High strength, high toughness, weldable, ballistic quality, castable aluminum alloy, heat treatment for same and articles produced from same

Abstract

An aluminum alloy cast product is composed of: TABLE-US-00001 Cu 5.00-6.75 weight %, Mg 0.05-0.50 weight %, Mn 0.05-0.65 weight %, Ti 0.05-0.40 weight %, Ag 0.00-0.40 weight %, Cr 0.00-0.20 weight %, V 0.00-0.40 weight %, Zr 0.00-0.30 weight %, Fe <0.15 weight %, Si <0.15 weight %, Ni <0.05 weight %, Zn <0.05 weight %, impurities <0.05 each weight %, <0.25 total weight %, Al balance Such an aluminum alloy cast product is heat treated to eliminate the interdendritic network of second phase particles. The heat treatment of such an aluminum alloy casting alloy includes solution heat treatment before hot isostatic pressing.

Description

FIELD OF THE INVENTION

[0001] This invention relates to 1) an aluminum alloy for casting operations, such as sand, investment or permanent mold casting operations, 2) a heat treatment process for aluminum alloys and 3) the application of the newly invented aluminum alloy casting alloy for cast products for racing, aerospace and military (land, sea and air) applications. TABLE-US-00002 TERMINOLOGY T4: solution heat treated and then naturally aged to a substantially stable condition; applies to products that are not cold worked after solution heat treatment, or in which the effect of cold work in flattening or straightening may not be recognized in mechanical property limits T6: solution heat treated and then artificially aged; applies to products that are not cold worked after solution heat treatment, or in which the effect of cold work in flattening or straightening may not be recognized in mechanical property limits T61: solution heat treated and then artificially aged to develop maximum strength with adequate ductility T7: solution heat treated and overaged/stabilized; applies to cast products that are artificially aged after solution heat treatment to provide dimensional and strength stability T87: solution heat treated, cold worked, and then artificially aged; applies to products that are cold worked to improve strength, or in which the effect of cold work in flattening or straightening is recognized in mechanical property limits ST: solution heat treatment; solution heat treatment is achieved by heating cast or wrought products to a suitable temperature, holding at that temperature long enough to allow constituents to enter solid solution and cooling rapidly enough to hold the constituent in solution HIP: hot isostatic pressing; simultaneous application of heat and pressure UTS: ultimate tensile strength YS: yield strength wt %: weight percent rem: remainder

BACKGROUND OF THE INVENTION

[0002] Only a few aluminum alloy casting alloys have attractive properties for racing, aerospace and military applications. These aluminum alloy casting alloys are commonly designated 354, C355, A356, A357, A201 and A206. However, none of these aluminum alloy casting alloys have the desirable combination of high strength, high ductility, high toughness, good resistance to stress corrosion cracking, good weldability and good castability (i.e. good resistance to hot tearing and good fluidity). Hot tearing is a catastrophic event that occurs during the casting process and renders the cast product unusable. Hot tearing occurs when the metal contraction due to solidification produces tensile stresses higher than the strength of the casting. "Spongy" areas, which have high levels of porosity, due to poor feeding will have low strength and hot spots caused by the combination of thick and thin sections will have high tensile contraction stresses that promote hot tearing.

[0003] Aluminum alloy casting alloys 354, C355, A356 and A357 have good castability but do not have good mechanical properties. Aluminum alloy casting alloys A201 and A206 have good mechanical properties but do not have good castability, good resistance to stress corrosion cracking or good weldability. Both A201 and A206 alloy have poor fluidity and poor resistance to hot tearing during casting.

[0004] The chemical compositions and mechanical properties of aluminum alloy casting alloys are found in ASTM B26/B26M-99, "Standard Specification for Aluminum-Alloy Sand Castings", Table 1, and ASTM B686-99, "Standard Specification for Aluminum Alloys Castings, High-Strength", Table 2 and Table 3. A comparison of the castability/fluidity, corrosion resistance and weldability of aluminum alloy casting alloys is shown in Table 4. TABLE-US-00003 TABLE 1 Chemical compositions of aluminum alloy casting alloys Composition (weight %)* Element A201 A206 354 C355 A356 A357 Cu 4.0-5.0 4.2-5.0 1.6-2.0 1.0-1.5 <0.20 <0.20 Mg 0.15-0.55 0.15-0.35 0.40-0.60 0.40-0.60 0.25-0.45 0.40-0.70 Mn 0.20-0.40 0.20-0.50 0.20 0.20 0.20 0.20 Cr -- -- -- -- -- -- Ti 0.15-0.35 0.15-0.30 0.20 0.20 0.20 0.20 V -- -- -- -- -- -- Zr -- -- -- -- -- -- Fe 0.10 0.10 0.20 0.20 0.20 0.20 Si 0.05 0.05 8.6-9.4 4.5-5.5 6.5-7.5 6.5-7.5 Ni -- 0.05 -- -- -- -- Zn -- 0.10 0.10 0.10 0.10 0.10 Ag 0.40-1.00 -- -- -- -- -- Be -- -- -- -- -- 0.04-0.07 impurities 0.03 each 0.05 each 0.05 each 0.05 each 0.05 each 0.05 each 0.10 total 0.15 total 0.15 total 0.15 total 0.15 total 0.15 total Al balance balance balance balance balance balance *a single value denotes the maximum amount permitted

[0005] TABLE-US-00004 TABLE 2 Mechanical properties of aluminum alloy casting alloys Mechanical Properties of Specimens Cut from Designated Areas of a Casting UTS (min), YS (min), Elongation Alloy Class No. ksi (MPa) ksi (MPa) (min), % A201 1 60.0 (414) 50.0 (345) 3 2 60.0 (414) 50.0 (345) 5 A206 not available not available not available not available not available not available 354 1 47.0 (324) 36.0 (248) 3 2 50.0 (345) 42.0 (290) 2 C355 1 41.0 (283) 31.0 (214) 3 2 44.0 (303) 33.0 (228) 3 A356 1 38.0 (262) 28.0 (193) 5 2 40.0 (276) 30.0 (207) 3 3 45.0 (310) 34.0 (234) 3 A357 1 45.0 (310) 35.0 (241) 3 2 50.0 (345) 40.0 (276) 5

[0006] TABLE-US-00005 TABLE 3 Mechanical properties of aluminum alloy casting alloys Mechanical Properties of Specimens Cut from Any Area of the Casting UTS (min), YS (min), Elongation Alloy Class No. ksi (MPa) ksi (MPa) (min), % A201 10 60.0 (414) 50.0 (345) 3 11 56.0 (386) 48.0 (331) 1.5 A206 not available not available not available not available not available not available 354 10 47.0 (324) 36.0 (248) 3 11 43.0 (297) 33.0 (228) 2 C355 10 41.0 (283) 31.0 (214) 3 11 37.0 (255) 30.0 (207) 1 12 35.0 (241) 28.0 (193) 1 A356 10 38.0 (262) 28.0 (193) 5 11 33.0 (228) 27.0 (186) 3 12 32.0 (221) 22.0 (152) 2 A357 10 38.0 (262) 28.0 (193) 5 11 41.0 (283) 31.0 (214) 3

[0007] TABLE-US-00006 TABLE 4 Comparison of the castability/fluidity, corrosion resistance and weldability of aluminum alloy casting alloys* Corrosion Alloy Castability/Fluidity Resistance Weldability A201 fair fair poor A206 average fair poor A357 excellent good excellent *www.sfsa.org/tutorials

[0008] The ASTM does not list A206 alloy as an aluminum alloy sand casting or high-strength aluminum alloy.

[0009] There are numerous aluminum alloy wrought alloys that have attractive properties for aerospace and military applications but products from these aluminum alloys must be machined from plate or billet, which is extremely time consuming and costly, or must be forged into useful shapes. Some of these aluminum alloy wrought alloys are 2024, 5083, 6061, 7075, 2219 and 2519.

