SHEET COLD-ROLLED STEEL FOR PUNCHING Russian patent published in 2009 - IPC C22C38/14 C22C38/12 

FIELD: metallurgy.

SUBSTANCE: invention relates to steel manufacturing and can be used for manufacturing of sheet cold-rolled steel, provided for deep punching. Steel contains carbon, manganese, silicon, sulphur, phosphorus, chrome, nickel, copper, nitrogen, aluminium, titanium, niobium and iron at following correlation of components, wt %: carbon 0.070÷0.071, manganese 0.080÷0.270, silicon 0.010÷0.030, sulphur 0.013÷0.015, phosphorus 0.012÷0.017, chrome 0.030÷0.040, nickel 0.030÷0.040, copper 0.050÷0.060, nitrogen 0.007÷0.008, aluminium 0.025÷0.070, titanium 2.4[S]+3.43[N] ÷ 2.4[S]+3.43[N]+0.03, niobium 7.75[C] ÷ 7.75[C]+0.02, iron is the rest, where [S] - sulphur content, [N] - nitrogen content, [C] - carbon content, and allows ultimate strength σ_u =270÷350 N/mm², yield strength σ_y≤180 N/mm² and percentage elongation δ₄≥38%.

EFFECT: increasing of sheets yield of formability category CB and OCB, and also extension and increasing of consumer properties.

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