FIELD: metallurgy.
SUBSTANCE: invention relates to the field of metallurgy, namely the manufacture of flexible-rolled flat steel product of variable thickness, consisting of high-strength manganese steel. To obtain a flat steel product of variable thickness, hot-rolled or cold-rolled steel strip, galvanized or non-galvanized, having a composition containing, wt %: С: from 0.0005 to 0.9, Мn: from 4 to 12, А1: up to 10, Р: <0.1, S: <0.1, N: <0.1, if necessary, one or more of the following: Si: up to 6, Сr: up to 6, Nb: up to 1, V: up to 1.5, Ti: up to 1.5, Мо: up to 3, Sn: up to 0.5, Сu: up to 3, W: up to 5, Со: up to 8, Zr: up to 0.5, Та: up to 0.5, Те: up to 0.5 and В: up to 1.5, the rest is iron with inevitable impurities. At least one step of rolling by a flexible method of the specified hot-rolled or cold-rolled strip is performed, while the temperature of the hot-rolled or cold-rolled strip before the first rolling step ranges from 60°С to a temperature below the Ас3 temperature, preferably 60-450°С. Non-galvanized flat steel product is galvanized.
EFFECT: flat steel product has high resistance to delayed hydrogen induced crack formation, hydrogen embrittlement and liquid metal embrittlement in welding.
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