LOW CARBON COLD ROLLED AUTOMOBILE BODY SHEET STEEL FOR DEEP PUNCHING Russian patent published in 2010 - IPC C22C38/50 C21D8/04 

FIELD: metallurgy.

SUBSTANCE: invention refers to ferrous metallurgy, particularly to low carbon cold rolled automobile body sheet steel for punched parts of automobile body. Steel contains carbon, silicon, manganese, sulphur, phosphorus, chromium, nickel, copper, nitrogen, aluminium, titanium, niobium, and iron at the following ratio of elements, wt %: carbon ≤ 0.007, manganese 0.15 ÷ 0.25, silicon ≤ 0.02, sulphur ≤ 0.013, phosphorus 0.012 ÷ 0.015, chromium ≤ 0.03, nickel ≤ 0.03, copper ≤ 0.05, nitrogen ≤ 0.007, aluminium 0.03 ÷ 0.06, titanium (2.4S+3.43N) ÷ (2.4S+3.43N)+0.03, niobium 7.75C ÷ 7.75C+0.02, iron the rest, where (S), (N) and (C) - are contents of sulphur, nitrogen and carbon in steel. Steel possesses ultimate stress σ_u.s = 270 ÷ 350 H/mm², yield point σ_y≤ 210 H/mm², specific elongation δ₄≥ 38 %, coefficient of plastic anisotropy r₉₀ ≥ 1.4 and index of deformation hardening n₉₀ ≥ 0.18.

EFFECT: improved consumer properties of steel.

1 ex