Copper alloy with high strength and excellent processability in bending and process for producing copper alloy sheet

Abstract

The present invention provides a Cu—Fe—P alloy which has a high strength, high conductivity and superior bending workability. The copper alloy comprises 0.01 to 1.0% Fe, 0.01 to 0.4% P, 0.1 to 1.0% Mg, and the remainder Cu and unavoidable impurities. The size of oxides and precipitates including Mg in the copper alloy is controlled so that the ratio of the amount of Mg measured by a specified measurement method in the extracted residue by a specified extracted residue method to the Mg content in said copper alloy is 60% or less, thus endowing the alloy with a high strength and superior bending workability.

1 . A copper alloy having a high strength and superior bending workability, comprising 0.01 to 1.0% by mass of Fe, 0.01 to 0.4% by mass of P, 0.1 to 1.0% by mass of Mg, and remainder Cu and unavoidable impurities, wherein:
 the size of oxides and precipitates including Mg in the copper alloy is controlled so that the ratio of the amount of Mg described below in the extracted residue by the extracted residue method described below using a filter with an opening size of 0.1 μm to the Mg content in said copper alloy is 60% or less;   said extracted residue method is a method in which 10 g of said copper alloy is immersed in 300 ml of a methanol solution with a 10 mass % concentration of ammonium acetate, constant-current electrolysis is performed at a current density of 10 mA/cm 2  using this copper alloy as an anode and using platinum as a cathode, said solution in which only the matrix of this copper alloy is dissolved is subjected to suction filtration using a polycarbonate type membrane filter with an opening size of 0.1 μm, and the residue is separated and extracted on this filter; and   said amount of Mg in said extracted residue is the amount that is determined by ICP following dissolution of the residue on said filter by means of a solution in which aqua regia and water are mixed at a ratio of 1 to 1.   
   
   
       2 . The copper alloy according to  claim 1 , wherein in the grain size measured by a crystal orientation analysis method in which an electron back scattering pattern system is mounted on a field emission scanning electron microscope, the mean grain size described below is 6.5 μm or less, and the standard deviation of the mean grain size described below is 1.5 μm or less:
 wherein when n indicates the number of crystal grains measured and x indicates the grain size values measured, the mean grain size is expressed as (Σx)/n, and the standard deviation of the mean grain size is expressed as [nΣx 2 −(Σx) 2 ]/[n/(n−1) 1/2 ].   
   
   
       3 . A copper alloy having a high strength and superior bending workability, respectively containing 0.01 to 3.0% by mass of Fe, 0.01 to 0.4% by mass of P and 0.1 to 1.0% by mass of Mg, and remainder Cu and unavoidable impurities, wherein in the grain size measured by a crystal orientation analysis method in which an electron back scattering pattern system is mounted on a field emission scanning electron microscope, the mean grain size described below is 6.5 μm or less, and the standard deviation of the mean grain size described below is 1.5 μm or less:
 wherein when n indicates the number of crystal grains measured and x indicates the grain size values measured, the mean grain size is expressed as (Σx)/n, and the standard deviation of the mean grain size is expressed as [nΣx 2 −(Σx) 2 ]/[n/(n−1) 1/2 ].   
   
   
       4 . The copper alloy according to  claim 2 , wherein the ratio of small-angle grain boundaries which are grain boundaries between crystal grains in which the difference in crystal orientation is small, i.e., 5 to 15°, as measured by the crystal orientation method in the copper alloy, is 4% to 30%, taken as the ratio of the total length of the small-angle grain boundaries to the total length of the crystal grain boundaries in which the difference in crystal orientation is 5 to 180°. 
   
   
       5 . The copper alloy according to  claim 1 , wherein said copper alloy further contains Ni or Co, or both, at the rate of 0.01 to 1.0%. 
   
   
       6 . The copper alloy according to  claim 1 , wherein said copper alloy further contains Zn at the rate of 0.005 to 3.0%. 
   
   
       7 . The copper alloy according to  claim 1 , wherein said copper alloy further contains Sn at the rate of 0.01 to 5.0%. 
   
   
       8 . The copper alloy according to  claim 1 , wherein a copper alloy plate contains Mn or Ca, or both, at a total content of 0.0001 to 1.0% by mass. 
   
