Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
  • C21D8/0226—Hot rolling
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
  • C21D8/0236—Cold rolling
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
  • C21D8/0273—Final recrystallisation annealing
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
  • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C21/00—Alloys based on aluminium
  • C22C21/02—Alloys based on aluminium with silicon as the next major constituent
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C21/00—Alloys based on aluminium
  • C22C21/02—Alloys based on aluminium with silicon as the next major constituent
  • C22C21/04—Modified aluminium-silicon alloys
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
  • C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
  • C22F1/043—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon of alloys with silicon as the next major constituent

Definitions

• Aluminum alloys are useful in a variety of applications. However, improving one property of an aluminum alloy without degrading another property often proves elusive. For example, it is difficult to increase the strength of an alloy without decreasing its corrosion resistance. Other properties of interest for aluminum alloys include formability and critical fracture strain, to name two.
• the present disclosure relates to new 6xxx aluminum alloys having an improved combination of properties, such as an improved combination of strength, formability, bending, and/or corrosion resistance, among others.
• the new 6xxx aluminum alloys comprise (and in some instances consist essentially of or consist of) from 0.65 to 0.85 wt. % Si, from 0.40 to 0.59 wt. % Mg wherein the ratio of wt. % Mg to wt. % Si is from 0.47: 1 to 0.90: 1 (Mg:Si), from 0.05 to 0.35 wt. % Fe, from 0.04 to 0.13 wt. % Mn, from 0 to 0.20 wt. % Cu, from 0 to 0.15 wt. % Cr, from 0 to 0.15 wt. % Zr, from 0 to 0.10 wt. % Ti, from 0 to 0.05 wt. % V, from 0 to 0.05 wt. % Zn, the balance being aluminum and impurities.
• the amount of magnesium (Mg) and silicon (Si) in the new 6xxx aluminum alloys may relate to the improved combination of properties (e.g., strength, formability).
• the new 6xxx aluminum alloy includes from 0.40 to 0.59 wt. % Mg.
• a new 6xxx aluminum alloy includes at least 0.425 wt. % Mg.
• a new 6xxx aluminum alloy includes at least 0.45 wt. % Mg.
• a new 6xxx aluminum alloy includes at least 0.475 wt. % Mg.
• a new 6xxx aluminum alloy includes at least 0.50 wt. % Mg.
• a new 6xxx aluminum alloy includes not greater than 0.57 wt. % Mg.
• a new 6xxx aluminum alloy includes from 0.49 to 0.59 wt. % Mg.
• the new 6xxx aluminum alloy includes from 0.65 to 0.85 wt. % Si. In one embodiment, a new 6xxx aluminum alloy includes at least 0.675 wt. % Si. In another embodiment, a new 6xxx aluminum alloy includes at least 0.70 wt. % Si. In one embodiment, a new 6xxx aluminum alloy includes not greater than 0.825 wt. % Si. In another embodiment, a new 6xxx aluminum alloy includes not greater than 0.80 wt. % Si. In one embodiment, a new 6xxx aluminum alloy includes from 0.70 to 0.80 wt. % Si.
• the new 6xxx aluminum alloy includes silicon and magnesium such that the weight ratio of magnesium-to-silicon of from 0.47: 1 to 0.90: 1, i.e., the ratio of wt. % Mg to wt. % Si is from 0.47: 1 to 0.90: 1 (Mg: Si).
• the ratio of wt. % Mg to wt. % Si is at least 0.50: l(Mg:Si).
• the ratio of wt. % Mg to wt. % Si is at least 0.52: l(Mg:Si).
• the ratio of wt. % Mg to wt. % Si is at least 0.54: l(Mg:Si). In another embodiment, the ratio of wt. % Mg to wt. % Si is at least 0.56:l(Mg:Si). In yet another embodiment, the ratio of wt. % Mg to wt. % Si is at least 0.58: l(Mg:Si). In another embodiment, the ratio of wt. % Mg to wt. % Si is at least 0.60: l(Mg:Si). In one embodiment, the ratio of wt. % Mg to wt. % Si is not greater than 0.88: 1 (Mg: Si). In another embodiment, the ratio of wt. % Mg to wt.
