THICK STEEL SHEET HAVING EXCELLENT IMPACT STRENGTH OF THERMAL EFFECT ZONE, AND METHOD FOR PRODUCTION THEREOF Russian patent published in 2025 - IPC C21D8/02 C22C38/14 C22C38/12 C22C38/08 C22C38/06 C22C38/04 C22C38/02 

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, namely to steel material used for fabrication of welded structures in shipbuilding. Material contains, wt.%: 0.04–0.07 of carbon, 1.5–1.7 of manganese, 0.1–0.3 of silicon, 0.01–0.04 of aluminium, 0.7–1.0 of nickel, 0.05–0.30 of molybdenum, 0.010–0.018 of titanium, 0.01–0.03 of niobium, 0.003–0.006 of nitrogen, 0.007 or less phosphorus, 0.002 or less sulphur, the rest is iron and unavoidable impurities. Heat-affected zone at welding with heat input of 100–200 kJ/cm contains bainite phase with area fraction of 90% or more and residual needle ferrite in the area from fusion line (FL) to FL+3 mm.

EFFECT: material possesses both high strength and impact strength of base metal, and high strength and impact strength of thermal influence zone.

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