Aluminum alloy material of Example 1 LT Aluminum alloy material of Comparative Example 1

Claims (7)

  1. 　アルミニウム合金材にＴ相を形成させる工程を含む、アルミニウム合金材の水素脆化防止方法。 A method for preventing hydrogen embrittlement of an aluminum alloy material, which includes a step of forming a T phase in the aluminum alloy material.
  2. 　アルミニウム合金材がＺｎおよびＭｇを少なくとも含む、請求項１に記載のアルミニウム合金材の水素脆化防止方法。 The method for preventing hydrogen embrittlement of an aluminum alloy material according to claim 1, wherein the aluminum alloy material contains at least Zn and Mg.
  3. 　アルミニウムおよびその他の金属添加剤を含む原料組成物が、前記金属添加剤としてＺｎおよびＭｇをＺｎ／Ｍｇの原子比が１．５以下で含む低Ｚｎ／Ｍｇ組成物であり、
    　前記Ｔ相を形成させる工程が、前記低Ｚｎ／Ｍｇ組成物を時効処理する工程である、請求項１または２に記載のアルミニウム合金材の水素脆化防止方法。     The raw material composition containing aluminum and other metal additives is a low Zn/Mg composition containing Zn and Mg as the metal additives at a Zn/Mg atomic ratio of 1.5 or less,
    The method for preventing hydrogen embrittlement of an aluminum alloy material according to claim 1 or 2, wherein the step of forming the T phase is a step of aging the low Zn/Mg composition.
  4. 　アルミニウムおよびその他の金属添加剤を含む原料組成物を時効処理する工程を含み、
    　前記Ｔ相を形成させる工程が前記時効処理を１２０℃より高い温度で行う工程である、請求項１または２に記載のアルミニウム合金材の水素脆化防止方法。     Including the step of aging a raw material composition containing aluminum and other metal additives,
    The method for preventing hydrogen embrittlement of an aluminum alloy material according to claim 1 or 2, wherein the step of forming the T phase is a step of performing the aging treatment at a temperature higher than 120°C.
  5. 　前記Ｔ相がＭｇ３２（Ａｌ，Ｚｎ，Ｃｕ）４９またはＭｇ３２（Ａｌ，Ｚｎ）４９である、請求項１または２に記載のアルミニウム合金材の水素脆化防止方法。 The method for preventing hydrogen embrittlement of an aluminum alloy material according to claim 1 or 2, wherein the T phase is Mg 32 (Al, Zn, Cu) 49 or Mg 32 (Al, Zn) 49 .
  6. 　前記Ｔ相の平均粒子径が１～５０ｎｍである、請求項１または２に記載のアルミニウム合金材の水素脆化防止方法。 The method for preventing hydrogen embrittlement of an aluminum alloy material according to claim 1 or 2, wherein the average particle diameter of the T phase is 1 to 50 nm.
  7. 　アルミニウム合金材の水素脆化を防止でき、アルミニウム合金材の内部に粒子として形成させる用途であるアルミニウム合金材の水素脆化防止剤であって、
    　前記粒子がＴ相である、アルミニウム合金材の水素脆化防止剤。     A hydrogen embrittlement inhibitor for aluminum alloy materials that can prevent hydrogen embrittlement of aluminum alloy materials and is used to form particles inside the aluminum alloy materials,
    A hydrogen embrittlement inhibitor for aluminum alloy materials, wherein the particles are T-phase.
PCT/JP2023/014043 2022-04-06 2023-04-05 Method for inhibiting hydrogen embrittlement of aluminum alloy material, and hydrogen embrittlement inhibitor WO2023195480A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2022063424A JP2023154234A (en) 2022-04-06 2022-04-06 Method for inhibiting hydrogen embrittlement of aluminum alloy material, and hydrogen embrittlement inhibitor for aluminum alloy material
JP2022-063424 2022-04-06

Publications (1)

Publication Number Publication Date
WO2023195480A1 true WO2023195480A1 (en) 2023-10-12

Family

ID=88243103

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2023/014043 WO2023195480A1 (en) 2022-04-06 2023-04-05 Method for inhibiting hydrogen embrittlement of aluminum alloy material, and hydrogen embrittlement inhibitor

Country Status (2)

