Aluminum alloy forging material, aluminum alloy forged product and method of producing same

Abstract

Provided is an aluminum alloy forging material having an alloy composition including Cu: 0.30 mass % to 1.0 mass %, Mg: 0.80 mass % to 1.8 mass %, Si: 0.90 mass % to 1.9 mass %, Mn: 0.30 mass % to 1.2 mass %, Fe: 0.20 mass % to 0.65 mass %, Zn: 0.25 mass % or less, Cr: 0.050 mass % to 0.30 mass %, Ti: 0.01 mass % to 0.1 mass %, B: 0.0010 mass % to 0.030 mass %, and Zr: 0.0010 mass % to 0.050 mass %, and having a ratio Fe/Mn of less than 1.4, and with the remainder being made up of Al and unavoidable impurities, wherein an average crystal particle size of an alloy structure after forging is 50 μm to 120 μm, and an average crystal particle size of an AlFeSi(Mn)-based compound present at crystal grain boundaries is 3.0 μm or less.

What is claimed is: 
     
         1 . An aluminum alloy forging material having an alloy composition including Cu in a range of 0.30 mass % or more and 1.0 mass % or less, Mg in a range of 0.80 mass % or more and 1.8 mass % or less, Si in a range of 0.90 mass % or more and 1.9 mass % or less, Mn in a range of 0.30 mass % or more and 1.2 mass % or less, Fe in a range of 0.20 mass % or more and 0.65 mass % or less, Zn in a range of 0.25 mass % or less, Cr in a range of 0.050 mass % or more and 0.30 mass % or less, Ti in a range of 0.01 mass % or more and 0.1 mass % or less, B in a range of 0.0010 mass % or more and 0.030 mass % or less, and Zr in a range of 0.0010 mass % or more and 0.050 mass % or less, and having a ratio Fe/Mn of the Fe content to the Mn content (mass ratio) of less than 1.4, and with the remainder being made up of Al and unavoidable impurities,
 wherein an average crystal particle size of an alloy structure after forging is in a range of 50 μm or more and 120 μm or less, and an average crystal particle size of an AlFeSi(Mn)-based compound present at crystal grain boundaries is 3.0 μm or less.   
     
     
         2 . An aluminum alloy forging material having an alloy composition including Cu in a range of 0.25 mass % or more and 0.55 mass % or less, Mg in a range of 0.85 mass % or more and 1.25 mass % or less, Si in a range of 1.02 mass % or more and 1.4 mass % or less, Mn in a range of 0.55 mass % or more and 1.0 mass % or less, Fe in a range of 0.32 mass % or more and 0.65 mass % or less, Zn in a range of 0.25 mass % or less, Cr in a range of 0.050 mass % or more and 0.30 mass % or less, Ti in a range of 0.01 mass % or more and 0.1 mass % or less, B in a range of 0.0010 mass % or more and 0.030 mass % or less, and Zr in a range of 0.0010 mass % or more and 0.050 mass % or less, and having a ratio Fe/Mn of the Fe content to the Mn content (mass ratio) of 0.3 or more and 1.2 or less, and with the remainder being made up of Al and unavoidable impurities,
 wherein an average crystal particle size of an alloy structure after forging is in a range of 50 μm or more and 120 μm or less, and an average crystal particle size of an AlFeSi(Mn)-based compound present at crystal grain boundaries is 3.0 μm or less.   
     
     
         3 . An aluminum alloy forging material having an alloy composition including Cu in a range of 0.25 mass % or more and 0.55 mass % or less, Mg in a range of 0.85 mass % or more and 1.25 mass % or less, Si in a range of 1.02 mass % or more and 1.4 mass % or less, Mn in a range of 0.61 mass % or more and 1.0 mass % or less, Fe in a range of 0.32 mass % or more and 0.65 mass % or less, Zn in a range of 0.25 mass % or less, Cr in a range of 0.050 mass % or more and 0.30 mass % or less, Ti in a range of 0.01 mass % or more and 0.1 mass % or less, B in a range of 0.0010 mass % or more and 0.030 mass % or less, and Zr in a range of 0.0010 mass % or more and 0.050 mass % or less, and having a ratio Fe/Mn of the Fe content to the Mn content (mass ratio) of 0.3 or more and 1.2 or less, and with the remainder being made up of Al and unavoidable impurities,
 wherein an average crystal particle size of an alloy structure after forging is in a range of 50 μm or more and 120 μm or less, and an average crystal particle size of an AlFeSi(Mn)-based compound present at crystal grain boundaries is 3.0 μm or less.   
     