• the ratio of wt. % Mg to wt. % Si is not greater than 0.86:l(Mg:Si). In yet another embodiment, the ratio of wt. % Mg to wt. % Si is not greater than 0.84: l(Mg:Si). In another embodiment, the ratio of wt. % Mg to wt. % Si is not greater than 0.82: l(Mg:Si). In one embodiment, the ratio of wt. % Mg to wt. % Si is from 0.61 : 1 to 0.84: 1 (Mg: Si).
• a new 6xxx aluminum alloy includes at least 0.08 wt. % Fe. In another one embodiment, a new 6xxx aluminum alloy includes at least 0.10 wt. % Fe. In yet another embodiment, a new 6xxx aluminum alloy includes at least 0.12 wt. % Fe. In another embodiment, a new 6xxx aluminum alloy includes at least 0.15 wt. %. In one embodiment, a new 6xxx aluminum alloy includes not greater than 0.32 wt. % Fe. In another embodiment, a new 6xxx aluminum alloy includes not greater than 0.30 wt. % Fe. In yet another embodiment, a new 6xxx aluminum alloy includes not greater than 0.28 wt. % Fe. In one embodiment, a new 6xxx aluminum alloy includes from 0.09 to 0.26 wt. % Fe.
• the amount of manganese (Mn) in the new 6xxx aluminum alloys may relate to the improved combination of properties (e.g., formability).
• the new 6xxx aluminum alloy includes from 0.04 to 0.13 wt. % Mn.
• a new 6xxx aluminum alloy includes at least 0.05 wt. % Mn.
• a new 6xxx aluminum alloy includes at least 0.06 wt. % Mn.
• a new 6xxx aluminum alloy includes not greater than 0.12 wt. % Mn.
• a new 6xxx aluminum alloy includes not greater than 0.11 wt. % Mn.
• a new 6xxx aluminum alloy includes not greater than 0.10 wt. % Mn. In one embodiment, a new 6xxx aluminum alloy includes from 0.06 to 0.10 wt. % Mn. [009] The new 6xxx aluminum alloy may optionally include copper (Cu) and in an amount of up to 0.20 wt. % Cu (e.g., for strengthening purposes). In one embodiment, a new 6xxx aluminum alloy includes at least 0.02 wt. % Cu. In another embodiment, a new 6xxx aluminum alloy includes at least 0.04 wt. % Cu. In yet another embodiment, a new 6xxx aluminum alloy includes at least 0.06 wt. % Cu.
• a new 6xxx aluminum alloy includes at least 0.07 wt. % Cu. In yet another embodiment, a new 6xxx aluminum alloy includes at least 0.08 wt. % Cu. In another embodiment, a new 6xxx aluminum alloy includes at least 0.09 wt. % Cu. In one embodiment, a new 6xxx aluminum alloy includes not greater than 0.19 wt. % Cu. In another embodiment, a new 6xxx aluminum alloy includes not greater than 0.18 wt. % Cu. In yet another embodiment, a new 6xxx aluminum alloy includes not greater than 0.17 wt. % Cu. In one embodiment, a new 6xxx aluminum alloy includes from 0.09 to 0.17 wt. % Cu.
• the new 6xxx aluminum alloy may optionally include chromium (Cr) and in an amount of up to 0.15 wt. % Cr (e.g., for grain structure control).
• a new 6xxx aluminum alloy includes at least 0.01 wt. % Cr.
• a new 6xxx aluminum alloy includes at least 0.02 wt. % Cr.
• a new 6xxx aluminum alloy incudes not greater than 0.10 wt. % Cr.
• a new a new 6xxx aluminum alloy incudes not greater than 0.08 wt. % Cr.
• a new a new 6xxx aluminum alloy incudes not greater than 0.06 wt. % Cr.
• a new a new 6xxx aluminum alloy incudes not greater than 0.05 wt. % Cr.
• a new 6xxx aluminum alloy includes from 0.01 to 0.05 wt. % Cr.
• the new 6xxx aluminum alloy may optionally include zirconium (Zr) and in an amount of up to 0.15 wt. % Zr (e.g., for grain structure control).