[0010] The chemical compositions and mechanical properties of aluminum alloy wrought alloys are found in ASTM B209/B209M-95, "Standard Specification for Aluminum and Aluminum-Alloy Sheet and Plate" and are summarized in Table 5 and Table 6. TABLE-US-00007 TABLE 5 Chemical compositions of aluminum alloy wrought alloys Composition (weight %)* Element 2024 5083 6061 7075 2219 2519** Cu 3.8-4.9 0.10 0.15-0.40 1.2-2.0 5.8-6.8 5.3-6.4 Mg 1.2-1.8 4.0-4.9 0.80-1.2 2.1-2.9 0.02 0.05-0.40 Mn 0.30-0.90 0.40-1.0 0.15 0.30 0.20-0.40 0.10-0.50 Cr 0.10 0.05-0.25 0.04-0.35 0.18-0.28 -- -- Ti 0.15 0.15 0.15 0.20 0.02-0.10 0.05-0.10 V -- -- -- -- 0.05-0.15 0.05-0.15 Zr -- -- -- -- 0.10-0.25 0.10-0.25 Fe 0.50 0.40 0.70 0.50 0.30 0.30 Si 0.50 0.40 0.40-0.80 0.40 0.20 0.25 Ni -- -- -- -- -- -- Zn 0.25 0.25 0.25 5.1-6.1 0.10 0.10 Ag -- -- -- -- -- -- Be -- -- -- -- -- -- impurities 0.05 each 0.05 each 0.05 each 0.05 each 0.05 each 0.05 each 0.10 total 0.15 total 0.15 total 0.15 total 0.15 total 0.15 total Al balance balance balance balance balance balance *a single value denotes the maximum amount permitted **from MIL-DTL-46192C(MR)

[0011] TABLE-US-00008 TABLE 6 Mechanical properties of aluminum alloy wrought alloys Approximate Mechanical Property Limits* UTS (min), YS (min), Elongation Alloy Temper ksi (MPa) ksi (MPa) (min), % 2024 T4 62.0 (427) 40.0 (276) 15 T62 63.0 (434) 50.0 (345) 5 T72 60.0 (414) 46.0 (317) 5 5083 as-cast 40.0 (276) 18.0 (124) 16 6061 T4 30.0 (207) 16.0 (110) 16 T62 42.0 (290) 35.0 (241) 10 7075 T6 78.0 (538) 68.0 (469) 7 T7651 71.0 (490) 60.0 (414) 5 2219 T31 46.0 (317) 28.0 (193) 10 T62 54.0 (372) 36.0 (248) 8 2519 T871 68.0 (469) 58.0 (400) 7*** T871 66.0 (455) 59.0 (407) 10**** *the properties of wrought alloys are a function of thickness **from MIL-DTL-46192C(MR) ***long transverse direction ****longitudinal direction

[0012] The ASTM does not list 2519 alloy as an aluminum alloy wrought alloy. The chemical composition and mechanical property data for 2519 alloy was taken from MIL-DTL-46192C(MR).

[0013] Aluminum alloy wrought alloy 2519 is currently the premier aluminum alloy wrought alloy because of its excellent tensile strength and ballistic qualities. However, aluminum alloy wrought alloy 2519 requires "stretching" to achieve these properties (see e.g. U.S. Pat. No. 4,610,733, entitled "High Strength Weldable Aluminum Base Alloy Product and Method of Making Same" and issued Sep. 9, 1986 to Sanders, Jr., et al.). Because "stretching" is a cold working process, the benefit of stretching is lost if the product is welded or heat treated after "stretching". Further, products that are cast to shape cannot be "stretched".

[0014] U.S. Pat. No. 2,706,680 (entitled "Aluminum Base Alloy" and issued Apr. 19, 1955 to Criner) describes aluminum base alloys that are adapted for service at elevated temperatures, particularly such as required in certain parts of jet engines. This patent discloses a magnesium-free aluminum base alloy containing copper as the chief added component and small amounts of manganese, vanadium and zirconium which displays a combination of strength and resistance to fatigue and creep at high temperatures.

[0015] More specifically the aluminum alloy includes from 5 to 13% copper, 0.15 to 1.7% manganese, 0.05 to 0.20% vanadium, 0.05 to 0.30% zirconium, with an iron impurity not exceeding 0.75% and a silicon impurity not exceeded 0.40%. The disclosed alloy contains no more than about 0.02% magnesium, hence it is referred to as being "magnesium-free". To obtain a finer grain size or enhance minor characteristics of the alloy it is disclosed to be desirable to add 0.01 to 0.25% of one or more of the following elements: cobalt, nickel, molybdenum, tungsten, chromium, titanium, boron, tantalum and niobium. The thermal treatment disclosed to enhance the alloy properties consists of heating to a temperature between 960 and 1000.degree. F. for a period of 2 to 24 hours followed by quenching, preferably in water at 70 to 160.degree. F. The quenched alloys are then reheated to 350 to 450.degree. F. for a period of 1 to 50 hours. Mechanical properties are disclosed for elevated temperatures (400 and 600.degree. F.).

[0016] U.S. Pat. No. 2,784,126 (entitled "Aluminum Base Alloy" and issued Mar. 5, 1957 to Criner) is similar to U.S. Pat. No. 2,706,680 (discussed above) and discloses an aluminum base alloy that is adapted for service at elevated temperatures. In this patent, the disclosed chemistry of the alloy consists of from 5 to 13% copper, 0.15 to 1.7% manganese, 0.05 to 0.20% vanadium, 0.05 to 0.30% zirconium and the addition of 0.05 to 0.70% magnesium. In this patent, the disclosed addition of magnesium is claimed to improve the strength and resistance to creep and fatigue at high temperatures. In this patent, samples were cast in the form of ingots and forged to 1' square bars. The bars were given a solution heat treatment of 2 hours at 990- 1000.degree. F., quenched in cold water and precipitation hardened by heating them for 12 hours at 375.degree. F. The disclosed room temperature properties of an alloy of composition 5.98 wt % Cu, 0.11 wt % Fe, 0.07 wt % Si, 0.21 wt % Mn, 0.10 wt % V and 0.23 wt % Zr are an average ultimate tensile strength of 61,600 psi, an average 0.2% offset yield strength of 43,000 psi and an average elongation of 17%. The disclosed room temperature properties of an alloy of composition 6.09 wt % Cu, 0.15 wt % Fe, 0.11 wt % Si, 0.32 wt % Mn, 0.18 wt % V, 0.20 wt % Zr and 0.25 wt % Mg are an average ultimate tensile strength of 71,100 psi, an average 0.2% offset yield strength of 55,700 psi and an average elongation of 13%. In this patent, it is presumed that forging was required to increase the density of the disclosed aluminum alloy. This patent does not disclose information on the properties of castings made from the disclosed alloy.

[0017] One of the reasons that castings typically have inferior properties compared to wrought products is porosity. However, a low cost process known as hot isostatic pressing (HIP) is available. Use of the HIP process with a proper process cycle can produce significant improvements in mechanical properties of castings with respect to porosity. The industry standard practice is to (1) produce a casting, (2) HIP the casting to eliminate detrimental porosity and then (3) heat treat the casting to develop the appropriate mechanical properties.

[0018] An aluminum alloy casting alloy and heat treatment process that produces a cast product with properties equivalent to the aluminum alloy wrought alloys is desired to reduce material usage, energy usage and machining time and expense.

BRIEF SUMMARY OF THE INVENTION

[0019] In accordance with principles of the present invention, a casting is made from an aluminum alloy containing, in weight percent: TABLE-US-00009 Cu 5.00-6.75; Mg 0.05-0.50; Mn 0.05-0.65; Ti 0.05-0.40; Ag 0.00-0.40; Cr 0.00-0.20; V 0.00-0.40; Zr 0.00-0.30; Fe <0.15; Si <0.15; Ni <0.05; Zn <0.05; impurities <0.05 each; <0.25 total; and Al balance.

[0020] The aluminum alloy casting is solution heat treated, then hot isostatically pressed, then solution heat treated again. This process produces a cast product having a multitude of second phase particles, and in particular a cast product in which an interdendritic network of second phase particles is eliminated.

