JP5231223B2 - Forged aluminum AA7000 series alloy product and method for producing the product - Google Patents

Description

Field of Invention

  The present invention relates to a weldable forged aluminum AA7000 series alloy in the form of a rolled, extruded or forged product and a method for producing the product. The invention further relates to a welded component comprising such a product.

  As will be apparent from the following, unless otherwise indicated, the names of alloys and tempering are according to the name of the Aluminum Association in the Aluminum Standards and Data and the Registration Records published by the Aluminum Association.

  For all descriptions of alloy compositions or preferred alloy compositions, all percentages are expressed by weight unless otherwise indicated.

  Aluminum Association (“AA”) 7000 series aluminum alloys have high strength and are suitable for applications such as aircraft structural components or tooling plates. Alloys AA7075 and AA7055 are examples of this type of alloy and are widely used in aerospace applications because of their high strength and other desirable properties. Alloy AA7055 contains Zn 7.6-8.4%, Mg 1.8-2.3%, Cu 2.0-2.6%, Zr 0.08-0.25%, Si less than 0.10%, and Fe 0.15 %, With the balance being aluminum and inevitable elements and impurities. Alloy AA7075 is composed of Zn 5.1 to 6.1%, Mg 2.1 to 2.9%, Cu 1.2 to 2.0%, Cr 0.18 to 0.28%, Si less than 0.40%, Fe 0.50% Less than and less than 0.30% Mn, the balance being aluminum and inevitable elements and impurities. When the alloy is artificially aged to its maximum strength by treatment for 20 hours or longer at a relatively low aging treatment temperature of usually 100 to 150 ° C., the alloy is obtained in a state generally called a T6 tempered state. However, in this state, alloy AA7075 and similar alloys are susceptible to stress corrosion cracking (“SCC”), exfoliation corrosion (“EXCO”), and intergranular corrosion (“IGC”). This sensitivity can be reduced by so-called T7x heat treatment, but significant strength loss is unavoidable. Higher strength is obtained by increasing the level of alloying additives (especially Zn, Mg and Cu), but this increase in strength lowers the toughness value. In addition, due to the high copper content of these alloys, these alloys are sensitive to hot cracking after welding. In addition to good weldability in consideration of the possibility of repair, it is also very important for the tool plate that the material gives a high hardness value.

Summary of the Invention

  The purpose of the present invention is to provide improved strength and toughness properties, reduced hot cracking susceptibility when welding, and 180HB in an artificially aged condition, ideally for aerospace applications or tool plates. It is to provide a forged alloy product of AA7000 series having a combination of hardness exceeding.

  Another object of the present invention is an AA7000 having a combination of improved IGC resistance, improved strength properties, reduced hot cracking susceptibility when welding, and hardness exceeding 180 HB in an artificially aged condition. It is to provide a series of forged alloy products.

  Yet another object of the present invention is to provide an AA7000 series forged alloy product having a combination of good weldability, improved strength properties, and hardness exceeding 180 HB in an artificially aged condition. .

  AA7000 series forged alloy products with improved strength and toughness characteristics, reduced hot crack susceptibility when welding, and hardness exceeding 180 HB in artificially aged condition, or improved IGC resistance Currently known for producing AA7000 series forged alloy products having a combination of improved strength properties, reduced hot cracking susceptibility when welding, and hardness exceeding 180 HB in an artificially aged condition It is also an object of the present invention to provide a method which can be carried out more economically than the industrial scale method which is actually performed.

One or more of these objectives and other advantages can be achieved or exceeded by the present invention with respect to a forged aluminum AA7000 series alloy product, wherein the product is -Zn 7.5-14.0 by weight percent.
-Mg 1.0-5.0
-Cu ≤ 0.28
-Fe <0.30
-Si <0.25
-And Zr <0.30, Ti <0.30, Hf <0.30, Mn <0.80, Cr <0.40, V <0.40, and Sc <0.70. More than one kind,
Each comprising <0.05, total <0.15 of the remaining inevitable elements and impurities, and the balance aluminum, with reduced hot cracking susceptibility and improved strength and toughness properties compared to AA7050 or AA7075 And has a hardness exceeding 180 HB in an artificially aged state.

Detailed Description of the Preferred Embodiment

The present invention is weight percent,
-Zn 7.5-14.0,
-Mg 1.0-5.0, preferably 2.0-4.5,
-Cu ≤ 0.28,
-Fe <0.30, preferably <0.14, more preferably <0.08,
-Si <0.25, preferably <0.12, more preferably <0.07,
-And one or more of the following elements:
-Zr <0.30, preferably 0.04-0.15, more preferably 0.04-0.13,
-Ti <0.30, preferably <0.20, more preferably <0.10,
-Hf <0.30,
-Mn <0.80, preferably <0.40,
-Cr <0.40,
-V <0.40, preferably <0.30,
-Sc <0.70, preferably ≤0.50
Provide forged aluminum AA7000 series alloy products, each consisting essentially of <0.05, total <0.15 of the remaining inevitable elements and impurities, and the balance aluminum, wherein the products are reduced in hot cracking susceptibility. It also has improved strength and toughness properties and has a hardness in excess of 180 HB in an artificially aged condition. Preferably the hardness is greater than 185 HB, more preferably greater than 190 HB. In the best example, a hardness exceeding 210 HB is obtained in an age-cured state. For this description, when reporting or describing hardness measurements, as will be apparent to those skilled in the art, these are measured at the thickness of the central portion, which is sensitive to the most rapid cooling of the forged product. This is to represent a special place.

  By reducing the hot cracking susceptibility, the weldability of the material is greatly improved. The iron and silicon content should preferably be kept low, for example not to exceed about 0.08% Fe and / or about 0.07% or less Si. In either case, slightly higher levels of both impurities, up to about 0.14% Fe, and / or up to about 0.12% Si are acceptable, but less preferred. In particular, up to 0.3% Fe and up to 0.25% Si are allowed in the embodiment of the template or tool plate.

