COLD-RESISTANT WELDABLE ARC-STEEL OF IMPROVED STRENGTH Russian patent published in 2019 - IPC C22C38/48 C22C38/16 

FIELD: metallurgy.

SUBSTANCE: invention relates to the field of metallurgy, in particular to the production of sheet metal from cold-resistant arc-steel of increased strength and improved weldability for use in shipbuilding, fuel and energy complex, mechanical engineering, bridge construction and other industries. Steel contains the following component ratio, wt. %: carbon 0.05–0.07, silicon 0.15–0.35, manganese 1.15–1.35, nickel 0.55–0.70, chromium not more than 0.15, copper 0.05–0.20, niobium 0.02–0.04, vanadium not more than 0.01, titanium is not more than 0.005, aluminum is 0.02–0.05, nitrogen is 0.001–0.009, sulfur 0.001–0.005, phosphorus 0.001–0.010, calcium 0.0001–0.0300, iron – balance. Steel has a Cequ carbon equivalent value of not more than 0.38 %, and an ultrafine ferrite-bainite structure with quasi-polygonal ferrite and bainite.

EFFECT: guaranteed yield strengths of 355 and 390 MPa in thicknesses from 25 to 50 mm, viscoplastic properties and characteristics of crack resistance is obtained according to the criterion of critical disclosure at the tip of the crack CTOD, the temperature of the viscous-brittle transition Tkb and the temperature of zero plasticity NDT.

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