• Zr zirconium
• a new 6xxx aluminum alloy incudes not greater than 0.10 wt. % Zr.
• a new a new 6xxx aluminum alloy incudes not greater than 0.05 wt. % Zr.
• a new a new 6xxx aluminum alloy incudes not greater than 0.03 wt. % Zr.
• a new a new 6xxx aluminum alloy incudes not greater than 0.01 wt. % Zr.
• the new 6xxx aluminum alloy may include up to 0.15 wt. % Ti. Titanium (Ti) may optionally be present in the new 6xxx aluminum alloy, such as for grain refining purposes.
• a new 6xxx aluminum alloy includes at least 0.005 wt. % Ti.
• a new 6xxx aluminum alloy includes at least 0.010 wt. % Ti.
• a new 6xxx aluminum alloy includes at least 0.0125 wt. % Ti.
• a new 6xxx aluminum alloy includes not greater than 0.10 wt. % Ti.
• a new 6xxx aluminum alloy includes not greater than 0.08 wt. % Ti.
• a new 6xxx aluminum alloy includes not greater than 0.05 wt. % Ti. In one embodiment, a target amount of titanium in a new 6xxx aluminum alloy is 0.03 wt. % Ti. In one embodiment, a new 6xxx aluminum alloy includes from 0.01 to 0.05 wt. % Ti.
• Zinc (Zn) may optionally be present in the new 6xxx aluminum alloy, and in an amount up to 0.10 wt. % Zn.
• a new alloy includes not greater than 0.05 wt. % Zn.
• a new alloy includes not greater than 0.03 wt. % Zn.
• a new alloy includes not greater than 0.01 wt. % Zn.
• Vanadium (V) may optionally be present in the new 6xxx aluminum alloy, and in an amount of up to 0.05 wt. % V.
• a new 6xxx aluminum alloy includes not greater than 0.03 wt. % V.
• a new 6xxx aluminum alloy includes not greater than 0.01 wt. % V.
• the balance of the new aluminum alloy is generally aluminum and impurities.
• a new 6xxx aluminum alloy includes not greater than 0.15 wt. %, in total, of the impurities, and wherein the 6xxx aluminum alloy includes not greater than 0.05 wt. % of each of the impurities.
• a new 6xxx aluminum alloy includes not greater than 0.10 wt. %, in total, of the impurities, and wherein the 6xxx aluminum alloy includes not greater than 0.03 wt. % of each of the impurities.
• the new 6xxx alloys may be useful in a variety of product forms, including ingot or billet, wrought product forms (sheet, plate, forgings and extrusions), shape castings, additively manufactured products, and powder metallurgy products.
• a new 6xxx aluminum alloy is a rolled product.
• the new 6xxx aluminum alloys may be produced in sheet form.
• a sheet made from the new 6xxx aluminum alloy has a thickness of from 1.5 mm to 4.0 mm.
• the new 6xxx aluminum alloys are produced using ingot casting and hot rolling.
• a method includes the steps of casting an ingot of the new 6xxx aluminum alloy, homogenizing the ingot, rolling the ingot into a rolled product having a final gauge (via hot rolling and/or cold rolling), solution heat treating the rolled product, wherein the solution heat treating comprises heating the rolled product to a temperature and for a time such that some or substantially all of Mg2Si of the rolled product is dissolved into solid solution, and after the solution heat treating, quenching the rolled product (e.g., water or air quenching). After the quenching, the rolled product may be artificially aged.
• one or more anneal steps may be completed before or after a rolling step (e.g., hot rolling to a first gauge, annealing, cold rolling to the final gauge).
• the artificially aged product can be painted (e.g., for an automobile part), and may thus be subjected to a paint-bake cycle.
• the rolled aluminum alloy products produced from the new alloy may be incorporated in an automobile.
• the new 6xxx aluminum alloys products are cast via continuous casting. Downstream of the continuous casting, the product can be (a) rolled (hot and/or cold), (b) optionally annealed (e.g., after hot rolling and prior to any cold rolling steps), (c) solution heat treated and quenched, (d) optionally cold worked (post-solution heat treatment), and (e) artificially aged, and all steps (a) - (e) may occur in-line or off-line relative to the continuous casting step.