     
         4 . An aluminum alloy forged product having an elongated part and a connecting part and having an aluminum alloy composition having an alloy composition including Cu in a range of 0.30 mass % or more and 1.0 mass % or less, Mg in a range of 0.80 mass % or more and 1.8 mass % or less, Si in a range of 0.90 mass % or more and 1.9 mass % or less, Mn in a range of 0.30 mass % or more and 1.2 mass % or less, Fe in a range of 0.20 mass % or more and 0.65 mass % or less, Zn in a range of 0.25 mass % or less, Cr in a range of 0.050 mass % or more and 0.30 mass % or less, Ti in a range of 0.01 mass % or more and 0.1 mass % or less, B in a range of 0.0010 mass % or more and 0.030 mass % or less, and Zr in a range of 0.0010 mass % or more and 0.050 mass % or less, and having a ratio Fe/Mn of the Fe content to the Mn content (mass ratio) of less than 1.4, and with the remainder being made up of Al and unavoidable impurities,
 wherein the cross section of a boundary part between the elongated part and the connecting part in a longitudinal direction has an alloy structure that has an average crystal particle size in a range of 5 μm or more and 60 μm or less and does not contain an AlFeSi(Mn)-based compound having an average crystal particle size of 2.0 μm or more, and has a fatigue limit at the number of repetitions to breakage of 10 7  cycles of 150 MPa or more in terms of fatigue properties at room temperature.   
     
     
         5 . An aluminum alloy forged product having an elongated part and a connecting part having an alloy composition including Cu in a range of 0.25 mass % or more and 0.55 mass % or less, Mg in a range of 0.85 mass % or more and 1.25 mass % or less, Si in a range of 1.02 mass % or more and 1.4 mass % or less, Mn in a range of 0.55 mass % or more and 1.0 mass % or less, Fe in a range of 0.32 mass % or more and 0.65 mass % or less, Zn in a range of 0.25 mass % or less, Cr in a range of 0.050 mass % or more and 0.30 mass % or less, Ti in a range of 0.01 mass % or more and 0.1 mass % or less, B in a range of 0.0010 mass % or more and 0.030 mass % or less, and Zr in a range of 0.0010 mass % or more and 0.050 mass % or less, and having a ratio Fe/Mn of the Fe content to the Mn content (mass ratio) of 0.3 or more and 1.2 or less, and with the remainder being made up of Al and unavoidable impurities,
 wherein the cross section of a boundary part between the elongated part and the connecting part in a longitudinal direction has an alloy structure that has an average crystal particle size in a range of 5 μm or more and 60 μm or less and does not contain an AlFeSi(Mn)-based compound having an average crystal particle size of 2.0 μm or more, and has a fatigue limit at the number of repetitions to breakage of 10 7  cycles of 150 MPa or more in terms of fatigue properties at room temperature.   
     
     
         6 . An aluminum alloy forged product having an elongated part and a connecting part having an alloy composition including Cu in a range of 0.25 mass % or more and 0.55 mass % or less, Mg in a range of 0.85 mass % or more and 1.25 mass % or less, Si in a range of 1.02 mass % or more and 1.4 mass % or less, Mn in a range of 0.61 mass % or more and 1.0 mass % or less, Fe in a range of 0.32 mass % or more and 0.65 mass % or less, Zn in a range of 0.25 mass % or less, Cr in a range of 0.050 mass % or more and 0.30 mass % or less, Ti in a range of 0.01 mass % or more and 0.1 mass % or less, B in a range of 0.0010 mass % or more and 0.030 mass % or less, and Zr in a range of 0.0010 mass % or more and 0.050 mass % or less, and having a ratio Fe/Mn of the Fe content to the Mn content (mass ratio) of 0.3 or more and 1.2 or less, and with the remainder being made up of Al and unavoidable impurities,
 wherein the cross section of a boundary part between the elongated part and the connecting part in a longitudinal direction has an alloy structure that has an average crystal particle size in a range of 5 μm or more and 60 μm or less and does not contain an AlFeSi(Mn)-based compound having an average crystal particle size of 2.0 μm or more, and has a fatigue limit at the number of repetitions to breakage of 10 7  cycles of 150 MPa or more in terms of fatigue properties at room temperature.   
     
     
         7 . The aluminum alloy forged product according to  claim 4 , which is used for a suspension arm. 
     
     
         8 . The aluminum alloy forged product according to  claim 5 , which is used for a suspension arm. 
     
     
         9 . The aluminum alloy forged product according to  claim 6 , which is used for a suspension arm. 
     
