Aluminum alloy for casting, aluminum alloy member, and method for manufacturing aluminum alloy member

Abstract

An aluminum alloy member having a satisfactory mechanical strength, an aluminum alloy for casting from which such an aluminum alloy member having a satisfactory mechanical strength can be manufactured, and a method for manufacturing such an aluminum alloy member are provided. In an aspect according to the present disclosure, an aluminum alloy for casting contains, in mass %, Si: 4.0-7.5%, Cu: 1.5-4.0%, Zn: 1.0% or more, and Mg: 0.2-0.8%, in which a remainder of the aluminum alloy for casting consists of Al and unavoidable impurities. Note that a content of Zn may be limited to, in mass %, 1.0% or more and 5.0% or less. Further, a content of Mg may be limited to, in mass %, 0.5% or more and 0.8% or less.

What is claimed is: 
     
         1 . An aluminum alloy for casting containing, in mass %, Si: 4.0-7.5%, Cu: 1.5-4.0%, Zn: 1.0% or more, and Mg: 0.2-0.8%, wherein a remainder of the aluminum alloy for casting consists of Al and unavoidable impurities. 
     
     
         2 . The aluminum alloy for casting according to  claim 1 , wherein a content of Zn is limited to, in mass %, 1.0% or more and 5.0% or less. 
     
     
         3 . The aluminum alloy for casting according to  claim 1 , wherein a content of Mg is limited to, in mass %, 0.5% or more and 0.8% or less. 
     
     
         4 . The aluminum alloy for casting according to  claim 1 , wherein a content of Si is limited to, in mass %, 4.0% or more and less than 5.0%, or a content of Cu is limited to, in mass %, 1.5% or more and 2.0% or less. 
     
     
         5 . An aluminum alloy member made of an aluminum alloy for casting containing, in mass %, Si: 4.0-7.5%, Cu: 1.5-4.0%, Zn: 1.0% or more, and Mg: 0.2-0.8%, wherein a remainder of the aluminum alloy for casting consists of Al and unavoidable impurities, and wherein
 the aluminum alloy member has a tensile strength of 230 MPa or larger, a 0.2% proof stress of 180 MPa or larger, a high-cycle fatigue strength of 100 MPa or larger, and a low-cycle fatigue strength of 8,000 cycles or more.   
     
     
         6 . The aluminum alloy member according to  claim 5 , wherein Mg 5 Si 6 , which can be measured by using TEM, is precipitated. 
     
     
         7 . A method for manufacturing an aluminum alloy member comprising:
 casting an aluminum alloy for casting into an aluminum-cast material, the aluminum alloy for casting containing, in mass %, Si: 4.0-7.5%, Cu: 1.5-4.0%, Zn: 1.0% or more, and Mg: 0.2-0.8%, and a remainder of the aluminum alloy for casting consisting of Al and unavoidable impurities; and   performing an artificial aging treatment on the aluminum-cast material by heating the aluminum-cast material to a heating temperature of 185 to 205° C. and keeping it at the heating temperature.