PROCEDURE FOR PRODUCTION OF TUBE STRIPS FOR MAINS Russian patent published in 2010 - IPC C21D8/02 C22C38/12 

FIELD: metallurgy.

SUBSTANCE: invention refers to metallurgy, particularly to production of high-duty tube strips of 15-28 mm thickness. There is produced steel containing, wt %: C-0.03-0.07, Mn-1.75-2.10, Si-0.16-0.40, Ni-0.040-0.80, Cu-0.001-0.50, Al-0.01-0.10, Mo-0.03-0.50, Nb-0.01-0.10, V-0.001-0.04, S-0.001-0.003, P-0.003-0.012, Ca-0.001-0.010, Ti-0.01-0.05, iron - the rest. Steel is cast into slabs and preliminary rolled across lengthwise axis of slabs at summary deformation of 60-80%. Further, a semi-finished rolled product is cooled in air to temperature of finish roll beginning equal to (Ar₃+150)°C and finish rolled in the direction of lengthwise axis at temperature of end of rolling equal to Ar₃+(20-40)°C. Finally, the strip is cooled to temperature 350-450°C first at rate of 15-50°C/s and then at rate of not more, than 1°C/s. Also ratio of summary degrees of deformations of preliminary rolling and finish rolling is (1:4)-(1:8).

EFFECT: upgraded strength, cold resistance and low temperature viscosity in zone of thermal effect at strip welding.

3 ex, 3 tbl