METHOD OF MAKING STRIPS FROM LOW-ALLOY STEEL Russian patent published in 2014 - IPC C21D8/02 C22C38/38 C22C38/40 B21B1/26 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, particularly, to pipe rolling and can be used for production of pipes for gas and oil mains in northern areas and seismic zones. Slabs are heated to 1200-1260°C, rolled, subjected to fast cooling and winding. Note here that rolling finishing and winding temperatures make 780-840°C and 530-590°C, respectively. Strip accelerated cooling is carried out in two steps. Note here that at first step at steel carbon equivalent C_eq=0.36-0.37% strip is cooled to 620±20°C, while at C_eq=0.42-0.43% - to 600±20°C. At second step strip is cooled at the rate of 5-30°C/s to winding temperature. Slab is made of steel containing in wt %: 0.05-0.11 C, 1.45-1.75 Mn, 0.15-0.30 Si, 0.001-0.06 V, 0.04-0.08 Nb, 0.01-0.025 Ti, 0.02-0.05 Al, 0.01-0.25 Cr, 0.01-0.25 Ni, 0.01-0.25 Cu, [Cr]+[Ni]+[Cu]≤0.60%, 0.0001-0.005 S, 0.0001-0.015 P, 0.001-0.010 N.

EFFECT: higher strength and ductility at negative temperatures, better rolled stock bondability.

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