STEEL OF UPGRADED CORROSION RESISTANCE Russian patent published in 2009 - IPC C22C38/58 C22C38/40 C22C38/38 C22C38/18 C22C38/08 C22C38/06 

FIELD: metallurgy.

SUBSTANCE: invention refers to metallurgy, particularly to production of carbonic and low-alloyed steels with upgraded corrosion resistance for fabricating pipe lines transporting liquids aggressive in corrosion respect. Steel contains carbon, manganese, silicon, chromium, nickel, copper, phosphorus, sulphur, aluminium, iron and unavoidable impurities, oxygen including, at the following ratio of components, wt %: carbon 0.03-0.25, manganese 0.15-1.60, silicon 0.01-0.80, chromium 0.01-0.50, nickel 0.01-0.60, copper 0.01-0.30, phosphorus not more, than 0.035, sulphur not more, than 0.010, aluminium 0.01-0.06, oxygen not more, than 0.005, iron and unavoidable impurities - the rest. The maximum alowed value of density of corrosion-active non-metallic inclusions in steel N_CANMI (corrosion active non-metallic inclusions)- inclusions/ mm²- is determined depending on oxygen contents in steel in compliance with condition |N_CANMI|≤7-1000|O₂|, where |N_CANMI| is the absolute value of density of corrosion-active non-metallic inclusions, and |O₂| is the absolute value of oxygen contents. Manganese contents are determined depending on sulphur contents in compliance with condition |Mn|≤2.0-145|S|, where |Mn| and [S| are the absolute values of manganese and sulphur contents. Additionally steel may contain niobium at amount of 0.01-0.07 wt %, vanadium at amount of 0.01-0.1 wt % and calcium at amount of 0.0001-0.008 wt %. Steel possesses upgraded corrosion resistance, hardness, viscosity, cold resistance and weldability at low production cost.

EFFECT: upgraded corrosion resistance, hardness, viscosity, cold resistance and weldability at low production cost.

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