  By increasing the Zn content of the alloy with the Mg content and keeping the Cu content low, the toughness level over the AA7055 reference material, and to some extent, the good copper content of the alloy is considered good. A very high strength can be obtained while maintaining the weldability. This alloy provides high hardness even in an artificially aged condition, such as T6 or T7 type tempering, but has improved weldability compared to A7075 reference material in T6 conditions, This is thought to be due to the low copper content. The artificially aged material can be, for example, T6, T74, T76, T751, T7451, T7651, T77 or T79 tempered.

  Each of the dispersoid-forming elements Zr, Sc, Hf, V, Cr and Mn can be added to control the crystal grain structure and quenching sensitivity. The optimal level of dispersoid former varies from process to process, but a single chemical component of the main elements (Zn, Cu and Mg) is selected within the preferred tolerances and used for all relevant product forms Then, the Zr level is preferably less than 0.13%.

  A preferred maximum value for Zr is 0.15%. A preferred range for the Zr level is 0.04 to 0.15%. A more preferred upper limit for adding Zr is 0.13%. Zr is a preferred alloying element for the alloy product of the present invention.

  The addition of Sc is preferably 0.50% or less, more preferably 0.3% or less, and still more preferably 0.18% or less. When combined with Sc, especially when the ratio of Zr to Sc is 0.7-1.4%, the sum of Sc + Zr is less than 0.3%, preferably less than 0.2%, more preferably up to 0.17% Should be.

  Another dispersoid former that can be added alone or with other dispersoid formers is Cr. The level of Cr is preferably less than 0.3%, more preferably at most 0.20%, even more preferably 0.15%. A preferred lower limit for Cr would be 0.04%. Although Cr alone is not as effective as Zr alone, a similar hardness result is obtained at least for use in tool plates of forged alloy products. When combined with Zr, the sum of Zr + Cr should not exceed 0.20% and is preferably 0.17% or less.

  The preferred sum of Sc + Zr + Cr should not exceed 0.4%, more preferably 0.27% or less.

  Mn can be added as a single dispersoid former or in combination with one of the other dispersoid formers. The maximum value of Mn addition is 0.80%. A suitable range of Mn addition is 0.05 to 0.40%, preferably 0.05 to 0.30%, and more preferably 0.12 to 0.30%. A preferred lower limit for Mn addition is 0.12%, more preferably 0.15%. When combined with Zr, the sum of Mn and Zr is less than 0.4%, preferably less than 0.32%, and a preferred minimum is 0.12%.

  In another embodiment of the aluminum alloy forging product of the present invention, the alloy does not contain Mn, which, in practical terms, has a Mn content of <0.02%, preferably <0.01%, More preferably, it means that the alloy is substantially or essentially free of Mn. “Essentially free” and “substantially free” means that the alloying element is not added to the composition for a certain purpose, but is leached by contact with impurities and / or production equipment. This means that trace amounts of elements can be mixed into the final alloy product.

  In a preferred embodiment of the aluminum alloy forging product of the present invention, no V is intentionally added to the alloy, but if present, it is only present at a normal impurity level of less than 0.05%.

  The copper content has a considerable influence on the hot cracking susceptibility of the alloy and thus also on the weldability of the alloy. It has been found that the weldability is further improved with a copper content of less than 0.28% or 0.25%. Very good weldability was obtained with a copper content of less than 0.25% or even less than 0.20%. The preferable minimum addition amount regarding Cu content is 0.03%, More preferably, it is 0.08%. When the alloy product of the present invention is used for a tool plate, the welding characteristics become particularly important during the work of repairing the tool plate.

  In one embodiment of the invention, the Zn content is in the range of 7.5 to 14.0%, preferably the amount of Zn has a lower limit of 8.5%, 9.0% or 9.5%. The upper limit is in the range of 12.0%, 11.0% or 10.0%, especially for use in aerospace applications, for example Zn is preferably in the range of 8.5 to 11.0% More preferably, Zn is in the range of 8.5 to 10.0%. On the other hand, for the use of a tool plate, the upper limit of the Zn content is 14.0%, preferably 12.0%, more preferably 11.0%.

  By limiting the Zn content to a maximum of 12.0%, 11.0% or even 10.0%, corrosion resistance and especially EXCO is maintained at a high level, which is useful for aerospace applications of the alloy products of the present invention. Of particular importance.

  In one embodiment of the invention, the Mg content is 1.0-5.0% or 2.5-5.0%. A preferable upper limit is 4.5%. When the alloy product of the present invention is used as a tool plate, the more preferable upper limit of the Mg content is 4.0%.

Addition of Mg significantly increases the strength of the alloy. A maximum content of 5.0% is used to avoid the formation of undesirable Mg precipitates, such as Mg ₅ Al ₃ or Mg ₅ Al ₈ , which can result in undesirable sensitivity to IGC and SSC.

  In one embodiment of the invention, the amount of Mg in the alloy is at least a value given by the relationship Mg ≧ 6.6− (0.45 × Zn), preferably Mg ≧ 10− (0.79 × Zn). is there.

Mg and Zn form MgZn ₂ precipitates that have a significant effect on the final hardness and strength properties after quenching and aging. If the Mg content is above the value given by the above relationship, excess Mg contributes to the strengthening of the alloy.

  The present invention is directed to alloy compositions that meet or exceed desired material properties when processed into a variety of products such as, but not limited to, sheets, plates, planks, and the like. . The product property balance is superior to that of products manufactured from alloys used commercially today.