[0021] More specifically, the aluminum alloy casting is solution heat treated at 950-960.degree. F. (510-516.degree. C.) for 2-4 hours followed by 980-1005.degree. F. (527-541.degree. C.) for 16-120 hours followed by quenching in water, hot isostatically pressed (HIP) at 950-975.degree. F. (510-524.degree. C.) and 15,000.+-.500 psi (103.+-.3.4 MPa) for 2 to 3 hours, heat treated at 950-960.degree. F. (510-516.degree. C.) for 2-4 hours followed by 980-1005.degree. F. (527-541.degree. C.) for 16-120 hours followed by quenching in water and aged. The casting may be either naturally aged at room temperature or artificially aged at 310-390.degree. F. (154-199.degree. C.) for 1 to 96 hours.

[0022] The resulting aluminum alloy product in the naturally aged condition T4 has a minimum ultimate tensile strength of 57,100 psi (394 MPa), a minimum 0.2% offset yield strength of 38,500 psi (265 MPa), a minimum elongation of 6.2%, a minimum unnotched impact strength of 88 joules/cm.sup.2 and passes the ASTM G47 test for resistance to stress corrosion cracking at an applied stress of 30,000 psi (207 MPa).

[0023] The resulting aluminum alloy product in the artificially aged condition T6 has a minimum ultimate tensile strength of 66,100 psi (458 MPa), a minimum 0.2% offset yield strength of 47,800 psi (330 MPa) and a minimum elongation of 3.1%.

[0024] The resulting aluminum alloy product in the artificially aged condition T7 has a minimum ultimate tensile strength of 48,600 psi (335 MPa), a minimum 0.2% offset yield strength of 43,900 psi (303 MPa), a minimum elongation of 1.0%, a minimum unnotched impact strength of 28 joules/cm.sup.2 and passes the ASTM G47 test for resistance to stress corrosion cracking at an applied stress of 40,000 psi (276 MPa).

[0025] The resulting aluminum alloy product in the artificially aged condition T61 has an average ultimate tensile strength of 69,660 psi (480 MPa), an average 0.2% offset yield strength of 59,390 psi (409 MPa), an average elongation of 6.3% and an average unnotched impact strength of 41 joules/cm.sup.2 and has similar ballistic performance to aluminum alloy wrought alloy 2519 in the T87 condition.

[0026] The aluminum alloy casting alloy of the present invention is desirable because it is weldable and retains the desired properties when heat treated after welding.

BRIEF DESCRIPTION OF THE DRAWING

[0027] In the drawing:

[0028] FIG. 1 is a picture of a seat frame cast with a prior art aluminum alloy;

[0029] FIG. 2 is a picture of a seat frame cast with an aluminum alloy according to principles of the present invention;

[0030] FIG. 3 is a picture of a single plate of a known aluminum alloy wrought alloy and a single plate of the aluminum cast alloy according to the present invention after ballistic testing; and

[0031] FIG. 4 is a picture of a double plate of a known aluminum alloy wrought alloy and a double plate of the aluminum cast alloy according to the present invention after ballistic testing.

DETAILED DESCRIPTION OF THE INVENTION

[0032] Aluminum alloy casting alloys A201 and A206 were purchased as ingots from a supplier. The aluminum alloy casting alloy in the illustrated embodiment was produced using A206 ingot with addition of aluminum-copper, aluminum-manganese, aluminum-chromium, aluminum-vanadium, aluminum-zirconium master alloys and pure magnesium. Commercially available aluminum-titanium-boron and aluminum-titanium-carbon grain refiners were used. The chemical compositions of a plurality of aluminum alloy casting alloys produced are shown in Table 7. In Table 7, the columns represent a weight percentage of the indicated element and each row represents one mixture of the constituent elements, termed a heat and designated by a letter A through W. TABLE-US-00010 TABLE 7 Chemical compositions of aluminum alloy casting alloys Amount in weight percent Heat ID Cu Cr Mg Mn V Zr Ti Fe Si other Al A 5.60 <0.01 0.26 0.29 0.14 0.23 0.37 0.03 0.08 rem B 6.08 0.18 0.23 0.29 0.13 0.22 0.20 0.03 0.11 rem C 4.50 0.01 0.26 0.40 0.12 0.15 0.19 0.04 0.04 rem D 5.20 0.01 0.24 0.40 0.11 0.14 0.18 0.04 0.04 rem E 5.84 0.11 0.25 0.34 0.13 0.20 0.19 0.04 0.10 rem F 5.88 <0.01 0.24 0.31 0.06 0.10 0.20 0.04 0.04 rem G 5.78 0.28 0.23 0.37 0.20 0.12 0.17 0.04 0.05 rem H 6.15 0.48 0.22 0.33 0.23 0.18 0.18 0.05 0.10 rem I 6.69 <0.01 0.24 0.29 0.11 0.15 0.14 0.05 0.10 rem J 5.61 <0.01 0.23 0.33 0.01 0.02 0.26 0.03 0.04 rem K 5.76 <0.01 0.53 0.33 0.04 0.02 0.23 0.04 0.04 rem L 5.81 <0.01 0.21 0.37 0.24 0.11 0.16 0.04 0.05 rem M 6.10 <0.01 0.24 0.39 0.09 0.12 0.20 0.04 0.05 rem N 6.22 <0.01 0.77 0.25 0.07 0.10 0.04 0.12 0.05 rem O 5.97 <0.01 0.24 0.40 0.08 0.09 0.18 0.05 0.05 High rem B&C P 5.35 0.01 0.25 0.29 0.10 0.13 0.15 0.05 0.08 0.21 Ag rem Q 5.94 <0.01 0.16 0.24 0.08 0.10 0.07 0.13 0.11 rem R 6.72 0.10 0.42 0.64 0.11 0.13 0.15 0.08 0.13 rem S 5.61 0.01 0.23 0.30 0.24 <0.01 0.11 0.06 0.05 rem T 5.75 0.01 0.22 0.31 0.03 0.13 0.15 0.05 0.05 rem U 6.12 0.01 0.40 0.41 0.12 0.24 0.14 0.05 0.05 rem V 5.37 <0.01 0.27 0.59 0.15 0.14 0.17 <0.01 0.05 rem W 5.09 <0.01 0.48 0.39 0.14 0.14 0.20 <0.01 0.05 rem

[0033] Castability. The castability of the aluminum alloy casting alloys of the illustrated embodiment is determined by qualitatively comparing the fluidity and hot tearing tendency of A201 and A206 alloys to that of the illustrated embodiment. A complex seat frame casting that has thick and thin sections is poured from each alloy at various temperatures in chemically bonded sand molds that contain aluminum chills. Pictures of such seat frame castings are shown in FIG. 1 and FIG. 2. Aluminum alloy casting alloys A201 and A206 typically have very limited pouring temperature ranges since 1) the alloy must be poured at a temperature sufficiently high to completely fill the mold but 2) the alloy must be poured at as low a temperature as possible to prevent hot tearing.

[0034] For the seat frame casting, good castings could not be produced in aluminum alloy casting alloy A206. Good castings could be produced in aluminum alloy casting alloy A201 when poured in the temperature range 1350-1360.degree. F. Good castings could be produced in the aluminum alloy casting alloy of this embodiment (Heats A, B, D & E) when poured in the temperature range 1330-1380.degree. F., a wider temperature range than with aluminum alloy casting alloy A201. Good seat frame castings could not be poured from Heat C. Thus, an aluminum alloy casting alloy should have a minimum copper content of about 5.20 wt % to produce good fluidity and good resistance to hot tearing. Seat frame castings were not poured from Heats F-W.

[0035] An example of an aluminum alloy casting alloy A206 casting with hot tears is shown in FIG. 1 and an example of a good casting poured in the aluminum alloy casting alloy of the illustrated embodiment is shown in FIG. 2. The larger pouring range of the aluminum alloy casting alloy of the illustrated embodiment is due to improved fluidity (ability to flow and fill a mold) and improved feeding (ability to supply metal during liquid contraction and the liquid-to-solid phase transformation). Good castability allows the production of complex castings at low scrap rates and, therefore, minimum cost.

