Aluminum alloy for structural and non-structural near-net continuous casting and production method thereof

Abstract

The invention relates to an aluminum alloy and a production method thereof. Aluminum alloys for near net shape continuous casting of structural components are disclosed. The alloy comprises the following components in percentage by weight: 2-10% of Zn, 0.5-5% of Mg, 0.5-5% of Fe and the balance of Fe. Optionally, Gu, Ti, Sr, Be, Zr, V, Cr, Sc, Na, Si, Mn, Mo, B and Ni; and the balance of aluminum. The alloy may be subjected to a heat treatment selected from the group consisting of solubilization, inoculation, aging, and two or more heat treatment steps.

Description

[0001] This application is a divisional application of the patent application with application number 201780084804.6, application date November 27, 2017, and invention name “Aluminum alloy for structural and non-structural near-final continuous casting and its production method”. Technical Field

[0002] The present invention relates to the field of aluminum alloys. The present invention is an aluminum alloy utilizing zinc, magnesium, and iron as primary alloying elements, and copper, manganese, titanium, boron, zirconium, vanadium, scandium, chromium, strontium, sodium, molybdenum, silicon, nickel, and beryllium as possible secondary alloying elements. In particular, the present invention relates to an aluminum-based alloy suitable for near-net shape casting of structural and non-structural components. Furthermore, the aluminum alloy exhibits reasonable corrosion resistance when cast. Background Art

[0003] Aluminum alloys are widely used in structural components and manufacturing where corrosion resistance and light weight are desired without compromising strength. There are many aluminum alloy formulations, all with different properties depending on the Al alloy formulation and the method used to produce the alloy. Depending on the formulation, there may be certain trade-offs, such as sacrificing toughness to increase strength. Cost and ease of production are also factors when considering aluminum alloy types. Summary of the Invention

[0004] Aluminum alloys have been developed to achieve near-net-shape structural and non-structural parts for automotive and non-automotive industrial applications. Any gravity or pressure-assisted metal mold or sand casting process, including but not limited to High Pressure Die Casting (HPDC), can be used to produce the alloys into near-net-shape parts. Manufacturing methods may include vacuum assist during the casting process. All parts made from the alloy family proposed herein can be heat treated to several temper combinations to improve tensile strength, ductility, and corrosion resistance in use.

[0005] This new aluminum alloy provides a formulation that can be used to manufacture components with high uniaxial tensile and fatigue properties, as well as other material advantages. Compared to the best existing commercially available aluminum alloys, this new aluminum alloy allows for improvements in strength and elongation of up to 200% - when compared to other alloys with similar heat treatment tempering conditions. Rather than focusing solely on maximizing a single property (such as strength) while minimizing the deterioration effects on other properties (such as toughness), the present invention also contemplates improvements in the manufacturing process while improving several key material properties. For example, when manufacturing this aluminum alloy, the occurrence of mold welding is reduced and the life of the metal mold cavity is improved, as well as improved fluidity and castability. In addition, the recyclability and re-claimability of the alloy are improved. In addition, this alloy specifies parameters for more elements and allows for a wider tolerance range for the elements used.

[0006] The new alloys have been tested using various compositional variations of the alloys. They have been evaluated on metal and sand casting processes such as high pressure die casting, permanent mold casting (gravity assisted) and sand casting, all with positive results.

[0007] The present invention is an aluminum alloy utilizing zinc, magnesium, and iron as primary alloying elements, and copper, manganese, titanium, boron, zirconium, vanadium, scandium, chromium, strontium, sodium, molybdenum, silicon, nickel, and beryllium as possible secondary alloying elements.

[0008] More specifically, an aluminum-based alloy for near-net-shape continuous casting of structural components, the aluminum-based alloy having zinc, magnesium, and iron as primary alloying elements, the aluminum-based alloy consisting of one or more of the following essential elements together with Al:

[0009] 2-10 wt.% (wt.%, percentage by weight) zinc

[0010] 0.5-5wt.% magnesium

[0011] 0.5-5wt.% iron

[0012] 0-4wt.% copper

[0013] 0-0.5wt.% titanium

[0014] 0-0.1wt.% strontium

[0015] 0-0.2wt.% beryllium

[0016] 0-0.5wt.% zirconium

[0017] 0-0.5wt.% vanadium

[0018] 0 - 0.5 wt. % of chromium

[0019] 0 - 0.5 wt. % of scandium

[0020] 0 - 0.1 wt. % of sodium

[0021] 0 - 0.5 wt. % of silicon

[0022] 0 - 1 wt. % of manganese

[0023] 0 - 5 wt. % of nickel

[0024] 0 - 0.5 wt. % of boron

[0025] 0 - 1 wt. % of molybdenum

[0026] The remainder of the weight percent (66.6 - 96) is aluminum.

