Aluminum alloy forging and production method thereof

Abstract

Provided are an Al—Mg—Si based aluminum alloy forging excellent in mechanical properties in room temperature and hardly causing recrystallized grains and a production method thereof. An aluminum alloy forging consists of: Cu: 0.15 mass % to 1.0 mass %, Mg: 0.6 mass % to 1.15 mass %; Si: 0.95 mass % to 1.25 mass %; Mn: 0.4 mass % to 0.6 mass %; Fe: 0.2 mass % to 0.3 mass %; Cr: 0.11 mass % to 0.25 mass %; Ti: 0.012 mass % to 0.035 mass %; B: 0.0001 mass % to 0.03 mass %; Zn: 0.25 mass % or less; Zr: 0.05 mass % or less; and the balance being aluminum and inevitable impurities. The number of intermetallic compounds of Mg 2 Si with a minor axis of 0.5 μm or more present in a visual field area of 1.5815 mm 2 is 100 or less when a sectional structure of the aluminum alloy forging is observed at a magnification of 1,000 times.

1 . (canceled) 
     
     
         2 . A method of producing an aluminum alloy forging, the aluminum alloy forging consisting of:
 Cu: 0.15 mass %, to 1.0 mass: Mg: 0.6 mass % to 1.15 mass %; Si: 0.95 mass % to 1.25 mass %; Mn: 0.4 mass % to 0.6 mass %: Fe: 0.2 mass % to 0.3 mass %: Cr: 0.11 mass % to 0.25 mass %; Ti: 0.012 mass to 0.035 mass %; B: 0.0001 mass % to 0.03 mass %; Zn 0.25 mass % or less; Zr: 0.05 mass % or less; and the balance being aluminum and inevitable impurities,   wherein the number of intermetallic compounds of Mg 2 Si with a minor axis of 0.5 μm or more present in a visual field area of 1.5815 mm 2  is 100 or less when a sectional structure of the aluminum alloy forging is observed at a magnification of 1,000 times   the method comprising:   a molten metal forming process of obtaining a molten metal;   a casting process of casting the molten metal obtained in the molten metal forming process to obtain a casting;   a homogenization heat treatment process of subjecting the casting obtained in the casting process to a homogenization heat treatment;   a forging process of forging the casting after the homogenization heat treatment process to obtain a forging;   a solution heat treatment process of subjecting the forging obtained in the forging process to a solution heat treatment;   a quenching process of quenching the forging after the solution heat treatment process; and   an aging process of aging the forging after the quenching process.   
     
     
         3 . The method of producing an aluminum alloy forging, as recited in  claim 2 ,
 wherein the homogenization heat treatment process is performed by holding the casting obtained in the casting process at a temperature of 370° C. to 560° C. for 4 hours to 10 hours;   wherein the forging process is performed by forging the casting after the homogenization heat treatment process at a heating temperature of 450° C. to 560° C.;   wherein the solution treatment process is performed by raising a temperature of the forging obtained in the forging process at a temperature raising rate of 5.0° C./min or more from 20° C. to 500° C. and holding the forging at 530° C. to 560° C. for 0.3 hours to 3 hours,   wherein the quenching process is performed by bringing an entire surface of the forging into contact with quenching water in a water tank within 5 seconds to 60 seconds after the solution treatment process for more than 5 minutes but not exceeding 40 minutes, and   wherein the aging process is performed by heating the forging after the quenching process at a temperature of 180° C. to 220° C. for 0.5 hours to 8 hours.   
     
     
         4 . The method of producing an aluminum alloy forging as recited in  claim 2 , wherein, in the aluminum alloy forging, the number of intermetallic compounds of Mg 2 Si with a minor axis of 0.5 μm or more present in a visual field area of 1.5815 mm 2  is 60 to 100 when a sectional structure of the aluminum alloy forging is observed at a magnification of 1,000 times. 
     
     
         5 . The method of producing an aluminum alloy forging as recited in  claim 2 , wherein, in the aluminum alloy forging, the number of intermetallic compounds of Mg 2 Si with a minor axis of 0.5 μm or more present in a visual field area of 1.5815 mm 2  is 60 to 78 when a sectional structure of the aluminum alloy forging is observed at a magnification of 1,000 times. 
     
     
         6 . The method of producing an aluminum alloy forging as recited in  claim 2 , wherein, in the aluminum alloy forging, the Zn content is 0%. 
     
     
         7 . The method of producing an aluminum alloy forging as recited in  claim 2 , wherein, in the aluminum alloy forging, the Zr content is 0%. 
     
     
         8 . The method of producing an aluminum alloy forging as recited in  claim 2 , wherein the aluminum alloy forging has a tensile strength at room temperature of 365 MPa or more. 
     
     
         9 . The method of producing an aluminum alloy forging as recited in  claim 2 , wherein the aluminum alloy forging has a tensile strength at room temperature of 385 MPa or more. 
     
     
         10 . The method of producing an aluminum alloy forging as recited in  claim 2 , wherein the aluminum alloy forging has a tensile strength at room temperature of 365 MPa to 401 MPa. 
     
     
         11 . The method of producing an aluminum alloy forging as recited in  claim 2 , wherein the aluminum alloy forging has a tensile strength at room temperature of 385 MPa to 401 MPa. 
     
     
         12 . The method of producing an aluminum alloy forging as recited in  claim 2 , wherein the solution treatment process is performed by raising a temperature of the forging obtained in the forging process at a temperature raising rate of 5.0° C./min to 240° C./min. 
     
     
         13 . The method of producing an aluminum alloy forging as recited in  claim 2 , wherein the solution treatment process is performed by raising a temperature of the forging obtained in the forging process at a temperature raising rate of 8.75° C./min to 240° C./min. 
     
     
         14 . The method of producing an aluminum alloy forging as recited in  claim 2 , wherein the solution treatment process is performed by raising a temperature of the forging obtained in the forging process at a temperature raising rate of 22.5° C./min to 240° C./min. 
     
     
         15 . The method of producing an aluminum alloy forging as recited in  claim 2 , wherein the solution treatment process is performed by raising a temperature of the forging obtained in the forging process at a temperature raising rate of 180° C./min to 240° C./min. 
     
     
         16 . The method of producing an aluminum alloy forging as recited in  claim 2 , wherein, in the aluminum alloy forging, the number of intermetallic compounds of Mg 2 Si with a minor axis of 0.5 μm or more present in a visual field area of 1.5815 mm 2  is 78 or less when a sectional structure of the aluminum alloy forging is observed at a magnification of 1,000 times. 
     
     
         17 . The method of producing an aluminum alloy forging as recited in  claim 2 , wherein, in the aluminum alloy forging, the number of intermetallic compounds of Mg 2 Si with a minor axis of 0.5 μm or more present in a visual field area of 1.5815 mm 2  is 65 or less when a sectional structure of the aluminum alloy forging is observed at a magnification of 1,000 times. 
     
     
         18 . The method of producing an aluminum alloy forging as recited in  claim 2 , wherein, in the aluminum alloy forging, the number of intermetallic compounds of Mg 2 Si with a minor axis of 0.5 μm or more present in a visual field area of 1.5815 mm 2  is 65 to 78 or less when a sectional structure of the aluminum alloy forging is observed at a magnification of 1,000 times. 
     
     
         19 . The method of producing an aluminum alloy forging as recited in  claim 2 , wherein, in the aluminum alloy forging, the number of intermetallic compounds of Mg 2 Si with a minor axis of 0.5 μm or more present in a visual field area of 1.5815 mm 2  is 60 to 65 or less when a sectional structure of the aluminum alloy forging is observed at a magnification of 1,000 times.