[0036] Heat Treatment and Mechanical Properties. The aluminum alloy casting alloy of the illustrated embodiment is processed using a pre-HIP solution heat treatment. That is, instead of applying a HIP process to the cast product, that product is first heat treated. The mechanical properties of an aluminum alloy cast product are determined by soundness, chemistry and microstructure. Soundness is a measure of porosity, which is determined by the feeding characteristics of the aluminum alloy cast alloy. Soundness can be improved by hot isostatic pressing (HIP) the cast product. The chemistry of the aluminum alloy cast alloy ultimately determines what microstructural phases can be produced. The size, quantity and distribution of the microstructural phases and porosity determine the mechanical properties. The size, quantity and distribution of the microstructural phases are determined by heat treatment.

[0037] The aluminum alloy casting alloys of the illustrated embodiment produced less porosity than A201 but more porosity than A206 alloy. For the seat frame casting (FIG. 1, FIG. 2), the average porosity for A201 alloy was 3.2%, for A206 alloy was 0.5% and for the aluminum alloy casting alloy of the illustrated embodiment was 1.5%.

[0038] The aluminum alloy casting alloy of the illustrated embodiment produced better mechanical properties compared to A201 alloy. Table 8 compares the mechanical properties of samples cut from seat frame castings produced from aluminum alloy casting alloy A201 and aluminum alloy casting alloy of heat A of the illustrated embodiment. TABLE-US-00011 TABLE 8 Average Mechanical Properties of Specimens Cut from Castings UTS, YS, Elongation, Alloy Heat Treatment ksi (MPa) ksi (MPa) % A201 ST then 340.degree. F. 46.9 (323) 46.1 (318) 1 (171.degree. C.) for 24 hours Heat A ST then 340.degree. F. 64.3 (443) 60.1 (414) 2 (171.degree. C.) for 24 hours

[0039] Hot isostatic pressing (HIP'ing) is a well known, commercial process for reducing the porosity in castings. HIP'ing is typically performed before any other heat treatment. In the illustrated embodiment, however, solution heat treatment performed before HIP'ing produces improved mechanical properties, particularly improved resistance to stress corrosion cracking. However, solution heat treatment before HIP'ing is not a requirement to produce satisfactory properties using the aluminum alloy casting alloy of the illustrated embodiment.

[0040] Sections were cut from castings produced from the aluminum alloy casting alloy of the illustrated embodiment and heat treated in various ways to quantitatively determine the effect of HIP'ing and heat treatment cycle on mechanical properties.

[0041] The heat treatment cycles were: (1) a long pre-HIP solution heat treatment at 950-960.degree. F. (510-516.degree. C.) for 2-4 hours followed by 990-995.degree. F. (532-535.degree. C.) 96 hours followed by quenching in water, followed by HIP'ing at 950-975.degree. F. (510-524.degree. C.), 15,000+/-500 psi (103+/-3.4 MPa) for 2 to 3 hours, followed by a post-HIP solution heat treatment (see below) and age; (2) a short pre-HIP solution heat treatment at 950-960.degree. F. (510-516.degree. C.) for 2-4 hours followed by 990-995.degree. F. for 16-20 hours followed by quenching in water, followed by HIP'ing at 950-975.degree. F. (510-524.degree. C.), 15,000+/-500 psi (103+/-3.4 MPa) for 2 to 3 hours, followed by a post-HIP solution heat treatment (see below) and age; and (3) HIP'ing at 950-975.degree. F. (510-524.degree. C.), 15,000+/-500 psi (103+/-3.4 MPa) for 2 to 3 hours, followed by a post-HIP solution heat treatment (see below) and age (i.e. no pre-HIP solution heat treatment).

[0042] The T4 condition was produced by post-HIP solution heat treatment at 950-960.degree. F. (510-516.degree. C.) for 2-4 hours followed by 990-995.degree. F. (532-535.degree. C.) for 16-20 hours followed by quenching in warm water at 120-180.degree. F. (49-82.degree. C.) and then naturally aging at room temperature for a minimum of seven days before testing. The T6 condition was produced by post-HIP solution heat treatment at 950-960.degree. F. (510-516.degree. C.) for 2-4 hours followed by 990-995.degree. F. (532-535.degree. C.) for 16-20 hours followed by quenching in warm water at 120-180.degree. F. (49-82.degree. C.), naturally aging at room temperature for 8-24 hours and then artificially aging at 325.degree. F. (163.degree. C.) for 24 hours. Material heat treated to the T6 condition exhibited the best combination of strength and ductility: HIP'ing increased the tensile ductility by 60 to 101%. The T61 condition was produced by post-HIP solution heat treatment at 950-960.degree. F. (510-516.degree. C.) for 2-4 hours followed by 990-995.degree. F. (532-535.degree. C.) for 16-20 hours followed by quenching in warm water at 120-180.degree. F. (49-82.degree. C.), naturally aging at room temperature for 8-24 hours and then artificially aging at 325.degree. F. (163.degree. C.) for 36 hours. The T7 condition was produced by post-HIP solution heat treatment at 950-960.degree. F. (510-516.degree. C.) for 2-4 hours followed by 990-995.degree. F. (532-535.degree. C.) for 16-20 hours followed by quenching in warm water at 120-180.degree. F. (49-82.degree. C.), naturally aging at room temperature for 8-24 hours and then artificially aging at 390.degree. F. (199.degree. C.) for 24 hours.

[0043] The mechanical properties of samples cut from seat frame castings produced from the aluminum alloy casting alloy of the illustrated embodiment and heat treated in various ways are listed in Table 9. TABLE-US-00012 TABLE 9 Average Mechanical Properties of Specimens Cut from Castings Impact YS Strength ID Process UTS ksi (MPa) ksi (MPa) Elongation % joules/cm.sup.2 Heat D Long ST-HIP-T4 -- -- -- 141.6 Short ST-HIP-T4 67.8 (467) 42.5 (293) 24.1 HIP-T4 68.4 (472) 41.4 (285) 24.0 137.7 Heat E Long ST-HIP-T4 68.0 (469) 41.6 (287) 20.0 88.1 Heat D Long ST-HIP-T6 70.6 (487) 49.1 (339) 15.2 88.2 Long ST-T6 69.8 (481) 52.7 (363) 7.6 -- Short ST-HIP-T6 71.7 (494) 50.8 (350) 13.7 -- Short ST-T6 66.7 (460) 52.2 (360) 7.5 -- HIP-T6 72.5 (500) 51.1 (352) 14.1 -- T6 68.1 (470) 51.2 (353) 8.3 -- Heat E Long ST-HIP-T6 70.8 (488) 50.8 (350) 12.2 40.0 Heat D Long ST-HIP-T61 72.0 (496) 56.6 (390) 13.7 97.2 Short ST-HIP-T61 69.9 (482) 52.5 (362) 12.7 -- HIP-T61 70.5 (486) 51.7 (356) 10.7 -- Heat E Long ST-HIP-T61 71.4 (492) 56.4 (389) 9.2 59.4 Heat D Long ST-HIP-T7 66.7 (460) 51.1 (352) 8.8 68.8 Short ST-HIP-T7 63.9 (441) 47.6 (328) 9.2 71.6 HIP-T7 -- -- -- 65.4 Heat E Long ST-HIP-T7 65.9 (454) 53.5 (369) 3.9 28.3