[0027] The alloy can be cast into near net shape parts using a pressure assisted casting process such as high pressure die casting.

[0028] The molten alloy can also be cleaned by degassing using argon or nitrogen purging in the liquid metal.

[0029] The use of vacuum can also be used in the die casting process to reduce the entrapped gases in the casting, resulting in improved tensile strength and ductility of the cast parts.

[0030] The parts manufactured by the casting process with or without vacuum assistance can be subjected to extensive heat treatment to achieve a variety of temper. The primary strengthening mechanisms during heat treatment are one or more of the following: solid solution strengthening, and strengthening from precipitation (through solid state phase transformation) in the first aluminum phase. A list of the temper that the parts can successfully be subjected to without any defects is given below:

[0031] Fx - As cast temper F, natural aging (incubation) at room temperature for x days.

[0032] T4-y - Solution heat treated T4, natural aging (incubation) at room temperature. y is a numerical identifier to represent the unique details of the T4 heat treatment for each part.

[0033] T5 - Artificial aging (age) at elevated temperature of the samples in the Fx temper.

[0034] T6-y - Near peak artificial aging process with thermal assistance at elevated temperature. y is a numerical identifier to represent the unique details of the T6 heat treatment for each part.

[0035] T7-y – An artificial aging process at elevated temperature, continued for the time required for the component to fully exceed peak strength at any given temperature. y is a numeric identifier representing the unique details of the T7 heat treatment used for each component.

[0036] Several exemplary parts were cast using this alloy in a pressure-assisted casting process, including: a small-scale test sample / specified (SSTS); a large-scale test sample / specified (LSTS); and a side impact door beam (SIB). BRIEF DESCRIPTION OF THE DRAWINGS

[0037] For a better understanding of the various embodiments described herein, and to more clearly show how these various embodiments may be practiced, reference is made, by way of example, to the accompanying drawings which illustrate at least one exemplary embodiment and which will now be briefly described.

[0038] Figure 1 Shown are typical castings of small-scale test sample components consisting of: A - standard thick tensile test sample; B - standard thin tensile test sample; C - standard fatigue test sample; D - standard wear test sample; and, E - standard impact strength test sample.

[0039] Figure 2 Shown in Figure 1 Dimensions of the small tensile test specimen designated B. This part conforms to ASTM E8 / E8-11 for tensile test specimens.

[0040] Figure 3 Shown in Figure 1 Dimensions of the large tensile test specimen designated A. This part conforms to ASTM E8 / E8-11 standards for tensile test specimens.

[0041] Figure 4 Shown in Figure 1 Dimensions (in millimeters) of the fatigue test specimen designated C. This component complies with ASTM E 466 & E 606 standards for fatigue test specimens (stress and strain control).

[0042] Figure 5 Shown in Figure 1 Dimensions (in millimeters) of the wear test specimen designated D. The component complies with ASTM G 65-04 standard for wear test specimens.

[0043] Figure 6Shown in Figure 1 Dimensions (in millimeters) of the impact strength test specimen designated E. This part complies with ASTM E 23 for impact strength test specimens.

[0044] Figure 7 A typical composite microstructure image obtained from an optical microscope is shown, showing the entire cross-section of a gauge length of a thin tensile specimen from a SSTS component. This image is from a specimen in the F temper.

[0045] Figure 8 A typical composite microstructure image obtained from an optical microscope is shown, showing the entire cross-section of a gauge length of a thin tensile specimen from a SSTS component. This image is from a specimen in the T4 temper.

[0046] Figure 9 A typical high magnification microstructural image obtained from an optical microscope is shown, showing the primary aluminum phase (lighter) and the secondary phase (darker). This image is from a sample in the F temper.

