PRODUCTION OF HIGH-STRENGTH CONTROLLED STEEL SHEET OF PERFECT MACHINABILITY Russian patent published in 2014 - IPC C21D8/02 C21D9/46 C22C38/14 B21C37/02 

FIELD: metallurgy.

SUBSTANCE: high-strength cold-rolled steel sheet of perfect machinability is made of steel slab including the following components in wt %: C 0.05-0.12, 0.05 and 0.12, Si 0.5 or less, Mn 1.8-4.0, 1.8 and 4.0, Ti 0.005-0.06, 0.005 and 0.06, Nb 0.005-0.1, 0.005 and 0.1, Al 0.1 or less, Fe and unavoidable impurities making the rest. Continuous annealing comprises heating at mean rate of V₁ 0.3-8°C/s to 700°C-steel sheet temperature T₁ (°C). Said temperature is defined by the formula T₁=0.98 T_M, where T_M is maximum final temperature (°C) of steel sheet at continuous annealing in the range of not under point Ac₁ to under point Ac₃.

EFFECT: preservation of shape and elongation, adaptability for application of chemical conversion coating and welding.

5 cl, 3 tbl, 3 dwg