[0044] Compared to aluminum alloy casting alloy A206, the aluminum alloy cast alloy of the illustrated embodiment has improved yield (design) strength in all heat treatment conditions. Also, the tensile ductility increased by 167% when subjected to the short solution heat treatment, followed by HIP'ing, followed by the T6 heat treatment. For comparison, sections from seat frame castings of each alloy were heat treated using identical processing conditions (e.g. solution heat treated, HIP'ed or not HIP'ed, then T6) and the results are listed in Table 10. TABLE-US-00013 TABLE 10 Average Mechanical Properties of Specimens Cut from Castings UTS YS Elongation Alloy Process ksi (MPa) ksi (MPa) % A206 Short ST-HIP-T6 62.0 (427) 44.4 (306) 18.4 Long ST-T6 63.6 (439) 49.4 (341) 14.7 T6 60.7 (419) 49.2 (339) 6.9 Heat D Short ST-HIP-T6 71.7 (494) 50.8 (350) 13.7 Long ST-T6 68.8 (474) 51.3 (354) 9.1 T6 69.0 (476) 50.5 (348) 9.0

[0045] To more fully determine the effect of chemistry, sections were cut from Y-block castings produced from different formulations of the aluminum alloy casting alloy of the illustrated embodiment, and heat treated using the same conditions. The heat treatment cycle was a long pre-HIP solution heat treatment at 950-960.degree. F. (510-516.degree. C.) for 2-4 hours followed by 990-995.degree. F. (532-535.degree. C.) for 96-120 hours followed by quenching in water, HIP'ing at 950-975.degree. F. (510-524.degree. C.), 15,000+/-500 psi (103+/-3.4 MPa) for 2 to 3 hours, followed by a post-HIP solution heat treatment and age.

[0046] The T4 condition was produced by post-HIP solution heat treatment at 950-960.degree. F. (510-516.degree. C.) for 2-4 hours followed by 990-995.degree. F. (532-535.degree. C.) for 16-20 hours followed by quenching in warm water at 120-180.degree. F. (49-82.degree. C.) and then naturally aging at room temperature for a minimum of seven days before testing.

[0047] The T6 condition was produced by post-HIP solution heat treatment at 950-960.degree. F. (510-516.degree. C.) for 2-4 hours followed by 990-995.degree. F. (532-535.degree. C.) for 16-20 hours followed by quenching in warm water at 120-180.degree. F. (49-82.degree. C.), naturally aging at room temperature for 8-24 hours and then artificially aging at 325.degree. F. (163.degree. C) for 24 hours.

[0048] The T7 condition was produced by post-HIP solution heat treatment at 950-960.degree. F. (510-516.degree. C.) for 2-4 hours followed by 990-995.degree. F. (532-535.degree. C.) for 16-20 hours followed by quenching in warm water at 120-180.degree. F. (49-82.degree. C.), naturally aging at room temperature for 8-24 hours and then artificially aging at 390.degree. F (199.degree. C) for 24 hours.

[0049] For an aluminum alloy casting alloy to have good mechanical properties, copper content should be limited to about 6.25 wt %, chromium content should be limited to about 0.20 wt % and magnesium content should be limited to about 0.50 wt %. The addition of silver was shown to significantly increase yield strength. The resulting data shows that ductility (e.g. tensile elongation) decreases as copper content increases, as chromium content increases and as magnesium content increases. Increasing manganese content or vanadium content was shown to decrease yield strength and increase ductility. Increasing zirconium content was shown to have an inconsistent effect on mechanical properties. The mechanical properties of samples cut from castings produced from the aluminum alloy casting alloy of the illustrated embodiment and heat treated in similar ways are displayed in Table 11. TABLE-US-00014 TABLE 11 Average Tensile Properties of Specimens Cut from Castings UTS YS Elongation, Alloy Condition ksi (MPa) ksi (MPa) % Heat A HIP-Long ST-T4 66.8 (461) 41.9 (289) 18.3 HIP-Long ST-T6 70.8 (488) 56.1 (387) 7.6 HIP-Short ST-T6 71.0 (490) 56.5 (390) 7.5 Heat B HIP-Short ST-T4 66.6 (459) 42.2 (291) 18.2 HIP-Long ST-T6 67.8 (467) 55.1 (380) 6.7 Long ST-HIP-T6 69.7 (481) 54.5 (376) 7.9 Heat C Long ST-HIP-T4 63.0 (434) 38.0 (262) 23.0 (insufficient Long ST-HIP-T6 66.4 (458) 47.4 (326) 17.4 Cu) Long ST-HIP-T7 -- -- -- Heat D Long ST-HIP-T4 -- -- -- Long ST-HIP-T6 70.6 (487) 49.1 (339) 15.3 Long ST-HIP-T7 66.7 (460) 51.1 (352) 8.8 Heat E Long ST-HIP-T4 68.0 (469) 41.6 (287) 20.0 Long ST-HIP-T6 70.8 (488) 50.8 (350) 12.2 Long ST-HIP-T7 65.9 (454) 53.5 (369) 3.9 Heat F Long ST-HIP-T4 64.4 (444) 40.5 (279) 21.6 Long ST-HIP-T6 70.7 (487) 51.9 (358) 14.0 Long ST-HIP-T7 64.5 (454) 51.2 (353) 4.5 Heat G Long ST-HIP-T4 52.0 (359) 40.9 (282) 6.0 (excessive Cr) Long ST-HIP-T6 61.9 (427) 47.1 (325) 4.7 Long ST-HIP-T7 51.2 (353) 46.7 (322) 2.2 Heat H Long ST-HIP-T4 43.6 (301) 40.3 (278) 2.1 (excessive Cr) Long ST-HIP-T6 49.3 (340) 45.1 (311) 1.4 Long ST-HIP-T7 45.4 (313) 43.9 (303) 0.8 Heat I Long ST-HIP-T4 57.1 (394) 40.7 (281) 6.2 (not optimum Long ST-HIP-T6 66.1 (456) 58.1 (401) 4.0 Cu) Long ST-HIP-T7 55.5 (383) 54.9 (379) 1.0 Heat J Long ST-HIP-T4 60.8 (419) 40.8 (287) 12.4 Long ST-HIP-T6 67.3 (464) 52.6 (362) 6.5 Long ST-HIP-T7 -- -- -- Heat K Long ST-HIP-T4 64.4 (444) 43.5 (300) 12.6 (excessive Mg) Long ST-HIP-T6 61.5 (424) 53.1 (366) 3.1 Long ST-HIP-T7 48.6 (335) 47.5 (328) 1.0 Heat L Long ST-HIP-T4 61.1 (422) 40.3 (278) 12.7 Long ST-HIP-T6 66.6 (459) 51.1 (352) 7.8 Long ST-HIP-T7 63.2 (436) 49.4 (341) 4.8 Heat M Long ST-HIP-T4 61.4 (424) 41.1 (283) 10.9 Long ST-HIP-T6 -- -- -- Long ST-HIP-T7 62.4 (430) 50.2 (346) 4.1 Heat N Long ST-HIP-T4 43.6 (300) 36.2 (249) 2.7 (excessive Mg) Long ST-HIP-T6 29.4 (202) na 0.2 Long ST-HIP-T7 14.2 (98) na 0.3 Heat O Long ST-HIP-T4 64.3 (443) 40.6 (280) 19.3 (not optimum Long ST-HIP-T6 67.4 (464) 51.9 (358) 6.4 grain refiner) Long ST-HIP-T7 57.6 (397) 49.0 (338) 1.4 Heat P Long ST-HIP-T4 65.0 (448) 40.2 (277) 17.1 Long ST-HIP-T6 75.8 (523) 64.9 (448) 8.0 Long ST-HIP-T7 70.2 (484) 57.5 (397) 5.5 Heat Q Long ST-HIP-T4 61.0 (420) 38.5 (265) 18.1 Long ST-HIP-T6 70.5 (486) 56.6 (390) 8.1 Long ST-HIP-T7 66.3 (457) 54.2 (374) 4.1 Heat R Long ST-HIP-T4 62.8 (433) 43.3 (299) 7.9 (not optimum Long ST-HIP-T6 69.4 (478) 54.3 (375) 7.2 Cu) Long ST-HIP-T7 61.0 (421) 52.3 (361) 2.7 Heat S Long ST-HIP-T4 61.2 (422) 39.3 (271) 15.2 Long ST-HIP-T6 68.0 (469) 51.3 (354) 11.2 Long ST-HIP-T7 63.4 (437) 48.6 (335) 5.8 Heat T Long ST-HIP-T4 64.2 (443) 40.3 (278) 18.2 Long ST-HIP-T6 66.7 (460) 53.1 (366) 4.6 Long ST-HIP-T7 62.7 (432) 51.6 (356) 3.4 Heat U Long ST-HIP-T4 68.3 (471) 43.8 (302) 15.9 Long ST-HIP-T6 67.6 (466) 53.1 (366) 4.9 Long ST-HIP-T7 62.0 (427) 48.3 (333) 4.0 Heat V Long ST-HIP-T4 62.5 (431) 38.5 (265) 16.0 Long ST-HIP-T6 68.0 (469) 47.8 (330) 9.7 Long ST-HIP-T7 59.7 (412) 43.9 (303) 5.5 Heat W Long ST-HIP-T4 64.3 (443) 42.4 (292) 11.7 Long ST-HIP-T6 69.0 (476) 50.8 (350) 10.4 Long ST-HIP-T7 60.2 (415) 44.9 (310) 6.2