• Some methods for producing the new 6xxx aluminum alloys products using continuous casting and associated downstream steps are described in, for example, U.S. Patent No. 7,182,825, U.S. Patent Application Publication No. 2014/0000768, and U.S. Patent Application Publication No. 2014/036998, each of which is incorporated herein by reference in its entirety.
• the artificially aged product can be painted (e.g., for an automobile part), and may thus be subjected to a paint-bake cycle.
• the hot rolling comprises hot rolling to an intermediate gauge product, wherein the intermediate gauge product exits the hot rolling apparatus at a temperature of not greater than 290°C.
• an optional anneal may be completed.
• the intermediate gauge product may be cold rolled to final gauge.
• the hot rolling comprises rolling to an intermediate gauge product, wherein the intermediate gauge product exits the hot rolling apparatus at a temperature of from 400-480°C.
• the intermediate gauge product may then be cold rolled to final gauge, i.e., no anneal is required after the hot rolling and prior to cold rolling in this embodiment.
• the cold rolling generally comprises reducing the thickness of the intermediate gauge thickness to the final gauge thickness.
• the cold rolling comprises cold rolling by at least 50%.
• the cold rolling comprises cold rolling by at least 60%.
• the cold rolling comprises cold rolling by at least 65%.
• the cold rolling is not greater than 85%.
• “cold rolled XX %" and the like means XXCR%, where XXCR% is the amount of thickness reduction achieved when the aluminum alloy body is reduced from a first thickness of Ti to a second thickness of T2, where Ti is the intermediate gauge thickness and wherein T2 is the thickness.
• XXCR% is equal to:
• XXCR% 80%.
• the peak metal temperature during solution heat treatment is in the range of from 504°C to 593°C.
• the peak metal temperature is the highest temperature realized by an alloy product during solution heat treatment.
• the new 6xxx aluminum alloy products are processed to a T4 temper as defined by ANSI H35.1 (2009), i.e., the new 6xxx are solution heat treated and then quenched and then naturally aged to a substantially stable condition.
• the natural aging amount is 30 days and the T4 properties of the new 6xxx aluminum alloy are measured at 30 days of natural aging.
• the new 6xxx aluminum alloys are processed to a T6 temper as defined by ANSI H35.1 (2009), i.e., the new 6xxx are solution heat treated and then quenched and then artificially aged.
• the artificial aging comprises paint baking.
• the artificial aging consist of paint baking.
• paint baking comprises heating the new 6xxx aluminum alloy product to 180°C and then holding for 20 minutes.
• the new 6xxx aluminum alloys are processed to a T8 temper as defined by ANSI H35.1 (2009), i.e., the new 6xxx are solution heat treated and then quenched and then cold worked (e.g., stretched), and then artificially aged.
• the artificial aging comprises paint baking.
• the artificial aging consist of paint baking.
• paint baking comprises heating the new 6xxx aluminum alloy product to 180°C and then holding for 20 minutes.
• the processing of the new 6xxx aluminum alloy steps may be accomplished such that a new aluminum alloy body product realizes a predominately recrystallized microstructure.
• a predominately recrystallized microstructure means that the aluminum alloy body contains at least 51% recrystallized grains (by volume fraction).
• the degree of recrystallization of a new 6xxx aluminum alloy product may be determined using appropriate metallographic samples of the material analyzed with EBSD by an appropriate SEM and computer software to determine intergranular misorientation.
• a new 6xxx aluminum alloy product is at least 60% recrystallized.
• a new 6xxx aluminum alloy product is at least 70% recrystallized.
• a new 6xxx aluminum alloy product is at least 80% recrystallized. In another embodiment, a new 6xxx aluminum alloy product is at least 90% recrystallized. In yet another embodiment, a new 6xxx aluminum alloy product is at least 95% recrystallized. In another embodiment, a new 6xxx aluminum alloy product is at least 98% recrystallized, or more.
• a new 6xxx aluminum alloy product may realize a fine grain size.
• a new 6xxx aluminum alloy product realizes an area weighted average grain size of not greater than 45 micrometers.
