HOT-ROLLED SECTION IRON MADE OF SPRING STEEL Russian patent published in 2009 - IPC C21D8/06 C22C38/60 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy field, particularly it relates to manufacturing of round bar of diametre from 12 up to 34 mm for manufacturing of heavy heavy duty springs of different allocation. For providing of increased level of consumer properties rolled stock is received from steel, containing components, wt %: C - 0.39-0.45, Mn - 0.60-0.90, Si -1.50-1.80, Cr - 0.005-0.30, S - 0.005-0.030, N 0.005-0.010, As - 0.0001-0.03, Sn -0.0001-0.02, Pb - 0.0001-0.01, Zn - 0.0001-0.005 iron and admixtures - the rest, at execution of correlation: (As+Sn+Pb+5×Zn)≤0.07. In the capacity of admixtures steel o contains, wt %: P no more than 0.030; Cu no more than 0.25; Ni no more than 0.15; Al no more than 0.030. Rolled stock is implemented as hot-rolled, subject to refinement, allows ferrite- pearlite composition excluding sections of graphite, martensite, bainite and Widmanstatten, size of effective grain is 6-12 points, depth of decarbonised layer no more than 1.5% per side, macrostructure by center porosity, punctated nonuniformity, segregate square, undershrinked gathering no more than 3 points per each kind, segregation streamers no more than 1 point, nonmetallics by punctated sulfides, punctated oxides, stitch oxides, fragile silicates, plastic silicates, rigid silicates no more than 2.5 points per each kind, σ_B - 750-1400 N/mm², σ_t - 680-1300 N/mm², δ no less than 10%, ϕ no less than 30%.

EFFECT: rolled stock allows minimal level of mechanical anisotropy.

5 cl, 2 ex