To provide a sheet material of a Cu-Ni-Si-based copper alloy, which has improved strength, improved bendability after having been notched, and improved stress relaxation resistance all in a high level.
The sheet material of the copper alloy has a composition comprising, by mass%, 0.7 to 4.2% Ni and 0.2 to 1.0% Si; further at least one of 1.2% or less Sn, 2.0% or less Zn, 1.0% or less Mg, 2.0% or less Co and 1.0% or less Fe as needed; or further at least one of Cr, B, P, Zr, Ti, Mn and V in a total amount of 3% or less; and the balance substantially Cu: and has a crystal orientation which satisfies the expression of I{420}/I0{420}1.0, wherein I{420} represents the X-ray diffraction intensity of a crystal face {420} on a sheet plane of the sheet material of the copper alloy; and I0{420} represents the X-ray diffraction intensity of the crystal face {420} of a standard powder of pure copper.
SUDA HISASHI
NARUEDA HIROTO
SUGAWARA AKIRA
Kenji Wada