Non-heat treated wire rod having excellent drawability and impact toughness and method for manufacturing same
Provided are a non-heat treated wire rod having high drawability and impact toughness, and a method for manufacturing the non-heat treated wire rod. The non-heat treated wire rod includes, by wt %, C: 0.02% to 0.30%, Si: 0.05% to 0.8%, Mn: 0.5% to 2.0%, Cr: 1.0% or less, P: 0.03% or less, S: 0.03% or less, sol.Al: 0.01% to 0.07%, N: from greater than 0.01% to 0.02%, Nb: 0.1% or less, V: 0.5% or less, and Ti: 0.1% or less, and a balance of Fe and inevitable impurities, wherein the non-heat treated wire rod has a microstructure including ferrite and pearlite.
1 . A non-heat treated wire rod, the non-heat treated wire rod comprising, by wt %, C: 0.02% to 0.30%, Si: 0.05% to 0.8%, Mn: 0.5% to 2.0%, Cr: 1.0% or less, P: 0.03% or less, S: 0.03% or less, sol.Al: 0.01% to 0.07%, N: from greater than 0.01% to 0.02%, Nb: 0.1% or less, V: 0.5% or less, and Ti: 0.1% or less, and a balance of Fe and inevitable impurities,
wherein the non-heat treated wire rod has a microstructure comprising ferrite and pearlite, and
the ferrite and the pearlite alternate with each other and are continuous or discontinuous in a direction parallel to a rolling direction of the non-heat treated wire rod such that the non-heat treated wire rod has a banded structure formed by ferrite bands and pearlite bands,
wherein the ferrite has an average grain size of 10 m in a C cross-section perpendicular to the rolling direction, and
wherein when a 30% to 60% drawing process is performed on the non-heat treated wire rod, the non-heat treated wire rod has an average room-temperature impact toughness of 100 J or more.
2 . A non-heat treated wire rod, the non-heat treated wire rod comprising, by wt %, C: 0.02% to 0.30%, Si: 0.05% to 0.8%, Mn: 0.5% to 2.0%, Cr: 1.0% or less, P: 0.03% or less, S: 0.03% or less, sol.Al: 0.01% to 0.07%, N: from greater than 0.01% to 0.02%, Nb: 0.1% or less, V: 0.5% or less, and Ti: 0.1% or less, and a balance of Fe and inevitable impurities,
wherein the non-heat treated wire rod has a microstructure comprising ferrite and pearlite,
the ferrite comprises a plurality of ferrite bands continuously or discontinuously formed in a direction parallel to a rolling direction of the non-heat treated wire rod with predetermined intervals therebetween, and
the pearlite comprises a plurality of pearlite bands continuously or discontinuously formed on inner or outer sides of the ferrite bands in the direction parallel to the rolling direction of the non-heat treated wire rod,
wherein the ferrite has an average grain size of 10 m in a C cross-section perpendicular to the rolling direction, and
wherein when a 30% to 60% drawing process is performed on the non-heat treated wire rod, the non-heat treated wire rod has an average room-temperature impact toughness of 100 J or more.
3 . The non-heat treated wire rod of claim 2 , wherein the ferrite bands and the pearlite bands are alternately formed in the direction parallel to the rolling direction of the non-heat treated wire rod.
4 . The non-heat treated wire rod of claim 2 , wherein a distance between the ferrite bands adjacent to the ferrite bands is within a range of 50 m or less.
5 . The non-heat treated wire rod of claim 2 , wherein the ferrite has an area fraction of 30% to 90%.
6 . The non-heat treated wire rod of claim 2 , wherein the pearlite bands have an average thickness of 30 m or less in an L-shaped cross-section parallel to the rolling direction.