[0050] The aluminum alloy casting alloy of the illustrated embodiment has good stress corrosion cracking properties that are enhanced when solution heat treated before HIP'ing. Aluminum alloy cast alloys and wrought alloys that contain copper typically have unacceptable stress corrosion cracking properties in the T6 condition but often have acceptable stress corrosion cracking properties in the T4 or T7 conditions. Samples from two heats (Heat B, Heat D) were given a variety of heat treatments and then subjected to the standard stress corrosion cracking test, ASTM G47-98 (2004). The heat subjected to long solution heat treatment prior to HIP'ing (Heat D) exhibited significantly improved resistance to stress corrosion cracking (almost produced "acceptable" results) in the T6 condition. The stress corrosion cracking performance, as determined by ASTM G47-98 (2004), for the two different heat treatment processes and aluminum alloy casting alloys of the illustrated embodiment are displayed in Table 12. TABLE-US-00015 TABLE 12 Stress Corrosion Cracking Performance, ASTM G47 Time to Applied Stress, Failure, Acceptable/ Heat/Condition ksi (MPa) Days Unacceptable Heat B/HIP-T4 30 (207) >20 acceptable Heat B/HIP-T6 40 (276) 3 unacceptable Heat B/HIP-T7 40 (276) >20 acceptable Heat D/Long ST-HIP-T4 30 (207) >20 acceptable Heat D/Long ST-HIP-T6 40 (276) 20 unacceptable* Heat D/Long ST-HIP-T7 40 (276) >20 acceptable *failed on the last day of the test

[0051] The aluminum alloy casting alloy of the illustrated embodiment is weldable. Aluminum alloy casting alloys are not normally welded so little or no published data exists for comparison purposes. However, aluminum alloy wrought alloys are often welded and the aluminum alloy casting alloy of the illustrated embodiment compared favorably to published data for material tested in the heat treated then welded condition. The welder had no prior experience welding the aluminum alloy casting alloy of the illustrated embodiment and very little experience with aluminum alloy 2319 welding wire. The aluminum alloy casting alloy of the illustrated embodiment can be heat treated after welding to develop improved properties. Further, solution treatment after welding but prior to HIP'ing results in significantly improved yield strength. Solution treatment after welding but prior to HIP'ing resulted in an 85% increase in yield strength in the T4 condition and a 27% increase in yield strength in the T6 condition. A comparison of the tensile properties after welding of aluminum alloy wrought alloy 2219, aluminum alloy wrought alloy 2519 (from published data) and the aluminum alloy casting alloy of the illustrated embodiment is displayed in Table 13 and the tensile properties of the aluminum alloy casting alloy of the illustrated embodiment after welding followed by heat treatment is displayed in Table 14. TABLE-US-00016 TABLE 13 Average Tensile Properties after Welding Alloy YS, ksi (MPa) Elongation, % 2219* 26.0 (179) 3.0 2519* 34.7 (239) 5.5 Heat A 29.5 (203) 1.2 *from U.S. Pat. No. 4,610,733

[0052] TABLE-US-00017 TABLE 14 Average Tensile Properties after Welding Followed by Heat Treatment Heat/Condition YS, ksi (MPa) Elongation, % Heat D/Weld-HIP-T4 20.0 (138) 0.9 Heat D/Weld-Long ST-HIP-T4 37.0 (255) 3.6 Heat D/Weld-HIP-T6 41.7 (288) 2.6 Heat D/Weld-Long ST-HIP-T6 53.1 (366) 1.7

[0053] The aluminum alloy casting alloy of the illustrated embodiment in the T61 condition has ballistic properties similar to aluminum alloy wrought alloy 2519 in the T87 condition. Samples of the aluminum alloy casting alloy of the illustrated embodiment in the T61 condition and aluminum alloy wrought alloy 2519 in the T87 condition were machined to the same size and dimensions and shot at with 0.223 caliber standard rounds at a distance of approximately 50 meters (150 feet). Single plates, 0.5'' thick, of the aluminum alloy casting alloy of the illustrated embodiment in the T61 condition and the aluminum alloy wrought alloy 2519 in the T87 condition were completely penetrated, as illustrated in FIG. 3. FIG. 3a is a picture of a single plate of the aluminum alloy casting alloy of the illustrated embodiment after the ballistic testing described above, and FIG. 3b is a picture of a single plate of the aluminum alloy wrought alloy 2519 after the ballistic testing described above.

[0054] Double plates of the aluminum alloy casting alloy of the illustrated embodiment in the T61 condition and the aluminum alloy wrought alloy 2519 in the T87 condition were not penetrated after the same ballistic testing described above, as illustrated in FIG. 4. FIG. 4a is a picture of a double plate of the aluminum alloy casting alloy of the illustrated embodiment after the ballistic testing described above, and FIG. 4b is a picture of a double plate of the aluminum alloy wrought alloy 2519 after the ballistic testing described above.

[0055] Articles Made From the Aluminum Alloy Casting Alloy of the Illustrated Embodiment

[0056] The aluminum alloy casting alloy of the present illustrated embodiment is ideally suited for articles requiring high strength, high toughness, resistance to penetration by ballistic objects, resistance to stress corrosion cracking and light in weight. These articles are commonly used in racing, aerospace and military (land, sea and air) vehicles. Specifically, a seat frame for a military vehicle, (FIG. 1 and FIG. 2), was used as a test casting for developing the aluminum alloy casting alloy of the illustrated embodiment. Light-weight armor, a turret rotor, a turret housing and hatches for a military weapon system, bolts and welding wire are currently being developed and evaluated. The aluminum alloy casting alloy of the illustrated embodiment could be a replacement for aluminum alloy casting alloy A201, which is currently used for the steering deflector on the AAAV amphibious military vehicle. Of course, the applications for the aluminum alloy casting alloy of the illustrated embodiment are not limited to only those articles discussed above.

[0057] Preferred Embodiments

[0058] The composition for an aluminum alloy casting alloy according to principles of the present invention, in weight percent, is as follows: TABLE-US-00018 Cu 5.00-6.75 Mg 0.05-0.50 Mn 0.05-0.65 Ti 0.05-0.40 Ag 0.00-0.40 Cr 0.00-0.20 Ti 0.05-0.40 V 0.00-0.40 Zr 0.00-0.30 Fe <0.15 Si <0.15 Ni <0.05 Zn <0.05 impurities <0.05 each <0.25 total Al balance

wherein the aluminum alloy casting alloy is grain refined using a 0.04-2.00 weight % addition of aluminum-5 weight % titanium-1 weight % boron and a 0.07-2.00 weight % addition of aluminum-3 weight % titanium-0.15 weight % carbon containing grain refiner.