• a new 6xxx aluminum alloy product realizes an area weighted average grain size of not greater than 40 micrometers.
• a new 6xxx aluminum alloy product realizes an area weighted average grain size of at least 20 micrometers.
• a new 6xxx aluminum alloy product realizes an area weighted average grain size of at least 25 micrometers.
• a new 6xxx aluminum alloy product realizes an area weighted average grain size of at least 30 micrometers.
• a new 6xxx aluminum alloy product may realize a unique texture.
• Texture means a preferred orientation of at least some of the grains of a crystalline structure.
• matchsticks as an analogy, consider a material composed of matchsticks. That material has a random texture if the matchsticks are included within the material in a completely random manner. However, if the heads of at least some of those matchsticks are aligned in that they point the same direction, like a compass pointing north, then the material would have at least some texture due to the aligned matchsticks.
• the same principles apply with grains of a crystalline material.
• Texture components resulting from production of aluminum alloy products may include one or more of copper, S texture, brass, cube, and Goss texture, to name a few. Each of these texture components is defined in Table 1, below. Table 1
• Electron backscatter diffraction (EB SD) patterns are to be collected using an ED AX EBSD Digiview 5 detection system, or equivalent.
• the EBSD acquisition is to be performed using ED AX TSL EBSD Data Collection (OIM)TM software, version 7, or equivalent.
• Samples are to be cross-sectioned and polished for analysis of the longitudinal (L) x short transverse (ST) plane, and prepared for standard metallographic analysis, e.g., by grinding the cross-sectioned and mounted sample flat and polishing with successively finer grits to 0.05 pm colloidal silica (SiCh). The final step is vibratory polishing for 45 minutes.
• the samples are to be ion milled for 15 minutes using an appropriate broad beam argon ion milling system (e.g., an Hitachi IM4000Plus) operated at 3kV and glancing angle incidence (10 degrees) on the sample surface, while the sample is rotated at 25 rotations per minute.
• an appropriate broad beam argon ion milling system e.g., an Hitachi IM4000Plus
• Data acquisition parameters are to include an electron beam energy of 20kV, a spot size 5 with a sample tilt angle of 70 degrees; a 0.8 micrometer step size and square grid scan type are to be used.
• Map dimensions are to be full thickness in the short transverse (ST) direction by 800 micrometers in the longitudinal (L) direction (i.e., the rolling direction for sheet products).
• the software used to analyze the acquired data should be an ED AX TSL OIMTM 8 data analysis package or similar.
• Data analysis included a 2-step clean-up procedure.
• the first step is a Neighbor Orientation Correlation level 2 clean up applied to data with a minimum confidence index (Cl) of 0.1 and grain tolerance angle of 5 degrees.
• the second step is a Grain Dilation using a grain tolerance angle of 5 degrees and a minimum of 5 points per grain for a single iteration.
• Grains are defined to have a minimum of 5 points per grain with a grain tolerance angle of 5 degrees.
• the software determines grain size (average grain diameter) via the Heyn linear intercept method, generally as per ASTM El 12- 12, ⁇ 13.
• individual grain sizes are determined by counting the number of points within each grain and multiplying by the area of each point (step size squared).
• a i is the area of each individual grain as measured per above “vi” is the calculated individual grain size assuming the grain is a circle.
• the number average grain size, v-bar_n, is the arithmetic mean of vi.
• The“area weighted average grain size” may be calculated using the following equation:
• Ai is the area of each individual grain, as per above, and where vi is the calculated individual grain size, as per above.
• v-bar_a is the area weighted average grain size.
• the quantification of texture components present (Cube%, Goss%, Brass%, S%, Copper%) is to be determined as the number fraction of measured points assigned to a specific texture component. Points are assigned to a texture component if the misorientation angle deviates from the ideal orientation by less than 13.74 degrees. This number fraction is multiplied by 100 to find the percentage of each texture component in the sample.
• the new 6xxx aluminum alloys disclosed herein may realize an improved combination of properties.
• a new 6xxx aluminum alloy realizes a T4 tensile yield strength in the LT (long transverse) direction of from 90 to 110 MPa.