  Preferably, the alloy product of the present invention is machined to a thick gauge greater than 1 inch (25.4 mm) and greater than or equal to about 11 inches (279.4 mm) and is integrally machined from a structural aviation component such as a plate. Used in the form of an integral part, or an integral girder for use in an aircraft wing structure, or in the form of a rib for use in an aircraft wing structure, or as an upper slat, to provide improved properties. Thicker gauge products can also be used as tool plates or stencils, for example, molds for producing molded plastic products by die casting, injection molding or equivalent methods. If the thickness range is as described above, it will be readily apparent to those skilled in the art that this is the thickness of the thickest cross-sectional point in an alloy product made from such a thin or thick plate. . The alloy products of the present invention can also be provided in the form of graded extrudates or extruded girders for use in aircraft structures, or in the form of forged girders used, for example, in aircraft wing structures.

  In embodiments where the alloy product is extruded, the alloy product is preferably extruded to a profile having a thickness of up to 10 mm, preferably 1-7 mm, at their thickest cross-sectional point. However, in extruded form, the alloy product can also be used in place of plank material that has been conventionally machined into structural components having a shape by high speed machining or grinding techniques. In this embodiment, the extruded alloy product preferably has a thickness of 2 inches (50.8 mm) to 6 inches (152.4 mm) at its thickest cross-sectional point.

  In one embodiment of the invention, the product is an aerospace plate having a high strength and toughness, for example an upper slat, and the Mg content of the product is preferably Mg ≧ 6.6- (0.45 × Zn), depending on the Zn content.

  A particularly advantageous combination of mechanical properties, toughness and corrosion resistance, i.e. a particularly attractive combination of high strength and toughness aerospace plates or extrudates, has a Mg content due to the above-mentioned relationship between Mg and Zn. It has been found that it is obtained when it is at least equal to or greater than a given value.

  In one embodiment of the invention, the product is a high strength tool board, preferably the hardness after artificial aging treatment is greater than 185 HB, preferably greater than 190 HB, and the Mg content of the product is preferably According to Mg ≧ 6.6− (0.45 × Zn), more preferably according to Mg ≧ 10− (0.79 × Zn), it varies depending on the Zn content. Note that all hardness values in this description and in the claims are Brinell hardness values measured according to ASTM E10, 2002 edition, with the hardness being measured by the thickness of the central portion.

  A particularly advantageous combination of mechanical properties, hardness, weldability and corrosion resistance, i.e. a particularly attractive combination for high strength tool plates, is that the Mg content is at least a value given by the relationship between Mg and Zn described above. It has been found that it can be obtained if it is equal or greater.

In a preferred embodiment, the forged alloy product is a tool plate in a T6 or T7 tempered state,
Zn 7.5-14.0, preferably 7.5-12.0, more preferably 8.5-11.0 or 9.5-12.0,
Mg 1.0-5.0, preferably 2.0-4.5 or 2.5-4.5, more preferably 2.5-3.5, preferably Mg content is Mg ≧ 6 .6- (0.45 × Zn), more preferably depending on the Zn content according to Mg ≧ 10− (0.79 × Zn),
Cu 0.03-0.25, preferably 0.03-0.20,
Zr 0.04-0.15, up to 0.20 with Cr if desired,
Ti <0.10,
Fe <0.30, preferably <0.14,
Si <0.25, preferably <0.12.
Each has a composition consisting essentially of <0.05, a total <0.15 of the remaining inevitable elements and impurities, and the balance aluminum.

  In another embodiment, the tool plate further comprises 0.05 to 0.40% Mn.

In a preferred embodiment, the forged alloy product is a tool plate in a T6 or T7 tempered state,
Zn 7.5-14.0, preferably 7.5-12.0, more preferably 8.5-11.0 or 9.5-12.0,
Mg 1.0-5.0, preferably 2.0-4.5 or 2.5-4.5, more preferably 2.5-3.5, preferably Mg content is Mg ≧ 6 .6- (0.45 × Zn), more preferably depending on the Zn content according to Mg ≧ 10− (0.79 × Zn),
Cu 0.03-0.25, preferably 0.03-0.20,
Cr 0.04-0.20,
Zr 0.15 or less,
Ti <0.10,
Fe <0.30, preferably <0.14,
Si <0.25, preferably <0.12.
Each has a composition consisting essentially of <0.05, a total <0.15 of the remaining inevitable elements and impurities, and the balance aluminum.

In another preferred embodiment, the forged alloy product of the invention consists of a sheet, plate, extrudate, or an aircraft structural component made from such a sheet, plate, extrudate and is in a T6 or T7 tempered state,
Zn 7.5-11.0,
Mg 1.0-5.0, Mg content depends on Zn content according to Mg ≧ 6.6− (0.45 × Zn), preferably Mg ≧ 10− (0.79 × Zn) And
Cu 0.03-0.25,
Zr 0.04 to 0.15,
Ti <0.10,
Fe <0.14, preferably <0.08,
Si <0.12, preferably <0.07,
Each has a composition consisting essentially of <0.05, a total <0.15 of the remaining inevitable elements and impurities, and the balance aluminum.

  In a more preferred embodiment of the aerospace product, the Mg content of the product is 2.0-4.5%, and the Mg content is according to Mg ≧ 10− (0.79 × Zn). Depends on. In another embodiment of the aerospace product, the Zn content is 7.5 to 11.0%, preferably 8.5 to 10.0%.

  In yet another embodiment of the aerospace product, the product further comprises 0.05 to 0.40% Mn, preferably 0.05 to 0.30%.

  The present invention comprises at least one first component part that is a product of the present invention and at least one second component part, the component parts being welded together to form a welded component. Also embodied by a welded component, preferably the welded component is a welded aircraft structural component. More preferably, the first and second component parts comprise the product of the present invention. More preferably, substantially all or even all components forming a welded component or welded aircraft structural component comprise the product of the present invention. Uses good weldability and other favorable properties to form welded components or welded aircraft structural components with superior strength, corrosion properties and weld quality.

