Copper alloy and process for producing the same

Abstract

A copper alloy that has a specific chemical composition, the balance being Cu and impurities, in which the relationship between the total number N and the diameter X satisfies the following formula (1). This copper alloy is obtained by cooling a bloom, a slab, a billet or an ingot in at least a temperature range from the temperature of the bloom, the slab, the billet or the ingot just after casting to 450° C., at a cooling rate of 0.5° C./s or more. After the cooling, working in a temperature range of 600° C. or lower and further heat treatment of holding for 30 seconds or more in a temperature range of 150 to 750° C. are desirably performed. The working and the heat treatment are most desirably performed for a plurality of times. log N <0.4742+17.629×exp(−0.1133× X )  (1) wherein N means the total number of precipitates and inclusions, having a diameter of not smaller than 1 μm which are found in 1 mm 2 of the alloy; and X means the diameter in μm of the precipitates and the inclusions having a diameter of not smaller than 1 μm.

1 . A copper alloy characterized in that the alloy consists of, by mass %, one or more elements selected from Zn, Sn, Ag, Mn, Fe, Co, Al, Ni, Si, Mo, V, Nb, Ta, W, Ge, Te and Se of 0.1 to 20% respectively or in total, and the balance Cu and impurities; and the alloy satisfies the following formula (1): 
       log  N≦ 0.4742+17.629 exp(−0.1133  X )  (1) wherein N means the total number of precipitates and inclusions, having a diameter of not smaller than 1 μm, which are found in 1 mm 2  of the alloy; and X means the diameter in μm of the precipitates and the inclusions having a diameter of not smaller than 1 μm.    
   
   
       2 . A copper alloy characterized in that the alloy consists of, by mass %, any one element selected from Ti of 0.01 to 5%, Zr of 0.01 to 5% and Hf of 0.01 to 5%, and one or more elements selected from Zn, Sn, Ag, Mn, Fe, Co, Al, Ni, Si, Mo, V, Nb, Ta, W, Ge, Te and Se of 0.01 to 20% respectively or in total, and the balance Cu and impurities; and the alloy satisfies the following formula (1): 
       log  N≦ 0.4742+17.629 exp(−0.1133  X )  (1) wherein N means the total number of precipitates and inclusions, having a diameter of not smaller than 1 μm, which are found in 1 mm 2  of the alloy; and X means the diameter in μm of the precipitates and the inclusions having a diameter of not smaller than 1 μm.    
   
   
       3 . A copper alloy characterized in that the alloy consists of, in mass %, Cr of 0.01 to 5%, and one or more elements selected from Zn, Sn, Ag, Mn, Fe, Co, Al, Ni, Si, Mo, V, Nb, Ta, W, Ge, Te and Se of 0.01 to 20% respectively or in total, and the balance Cu and impurities; and the alloy satisfies the following formula (1): 
       log  N≦ 0.4742+17.629 exp(−0.1133  X )  (1) 
     wherein N means the total number of precipitates and inclusions, having a diameter of not smaller than 1 μm, which are found in 1 mm 2  of the alloy; and X means the diameter in μm of the precipitates and the inclusions having a diameter of not smaller than 1 μm.  
   
   
       4 . A copper alloy according to  claim 1 , characterized in that the alloy contains, instead of a part of Cu, one or more elements selected from Mg, Li, Ca and rare earth elements of 0.001 to 2 mass % respectively or in total.  
   
   
       5 . A copper alloy according to  claim 1 , characterized in that the alloy contains, instead of a part of Cu, one or more elements selected from P, B, Bi, TI, Rb, Cs, Sr, Ba, Tc, Re, Os, Rh, In, Pd, Po, Sb, Au, Ga, S, Cd, As and Pb of 0.001 to 3 mass % respectively or in total.  
   
   
       6 . A copper alloy according to  claim 1 , characterized in that the alloy contains, instead of a part of Cu, Be of 0.1 to 5 mass %.  
   
   
       7 . A copper alloy according to  claim 1 , wherein the ratio of the “maximum value of an average content” and the “minimum value of an average content” of at least one alloy element in a micro area is not smaller than 1.5.  
   
   
       8 . A copper alloy according to  claim 1 , wherein the grain diameter is 0.01 to 35 μm.  
   
   
       9 . A method for producing a copper alloy, comprising cooling a bloom, a slab, a billet or an ingot obtained by melting a copper alloy having a chemical composition described in  claim 1  followed by cooling in at least a temperature range from the temperature of the bloom, the slab, the billet or the ingot just after casting to 450° C. at a cooling rate of 0.5° C./s or more, so that the relationship between the total number N and the diameter X satisfies the following formula (1): 
       log  N≦ 0.4742+17.629 exp(−0.1 133  X )  (1) wherein N means the total number of precipitates and inclusions, having a diameter of not smaller than 1 μm which are found in 1 mm 2  of the alloy; and X means the diameter in μm of the precipitates and the inclusions having a diameter of not smaller than 1 μm.    
   
   
       10 . A method for producing a copper alloy, comprising cooling a bloom, a slab, a billet or an ingot obtained by melting a copper alloy having a chemical composition described in  claim 1  followed by cooling in at least a temperature range from the temperature of the bloom, the slab, the billet or the ingot just after casting to 450° C. at a cooling rate of 0.50° C./s or more, and performing working in a temperature range of 600° C. or lower, so that the relationship between the total number N and the diameter X satisfies the following formula (1): 
       log  N≦ 0.4742+17.629 exp(−0.1133  X )  (1) 
     wherein N means the total number of precipitates and inclusions, having a diameter of not smaller than 1 μm which are found in 1 mm 2  of the alloy; and X means the diameter in μm of the precipitates and the inclusions having a diameter of not smaller than 1 μm.  
   
   
       11 . A method for producing a copper alloy, comprising cooling a bloom, a slab, a billet, or a ingot obtained by melting a copper alloy having a chemical composition described in  claim 1  followed by cooling in at least a temperature range from the temperature of the bloom, the slab, the billet or the ingot just after casting to 450° C. at a cooling rate of 0.5° C./s or more, performing working in a temperature range of 600° C. or lower, and then performing heat treatment of holding for 30 seconds or more in a temperature range of 150 to 750° C., so that the relationship between the total number N and the diameter X satisfies the following formula (1): 
       log  N≦ 0.4742+17.629 exp(−0.1133  X )  (1) wherein N means the total number of precipitates and inclusions, having a diameter of not smaller than 1 μm which are found in 1 mm 2  of the alloy; and X means the diameter in μm of the precipitates and the inclusions having a diameter of not smaller than 1 μm.    
   
   
       12 . A method for producing a copper alloy according to  claim 11 , wherein the working in a temperature range of 600° C. or lower and the heat treatment of holding for 30 seconds or more in a temperature range of 150 to 750° C. are performed for a plurality of times.  
   
   
       13 . The method for producing a copper alloy according to  claim 1 , wherein the working in a temperature range of 600° C. or lower is performed after the final heat treatment.