MANUFACTURING METHOD OF ZINC-PLATED STRIP STEEL COIL Russian patent published in 2012 - IPC C23C2/06 C23C2/36 C22C38/40 

FIELD: metallurgy.

SUBSTANCE: method involves passage of cold-rolled strip steel coil through bath with molten slag, cooled and rolled; at that, steel strip containing the following components is used, wt %: carbon 0.04 - 0.08, manganese 0.24 - 0.39, silicon 0.01 - 0.03, sulphur 0.013 - 0.09, phosphorus 0.001 - 0.017, up to 0.1 of chrome and nickel, which is zinc-plated by being passed through the above bath at temperature of T_{hot z.p.}°C, and at the speed V_{hot z.p.}, m/s, which are determined based on empirically obtained parameters of hot zinc plating as per equations T_{hot z.p.} = 480.63 - 0.015 σ_u.r.c + 12.73 C_equiv - 0.057 δ_{hot z.p.} and V_{hot z.p.}=161.93 - 0.017 σ_y.s.+ 0.069 σ_u.r.h, where σ_u.r.c and σ_y.s.c - ultimate resistance and yield strength of cold-rolled metal, σ_u.r.h and δ_h.r. - ultimate resistance and relative elongation of hot-rolled strip, and C_equiv - carbon equivalent equal to C_equiv = [C] + [Mn]/9 + [Si]/3; at that, [C], [Mn], [Si] - content of carbon, manganese and silicon in steel, wt %, and strip steel obtaining is provided with σ_u.r.h= 370 - 420 MPa and δ_h.r. = 28 - 36 % with zinc coating with fine irregularities Ra = 0.4 - 0.7 mcm.

EFFECT: invention allows improving consumer properties of zinc-plated strip steel coil owing to optimising the parameters of zinc-plating process.

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