Copper-coated steel wire, spring, stranded wire, insulated electric wire, and cable

A copper-coated steel wire comprising:

• a core wire made of a stainless steel;
• and
• a coating layer made of copper or a copper alloy and covering an outer peripheral surface of the core wire;
• a thickness of the coating layer being not less than 7.5 μm and not more than 200 μm, and
• in a cross section perpendicular to a longitudinal direction of the core wire, the outer peripheral surface of the core wire having a value of a maximum cross-sectional height Rt of not less than 45% and not more than 300% of a thickness of the coating layer.

A copper-coated steel wire comprising:

• a core wire made of a stainless steel;
• and
• a coating layer made of copper or a copper alloy and covering an outer peripheral surface of the core wire;
• a thickness of the coating layer being not less than 7.5 μm and not more than 200 μm,
• in a cross section perpendicular to a longitudinal direction of the core wire, the outer peripheral surface of the core wire having a value of an arithmetic mean roughness Ra of not less than 25% and not more than 90% of a thickness of the coating layer,
• in the cross section perpendicular to the longitudinal direction of the core wire, the outer peripheral surface of the core wire having a value of a maximum cross-sectional height Rt of not less than 45% and not more than 300% of the thickness of the coating layer,
• the steel constituting the core wire being an austenitic stainless steel,
• the coating layer having an alloy layer disposed in a region including an interface with the core wire, the alloy layer containing an alloy of nickel and a metallic element contained in the steel constituting the core wire, and
• the copper-coated steel wire having a tensile strength of not less than 300 MPa and not more than 3400 MPa.