[0047] Figure 10 A typical casting of an LSTS component is shown, consisting of the following: A - corrosion plate; B - butterfly shear test specimen; C - standard fatigue test flat specimen; D - standard impact strength test specimen; E - standard fatigue test round specimen; F - standard flat tensile test specimen; G - standard thin tensile test round specimen; H - standard tear test specimen.

[0048] Figure 11 Shown in Figure 10 The dimensions of the etched plate designated A in the figure (in millimeters).

[0049] Figure 12 Shown in Figure 10 Dimensions (in millimeters) of the butterfly shear test specimen designated B.

[0050] Figure 13 Shown in Figure 10 The dimensions (in millimeters) of the tensile test flat specimen designated F in FIG.

[0051] Figure 14 Shown in Figure 10 Dimensions (in millimeters) of the tensile test flat specimen designated H. This part complies with ASTM B 871 for wear test specimens.

[0052] Figure 15 Shown Figure 10 Shown are room temperature S–N curves of a smooth round fatigue bar of alloy LSTS#1 after T7-6 heat treatment.

[0053] Figure 16 A typical composite microstructure image obtained from an optical microscope is shown, showing the entire cross-section of a gauge length of a circular tensile specimen from an LSTS component. This image is from a specimen in the F temper.

[0054] Figure 17 A typical composite microstructure image obtained from an optical microscope is shown, showing the entire cross-section of a gauge length of a flat tensile specimen from an LSTS component. This image is from a specimen in the F temper.

[0055] Figure 18 A typical composite microstructure image obtained from an optical microscope is shown, showing the entire cross-section of a gauge length of a circular tensile specimen from an LSTS component. This image is from a specimen in the T4 temper.

[0056] Figure 19 A typical high magnification microstructural image obtained from an optical microscope is shown, showing the primary aluminum phase (lighter) and the secondary phase (darker).This image is from a circular tensile test specimen in the F temper.

[0057] Figure 20 A typical high magnification microstructural image obtained from an optical microscope is shown, showing the primary aluminum phase (lighter color) and the secondary phase (darker color).This image is from a circular tensile test specimen in the F temper having alloy LSST#5.

[0058] Figure 21 A typical casting of a SIB component is shown.

[0059] Figure 22 Shown are the locations of five (5) tensile test specimens cut and machined from the SIB component.

[0060] Figure 23 Shown Figure 20 Dimensions of the tensile tested flat specimens shown in .

[0061] Figure 24 A typical composite microstructure image obtained from an optical microscope is shown showing the entire cross section of a gauge length section of a flat tensile specimen M5 from a SIB component having alloy SIB #1 and fabricated with vacuum-assisted HPDC. This image is from a specimen in the F temper.

[0062] Figure 25 A typical composite microstructure image obtained from an optical microscope is shown showing the entire cross section of a gauge length section of a flat tensile specimen M5 from a SIB component having alloy SIB #1 and fabricated with HPDC without vacuum assistance. This image is from a specimen in the F temper.

[0063] Figure 26A typical composite microstructure image obtained from an optical microscope is shown showing the entire cross section of a gauge length section of a flat tensile specimen M5 from a SIB component having alloy SIB #1 and fabricated with HPDC without vacuum assistance. This image is from a specimen in the T4-3 temper.

[0064] Figure 27 A typical composite microstructure image obtained from an optical microscope is shown showing the entire cross section of a gauge length section of a flat tensile specimen M3 from a fabricated SIB component having alloy SIB #1 and HPDC with vacuum assistance. This image is from a specimen in the T6 temper.

[0065] Figure 28 A typical composite microstructure image obtained from an optical microscope is shown showing the entire cross section of a gauge length section of a flat tensile specimen M5 from a SIB component having alloy SIB #1 and fabricated with vacuum-assisted HPDC. This image is from a specimen in the T7 temper.

[0066] Figure 29 A typical high magnification microstructural image obtained from an optical microscope is shown, showing the primary aluminum phase (lighter color) and the secondary phase (darker color).

[0067] Figure 30 A schematic diagram of a constrained rod casting (CRC) mold is shown (dimensions are in inches).

[0068] Figure 31 The hot cracking sensitivity index of Al-5Zn-2Mg alloys with different Fe contents is shown.

[0069] Figure 32 A photograph of the cast component is shown. DETAILED DESCRIPTION

[0070] I. Definition

[0071] Unless otherwise stated, the definitions and embodiments described in this section and elsewhere are intended to apply to all embodiments and aspects of the application described herein to which they are appropriate, as will be understood by those skilled in the art.