In another aspect of the present invention, there is provided a method for producing a forged aluminum AA7000 series alloy product as described above and in the examples, wherein the following processing steps are performed: a) casting an ingot having the composition described in the present description. ,
b) homogenizing and / or preheating the ingot after casting;
c) a step of hot working the ingot into a pre-processed product by one or more methods selected from the group consisting of rolling, extrusion and forging;
d) optionally reheating the pre-processed product and either
e) hot-working and / or cold-working the pre-processed product into a desired workpiece shape;
f) solution treating (SHT) the formed workpiece at a temperature and for a time sufficient to bring substantially all of the soluble components in the alloy into solid solution;
g) a step of quenching the solution-treated workpiece, preferably by spray quenching or immersion quenching in water or oil or other quenching medium;
h) optionally stretching or compressing the quenched or otherwise cold worked workpiece to relieve stress, for example to flatten the sheet product;
i) Artificially aging the quenched, optionally stretched or compressed workpiece as desired, to achieve the desired tempering, especially T6 or T7 type tempering, for example T6, T74, T76, T751, T7451, T7651, T77 and T79. Comprising the step of achieving a temper selected from the group comprising, wherein the homogenization process comprises a first homogenization stage and optionally a second homogenization stage, wherein the first homogenization for an ingot or slab The duration and temperature during the crystallization step is required for the cold spot in the ingot or slab, defined as the coldest point in the ingot or slab, to dissolve substantially all m-phase precipitates. A method is provided that is selected to be at or above the dissolution temperature and dissolution time.

  Optionally, the homogenization process comprises at least a second homogenization stage following the first homogenization stage. It should be noted that the melting temperature reaches an early time at the periphery of the ingot or casting and that the temperature in the cold spot gradually increases to the melting temperature. In practice, the melting temperature is usually called the homogenization temperature.

  The alloy product of the present invention is manufactured by melting as usual and by direct cooling (“DC”) casting into an ingot or by other suitable casting techniques. The hot working of the alloy product can be performed by one or more methods selected from the group consisting of rolling, extrusion and forging. For this alloy, hot rolling is preferred. The solution treatment is typically carried out in the same temperature range as used for homogenization, but the immersion time can be selected somewhat shorter.

  In one embodiment, there is provided a method for selecting the duration of the first homogenization stage for an ingot or slab so that the cold spot is at a temperature at which the m-phase precipitate is dissolved, at least the dissolution time required to dissolve it. Provided, however, the dissolution time is preferably up to 2 hours, preferably 1 hour, more preferably as short as possible, for example 30 minutes or 20 minutes or even shorter. Preferably, the dissolution temperature is about 470 ° C.

  In one embodiment, a process is provided wherein the duration of the first homogenization stage for the ingot or slab is up to 24 hours, preferably up to 12 hours, preferably the homogenization temperature is about 470 ° C.

  In one embodiment, for ingots or slabs where Cu ≦ 0.28%, more preferably Cu ≦ 0.20%, the first homogenization stage is up to 12 hours at 470 ° C., wherein the second Provide a method without homogenization.

  In one embodiment, for ingots or slabs where Cu> 0.20%, preferably Cu> 0.25%, more preferably up to 0.28% Cu, the homogenization step is a first homogenization stage. And a second homogenization stage, wherein the first homogenization stage is up to 24 hours at 470 ° C., preferably up to 12 hours, and the second homogenization stage is up to 24 hours at 475 ° C., preferably up to 12 hours. To provide a way to be.

  In the method of the present invention, hot cracking susceptibility is reduced, strength and toughness properties are improved, and a product with a hardness exceeding 180 HB is obtained under artificial aging conditions. For Cu, preferably Cu ≦ 0.25% or even Cu ≦ 0.20%, a homogenization treatment at 470 ° C. for a maximum of 24 hours, preferably a maximum of 12 hours, results in all m-phase precipitates. And is sufficient to obtain a product having the desired properties after SHT, quenching, optionally stretching, and aging treatment. Depending on the copper content, by selecting the shortest homogenization step possible and the lowest possible homogenization temperature, the process is carried out very economically, maintaining excellent properties and achieving excellent weldability be able to. If the aging treatment is a one-step aging treatment, the method can be performed more economically. In this way, a high-strength tool plate application product is obtained in which the hot cracking sensitivity is reduced, the strength is improved, and the hardness exceeds 180 HB under T6 tempering conditions. The two-stage aging treatment provides an excellent product as a weldable aerospace plate with high strength and toughness that combines improved mechanical properties, hardness, toughness and corrosion resistance under artificial aging conditions. It has been found that after one or two-stage aging treatment, the resistance to corrosion, in particular IGC and EXCO, is improved.

  The m-phase precipitate dissolves rapidly with the Cu ≦ 0.28% alloy of the present invention and more rapidly with the lower copper content ≦ 0.25% or ≦ 0.20%. The cold spot, defined as the coldest spot in the slab, usually in the center of the ingot or slab, is at least at the melting time, homogenization temperature, eg 470 ° C., required to dissolve the m-phase precipitate In addition, by selecting the duration of the first homogenization stage, the process can be carried out more economically, preferably with a dissolution time of up to 2 hours, preferably 1 hour, as short as possible Is more preferable. Ideally, the homogenization process ends when all m-phase precipitates are dissolved, after which the slab or ingot is sent to a hot rolling mill where the slab reaches the rolling temperature and then reheated as desired. After processing, the slab or ingot can be brought to rolling temperature or lowered to rolling temperature and then hot rolled.

