Copper alloy with excellent stress relaxation resistance property and production method therefor

#1. Field of the Invention

#The present invention relates to copper alloy having a stress relaxation resistance property suitable for use in applications such as electrical and electronic equipment related components, i.e., springs, switches, connectors, diaphragms, sockets, bellows, fuse-clips, sliding pieces, bearings and bushes, and automobile sheet-belt springs, washers, etc., such as those being worked from sheets or strips; bourdon tubes, flexible metal hoses, hose bellows, and sleeve bearings, etc., such as those being worked from tubes; and furthermore, coil springs and others, etc., such as those being worked from wires and rods.

#2. Discussion of the Background

#Having generally described this invention, a further understanding can be obtained by reference to certain specific examples which are provided herein for purposes of illustration only and are not intended to be limiting unless otherwise specified.

#Ingots of various compositions (Nos. 1 to 15) shown in Table 1 were casted by melting in graphite crucibles covered with charcoal in an electric furnace in the air atmosphere. A size of an ingot was typically of a thickness of 50 mm×a width of 80 mm×a length of 190 mm and the surfaces, front and back, were surface ground, thereafter, heated at 800° C. and following the heating, hot rolled to a thickness of 10 mm. The sheet of a thickness of 10 mm was heated at 800° C. for 30 min, thereafter, quenched in water and the surfaces were surface ground to a thickness of 9.8 mm. The sheet of a thickness of 9.8 mm is cold rolled to a thickness of 0.50 mm without applying annealing in the course of the cold rolling. The sheet was then held in a salt bath at 600° C. for 30 sec and thereafter, quenched in water. Thereafter, the sheet is further cold rolled to a thickness of 0.25 mm. The thus thinned sheet was held in a salt bath at 425° C. for 30 sec and thereafter, quenched in water to prepare a copper alloy sheet.

#Further, 6% phosphor bronze C5191 of a comparative alloy No. 16 is produced in horizontal casting, after a homogenization treatment, cold rolling and annealing are repeated as a pair on the alloy sheet to a thickness of 0.25 mm and the thinned sheet was held in a salt bath at 350° C. for 30 sec to prepare a comparative specimen. 1 TABLE 1 alloy compositions (O, H and S in ppm and the other elements in wt %) specimen No. Cu Sn Ni Zn O H S others Present invention alloys 1 residue 3.6 0.6 2.0 13 0.6 8 0.001 Ag, 0.005 Mg, 0.02Si, 0.001 Al, 0.0002 Ca 2 residue 3.6 0.7 1.0 18 0.7 6 0.01 Mg, 0.02 Si, 0.1 Mn, 0.005 Cr, 0.001 Zr 3 residue 3.5 1.0 2.0 13 0.5 7 0.01 Mg, 0.01 B, 0.001 Pb, 0.001 C 4 residue 3.4 0.8 0.1 18 0.6 4 0.01 Mg, 0.02 P 5 residue 3.6 0.8 4.5 9 0.4 5 0.0001 Ca, 0.01 P, 0.005 Mg, 0.001 Be 6 residue 3.1 0.6 0.5 18 0.5 5 0.01 Mg, 0.01 P, 0.001 Co, 0.002 Sb 7 residue 3.1 0.9 4.8 8 0.5 6 0.01 Mg, 0.01 P, 0.001 B, 0.001 C 8 residue 3.9 0.6 0.1 20 0.8 8 0.001 Fe, 0.0002 Pb, 0.05 Mg, 0.002 ln 9 residue 3.9 0.9 4.9 13 0.4 5 0.01 Mg, 0.01P, 0.000 2Pb, 0.002 Ti comparative alloys 10 residue 3.5 0.8 0* 35* 0.6 28* 0.1 Si*, 0.02 Pb* 11 residue 2.8* 0.3* 6.0* 15 2.5* 17 0.05 P* 12 residue 4.2* 0.4* 2.0 18 0.8 5 0.15 Mg* 13 residue 3.5 0.4* 2.0 10 0.6 6 0.01 Mg, 0.01 P 14 residue 3.4 1.2* 6.0* 13 0.5 4 0.02 Ca*, 0.2 Mn*, 0.01 P, 0.1 Fe* 15 residue 4.1* 1.1* 2.0 15 0.6 25* 0.05 P*, 0.2 Be*, 0.01 C* 16 residue 6.0* 0* 0* 15 2 18 0.10 P* *outside a range of the present invention.