[0072] In understanding the scope of the present application, as used herein, the term "comprising" and its derivatives are intended to be open terms, which specifically specify the presence of stated features, elements, components, groups, wholes and / or steps, but do not exclude the presence of other unspecified features, elements, components, groups, wholes and / or steps. The foregoing also applies to words with similar meanings, such as the terms "including", "having" and their derivatives. As used herein, the term "consisting of" and its derivatives are intended to be closed terms, which specifically specify the presence of stated features, elements, components, groups, wholes and / or steps, but exclude the presence of other unspecified features, elements, components, groups, wholes and / or steps. As used herein, the term "consisting essentially of" is intended to specify the presence of stated features, elements, components, groups, wholes and / or steps, as well as the presence of those features, elements, components, groups, wholes and / or steps that do not materially affect the basic and novel characteristics.

[0073] As used herein, terms of degree such as "substantially", "about" and "approximately" mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed. These terms of degree should be construed to include a deviation of at least ±5% of the modified term if such deviation would not negate the meaning of the word it modifies.

[0074] Unless the context clearly indicates otherwise, as used in this application, the singular forms "a", "an", and "the" include plural referents. For example, an embodiment including "an alloy" should be understood to include one substance or two or more additional substances in some aspects.

[0075] In embodiments containing an "additional" or "second" component (e.g., an additional element or a second element), the second component, as used herein, is chemically different from the other components or the first component. The "third" component is different from the other components, the first component, and the second component, and similarly further listed or "additional" components are different.

[0076] As used herein, the term "and / or" means that the listed items are present or used alone or in combination. In practice, the term means "at least one" or "one or more" of the listed items are used or present.

[0077] Aluminum alloys have been developed to achieve near-net-shape structural and non-structural parts for automotive and non-automotive industrial applications. Any pressure-assisted metal mold casting process, including but not limited to high pressure die casting (HPDC), can be used to produce the alloys into near-net-shape parts. Manufacturing methods may include vacuum assist during the casting process. All parts made from the alloy families presented herein can be heat treated to several temper combinations to improve tensile strength, ductility, and corrosion resistance during use.

[0078] This new aluminum alloy provides a formulation that can be used to manufacture components with high uniaxial tensile and fatigue properties, as well as other material advantages. Compared to the best existing commercially available aluminum alloys, this new aluminum alloy allows for improvements in strength and elongation of up to 200% - when compared to other alloys with similar heat treatment tempering conditions. Rather than focusing solely on maximizing a single property (such as strength) while minimizing the deterioration effects on other properties (such as toughness), the present invention also contemplates improvements in the manufacturing process while improving several key material properties. For example, in the manufacture of this aluminum alloy, the occurrence of mold welding is reduced and the life of the metal mold cavity is improved, as well as improved fluidity and castability. In addition, the recyclability and reusability of the alloy are improved. In addition, this alloy specifies parameters for more elements and allows for a wider tolerance range for the elements used.

[0079] The new alloys have been tested using various compositional variations of the alloys. They have been evaluated on metal and sand casting processes such as high pressure die casting, permanent mold casting (gravity assisted) and sand casting, all with positive results.

[0080] The present invention is an aluminum alloy utilizing zinc, magnesium, and iron as primary alloying elements, and copper, manganese, titanium, boron, zirconium, vanadium, scandium, chromium, strontium, sodium, molybdenum, silicon, nickel, and beryllium as possible secondary alloying elements.

[0081] More specifically, an aluminum-based alloy for near-net-shape continuous casting of structural components, the aluminum-based alloy having zinc, magnesium, and iron as primary alloying elements, the aluminum-based alloy consisting of one or more of the following essential elements together with Al:

[0082] 2-10 wt.% zinc

[0083] 0.5-5wt.% magnesium

[0084] 0.5-5wt.% iron

[0085] 0-4wt.% copper

[0086] 0-0.5wt.% titanium

[0087] 0-0.1wt.% strontium

[0088] 0-0.2wt.% beryllium

[0089] 0-0.5wt.% zirconium

[0090] 0-0.5wt.% vanadium

[0091] 0-0.5wt.% chromium

[0092] 0-0.5wt.% scandium

[0093] 0-0.1 wt.% sodium

[0094] 0-0.5wt.% silicon

[0095] 0-1wt.% manganese

[0096] 0-5wt.% nickel

[0097] 0-0.5wt.% boron

[0098] 0-1wt.% molybdenum

[0099] The remaining weight percent (66.6-96) is aluminum.

