Aluminum alloy forged material and method for manufacturing the same

Abstract

Provided is an aluminum alloy forged material comprising an excess amount of Si and a large quantity of a strength-increasing element such as Cu or Mn, and by which high strength and high toughness can be stably obtained even if the forged material is thinned, and also provided is a method for producing the same. A forged material constituted from an aluminum alloy which contains prescribed quantities of Mg, Si, Cu, Fe, Ti and B and further contains one or more elements selected from among Mn, Cr and Zr, with the remainder comprising Al and inevitable impurities, wherein the electrical conductivity measured at 20° C. on the surface of the aluminum alloy is greater than 42.5% IACS but not more than 46.0% IACS, and the forged aluminum alloy material has 0.2% proof stress of 360 MPa or more and Charpy impact value of 6 J/cm 2 or more.

1 . An aluminum alloy forged material comprising Al and
 Mg: from 0.60 to 1.80 mass %;   Si: from 0.80 to 1.80 mass %;   Cu: from 0.20 to 1.00 mass %;   Fe: from 0.05 to 0.40 mass %;   Ti: from 0.001 to 0.15 mass %;   B: from 1 to 500 ppm; and   at least one element selected from Mn: from 0.10 to 0.60 mass %, Cr: from 0.10 to 0.40 mass % and Zr: from 0.10 to 0.20 mass %;   wwherein   the electrical conductivity measured at the surface of the aluminum alloy forged material at 20° C. is greater than 42.5% IACS but less than or equal to 46.0% IACS,   the 0.2% proof stress is greater than or equal to 360 MPa, and   the Charpy impact value is greater than or equal to 6 J/cm 2 .   
     
     
         2 . The aluminum alloy forged material according to  claim 1 , wherein the mass ratio of Si/Mg is greater than or equal to 1. 
     
     
         3 . The aluminum alloy forged material according to  claim 1 , wherein a hydrogen concentration is 0.25 ml/100 g-Al or less. 
     
     
         4 . A method for manufacturing the aluminum alloy forged material according to  claim 1 , the method comprising:
 melting the aluminum alloy into a molten metal,   casting the molten metal at a cooling rate of 10° C./sec or more to form an ingot,   subjecting the ingot to heating at a rate of 5° C./min or less, and to a homogenizing heat treatment at 450-550° C. to form a homogenized ingot,   forging the homogenized ingot, wherein the forging start temperature is from 460 to 540° C., and   subjecting the forged homogenized ingot to a solution heat treatment at 520-570° C. to form a forged ingot, and   subjecting the forged ingot to an artificial aging treatment at 170-200° C. for 4-9 hours to produce the aluminum alloy forged material.   
     
     
         5 . The aluminum alloy forged material according to  claim 2 , wherein a hydrogen concentration is 0.25 ml/100 g-Al or less. 
     
     
         6 . A method for manufacturing the aluminum alloy forged material according to  claim 2 , the method comprising:
 melting the aluminum alloy into a molten metal,   casting the molten metal at a cooling rate of 10° C./sec or more to form an ingot,   homogenizing the ingot to heating at a rate of 5° C./min or less, and a homogenizing heat treatment at 450-550° C. to form a homogenized ingot,   forging the homogenized ingot at 460-540° C. at the forging start temperature,   subjecting the forged homogenized ingot to a solution heat treatment at 520-570° C. to form a forged ingot, and   subjecting the forged ingot to an artificial aging treatment at 170-200° C. for 4-9 hours to produce the aluminum alloy forged material.   
     
     
         7 . An aluminum alloy forged material comprising Al and
 Mg: from 0.60 to 1.80 mass %;   Si: from 0.80 to 1.80 mass %;   Cu: from 0.30 to 1.00 mass %;   Fe: from 0.05 to 0.35 mass %;   Ti: from 0.001 to 0.15 mass %;   B: from 1 to 500 ppm; and   at least one element selected from Mn: from 0.10 to 0.60 mass %, Cr: from 0.10 to 0.40 mass % and Zr: from 0.10 to 0.20 mass %; wherein   the electrical conductivity measured at the surface of the aluminum alloy forged material at 20° C. is greater than 42.5% IACS but less than 46.0% IACS,   the 0.2% proof stress is greater than or equal to 360 MPa, and   the Charpy impact value is greater than or equal to 6 J/cm 2 .