SECTION IRON MADE OF BORON STEEL OF INCREASED HARDENABILITY Russian patent published in 2009 - IPC C21D8/06 C22C38/54 C22C38/60 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy field. Particularly it relates to section iron for manufacturing of tooth gears, shafts, other critical parts, operating in conditions of load impacts. For cutability improvement with simultaneous increasing of plasticity and viscosity rolled metal is received from the steel, containing, wt %: C 0.16-0.23, Mn 0.60-0.90, Si 0.17-0.37, Cr 0.70-1.10, S 0.005-0.035, Ni 0.80-1.00, Al 0.02-0.05, Ti 0.01-0.06, N 0.005-0.010, B 0.001-0.005, Ca 0.001-0.010, As 0.0001-0.03, Sn 0.0001- 0.02, Pb 0.0001-0.01, Zn 0.0001-0.005, iron and unavoidable admixtures - the rest, at ratios: (As+Sn+Pb+5×Zi)≤0.07; (Ti/48)+(Al/27)-(N/14)≥(0.6×10^-3). Admixtures, wt %: Cu no more than 0.30, Mo no more than 0.03, P no more than 0.035. Tempered and annealed rolled stock allows lamellar ferrite - pearlite structure, size of effective grain 5-9 points, nonmetallics by punctated sulfides, punctated oxides, stitch oxides, fragile silicates, plastic silicates, rigid silicates with average grades no more than 3.5 per each kind, macrostructure by center porosity, punctated nonuniformity, segregation square, undershrinked gathering no more than 3 point per each kind, segregation streamers no more than 1 point, σ_B no more than 1200 MPa, σ_t no more than 1110 MPa, 5 no more than 12%, ψ no more than 62%, a_H KCU(+20) no more than 1470 kJ/m². Cutability - magnitude of wear by flank of cutting tool (h₃) with equal cutting path (L) - with L=1320 m, h₃ no more than 0.30 mm.

EFFECT: cutability improvement with simultaneous increasing of flexibility and viscosity of rolled stock.

4 cl, 2 ex