  In one embodiment, the homogenization process is controlled using control means, for example a computer model based on mathematical or physical principles that calculates the temperature evolution of the ingot or slab during the homogenization process, and at the homogenization temperature. The optimum residence time of the slab or ingot is determined and the ingot or slab cold spot is maintained at the dissolution temperature, eg, about 470 ° C., for the dissolution time required to dissolve the m-phase precipitate. As will be apparent to those skilled in the art, the annealing time and temperature may vary somewhat depending on the concept of equivalent time, as defined in EP 087 514 (paragraph [[0028]), which is hereby incorporated by reference. Of course, of course, the minimum annealing temperature needs to be high enough to allow dissolution of the precipitate. Since it is also important to avoid dissolution of certain other precipitates, the freedom to choose the annealing temperature is limited by the highest and lowest homogenization temperatures.

  In one embodiment of the method of the invention, the artificial aging treatment step i) is preferably carried out at a temperature of 105 ° C. to 135 ° C., preferably for a first temporary treatment step of 2 to 20 hours, and at a temperature of 135 ° C. to 210 ° C. Comprises a second aging treatment step of 4 to 20 hours. In another embodiment, the third aging treatment step can be performed at a temperature of 105 ° C to 135 ° C for 20 to 30 hours.

  In the following, the present invention is illustrated by non-limiting examples.

Example 1
Chemical composition shown in Table 1 1-A. Seven laboratory ingots were cast and processed by the following route (v = heating rate, @ = ˜).
Homogenization treatment: v = 35 ° C./h+12 h @ 470 ° C.
Preheating: v = 35 ° C / h + 6h @ 420 ° C
Hot rolling: From 80mm gauge to 30mm,
SHT: v = as fast as possible 2h @ 470 ° C., followed by water quenching,
Stretching: 1.5%
Aging treatment: T76, v = 30 ° C / h + 5h @ 120 ° C / h plus 15 ° C / h + 12h @ 145 ° C / h

Table 1. Alloy composition in mass% (0.06Fe, 0.04Si, 0.04Ti, 0.10Zr, balance aluminum), alloy mechanical properties (L direction) and fracture toughness (LT direction)

Alloy Zn Mg Cu R _p R _m K _IC
(MPa) (MPa) (MPa√m)
AA7055-T7751 Standard AMS4206 593 614 24.2
AA7449-T7651 Standard AMS4250 538 579 24.2
A. 1 7.5 2.8 0.15 531 549 70.1
A. 2 7.4 4.2 0.16 589 614 40.6
A. 3 9.5 1.9 0.16 554 558 62.1
A. 4 9.5 2.3 0.15 580 595 41.3
A. 5 9.5 2.8 0.15 623 636 30.8
A. 6 9.4 3.3 0.17 647 666 26.4
A. 7 11.0 2.8 0.18 659 669 24.2

  Table 1. As can be seen from the above, Zn and Mg are increased, but by keeping the Cu level low, a very high strength can be obtained while maintaining a toughness level higher than that of the reference material. From Table 1, it appears that the Mg level depends on the Zn level according to Mg ≧ 6.6 (0.45 × Zn) to reach the desired strength level of at least 580 MPa.

Example 2
Chemical composition shown in Table 2 1-B. No. 4 laboratory ingot was cast and processed by the above route except that the final hot rolled thickness was 3 mm and alloy B. 2 is homogenized for a longer time (12h @ 470 ° C. followed by 24h @ 475 ° C.), where the homogenization process comprises a first and a second stage.

Table 2. Alloy composition expressed as mass% (0.06Fe, 0.04Si, 0.04Ti, 0.10Zr, balance aluminum)

Alloy Zn Mg Cu R _p (MPa) EXCO
B. 1 9.3 2.3 0.16 565 EA / B
B. 2 9.4 2.3 0.80 564 EC
B. 3 9.3 2.8 0.16 598 EA
B. 4 10.7 2.8 0.15 626 EA

  Also shown in Table 2 are the mechanical (L direction) and corrosion (EXCO, measured according to standard ASTM G34-97) properties of the alloy. The 0.8% Cu level (see Alloy B.2) does not improve the mechanical properties and adversely affects the corrosion behavior of the alloy. On the other hand, the addition of Mg and Zn (see alloys B.3 and B.4) improves the corrosion properties and significantly increases the strength.

Example 3
Seven alloys with compositions shown in Table 3 were tested. Most alloys (C.1-C.5) have low Cu levels and some (alloys C.6, C.7) contain more Cu. All of these alloys were processed to 3.5 mm gauge by the following route.
Casting of ingot, rolling 80 × 80 × 100 mm ³ block from machined ingot Homogenization treatment: v = 30 ° C./h+470° C. @ 12h for Cu ≦ 0.20%
For Cu> 0.20%, v = 30 ° C./h+470° C. @ 12 h, v = 15 ° C./h+475° C. @ 24 h,
Hot rolling: Preheating @ 430 ° C, rolling from 80mm to 3.5mm thickness,
SHT: 1h @ 470 ° C., followed by quenching in water or oil,
Stretching: 1.5%
After SHT, all alloys in this example were aging to T6 tempering.

  Prior to artificial aging treatment, the alloy was quenched with both water and oil and the quench sensitivity of the alloy was tested. Oil quenching is equivalent to the quenching rate in a plate core of about 70 mm thickness, where the plate core cannot be cooled as rapidly as the surface. After aging treatment, Brinell hardness was measured by ASTM E10, 2002 edition. The achieved hardness values are shown in Table 3. Table 3 shows that the water quench value is typically higher than or similar to the oil quench value. Alloys with the highest overall alloying content are most sensitive to quenching. Alloy C. All with Zn ≧ 9.3% 2, C.I. 3, C.I. 5, C.I. 7 has a hardness value of at least 190 HB. Alloy C. In No. 6, although the hardness is greatly increased by the addition of Cu compared to the alloy (alloy C.1) to which this is not added, the high Zn alloy C.I. In No. 7, the hardness hardly increases under oil quenching conditions due to the addition of Cu. Contrary to the metallurgical expectation that the combination of Mg and Cu yields higher strength compared to the same amount of Mg alone, surprisingly, at higher Zn contents, Cu is more than additional Mg. Is no longer effective in increasing hardness.

