Steel for Cold Forging and Nitriding Excellent in Cold Forgeability and Nitriding Properties, and Cold-Forged and Nitrided Part Using Same

Steel for cold forging and nitriding, comprising, in mass %,

• C:
• 0.15% to 0.30%,
• Si:
• 0.15% to 0.40%,
• Mn:
• 0.50% to 1.50%,
• Cr:
• 0.50% to 2.00%,
• Mo:
• 0.02% to 0.30%,
• Al:
• 0.025% to 0.300%,
• V:
• 0.05% to 0.30%, and
• N:
• 0.004% to 0.030%,
• with the balance consisting of Fe and inevitable impurities,
• wherein the steel satisfies the following formulas 1 and 2:
• 0.15
• <
• 0.1
• ×
• [
• Cr
• ]
• +
• 0.67
• ×
• [
• Al
• ]
• +
• 0.24
• ×
• [
• V
• ]
• <
• 0.43
• (
• 1
• )
• 0.25
• <
• 0.8
• ×
• [
• C
• ]
• +
• 0.1
• ×
• [
• Cr
• ]
• +
• 0.36
• ×
• [
• V
• ]
• <
• 0.5
• (
• 2
• )
• wherein [Cr], [Al], [V], [C], and [Mo] represent Cr, Al, V, C, and Mo contents (mass %), respectively,
• wherein the steel has a structure that contains ferrite and perlite and may contain bainite, wherein an area fraction of perlite is 10% or more and 60% or less, and an area fraction of bainite is 0% or more and 10% or less, and
• wherein the steel has a surface hardness of 173Hv or less in terms of Vickers hardness.