Country Link
JP (1) JP2023154234A (en)
WO (1) WO2023195480A1 (en)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH03140433A (en) * 1989-10-27 1991-06-14 Nkk Corp High strength aluminum alloy having excellent corrosion resistance
JP2009221566A (en) * 2008-03-18 2009-10-01 Kobe Steel Ltd Aluminum alloy material for high pressure gas vessel having excellent hydrogen embrittlement resistance
JP2011214149A (en) * 2010-03-18 2011-10-27 Kobe Steel Ltd Aluminum alloy material for storage container for high-pressure hydrogen gas
JP2014101541A (en) * 2012-11-19 2014-06-05 Kobe Steel Ltd Aluminum alloy material for high-pressure hydrogen gas container and method of producing the same
JP2022512876A (en) * 2018-11-12 2022-02-07 アレリス、ロールド、プロダクツ、ジャーマニー、ゲゼルシャフト、ミット、ベシュレンクテル、ハフツング 7XXX series aluminum alloy products

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH03140433A (en) * 1989-10-27 1991-06-14 Nkk Corp High strength aluminum alloy having excellent corrosion resistance
JP2009221566A (en) * 2008-03-18 2009-10-01 Kobe Steel Ltd Aluminum alloy material for high pressure gas vessel having excellent hydrogen embrittlement resistance
JP2011214149A (en) * 2010-03-18 2011-10-27 Kobe Steel Ltd Aluminum alloy material for storage container for high-pressure hydrogen gas
JP2014101541A (en) * 2012-11-19 2014-06-05 Kobe Steel Ltd Aluminum alloy material for high-pressure hydrogen gas container and method of producing the same
JP2022512876A (en) * 2018-11-12 2022-02-07 アレリス、ロールド、プロダクツ、ジャーマニー、ゲゼルシャフト、ミット、ベシュレンクテル、ハフツング 7XXX series aluminum alloy products

Also Published As

Publication number Publication date
JP2023154234A (en) 2023-10-19

Similar Documents

Publication Publication Date Title
Gu et al. Microstructure, defects, and mechanical properties of wire+ arc additively manufactured AlCu4. 3-Mg1. 5 alloy
Mondol et al. Development of a high temperature high strength Al alloy by addition of small amounts of Sc and Mg to 2219 alloy
Ghiaasiaan et al. Quantitative metallography of precipitating and secondary phases after strengthening treatment of net shaped casting of Al-Zn-Mg-Cu (7000) alloys
Pandey et al. Study of fabrication, testing and characterization of Al/TiC metal matrix composites through different processing techniques
JP6022882B2 (en) High strength aluminum alloy extruded material and manufacturing method thereof
Peng et al. Quench sensitivity and microstructures of high-Zn-content Al− Zn− Mg− Cu alloys with different Cu contents and Sc addition
Jiang et al. Effect of trace amounts of added Sc on microstructure and mechanical properties of 2055 aluminum alloy
Dong et al. Precipitation-induced mitigation of recrystallization in ultra-thin, cold-rolled AlScZrMn (Mg) sheets at brazing temperatures: The critical effect of alloy composition and thermal processing route
Doumenc et al. Investigation of microstructure, hardness and residual stresses of wire and arc additive manufactured 6061 aluminium alloy
Zhang et al. Evolution of the microstructure and mechanical properties of an sigma-hardened high-entropy alloy at different annealing temperatures
Ozer et al. Effect of post fabrication aging treatment on the microstructure, crystallographic texture and elevated temperature mechanical properties of IN718 alloy fabricated by selective laser melting
Wei et al. Evolution of microstructure and properties in 2219 aluminum alloy produced by wire arc additive manufacturing assisted by interlayer friction stir processing
Liang et al. Effects of rare earth modification on microstructure refinement and mechanical properties of Al-2 wt% Fe alloys
Jeon et al. Deformation behavior of an A356 alloy containing small sub-grains with wide low-angle boundary
Attallah et al. Influence of base metal microstructure on microstructural development in aluminium based alloy friction stir welds
Chang et al. Tailoring precipitation of directed energy deposited Al-Cu alloy via laser shock peening
WO2023195480A1 (en) Method for inhibiting hydrogen embrittlement of aluminum alloy material, and hydrogen embrittlement inhibitor
Wang et al. Novel high-strength Al-Cu-Cd alloy fabricated by arc-directed energy deposition: Precipitation behavior of the Cd phase and grain evolution
Kaviyarasan et al. Metallurgical enhancement and mechanical performance of GTAW of AA5083 plates using medium and high-entropy fillers
WO2022270483A1 (en) Hydrogen embrittlement prevention agent for aluminum alloy material
Ma et al. On the study of a TiB2 nanoparticle reinforced 7075Al composite with high tensile strength and unprecedented ductility
RU2741022C1 (en) Powdered aluminium material
JP6526404B2 (en) Aluminum alloy brazing sheet
Himuro et al. Precipitation behaviour of zirconium compounds in Zr-bearing Al-Mg-Si alloy
WO2021246267A1 (en) Aluminum alloy material and hydrogen embrittlement inhibitor for aluminum alloy materials

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 23784764

Country of ref document: EP

Kind code of ref document: A1