Table 3. Contains series C composition in mass%, balance aluminum, Brinell hardness value (HB) for different quench media (WQ = water quench, OQ = oil quench).

Alloy Zn Mg Cu Ti Zr Fe Si HB HB ΔHB IGC type
WQ OQ (WQ-OQ) OQ
C.1 7.4 1.92 0.17 0.04 0.10 0.04 0.02 164 164 0 1
C.2 9.3 2.8 0.16 0.04 0.11 0.03 0.02 192 190 2 1
C.3 9.5 3.3 0.16 0.04 0.098 0.03 0.02 209 197 12 1
C.4 7.4 4.2 0.17 0.04 0.098 0.04 0.02 189 189 0 1
C.5 10.7 2.8 0.16 0.04 0.097 0.03 0.02 210 197 13 1
C.6 7.4 1.86 1.65 0.05 0.10 0.03 0.02 179 179 0 2
C.7 9.4 2.3 1.66 0.04 0.099 0.03 0.02 204 191 13 2

  In addition, the low Cu alloy showed excellent resistance to intergranular corrosion (IGC, test conducted according to standard ASTM G110-92), even when quenched in oil, whereas the Cu content was high The alloy exhibited a slight degree of IGC. Therefore, this alloy has various advantages in the processing of the alloy due to its low sensitivity to quenching and high tolerance to processing changes.

Example 4
Five alloys with compositions shown in Table 4 were tested. These alloys have low Cu levels. These alloys were processed into 3 mm gauge plates by the following route.
Casting of ingot, rolling 80 × 80 × 100 mm ³ block from machined ingot Homogenization treatment: v = 30 ° C./h+470° C. @ 12h
Hot rolling: Preheating @ 430 ° C, rolling from 80mm to 3mm thickness,
SHT: 1h @ 470 ° C, followed by quenching in water,
Stretching: 1.5%
Aging treatment: One-step or two-step artificial aging treatment for T6 tempering

  Table 4 shows the average hardness values obtained after the 1 and 2 step aging treatments. The results shown in Table 4 show that the minimum Mg content is 1.92% to 2.85% with a Zn content of 9.47% for 190 or more HB. Table 3 gives a value of 2.8. Furthermore, the same hardness level is obtained for the one-step and two-step artificial aging treatments. This increases the applicability of the alloy to various product ranges where a two-step aging treatment is required (aerospace material requirement) or one step is preferred (cost savings).

  Table 4 shows that a wide range is possible to reach a hardness level of 190 HB or higher in the aging time of the 145 ° C. process in the artificial aging treatment.

Table 4. It is shown together with the composition of the alloy of Example 2 expressed in mass%, the balance aluminum, the average hardness for one-step and two-step aging treatment.

Alloy Zn Mg Cu Zr Fe Si Ti Ti 1 step 2 steps
(HB) (HB)
D.1 9.47 1.92 0.16 0.10 0.06 0.03 0.05 174 175
D.2 9.41 2.85 0.16 0.10 0.06 0.03 0.05 192 190
D.3 9.52 3.37 0.16 0.096 0.08 0.03 0.05 197 195
D.4 9.61 4.57 0.16 0.092 0.07 0.03 0.06 198 204
D.5 8.94 3.99 0.16 0.095 0.07 0.03 0.06 200 197

From Tables 3 and 4, the lowest compositional relationship between Mg and Zn content, which can be expected to have high hardness by appropriate alloy treatment, can be derived. The relationship between Mg and Zn content can be approximated by Mg = 10−0.79 ^* Zn in mass%. In relation to the Zn content, a Mg content higher than the content given by this relationship gives a hardness of at least 185 HB, even at least 190 HB, especially in alloys with a Zn content above 7.4%.

Example 5
Three alloys (E.1 to E.3) particularly suitable for tool plates according to the invention were treated according to the method of the invention, followed by a peak aging treatment at 130 ° C. for 24 hours. Tensile properties (yield strength and tensile strength) were measured in the L direction, and hardness was measured by the thickness of the central portion. These alloys were compared to AA7050 and AA7075 alloys in T651 tempering.

  The composition and properties of the alloy are shown in Table 5. From these results, it can be seen that the alloy of the present invention can achieve very high hardness, which is very suitable for tool plates.

Table 5. Composition (Zr0.12%, Fe0.05%, Si0.03%, Cu0.15%, balance aluminum) and tensile properties and hardness expressed in mass%

Alloy Zn Mg Tempering Rp Rm Hardness
(Mass%) (mass%) (MPa) (MPa) (HB)
AA7050 6.2 2.3 T651 532 575 180
AA7075 5.6 2.5 T651 533 462 150
E.1 9.4 3.5 Peak aging treatment 695 708 236
E.2 11.5 3.1 Peak aging treatment 734 736 246
E.3 11.4 3.0 Peak aging treatment 680 689 245

Example 6
PT Houldcroft, British Welding Journal, October 1955, incorporated herein by reference, the weldability of the three alloys (F.1-F.3) treated according to the present invention are used to evaluate the hot cracking susceptibility of aluminum alloys. , pp.471-475, also referred to as the Houldcroft test described in the document "A simple Cracking Test for use With Argon-Arc Welding". The procedure was evaluated. This procedure used a fish bone shaped sample or a tapered sample, preferably a tapered sample for laser welding, in this example a sample having a thickness of 2 mm. A laser was used to form a fully transmissive bead-on-plate weld. The weld starts from the thin end of the sample and extends the entire length of the sample. Hot cracks are formed when the weld pool solidifies and finish at certain points. The length of this crack is a measure of hot cracking sensitivity, and the longer the crack, the higher the hot cracking sensitivity. During the test, the sample was not constrained and all welds were formed without the addition of filler wire. In these tests, an Nd: YAG laser with a spot size of 0.45 mm (150 mm focal lens) was used, and the focal position was adjusted on the upper surface of the plate. The laser processing parameters were kept constant at 4500 W laser power and a welding speed of 4 m / min.