• a new 6xxx aluminum alloy realizes a T4 uniform elongation in the LT (long transverse) direction of at least 21%.
• a new 6xxx aluminum alloy realizes a T4 n value (10-20%) in the LT (long transverse) direction of at least 0.245.
• T4 properties are to be measured after 30 days of natural aging.
• tensile yield strength and uniform elongation are to be measured in accordance with ASTM E8 and B557.
• “n value (10-20%)” is to be measured in accordance with ASTM E646 using 10-20% strain.
• a new 6xxx aluminum alloy realizes a T6 (0% pre strain/stretch) tensile yield strength of at least 160 MPa when artificially aged by paint baking at 180°C for 20 minutes.
• a new 6xxx aluminum alloy realizes a T6, (0% pre-strain/ stretch) tensile yield strength of at least 170 MPa when artificially aged by paint baking at 180°C for 20 minutes.
• a new 6xxx aluminum alloy realizes a T6 (0% pre-strain/stretch) tensile yield strength of at least 180 MPa when artificially aged by paint baking at 180°C for 20 minutes.
• a new 6xxx aluminum alloy realizes a T8 tensile yield strength of at least 215 MPa when post-SHT stretched 1-3 % and then artificially aged by paint baking at 180°C for 20 minutes.
• a new 6xxx aluminum alloy realizes a Hem rating of 2 or better.
• Hem rating is defined in the below Examples.
• a new 6xxx aluminum alloy realizes a Hem rating of 1.
• a new 6xxx aluminum alloy realizes a VDA bend angle of at least 125°.
• VDA testing is to be tested by natural aging the product for 30 days, and then stretching the product 10% in the L (longitudinal) direction, and then conducting the VDA bend test in accordance with the VDA 238-100 bend test specification. (https://www.vda.de/en/services/Publications/vda-238-100-plate-bending-test-for-metallic- materials.html).
• a new 6xxx aluminum alloy realizes a VDA bend angle of at least 130°.
• a new 6xxx aluminum alloy realizes a VDA bend angle of at least 135°.
• a new 6xxx aluminum alloy realizes a VDA bend angle of at least 140°.
• a new 6xxx aluminum alloy realizes a VDA bend angle of at least 143°.
• a new 6xxx aluminum alloy is absent of Ludering.
• Ludering is to be tested by naturally aging the product for 8 days, and then stretching the product 10% in the L (longitudinal) direction. If Luder lines are visible to the naked eye, the product is not absent of Ludering. If Luder lines are invisible to the naked eye, the product is absent of Ludering.
• a new 6xxx aluminum alloy realizes a combination of properties shown in the“Preferred Property Box” of FIG. 1.
• a new 6xxx aluminum alloy realizes a VDA bend angle of at least 140°. Others of the above- identified properties may also be realized.
• a new 6xxx aluminum alloy realizes a combination of properties shown in the“Preferred Property Box” of FIG. 2.
• a new 6xxx aluminum alloy realizes a VDA bend angle of at least 140°. Others of the above- identified properties may also be realized.
• a new 6xxx aluminum alloy realizes a combination of properties shown in the“Preferred Property Box” of FIG. 3.
• a new 6xxx aluminum alloy realizes a VDA bend angle of at least 140°. Others of the above- identified properties may also be realized.
• a new 6xxx aluminum alloy realizes a combination of properties shown in the“Preferred Property Box” of FIG. 4.
• a new 6xxx aluminum alloy realizes a VDA bend angle of at least 140°.
• Others of the above- identified properties may also be realized.
• the figures constitute a part of this specification and include illustrative embodiments of the present invention and illustrate various objects and features thereof.
• any measurements, specifications and the like shown in the figures are intended to be illustrative, and not restrictive. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.
• the term“or” is an inclusive“or” operator, and is equivalent to the term“and/or,” unless the context clearly dictates otherwise.
• the term“based on” is not exclusive and allows for being based on additional factors not described, unless the context clearly dictates otherwise.
• the meaning of “a,” “an,” and “the” include plural references, unless the context clearly dictates otherwise.
• the meaning of“in” includes“in” and“on”, unless the context clearly dictates otherwise.