[0100] The alloy can be cast into near-net-shape parts using pressure-assisted casting processes such as high pressure die casting.

[0101] Degassing by purging the liquid metal with argon or nitrogen can also be used to clean the molten alloy.

[0102] The use of vacuum can also be used in the die casting process to reduce entrapped gases in the casting, resulting in improved tensile strength and ductility of the cast part.

[0103] Components manufactured by the casting process with or without vacuum assistance can be extensively heat treated to achieve a variety of tempers. The main strengthening mechanisms during heat treatment are one or more of the following: solid solution strengthening, and strengthening due to precipitation (through solid-state phase transformation) in the first aluminum phase. The following is a list of heat treatment tempers that the component can successfully undergo without any defects:

[0104] Fx - cast temper F, natural aging (incubation) at room temperature for x days.

[0105] T4-y—Solution treated T4, naturally aged (inoculated) at room temperature. y is a numeric identifier representing the unique details of the T4 heat treatment used for each part.

[0106] T5 - Artificial aging at elevated temperature of samples in Fx temper.

[0107] T6-y – A near-peak artificial aging process performed with heat assistance at elevated temperatures. y is a numeric identifier representing the unique details of the T6 heat treatment used for each part.

[0108] T7-y – An artificial aging process at elevated temperature, continued for the time required for the component to fully exceed peak strength at any given temperature. y is a numeric identifier representing the unique details of the T7 heat treatment used for each component.

[0109] Several exemplary parts were cast using this alloy in a pressure-assisted casting process. These included: a small-scale test specimen (SSTS); a large-scale test specimen (LSTS); and a side-door intrusion beam (SIB).

[0110] II. Examples

[0111] The following non-limiting examples are used to illustrate the present application:

[0112] One embodiment of the alloy consists of a thin-walled part cast with an Al composition comprising 5 wt.% Zn, 2 wt.% Mg, 0.35 wt.% Cu, and 15 wt.% Fe. The casting process is high-pressure die casting without vacuum assistance, and the final part has a yield strength, ultimate tensile strength, and elongation of 200 MPa, 315 MPa, and 3.80%, respectively, in the as-cast state after 21 days of natural aging.

[0113] Another example of an alloy consists of a cast LSTS using an Al-5wt.% Zn-2wt.% Mg-15wt.% Fe composition. The casting process is vacuum-assisted high-pressure die casting, and the final part has an as-cast yield strength of 201 MPa, an ultimate tensile strength of 312 MPa, and an elongation of 4.63%, respectively.

[0114] The heat treatment method (any combination of the following: solution treatment only, inoculation only, aging only, no treatment, or two or more heat treatment steps together) may include one or more of the following:

[0115] a) One-step solution treatment: 460℃ for 3.5hr-24hr, quenched with water

[0116] b) Two-step solution treatment: 450°C for 12-22 hours + 5-30°C / h to 475-500°C + 475-500°C for 4-7 hours, quench with water

[0117] c) Incubation between solution treatment and aging: 1-24 hours at room temperature

[0118] d) Aging (one-step): 120-170℃ for 1-24 hours

[0119] e) Aging (two steps): 120-170°C for 1-24 hr + 120-170°C for 1-24 hr.

[0120] Small Scale Test Sample (SSTS)

[0121] Alloy composition

[0122] The following alloy compositions were used to fabricate small scale test specimen (SSTS) parts.

[0123] Table 1: List of typical alloy compositions used for casting SSTS components

[0124]

[0125] part

[0126] Figure 1 A photograph of typical SSTS components is shown. Figures 2 to 6 It elaborates in detail Figure 1 Details of each of the five (5) types of test specimens in the component shown.

[0127] Casting process

[0128] Table 2 presents the Figure 1 General details of the casting process for the SSTS components shown.

[0129] Table 2: For manufacturing Figure 1 Casting process of SSTS components shown

[0130] project describe casting machine 600-ton high-pressure die-casting machine Mold tool materials H13 tool steel Metal Cleaning Degassing with argon injection using a rotary degasser Metal temperature 700℃-735℃ vacuum No vacuum assistance

[0131] Heat treatment

[0132] Table 3 lists the various heat treatments and tempers to which SSTS was subjected.