  Table 6 shows the alloys selected for the test and the results of the welding test. The crack susceptibility is expressed by the crack% obtained by dividing the crack length by the sample length. Therefore, the lower the crack%, the lower the hot crack sensitivity. It is clear that as the total Zn and Mg solute content increases, the crack sensitivity decreases and the weldability increases. Since aluminum AA7017 is accepted as a weldable aluminum in the aluminum industry, this aluminum was tested for comparison. It is clear that all the alloys of the present invention have better weldability than AA7017.

Table 6. Composition of alloys according to the invention in terms of% by weight (Zr 0.12%, Fe 0.05%, Si 0.03%, Cu 0.15%, balance aluminum) and results of the Houldcroft welding test

Alloy Zn Mg Zn + Mg Crack%
AA7018 4.0-5.2 2.0-3.0 6.0-8.2 53
(Comparison)
F. 1 9.3 2.8 12.1 31
F. 2 9.5 3.3 12.8 28
F. 3 10.7 2.8 13.5 31

  Of course, the present invention is not limited to the embodiments and examples described above, but encompasses all embodiments that fall within the scope of the description and the following claims.

Claims (32)

% By mass
-Zn 9.0 to 14.0,
-Mg 1.0-5.0,
-Cu 0.03-0.25 ,
-Fe <0.30,
-Si <0.25,
-Zr 0.04 to less than 0.3- and one or more of the following elements:
-Ti <0.30,
-Hf <0.30,
-Mn <0.80,
-Cr <0.40,
−V <0.40,
-Sc <0.70,
Each <0.05, total <Ri Rana or 0.15 remaining inevitable elements and impurities and balance aluminum, of the reduced hot crack sensitivity, strength and toughness properties are improved, and artificially aged A forged aluminum AA7000 series alloy product having a hardness exceeding 180 HB in the state. The product of claim 1, wherein Cu is ≦ 0.20%. Lower limit of Cu content is 0 . The product of claim 1, which is 08%.   2. Product according to claim 1, wherein the Zr content is 0.04 to 0.15%, preferably 0.04 to 0.13%.   The product according to claim 1, wherein the lower limit of the Zn content is 9.5%.   The product according to claim 1, wherein the upper limit of the Zn content is 12.0%.   The product according to claim 1, wherein the upper limit of the Zn content is 11.0%.   The product according to claim 1, wherein the upper limit of the Zn content is 10.0%.   The product according to claim 1, wherein the lower limit of the Mg content is 2.5%.   The product according to claim 1, wherein the upper limit of the Mg content is 4.5%, preferably the upper limit is 4.0%.   2. Product according to claim 1, wherein the Fe content is up to 0.14%, preferably up to 0.08%.   2. Product according to claim 1, wherein the Si content is up to 0.12%, preferably up to 0.07%.   The product according to claim 1, wherein the Mn content is 0.05 to 0.40%.   2. Product according to claim 1, wherein the Mn content is <0.02%.   2. Product according to claim 1, wherein Mg ≧ 6.6− (0.45 × Zn), preferably Mg ≧ 10− (0.79 × Zn).   The product of claim 1, wherein the product is in the form of a sheet, plate, or extrudate.   The product of claim 1, wherein the product is in a T6 or T7 state.   A welded component comprising at least one first component part that is the product of claim 1 and at least one second component part, wherein the component parts are welded together to form the welded component. A welded component is formed, the at least one first and the at least one second component part being a product according to claim 1, wherein the welded component is a welded aircraft structural component. , Welded components. The forged product is a weldable aerospace sheet or plate product in a T6 or T7 state, the product in weight percent;
Zn 9.0 ~11.0,
Mg 1.0-5.0, where the Mg content depends on the Zn content according to Mg ≧ 6.6- (0.45 × Zn),
Cu 0.03-0.25,
Zr 0.04 to 0.15,
Ti <0.10,
Fe <0.08,
Si <0.07,
Each <0.05, total <0.15 remaining inevitable elements and impurities, and Ru balance aluminum or Rana, wrought product according to claim 1. The forged product is a weldable aerospace sheet or plate product in a T6 or T7 state, the product in weight percent;
Zn 9.0 ~11.0,
Mg 2.0-4.5, where the Mg content depends on the Zn content according to Mg ≧ 10− (0.79 × Zn),
Cu 0.03-0.25,
Zr 0.04 to 0.15,
Ti <0.10,
Fe <0.08,
Si <0.07,
Each <0.05, total <0.15 remaining inevitable elements and impurities, and Ru balance aluminum or Rana, wrought product according to claim 1. The forged product is a weldable aerospace sheet or plate product in a T6 or T7 state, the product in weight percent;
Zn 9.0 ~10.0,
Mg 2.0-4.5, where the Mg content depends on the Zn content according to Mg ≧ 10− (0.79 × Zn),
Cu 0.03-0.25,
Zr 0.04 to 0.15,
Ti <0.10,
Fe <0.08,
Si <0.07,
Each <0.05, total <0.15 remaining inevitable elements and impurities, and Ru balance aluminum or Rana, wrought product according to claim 1. The forged product is a weldable aerospace sheet or plate product in a T6 or T7 state, the product in weight percent;
Zn 9.0 ~10.0,
Mg 2.5-4.5, where the Mg content depends on the Zn content according to Mg ≧ 10− (0.79 × Zn),
Cu 0.03-0.25,
Zr 0.04 to 0.15,
Ti <0.10,
Fe <0.08,
Si <0.07,
