PCT No. PCT / JP97 / 01338 Sec. 371 Date Nov. 24, 1997 Sec. 102(e) Date Nov. 24, 1997 PCT Filed Apr. 18, 1997 PCT Pub. No. WO97 / 39176 PCT Pub. Date Oct. 23, 1997A
corrosion resistant steel cord for reinforcing rubber articles, particularly a belt and / or carcass of a pneumatic tire, has a
residual compressive stress inside the twisting
helix of each steel filament such that a ratio R1 / R0 is less than one, where R0 is the
radius of curvature of a
helix in each helically formed steel filament obtained by untwisting of the cord and R1 is the
radius of curvature of the
helix after removal of a
surface layer from the inside of the helix in the steel filament. The steel filaments have a tensile strength of 4,000-4,800 N / mm2. The cord does not have a wrapping wire around its outer
peripheral surface and has either a single twisted construction obtained by twisting 3 to 6 steel filaments in an
open structure having a space between adjacent filaments or a two-layer twisted construction obtained by surrounding a core of n=1-4 steel filaments with a sheath of n+(2-6) steel filaments in a rubber penetration structure having a space between adjacent filaments of the sheath or a three-layer twisted construction obtained by surrounding a core of a single steel filament with a first sheath of m=3-6 steel filaments and a second sheath of m+(2-6) steel filaments in a rubber penetration structure having a space between adjacent filaments of each sheath.