PRODUCTION METHOD OF CANDIES FROM LOW-ALLOYED STEEL Russian patent published in 2009 - IPC C21D8/10 C22C38/46 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy field, particularly to rolling manufacturing and can be used for receiving of candies for hydrogen-sulphidous resistant gas-oil pipelines welded with usage of heating by high-frequency currents. For increasing of candies cold resistance and resistance against hydrogen-sulphidous cracking it is implemented heating of slabs, multipass rough and finish rolling which is started at temperature not higher than 980°C with total reduction of cross-sectional area not less than 70% and is finished at temperature 830-870°C, cooling of candies by water is implemented up to temperature 520-620°C, herewith steel allows following chemical composition, wt %: 0.04-0.09 C, 0.15-0.37 Si, 0.60-1.30 Mn, 0.05-0.50 Cr, 0.01-0.04 Nb, 0.01-0.03 Ti, 0.01-0.05 Al, not more than: 0.04 V, 0.005 Ca, 0.010 N, 0.005 B, 0.30 Ni, 0.30 Cu, 0.012 P, 0.005 S, the rest is Fe, at following components correlation: P_CM=C+[Mn+Cr+Cu/20]+Si/30+Ni/60+V/10+5B<0.20; Al/N>2.0 , where: C, Mn, Cr, Cu, Si, Ni, V, B, Al, N - content in steel of carbon, manganese, chrome, copper, silicon, nickel, vanadium, aluminium and nitrogen correspondingly, P_CM - parametre of fracture strength.

EFFECT: increasing of candies cold resistance and stability against hydrogen-sulphidous cracking.

2 cl, 3 tbl