[0133]

[0134] Mechanical properties

[0135] Table 4 shows typical average mechanical properties obtained from uniaxial tensile tests performed on SSTS components at various heat treatment tempers.

[0136] Table 4: Various heat treatments to which SSTS components were subjected after casting and before evaluation of mechanical properties

[0137]

[0138] microstructure

[0139] For the selected alloys, Figure 7-9Typical microstructure images of SSTS castings are shown.

[0140] Prominent features

[0141] None of the alloys shown in Table 1 exhibited any die welding or die sticking tendencies to the H13 tool steel material of the die.

[0142] The H13 tool steel die material did not exhibit any hot cracking tendencies when used with any of the alloys shown in Table 1.

[0143] The integrity and quality of the castings of all SSTS parts was acceptable according to the view of the conventional commercial casting industry; no observable visual defects, filling issues or mis-runs.

[0144] Large Scale Test Sample (LSTS)

[0145] Alloy compositions

[0146] The following alloy compositions were used to manufacture Large Scale Test Sample (LSTS) parts.

[0147] Table 5: List of typical alloy compositions used to cast LSTS parts

[0148]

[0149] Parts

[0150] Figure 10 Photos of typical LSTS parts are shown. Figures 11 to 14 Details of Figure 10 The details of the new four (4) types of test samples in the parts shown.

[0151] Casting process

[0152] Table 6 presents general details of the casting process used to manufacture Figure 10 the LSTS parts shown.

[0153] Table 6: Casting process used to manufacture Figure 10 the LSTS parts shown

[0154] project describe casting machine Buhler Carat 105L high-pressure die-casting machine Mold tool materials P20 tool steel. Metal Cleaning Degassing with chlorine-based tablets Metal temperature 680℃-735℃ vacuum Vacuum Assist

[0155] Heat treatment

[0156] The various heat treatment tempering that the LSTS was subjected to is listed in Table 7.

[0157] Table 7: Various heat treatments that the LSTS parts were subjected to after casting, prior to evaluating mechanical properties

[0158]

[0159] Mechanical properties

[0160] Table 8 shows typical average mechanical properties obtained from uniaxial tensile tests performed on LSTS components at various heat treatment tempers.

[0161] Table 8: Various heat treatments to which LSTS components were subjected after casting and before evaluation of mechanical properties

[0162]

[0163]

[0164] Figure 15 Shown are the room temperature fatigue properties of a smooth round fatigue bar having alloy LSTS#1 after T7-6 heat treatment.

[0165] microstructure

[0166] For the selected alloys, Figure 16-20 Typical microstructural images of LSTS castings are shown.

[0167] Outstanding Features

[0168] None of the alloys shown in Table 5 showed any tendency to die welding or die sticking to the P20 tool steel material of the die.

[0169] P20 tool steel die material does not exhibit any hot cracking tendency when used with any of the alloys shown in Table 5.

[0170] The integrity and quality of the castings for all LSTS components were acceptable according to conventional commercial foundry industry opinion; there were no observable visual defects, filling issues, or discharging problems.

[0171] Side door impact beam (SIB)

[0172] Alloy composition

[0173] The following alloy compositions were used to manufacture the side-intrusion beam (SIB) components.

[0174] Table 9: List of typical alloy compositions used for casting SIB components

[0175]

[0176] part

[0177] Figure 19 A photograph of a typical SIB component is shown. The location and dimensions of the tensile rods in the SIB component are shown in Figure 20-21 middle.

[0178] Casting process

[0179] Table 10 presents the Figure 19 General details of the casting process for SIB components are shown in .

[0180] Table 10: For manufacturing Figure 19 Casting process of SIB components shown in .

[0181]

[0182] Heat treatment

[0183] Table 11 lists the various heat treatment tempers to which the SIBs were subjected.

[0184] Table 11: Various heat treatments to which SIB components were subjected after casting and before evaluation of mechanical properties

[0185]

[0186]

[0187] Mechanical properties

[0188] Table 12 shows typical average mechanical properties obtained from uniaxial tensile tests performed on SIB components at various heat treatment tempers.