Each <0.05, total <0.15 remaining inevitable elements and impurities, and Ru balance aluminum or Rana, wrought product according to claim 1. The forged product is a weldable extrudate in a T6 type or T7 type state, the product is in% by weight,
Zn 9.0 ~11.0,
Mg 1.0-5.0, where the Mg content depends on the Zn content according to Mg ≧ 6.6- (0.45 × Zn),
Cu 0.03-0.25,
Zr 0.04 to 0.15,
Ti <0.10,
Fe <0.14,
Si <0.12,
Each <0.05, total <0.15 remaining inevitable elements and impurities, and Ru balance aluminum or Rana, wrought product according to claim 1. The forged product is a weldable aerospace sheet or plate product in a T6 or T7 state, the product in weight percent;
Zn 9.0 ~10.0,
Mg 2.5-4.5, where the Mg content depends on the Zn content according to Mg ≧ 10− (0.79 × Zn),
Cu 0.03-0.25,
Cr 0.04-0.20,
Zr 0.15 or less,
Ti <0.10,
Fe <0.08,
Si <0.07,
Each <0.05, total <0.15 remaining inevitable elements and impurities, and Ru balance aluminum or Rana, wrought product according to claim 1. The forged product is a weldable tool plate product in a T6 type or T7 type state, and the plate product is in% by mass,
Zn 9.0 to 14.0,
Mg 1.0-5.0, where the Mg content depends on the Zn content according to Mg ≧ 6.6- (0.45 × Zn),
Cu 0.03-0.25,
Zr 0.04 to 0.15,
Ti <0.10,
Fe <0.30,
Si <0.25,
Each <0.05, total <0.15 remaining inevitable elements and impurities, and Ru balance aluminum or Rana, wrought product according to claim 1. The forged product is a weldable tool plate product in a T6 type or T7 type state, and the plate product is in% by mass,
Zn 9.0 to 14.0,
Mg 2.0-4.0, where the Mg content depends on the Zn content according to Mg ≧ 10− (0.79 × Zn),
Cu 0.03-0.25,
Zr 0.04 to 0.15,
Ti <0.10,
Fe <0.30,
Si <0.25,
Each <0.05, total <0.15 remaining inevitable elements and impurities, and Ru balance aluminum or Rana, wrought product according to claim 1. The forged product is a weldable tool plate product in a T6 type or T7 type state, and the plate product is in% by mass,
Zn 9.0 to 12.0,
Mg 2.0-4.0, where the Mg content depends on the Zn content according to Mg ≧ 10− (0.79 × Zn),
Cu 0.03-0.25,
Zr 0.04 to 0.15,
Ti <0.10,
Fe <0.30,
Si <0.25,
Each <0.05, total <0.15 remaining inevitable elements and impurities, and Ru balance aluminum or Rana, wrought product according to claim 1. The forged product is a weldable tool plate product in a T6 type or T7 type state, and the plate product is in% by mass,
Zn 9.5 to 12.0,
Mg 2.5-4.5, where the Mg content depends on the Zn content according to Mg ≧ 10− (0.79 × Zn),
Cu 0.03-0.25,
Zr 0.04 to 0.15,
Ti <0.10,
Fe <0.30,
Si <0.25,
Each <0.05, total <0.15 remaining inevitable elements and impurities, and Ru balance aluminum or Rana, wrought product according to claim 1. The forged product is a weldable tool plate product in a T6 type or T7 type state, and the plate product is in% by mass,
Zn 9.0 ~11.0,
Mg 2.5-4.5, where the Mg content depends on the Zn content according to Mg ≧ 10− (0.79 × Zn),
Cu 0.03-0.25,
Zr 0.04 to 0.15,
Ti <0.10,
Fe <0.30,
Si <0.25,
Each <0.05, total <0.15 remaining inevitable elements and impurities, and Ru balance aluminum or Rana, forged product of claim 1. The forged product is a weldable tool plate product in a T6 type or T7 type state, and the plate product is in% by mass,
Zn 9.5 to 12.0,
Mg 2.5-3.5,
Cu 0.03-0.25,
Zr 0.04 to 0.15,
Ti <0.10,
Fe <0.30,
Si <0.25,
Each <0.05, the remainder of inevitable elements and impurities total <0.15, and Ri balance aluminum or Rana has a hardness of greater than 190HB, forged product according to claim 1. A method for producing a forged aluminum AA7000 series alloy product according to any one of claims 1 to 30 ,
a) casting an ingot having the composition of claim 1;
b) homogenizing and / or preheating the ingot after casting;
c) a step of hot working the ingot into a pre-processed product by one or more methods selected from the group consisting of rolling, extrusion and forging;
d) reheating said pre-processed product and either if desired;
e) hot-working and / or cold-working the pre-processed product into a desired workpiece shape;
f) solution treating (SHT) the formed workpiece at a temperature and for a time sufficient to bring substantially all of the soluble constituents in the alloy into solid solution;
g) a step of quenching the solution-treated processed product, preferably by either spray quenching or immersion quenching in water or another quenching medium;
h) optionally stretching or compressing the quenched or otherwise cold worked workpiece to relieve stress, eg flattening the sheet product, and i) quenching and optionally stretching Or a step of artificially aging the compressed workpiece to achieve the desired tempering, wherein the homogenization treatment comprises a first homogenization stage and optionally a second homogenization stage, Or the duration and temperature during the first homogenization stage for the slab is defined as the cold spot in the ingot or slab required for the cold spot in the ingot or slab to dissolve the m-phase precipitates Selected to be above the melting temperature and melting time. 32. The method of claim 31 , wherein during step i), the product is artificially aged to T6 or T7 tempering.