Wire rod and steel wire for spring, having enhanced toughness and corrosion fatigue properties, and respective manufacturing methods therefor

A steel wire for springs with improved toughness and corrosion fatigue properties, the steel wire comprising, by weight percent:

• carbon (C):
• 0.4 to 0.7%,
• silicon (Si):
• 1.2 to 2.3%,
• manganese (Mn):
• 0.2 to 0.69%,
• chromium (Cr):
• 0.2 to 0.8%, and
• a balance of iron (Fe) and inevitable impurities, and
• a grain size of ferrite and colony is 10.3 μm or less,
• a grain size of the colony is 8.0 μm or less, and
• a Charpy impact energy value is 45 J/cm2 or more.

A wire rod for springs with improved toughness and corrosion fatigue properties, the wire rod consisting of, by weight percent:

• carbon (C):
• 0.4 to 0.7%,
• silicon (Si):
• 1.2 to 2.3%,
• manganese (Mn):
• 0.2 to 0.8%,
• chromium (Cr):
• 0.2 to 0.8%, and
• a balance of iron (Fe) and inevitable impurities,
• wherein a grain size of ferrite and colony is 13.2 μm or less,
• wherein a grain size of the colony is 8.0 μm or less, and
• wherein a Charpy impact energy is 38 J/cm2 or more.