[0189] Table 12: Various heat treatments to which SIB components were subjected after casting and before evaluation of mechanical properties

[0190]

[0191] microstructure

[0192] For the selected alloys, Figure 22-27 Typical microstructural images of SIB castings are shown in .

[0193] Outstanding Features

[0194] None of the alloys shown in Table 9 showed any tendency to die welding or die sticking to the P20 tool steel material of the die.

[0195] The P20 tool steel die material did not exhibit any appreciable tendency to hot cracking when used with any of the alloys shown in Table 9.

[0196] The integrity and quality of the castings for all SIB components were acceptable according to conventional commercial foundry industry opinion; there were no observable visual defects, filling problems, or discharging problems.

[0197] Hot Tear Sensitivity (HTS) Index

[0198] The hot cracking sensitivity index of Al-Zn-Mg and Al-Zn-Mg-Fe alloys was evaluated using a constrained rod casting (CRC) mold.

[0199] CRC molds are made of cast iron ( Figure 28 ) and was able to produce four cylindrical constrained rods with lengths of 2″ (rod A), 3.5″ (rod B), 5″ (rod C), and 6.5″ (rod D) and a diameter of 0.5″. The rods were constrained at one end by a sprue and at the other end by a spherical riser (feeder) with a diameter of 0.75″.

[0200] The HTS values ​​are given as follows:

[0201]

[0202] where C is a numerical value assigned to the severity of a crack in the rod (Table 13), L is a numerical value assigned to the length of the rod (Table 14), and represents rods A, B, C, and D.

[0203] Table 13: Criteria representing the severity of cracks i

[0204] category <![CDATA[数值(C i )]]> Complete crack 4 Severe cracks 3 Slight cracks 2 Very fine cracks 1 No cracks 0

[0205] Table 14: Values ​​L representing rods of different lengths i

[0206] Rod Type (Length, inches) <![CDATA[数值(L i )]]> A(2.0) 1 B(3.5) 2 C(5.0) 3 D(6.5) 4

[0207] Alloy composition

[0208] As listed in Table 15, the following alloy compositions were used to evaluate hot cracking sensitivity.

[0209] Table 15: List of alloy compositions used for casting HTS samples

[0210]

[0211] Casting process

[0212] One kilogram of each alloy in Table 15 was melted and degassed with high-purity argon for 20 minutes. The pouring temperature for the samples was maintained at 720°C. The CRC mold was preheated at 300°C before pouring. Two hot cracking samples were obtained for each alloy.

[0213] HTS results

[0214] like Figure 29As shown in Figure 2, without Fe addition, Al-Zn-Mg alloys are highly sensitive to hot cracking. However, when Fe is added to Al-Zn-Mg, the hot cracking sensitivity of Al-Zn-Mg alloys is significantly reduced. When 1.3 wt% Fe is added, the HTS index drops to 1.67.

[0215] Pilot Scale Trial

[0216] A pilot test was carried out at an automotive foundry facility using one of the specified compositions of the alloy to produce structural parts for passenger cars. The alloy composition used was Al-5 wt% Zn-1.6 wt% Mg-1 wt% Fe-0.05 wt% Ti.

[0217] The salient details of the casting process are as follows:

[0218] Parts: Automobile shock absorber

[0219] Amount of molten alloy: ~10000kg

[0220] Melting temperature: 690-730℃

[0221] Degassing: Rotary degasser, using industrial pure Ar for 10 minutes

[0222] Vacuum system: 3 chill blocks on the mold

[0223] Composition (wt.%): Al-5.0Zn-1.6Mg-1.0Fe-0.05Ti

[0224] Number of crack-free parts cast: (excluding preheat attempts)

[0225] Main alloy: 180

[0226] 50% remelted alloy: 80

[0227] 100% remelted alloy: 110

[0228] In addition to producing defect-free, flawless castings in a production environment, other significant advantages of using this new alloy are a significantly reduced tendency to die weld on H13 die tools and 100% reusability of the alloy composition. The average uniaxial tensile properties of the as-cast parts, measured in samples from various locations within each part and obtained from several cast parts, were:

[0229] UTS=263MPa

[0230] YS=145MPa

[0231] %E1=8.2%

[0232] Notably, the properties did not change between the virgin, 50% recycled, and 100% recycled initial alloy metals. In addition, all parts could be heat treated to the solutionizing temperature without any discernible blistering. These outstanding properties and observations make the new alloy possible for use in the manufacture of structural automotive parts.