• FIG. 1 is an image of the grain structure of alloy Al-1.
• FIG. 2 is an image of the grain structure of alloy Al-10.
• FIG. 3 is an image of the grain structure of alloy Al-19.
• FIG. 4 is an image of the grain structure of alloy Al-22.
• FIG. 5 is a graph illustrating the tensile yield strength (after paint bake, no pre strain, i.e., T6) versus n value (10-20%) in the as is (T4) temper for various example alloys.
• FIG. 6 is a graph illustrating the tensile yield strength (after paint bake, no pre strain, i.e., T6) versus uniform elongation in the as is (T4) temper for various example alloys.
• FIG. 7 is a graph illustrating the tensile yield strength (after paint bake, 2% pre strain, i.e., T8) versus n value (10-20%) in the as is (T4) temper for various example alloys.
• FIG. 8 is a graph illustrating the tensile yield strength (after paint bake, 2% pre strain, i.e., T8) versus uniform elongation in the as is (T4) temper for various example alloys.
• the ingots were then homogenized and then hot rolled to an intermediate gauge with an exit temperature of not greater than 290 °C.
• the alloys were then cold rolled to a final gauge of 0.95 or 1.2 mm.
• the cold rolling amounts (reduction from the intermediate gauge to the final gauge) are provided in Table 2, below.
• the final gauge products were then solution heat treated by heating to various peak metal temperatures (shown in Table 2), after which the alloys were immediately air quenched. After quenching, some alloys were then stretched while others were not, as shown in Table 2.
• the invention alloys achieved higher tensile yield strengths (TYS) and ultimate yield strengths (UTS) than non-invention alloys. Further, the invention alloys showed less strength loss at lower peak metal temperatures. The invention alloys also generally had higher elongation and higher n values over non-invention alloys at most processing conditions, indicating improved formability.
• Example 2 Hem Performance Testing
• Example 1 alloys were tested for hemming performance by stretching them 15% in the L direction after which a flat hem test was performed. The stretching was completed on alloys that had been naturally aged for 30 days and without subsequent artificial aging, i.e., the alloys were in a T4 temper prior to the 15% stretching. Four hems were completed for each processing condition. The hem ratings were then evaluated per the below scale.
• Table 4 shows the achieved hem ratings for A1 and A2 alloys.
• A1 alloys have more iron than A2 alloys. Those in industry have associated higher iron content to poorer hemming performance. However, the A1 alloys demonstrated better hemming performance than the A2 alloys. Further, higher iron content improved hemming performance in samples with lower levels of cold working (e.g. alloys Al-22, Al-23 and Al- 24 had 65% cold work and demonstrated the same hemming performance as alloys Al-10, Al- 11 and Al-12, which were the same gauge but only 81% cold work).
• Example 3 VDA Bend Performance Testing
• Example 1 alloys were naturally aged 8 days and then stretched 10% in the LT direction, after which a coating of paint was applied. After painting, the alloys were examined to determine if Luder bands were present. Table 6, below, shows the tensile yield strength and Luder band results for select Example 2 alloys.
• Grain size and texture measurements of select A1 samples from Example 2 were obtained via electron backscattering detection in a scanning electron microscope. The results of the grain size and texture measurements are shown in Table 7, below. Further, grain structure images obtained via SEM are shown in FIGS. 1-4.
• Table 7 show that with higher levels of cold working, the A1 alloys have finer (smaller) grain structure and higher levels of Cube texture.
• FIGS. 1-4 show the grain structure images obtained via SEM for alloys Al-1, Al-10, Al-19, and Al-22. The weighted average grain sizes obtained from these images for alloys Al-1, Al-10, Al-19, and Al-22 were 32 pm, 32 pm, 34 pm, and 41 pm, respectively.
• the A1 alloy have finer (smaller) grain structure.
• alloy Al-1 had a coarser grain structure than alloy B 1 -1.
• the new alloys disclosed herein may have grain size area weighted average of from 20 micrometers to 45 micrometers. In one embodiment, the new alloys have a grain size of from 30 to 40 micrometers.
• the new alloys disclosed herein may be in sheet form and have the following texture characteristics:

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