     
         10 . A method of producing the aluminum alloy forged product according to  claim 4 , comprising:
 an alloy molten metal forming process in which an aluminum alloy molten metal having the same alloy composition as the aluminum alloy forged product is formed;   a casting process in which the aluminum alloy molten metal obtained in the alloy molten metal forming process is cooled and coagulated to form an aluminum alloy cast product;   a forging process in which the aluminum alloy cast product subjected to the casting process is forged at a heating temperature of 450° ° C. or higher and 560° C. or lower;   a solution treatment process in which the forged product obtained in the forging process is subjected to a solution treatment in which it is held at a treatment temperature of 530° C. or higher and 560° C. or lower for 0.3 hours or longer and 3 hours or shorter;   a quenching treatment process in which, after the solution treatment process is completed, the entire surface of the forged product is brought into contact with quenching water within a range of 5 seconds or longer and 60 seconds or shorter, and quenching is performed in a water tank for 1 minute or longer and 30 minutes or shorter; and   an aging treatment process in which the forged product after the quenching treatment process is subjected to an aging treatment at a heating temperature of 170° C. or higher and 210° C. or lower for 0.5 hours or longer and 7 hours or shorter.   
     
     
         11 . The method of producing the aluminum alloy forged product according to  claim 10 , further comprising
 a homogenization heat treatment process in which the aluminum alloy cast product is subjected to a homogenization heat treatment in which it is held in a temperature range of 370° ° C. or higher and 560° C. or lower for 2 hours or longer and 10 hours or shorter between the casting process and the forging process.   
     
     
         12 . A method of producing the aluminum alloy forged product according to  claim 5 , comprising:
 an alloy molten metal forming process in which an aluminum alloy molten metal having the same alloy composition as the aluminum alloy forged product is formed;   a casting process in which the aluminum alloy molten metal obtained in the alloy molten metal forming process is cooled and coagulated to form an aluminum alloy cast product;   a forging process in which the aluminum alloy cast product subjected to the casting process is forged at a heating temperature of 450° ° C. or higher and 560° C. or lower;   a solution treatment process in which the forged product obtained in the forging process is subjected to a solution treatment in which it is held at a treatment temperature of 530° C. or higher and 560° C. or lower for 0.3 hours or longer and 3 hours or shorter;   a quenching treatment process in which, after the solution treatment process is completed, the entire surface of the forged product is brought into contact with quenching water within a range of 5 seconds or longer and 60 seconds or shorter, and quenching is performed in a water tank for 1 minute or longer and 30 minutes or shorter; and   an aging treatment process in which the forged product after the quenching treatment process is subjected to an aging treatment at a heating temperature of 170° C. or higher and 210° C. or lower for 0.5 hours or longer and 7 hours or shorter.   
     
     
         13 . The method of producing the aluminum alloy forged product according to  claim 12 , further comprising
 a homogenization heat treatment process in which the aluminum alloy cast product is subjected to a homogenization heat treatment in which it is held in a temperature range of 370° C. or higher and 560° ° C. or lower for 2 hours or longer and 10 hours or shorter between the casting process and the forging process.   
     
     
         14 . A method of producing the aluminum alloy forged product according to  claim 6 , comprising:
 an alloy molten metal forming process in which an aluminum alloy molten metal having the same alloy composition as the aluminum alloy forged product is formed;   a casting process in which the aluminum alloy molten metal obtained in the alloy molten metal forming process is cooled and coagulated to form an aluminum alloy cast product;   a forging process in which the aluminum alloy cast product subjected to the casting process is forged at a heating temperature of 450° ° C. or higher and 560° C. or lower;   a solution treatment process in which the forged product obtained in the forging process is subjected to a solution treatment in which it is held at a treatment temperature of 530° C. or higher and 560° C. or lower for 0.3 hours or longer and 3 hours or shorter;   a quenching treatment process in which, after the solution treatment process is completed, the entire surface of the forged product is brought into contact with quenching water within a range of 5 seconds or longer and 60 seconds or shorter, and quenching is performed in a water tank for 1 minute or longer and 30 minutes or shorter; and   an aging treatment process in which the forged product after the quenching treatment process is subjected to an aging treatment at a heating temperature of 170° C. or higher and 210° ° C. or lower for 0.5 hours or longer and 7 hours or shorter.   
     
     
         15 . The method of producing the aluminum alloy forged product according to  claim 14 , further comprising
 a homogenization heat treatment process in which the aluminum alloy cast product is subjected to a homogenization heat treatment in which it is held in a temperature range of 370° C. or higher and 560° C. or lower for 2 hours or longer and 10 hours or shorter between the casting process and the forging process.