Abstract: Provided is a steel wire rod for a high strength and high toughness spring having excellent cold workability, the steel wire rod having a composition comprising: in weight %, C: 0.4 to 0.7%, Si: 1.5 to 3.5%, Mn: 0.3 to 1.0%, Cr: 0.01 to 1.5%, Ni: 0.01 to 1.0%, Cu: 0.01 to 1.0%, B: 0.005 to 0.02%, Al: 0.1% or less, O: 0.0020% or less, P: 0.02% or less, S: 0.02% or less, N: 0.02% or less, remainder Fe, and other unavoidable impurities, having a microstructure formed of ferrite and pearlite, and in which a prior (before cooling) austenite grain size is 8 ?m or less.

Abstract: Provided is a die for shear drawing capable of performing continuous drawing and shear deformation at the same time. The die for shear drawing includes a material processing channel in which a material is sheared and drawn while passing therethrough, wherein the processing channel includes an inlet path positioned at a front end thereof, and an outlet path positioned at a rear end thereof, when viewed from a movement direction of a material. The inlet path and the outlet path are connected to intersect a central axes thereof at a certain angle, and the processing channel includes a cross-section reduction segment allowing an outlet cross-sectional area of the outlet path to be smaller than an inlet cross-sectional area of the inlet path to thereby draw out a material from an exit of the outlet path with the material filled therein.

Abstract: Provided is a die for shear drawing capable of performing continuous drawing and shear deformation at the same time. The die for shear drawing includes a material processing channel in which a material is sheared and drawn while passing therethrough, wherein the processing channel includes an inlet path positioned at a front end thereof, and an outlet path positioned at a rear end thereof, when viewed from a movement direction of a material. The inlet path and the outlet path are connected to intersect a central axes thereof at a certain angle, and the processing channel includes a cross-section reduction segment allowing an outlet cross-sectional area of the outlet path to be smaller than an inlet cross-sectional area of the inlet path to thereby draw out a material from an exit of the outlet path with the material filled therein.

Abstract: Provided is a steel wire rod for a high strength and high toughness spring having excellent cold workability, the steel wire rod having a composition comprising: in weight %, C: 0.4 to 0.7%, Si: 1.5 to 3.5%, Mn: 0.3 to 1.0%, Cr: 0.01 to 1.5%, Ni: 0.01 to 1.0%, Cu: 0.01 to 1.0%, B: 0.005 to 0.02%, Al: 0.1% or less, O: 0.0020% or less, P: 0.02% or less, S: 0.02% or less, N: 0.02% or less, remainder Fe, and other unavoidable impurities, having a microstructure formed of ferrite and pearlite, and in which a prior (before cooling) austenite grain size is 8 ?m or less.