METHOD OF BLADES MANUFACTURING Russian patent published in 2009 - IPC C21D8/02 C22C38/42 C22C38/46 

FIELD: metallurgy.

SUBSTANCE: invention concerns metallurgy field. Particularly it concerns rolling mill, and can be used at manufacturing on continuous broad-strip mill of strips for electro-welded straight-line-seam casings, intended for development of oil and gas wells. For improving of blades and screening yield it is received slab from steel, containing following chemical composition: wt %: 0.18-0.26 C; 0.14-0.36 Si; 0.30-0.80 Mn; 0.7-1.1 Cr; 0.10-0.30 Mo; 0.01-0.06 Nb; 0.01-0.06 Al; not more than 0.06 V; not more than 0.05 Ti; not more than 0.30 Ni; not more than 0.20 Cu; not more than 0.005 S; not more than 0.015 P; not more than 0.008 N; the rest is Fe, at fulfillment of conditions: Nb+V+Ti≤0.15% and at pollution of steel structure by nitrides which are not larger than 2 points and other nonmetallics not larger than 2.5 points. Slab is exposed to heating, hot rolling with regulated finishing temperature with receiving of blade, cooling by water and blade is reeled into rolls. Finishing temperature is kept equal 880-920°C, and blades cooling is implemented by water till temperature 630-690°C. At that before heating for rolling slab is exposed to annealing by means of heating till 600-650°C, cooling with speed not more than 25°C/h till temperature not lower than 250°C, reheating with speed not more than 60°C/h till temperature 630-650°C and further cooling by means of furnace.

EFFECT: improving of blades and recovery.

3 cl, 1 ex, 3 tbl