   
       9 . The copper alloy according to  claim 1 , wherein said copper alloy plate further contains one or more elements selected from a set comprising Zr, Ag, Cr, Cd, Be, Ti, Co, Ni, Au and Pt at a total content of 0.001 to 1.0% by mass. 
   
   
       10 . The copper alloy according to  claim 1 , wherein said copper alloy contains Hf, Th, Li, Na, K, Sr, Pd, W, S, Si, C, Nb, Al, V, Y, Mo, Pb, In, Ga, Ge, As, Sb, Bi, Te, B or mischmetal so that the total content of the elements is 0.1 by mass or less. 
   
   
       11 . A method for manufacturing a plate of the copper alloy according to  claim 1 , in which a copper alloy plate is obtained by casting, hot rolling, cold rolling and annealing, wherein the required time from the completion of the addition of the alloying elements in a melting furnace to the initiation of casting is set at 1200 seconds or less, and wherein the required time from the ejection of a ingot from the heating furnace to the completion of hot rolling is set at 1200 seconds or less. 
   
   
       12 . A method for manufacturing a plate of the copper alloy according to  claim 3 , in which a copper alloy plate is obtained by a process including casting, hot rolling, cold rolling, annealing and cold rolling, wherein the temperature upon the completion of hot rolling is set at 550° C. to 850° C., the subsequent cold rolling rate is set at 70 to 98%, the mean heating rate in the subsequent annealing is set at 50° C./s or greater, the mean cooling rate following the annealing is set at 100° C./s or greater, and the cold rolling rate in the subsequent final cold rolling is set in the range of 10 to 30%. 
   
   
       13 . A method for manufacturing a plate of the copper alloy according to  claim 1 , in which a copper alloy plate is obtained by a process including casting, hot rolling, cold rolling, annealing and cold rolling,
 wherein the required time from the completion of addition of alloying elements in a melting furnace to the initiation of casting is set at 1200 seconds or less, the required time from the ejection of a ingot from the heating furnace to the completion of hot rolling is set at 1200 seconds or less; and   wherein the temperature upon the completion of hot rolling is set at 550° C. to 850° C., the subsequent cold rolling rate is set at 70 to 98%, the mean heating rate in the subsequent annealing is set at 50° C./s or greater, the mean cooling rate following the annealing is set at 100° C./s or greater, and the cold rolling rate in the subsequent final cold rolling is set in the range of 10 to 30%.   
   
   
       14 . The copper alloy according to  claim 3 , wherein the ratio of small-angle grain boundaries which are grain boundaries between crystal grains in which the difference in crystal orientation is small, i.e., 5 to 15°, as measured by the crystal orientation method in the copper alloy, is 4% to 30%, taken as the ratio of the total length of the small-angle grain boundaries to the total length of the crystal grain boundaries in which the difference in crystal orientation is 5 to 180°. 
   
   
       15 . The copper alloy according to  claim 3 , wherein said copper alloy further contains Ni or Co, or both, at the rate of 0.01 to 1.0%. 
   
   
       16 . The copper alloy according to  claim 3 , wherein said copper alloy further contains Zn at the rate of 0.005 to 3.0%. 
   
   
       17 . The copper alloy according to  claim 3 , wherein said copper alloy further contains Sn at the rate of 0.01 to 5.0%. 
   
   
       18 . The copper alloy according to  claim 3 , wherein a copper alloy plate contains Mn or Ca, or both, at a total content of 0.0001 to 1.0% by mass. 
   
   
       19 . The copper alloy according to  claim 3 , wherein said copper alloy plate further contains one or more elements selected from a set comprising Zr, Ag, Cr, Cd, Be, Ti, Co, Ni, Au and Pt at a total content of 0.001 to 1.0% by mass. 
   
   
       20 . The copper alloy according to  claim 3 , wherein said copper alloy contains Hf, Th, Li, Na, K, Sr, Pd, W, S, Si, C, Nb, Al, V, Y, Mo, Pb, In, Ga, Ge, As, Sb, Bi, Te, B or mischmetal so that the total content of the elements is 0.1 by mass or less.