THERMOMECHANICAL TREATMENT METHOD FOR ROLLED METAL Russian patent published in 2012 - IPC C21D8/08 

FIELD: metallurgy.

SUBSTANCE: hot rolling of workpiece is performed in two stages with total reduction of 60-76% of cross section area of workpiece at each stage, exposure after each rolling stage, preliminary cooling of workpiece to temperature of not lower than Ar₃, final rolling in that temperature zone, cyclic cooling of rolled surface with intermediate and final heating of surface to temperatures of lower than point Ac₁ and final cooling in the air; at that, after the first stage of hot rolling there performed is exposure during 15-17 s, and cyclic cooling of surface is performed using the number of cycles equal to three. In the first and the second cycles the cooling is performed during (0.015-0.020)D s, and in the third one -during (0.045-0.060)D s; at that, after the first and the second cooling cycles there performed is intermediate heating during 0.8-1.1 s and 0.2-0.3 s respectively, where D - rolled metal diameter, mm.

EFFECT: high strength characteristics of fittings and higher relative elongation at maximum stress.

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