[0059] An optimum composition for the aluminum alloy casting alloy, in weight percent, is as follows: TABLE-US-00019 Cu 5.00-6.25 Mg 0.20-0.50 Mn 0.20-0.40 Ti 0.05-0.40 Ag 0.00-0.40 Cr 0.00-0.20 V 0.05-0.25 Zr 0.05-0.25 Fe <0.10 Si <0.10 Ni <0.05 Zn <0.05 impurities <0.05 each <0.25 total Al balance

wherein the aluminum alloy casting alloy is grain refined using a 0.04-0.08 weight % addition of aluminum-5 weight % titanium-1 weight % boron and a 0.07-0.10 weight % addition of aluminum-3 weight % titanium-0.15 weight % carbon containing grain refiner.

[0060] A heat treatment for an aluminum alloy casting alloy according to principles of the present invention is as follows: [0061] 1. Solution heat treat at 950-960.degree. F. (510-516.degree. C.) for 2-4 hours followed by 980-1005.degree. F. (527-541.degree. C.) for 16-120 hours followed by quenching in water (this step is optional) [0062] 2. Hot isostatic pressing (HIP'ing) at 950-975.degree. F. (510-524.degree. C.), 15,000+/-500 psi (103+/-3.4 MPa) for 2 to 3 hours [0063] 3. Solution heat treat at 950-960.degree. F. (510-516.degree. C.) for 2-4 hours followed by 980-1005.degree. F. (527-541.degree. C.) for 16-120 hours followed by quenching in water [0064] 4. Naturally age at room temperature or artificially age at 310-390.degree. F. (154-199.degree. C.) for 1 to 96 hours

[0065] The optimum heat treatment for the aluminum alloy casting alloy is as follows: [0066] 1. Solution heat treat at 950-960.degree. F. (510-516.degree. C.) for 2-4 hours followed by 990-995.degree. F. (532-535.degree. C.) for 68-120 hours followed by quenching in water [0067] 2. Hot isostatic pressing (HIP'ing) at 950-975.degree. F (510-524.degree. C.), 15,000+/-500 psi (103+/-3.4 MPa) for 2 to 3 hours [0068] 3. Solution heat treat at 990-995.degree. F. (532-535.degree. C.) for 16-24 hours followed by quenching in water [0069] 4. T4: Naturally age at room temperature; [0070] T6: Artificially age at 325.degree. F. (163.degree. C.) for 24 hours; [0071] T61: Artificially age at 325-340.degree. F. (163-171.degree. C.) for 24-36 hours; [0072] T7: Artificially age at 390.degree. F. (199.degree. C.) for 24 hours.

Claims

1. An aluminum alloy cast product consisting essentially of: TABLE-US-00020 Cu 5.00-6.75 weight %, Mg 0.05-0.50 weight %, Mn 0.05-0.65 weight %, Ti 0.05-0.40 weight %, Ag 0.00-0.40 weight %, Cr 0.00-0.20 weight %, V 0.00-0.40 weight %, Zr 0.00-0.30 weight %, Fe <0.15 weight %, Si <0.15 weight %, Ni <0.05 weight %, Zn <0.05 weight %, impurities <0.05 each weight %, <0.25 total weight %, Al balance

wherein an aluminum alloy cast product contains an interdendritic network of second phase particles in the as-cast condition.

2. The cast product of claim 1 wherein the interdendritic network of second phase particles is eliminated by solution heat treatment prior to hot isostatic pressing.

3. The cast product of claim 1 wherein the cast product after heat treatment exhibits relatively high strength, high toughness, high resistance to penetration from ballistic objects, high resistance to stress corrosion cracking and low weight.

4. The cast product of claim 1 wherein the cast product is weldable.

5. A method for producing a cast product of an aluminum alloy, comprising the steps of: melting the following to form a cast alloy of: TABLE-US-00021 Cu 5.00-6.75 weight %, Mg 0.05-0.50 weight %, Mn 0.05-0.65 weight %, Ti 0.05-0.40 weight %, Ag 0.00-0.40 weight %, Cr 0.00-0.20 weight %, V 0.00-0.40 weight %, Zr 0.00-0.30 weight %, Fe <0.15 weight %, Si <0.15 weight %, Ni <0.05 weight %, Zn <0.05 weight %, impurities <0.05 each weight %, <0.25 total weight %, and Al balance;

casting a product from the melted cast alloy; heat treating the cast product to eliminate an interdendritic network of second phase particles; hot isostatically pressing the heat treated cast product to eliminate porosity; and heat treating the hot isostatically pressed cast product to obtain desired mechanical and physical properties.

6. A product made by the process of claim 5.

7. A cast product of an aluminum alloy consisting essentially of, in weight percent: TABLE-US-00022 Cu 5.00-6.75 weight %, Mg 0.05-0.50 weight %, Mn 0.05-0.65 weight %, Ti 0.05-0.40 weight %, Ag 0.00-0.40 weight %, Cr 0.00-0.20 weight %, V 0.00-0.40 weight %, Zr 0.00-0.30 weight %, Fe <0.15 weight %, Si <0.15 weight %, Ni <0.05 weight %, Zn <0.05 weight %, impurities <0.05 each weight %, <0.25 total weight %, Al balance

wherein the aluminum alloy casting alloy is grain refined using aluminum-titanium-boron and/or aluminum-titanium-carbon containing grain refiner; wherein the aluminum alloy casting alloy is cast in a sand, ceramic or metal mold to form the cast product; wherein the aluminum alloy cast product is hot isostatically pressed (HIP'ed) at 950-975.degree. F. (510-524.degree. C.), 15,000+/-500 psi (103+/-3.4 MPa) for 2 to 3 hours, solution treated at 950-960.degree. F. (510-516.degree. C.) for 2-4 hours followed by 980-1005.degree. F. (527-541.degree. C.) for 16-120 hours followed by quenching in water and naturally aged at room temperature or artificially aged at 310-390.degree. F. (154-199.degree. C.) for 1 to 96 hours; whereby the aluminum alloy product in the naturally aged condition T4 has a minimum ultimate tensile strength of 57,100 psi (394 MPa), a minimum 0.2% offset yield strength of 38,500 psi (265 MPa), a minimum elongation of 6.2%, a minimum unnotched impact strength of 88 joules/cm.sup.2 and passes the ASTM G47 test for resistance to stress corrosion cracking at an applied stress of 30,000 psi (207 MPa); whereby the aluminum alloy product in the artificially aged condition T6 has a minimum ultimate tensile strength of 61,500 psi (424 MPa), a minimum 0.2% offset yield strength of 47,800 psi (330 MPa) and a minimum elongation of 3.1%; whereby the aluminum alloy product in the artificially aged condition T7 has a minimum ultimate tensile strength of 48,600 psi (335 MPa), a minimum 0.2% offset yield strength of 43,900 psi (303 MPa), a minimum elongation of 1.0%, a minimum unnotched impact strength of 28 joules/cm.sup.2 and passes the ASTM G47 test for resistance to stress corrosion cracking at an applied stress of 40,000 psi (276 MPa); whereby the aluminum alloy product in the artificially aged condition T61 has an average ultimate tensile strength of 69,660 psi (480 MPa), an average 0.2% offset yield strength of 59,390 psi (409 MPa), an average elongation of 6.3% an average unnotched impact strength of 41 joules/cm.sup.2 and has similar ballistic performance to aluminum alloy wrought alloy 2519 in the T87 condition.

8. An aluminum alloy cast product according to claim 7, wherein, before the aluminum alloy cast product is hot isostatically pressed, it is solution treated at 950-960.degree. F. (510-516.degree. C.) for 2-4 hours followed by 980-1005.degree. F. (527-541.degree. C.) for 16-120 hours followed by quenching in water.

9. An aluminum alloy cast product according to claim 7, wherein the sand cast aluminum alloy product is a seat frame of a military vehicle.

10. An aluminum alloy cast product according to claim 7, wherein the sand cast aluminum alloy product is a turret rotor of a military weapon system.

11. An aluminum alloy cast product according to claim 7, wherein the sand cast aluminum alloy product is a hatch of a military weapon system.

12. An aluminum alloy cast product according to claim 7, wherein the sand cast aluminum alloy product is ballistic armor.

