BAR OUT OF MEDIUM ALLOYED STEEL FOR COLD DIE FORGING Russian patent published in 2008 - IPC C21D8/06 C22C38/60 

FIELD: metallurgy.

SUBSTANCE: invention refers to production of bar of 12-36 mm diameter for cold die forging of parts. To facilitate rational conditions of cold die forging simultaneously upgrading process plasticity and viscosity bar is produced out of steel containing wt %: C 0.37-0.43, Mn 0.70-1.00, Si 0.17-0.37, Ni 0.40-0.70, Cr 0.40-0.60, Mo 0.15-0.25, S 0.005-0.035, P 0.005-0.035, N 0.005-0.015, O₂ 0.001-0.015, As 0.0001-0.03, Sn 0.0001-0.02, Pb 0.0001-0.01, Zn 0.0001-0.005, iron and impurities at maintaining the ratio: (As+Sn+Pb+5×Zn)≤0.07; 0.60≤(C+Mn/6)+(Cr+Mo)/5≤0.76, at that a bar has uniform spheroidising structure, containing of not less, than 60% of grain pearlite, dimension of actual grain 5-10 points, non-metallic inclusions for suplhides, oxides, and nitrides not more, than 3 points in each kind, macrostructure for central porosity, pointed non-uniformity, liquation square, sub-shrinking liquation not more, than 3 points in each kind, liquation strips not more, than 1 point, σ_t not more, than 660 Mpa, δ not less, than 15%, Ψ less, than 55%, hardenability on hardness of a sample at end hardening at the distance of 1.5 mm from the end 43-58 HRC, at the distance 5.0 mm from the end 40-55 HRC at the distance 9.0 from the end 38-54 HRC, cutability for value of wear of back edge of cutter h₃ not more, than 0.40 mm at cutting path L-1320 m, cold shrinkage not less, than 1/3 of bar height.

EFFECT: facilitating rational conditions of cold die forging of parts at simultaneous upgrading of process plasticity and viscosity.

4 cl, 2 ex