[0233] Other features and advantages of the present application will become apparent from the following detailed description. It should be understood, however, that the detailed description and the specific examples, while indicating embodiments of the application, are given by way of illustration only, and should not be taken by way of limitation.

[0234] While the application has been described with reference to examples, it is to be understood that the scope of the claims is not to be limited by the examples set forth herein, but is to be given the broadest interpretation consistent with the specification as a whole.

[0235] All publications, patents, and patent applications are herein incorporated by reference in their entirety to the same extent as if each individual publication, patent, or patent application was specifically and individually indicated to be incorporated by reference in its entirety. Where a term in the present application is found to be defined differently in a document incorporated herein by reference, the definition provided herein is to serve as the definition for that term.

[0236] Full citations for documents referred to in the present application

[0237] ASTM E8 / E8M-11a Standard Test Methods for Tension Testing of Metallic Materials, ASTM International, West Conshohocken, PA, 2011

[0238] ASTM E466-15 Standard Practice for Conducting Force Controlled Constant Amplitude Axial Fatigue Tests of Metallic Materials, ASTM International, West Conshohocken, PA, 2015

[0239] ASTM E606 / E606M-12 Standard Test Method for Strain-Controlled Fatigue Testing, ASTM International, West Conshohocken, PA, 2012

[0240] ASTM G65-04 Standard Test Method for Measuring Abrasion Using the Dry Sand / Rubber Wheel Apparatus, ASTM International, West Conshohocken, PA, 2004

[0241] ASTM E23-16b Standard Test Methods for Notched Bar Impact Testing of Metallic Materials, ASTM International, West Conshohocken, PA, 2016.

Claims

1. An aluminium alloy according to the accompanying text and figures.

2. An aluminum alloy, comprising: 2-10 wt.% zinc (Zn); 0.5-5 wt.% magnesium (Mg); 0.5-5wt.% iron (Fe), Aluminum (Al) and other elements (copper, titanium, strontium, beryllium, zirconium, vanadium, chromium, scandium, sodium, silicon, manganese, molybdenum, boron and nickel) and impurities constitute the balance wt.%.

3. An aluminum alloy comprising: 4-10 wt.% zinc (Zn); 1.5-3 wt.% magnesium (Mg); 1.5-3% iron (Fe); and, Unavoidable impurities.

4. An aluminum alloy comprising: 4.5-7 wt.% zinc (Zn); 2-2.5 wt.% magnesium (Mg); 1.5-4% iron (Fe); and, Unavoidable impurities.

5. An aluminum alloy comprising: 4.7-6.9 wt.% zinc (Zn); 2.1-2.24 wt.% magnesium (Mg); 1.56-3.78% iron (Fe); 0.05-0.38 copper (Cu); 0.02-0.24 of manganese (Mn); and Unavoidable impurities.

6. An aluminum alloy, comprising: 2-10 wt.% zinc; 0.5-5 wt.% magnesium; 0.5-5 wt.% iron; 0-4 wt.% copper; 0-1 wt.% manganese; 0-0.5 wt.% titanium; 0-0.15 wt.% boron; 0-0.5 wt.% zirconium; 0-0.5 wt.% vanadium; 0-0.5 wt.% scandium; 0-0.5 wt.% chromium; 0-0.1 wt.% strontium; 0-0.1 wt.% sodium; 0-0.5 wt.% boron; and, 0-0.2 wt.% beryllium.

7. An aluminium alloy as claimed in any one of claims 1 to 6, which has been subjected to a heat treatment which is one or more members of the group consisting of: solution treatment only, inoculation only, aging only, no treatment or two or more heat treatment steps together.

8. The aluminum alloy according to any one of claims 1 to 6, which has been heat treated by one of the following: One-step solution treatment: 460°C for 3.5 to 24 hours, quenched with cold water; Two-step solution treatment: 12-22 hours at 450°C, followed by a temperature increase of 5-30°C / hour to 475-500°C, followed by a 4-7 hour cold water quench at 475-500°C. Incubate at room temperature for 1-24 hours between solution treatment and aging; One-step aging: 120-170°C for 1-24 hours; and, Two-step aging: 120°C for 1-24 hours, plus 150-180°C for 1-24 hours.

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