13. An aluminum alloy cast product according to claim 7, wherein the aluminum alloy product is welding wire.

14. An aluminum alloy cast product consisting essentially of: TABLE-US-00023 Cu 5.00-6.25 weight %, Mg 0.20-0.50 weight %, Mn 0.20-0.65 weight %, Ti 0.05-0.40 weight %, Ag 0.00-0.40 weight %, Cr 0.00-0.20 weight %, V 0.05-0.25 weight %, Zr 0.05-0.25 weight %, Fe <0.15 weight %, Si <0.15 weight %, Ni <0.05 weight %, Zn <0.05 weight %, impurities <0.05 each weight %, <0.25 total weight %, Al balance

wherein the aluminum alloy casting alloy is grain refined using aluminum-titanium-boron and/or aluminum-titanium-carbon containing grain refiner; wherein the aluminum alloy casting alloy is cast in a sand mold, wherein the aluminum alloy cast product is hot isostatically pressed (HIP'ed) at 950-975.degree. F. (510-524.degree. C.), 15,000+/-500 psi (103+/-3.4 MPa) for 2 to 3 hours, solution treated at 980-1005.degree. F. (527-541.degree. C.) for 16-120 hours followed by quenching in water and naturally aged at room temperature or artificially aged at 310-390.degree. F. (154-199.degree. C.) for 12 to 96 hours.

15. An aluminum alloy cast product according to claim 14, wherein the sand cast aluminum alloy product is a seat frame of a military vehicle.

16. An aluminum alloy cast product according to claim 14, wherein the sand cast aluminum alloy product is a turret rotor of a military weapon system.

17. An aluminum alloy cast product according to claim 14, wherein the sand cast aluminum alloy product is a hatch of a military weapon system.

18. An aluminum alloy cast product according to claim 14, wherein the sand cast aluminum alloy product is ballistic armor.

19. An aluminum alloy cast product according to claim 14, wherein the aluminum alloy product is welding wire.

20. An aluminum alloy cast product consisting essentially of: TABLE-US-00024 Cu 5.00-6.25 weight %, Mg 0.20-0.50 weight %, Mn 0.20-0.65 weight %, Ti 0.05-0.40 weight %, Ag 0.00-0.40 weight %, Cr 0.00-0.20 weight %, V 0.05-0.25 weight %, Zr 0.05-0.25 weight %, Fe <0.15 weight %, Si <0.15 weight %, Ni <0.05 weight %, Zn <0.05 weight %, impurities <0.05 each weight %, <0.25 total weight %, Al balance

wherein the aluminum alloy casting alloy is grain refined using aluminum-titanium-boron and/or aluminum-titanium-carbon containing grain refiner; wherein the aluminum alloy casting alloy is cast in a sand mold; wherein the aluminum alloy product is solution treated at 950-960.degree. F. (510-516.degree. C.) for 2-4 hours followed by 980-1005.degree. F. (527-541.degree. C.) for 16-120 hours followed by quenching in water, hot isostatically pressed (HIP'ed) at 950-975.degree. F. (510-524.degree. C.), 15,000+/-500 psi (103+/-3.4 MPa) for 2 to 3 hours, solution treated at 980-1005.degree. F. (527-541.degree. C.) for 16-120 hours followed by quenching in water and naturally aged at room temperature or artificially aged at 310-390.degree. F. (154-199.degree. C.) for 12 to 96 hours; whereby the aluminum alloy product in the naturally aged condition T4 has a minimum ultimate tensile strength of 61,000 psi (420 MPa), a minimum 0.2% offset yield strength of 38,500 psi (265 MPa), a minimum elongation of 10.9%, a minimum unnotched impact strength of 88 joules/cm.sup.2 and passes the ASTM G47 test for resistance to stress corrosion cracking at an applied stress of 30,000 psi (207 MPa); whereby the aluminum alloy product in the artificially aged condition T6 has a minimum ultimate tensile strength of 66,600 psi (459 MPa), a minimum 0.2% offset yield strength of 47,800 psi (330 MPa), a minimum elongation of 4.9%, a minimum unnotched impact strength of 40 joules/cm.sup.2 and nearly passes the ASTM G47 test for resistance to stress corrosion cracking at an applied stress of 40,000 psi (276 MPa); whereby the aluminum alloy product in the artificially aged condition T61 has an average ultimate tensile strength of 69,660 psi (480 MPa), an average 0.2% offset yield strength of 59,390 psi (409 MPa), an average elongation of 6.3%, an average unnotched impact strength of 41 joules/cm.sup.2 and similar ballistic performance to aluminum alloy wrought alloy 2519 in the T87 condition; whereby the aluminum alloy product in the artificially aged condition T7 has a minimum ultimate tensile strength of 59,700 psi (412 MPa), a minimum 0.2% offset yield strength of 43,900 psi (303 MPa), a minimum elongation of 3.9%, a minimum unnotched impact strength of 28 joules/cm.sup.2 and passes the ASTM G47 test for resistance to stress corrosion cracking at an applied stress of 40,000 psi (276 MPa).

21. An aluminum alloy cast product according to claim 20, wherein the sand cast aluminum alloy product is a seat frame of a military vehicle.

22. An aluminum alloy cast product according to claim 20, wherein the sand cast aluminum alloy product is a turret rotor of a military weapon system.

23. An aluminum alloy cast product according to claim 20, wherein the sand cast aluminum alloy product is a hatch of a military weapon system.

24. An aluminum alloy cast product according to claim 20, wherein the sand cast aluminum alloy product is ballistic armor.

25. An aluminum alloy cast product according to claim 20, wherein the aluminum alloy product is welding wire.

26. An aluminum alloy casting alloy consisting essentially of: TABLE-US-00025 Cu 5.00-6.25 weight %, Mg 0.20-0.50 weight %, Mn 0.20-0.65 weight %, Ti 0.05-0.40 weight %, Ag <0.40 weight %, Cr <0.20 weight %, V <0.05 weight %, Zr <0.10 weight %, Fe <0.15 weight %, Si <0.15 weight %, Ni <0.05 weight %, Zn <0.05 weight %, impurities <0.05 eachweight %, <0.25 total weight %, Al balance

wherein the aluminum alloy casting alloy is grain refined using aluminum-titanium-boron and/or aluminum-titanium-carbon containing grain refiner; wherein the aluminum alloy casting alloy is cast in a sand mold to form a cast product; and wherein the aluminum alloy cast product is solution treated at 950-960.degree. F. (510-516.degree. C.) for 2-4 hours followed by 980-1005.degree. F. (527-541.degree. C.) for 16-120 hours followed by quenching in water, hot isostatically pressed (HIP'ed) at 950-975.degree. F. (510-524.degree. C.), 15,000+/-500 psi (103+/-3.4 MPa) for 2 to 3 hours, solution treated at 980-1005.degree. F. (527-541.degree. C.) for 16-120 hours followed by quenching in water and naturally aged at room temperature or artificially aged at 310-390.degree. F. (154-199.degree. C.) for 12 to 96 hours; whereby the aluminum alloy cast product in the naturally aged condition T4 has a minimum ultimate tensile strength of 60,800 psi (419 MPa), a minimum 0.2% offset yield strength of 40,800 psi (287 MPa) and a minimum elongation of 12.4%; and whereby the aluminum alloy product in the artificially aged condition T6 has a minimum ultimate tensile strength of 67,300 psi (464 MPa), a minimum 0.2% offset yield strength of 52,600 psi (362 MPa) and a minimum elongation of 6.5%;

27. An aluminum alloy cast product according to claim 26, wherein the sand cast aluminum alloy product is a seat frame of a military vehicle.

28. An aluminum alloy cast product according to claim 26, wherein the sand cast aluminum alloy product is a turret rotor of a military weapon system.

29. An aluminum alloy cast product according to claim 26, wherein the sand cast aluminum alloy product is a hatch of a military weapon system.

30. An aluminum alloy cast product according to claim 26, wherein the sand cast aluminum alloy product is ballistic armor.

31. An aluminum alloy cast product according to claim 26, wherein the aluminum alloy product is welding wire.