PROCEDURE FOR PRODUCTION OF PLATE IRON Russian patent published in 2010 - IPC C21D8/02 C22C38/38 

FIELD: metallurgy.

SUBSTANCE: at melting iron in zone of thermal treatment procedure for plate iron production consists in melting steel, tapping, heating, thermo-deforming work-piece rolling and in finished plate accelerated cooling. For this purpose there is melted steel of the following chemical composition, wt %: carbon 0.03-0.20, manganese 0.50-2.10, silicon 0.10-0.50, niobium 0.01-0.15, aluminium 0.01-0.10, titanium 0.005-0.05, nitrogen 0.002-0.012, sulphur 0.0005-0.010, phosphorus 0.003-0.050, iron - the rest. Thermo-deformation rolling is finished in interval of temperatures from ((Aht+30°C) to (Aht-30°C) (ht - hot tempering). Successive accelerated cooling is performed in two stages:during the first stage - at rate 10-30°C/sec to temperature 650-550°C, then after an interval of 3-10 sec, during the second stage at rate 5-20°C/sec to temperature 550-450°C. Successive cooling in air to 100°C is performed with delays at rate 0.1-0.01°C/sec. Additionally steel contains one or several elements out of series, wt %: V-0.01-0.15, Mo-0.05-0.50, Ni-0.01-0.80, Cr-0.01-0.80, Cu-0.01-0.80 at carbon equivalent C_equiv=0.32-0.46 calculated from formula: Ce=C+Mn/6+(Cr+Mo+Nb+V+Ti)/5+(Ni+Cu)/15.

EFFECT: production of high-duty plate iron with upgraded indices of durability at simultaneous upgraded cold resistance and low-temperature viscosity.

2 cl, 1 ex, 3 tbl