COLD ROLLED STEEL WITH EXCELLENT ABILITY TO STEEL THERMAL STRENGTHENING AT SOLIDIFICATION OF PAINT AND WITH PROPERTY OF NON-AGEING AT NORMAL TEMPERATURE AND PROCEDURE FOR ITS PRODUCTION Russian patent published in 2010 - IPC C21D8/04 C22C38/38 C22C38/32 C23C2/06 

FIELD: metallurgy.

SUBSTANCE: slab is subject to hot rolling with temperature of rolled piece end (Ar₃-100)°C or above. Slab is reeled at temperature 200-750°C, further hot rolled slab is cold rolled at reduction ratio 90 % or less. Cold rolled product is annealed to maximal temperature 750-920°C, cooled to temperature 550-750°C and annealed product is conditioned during 15 sec or more producing a sheet containing wt %: carbon 0.0005- 0.0040, silicon 0.8 or less, manganese 2.2 or less, sulphur 0.0005-0.009, chromium 0.4-1.3, oxygen 0.003-0.02, phosphorus 0.045-0.12, boron 0.0002-0.0010, aluminium 0.008 or less, nitrogen 0.001-0.007, the rest is iron and unavoidable impurities. Upon conditioning the sheet can be subject to heat treatment during 120 sec or more at temperature 150-450°C. Annealing of cold rolled product can be performed at continuous line of hot zincing by the immersion method, when produced product is immersed into an electroplating bath upon conditioning.

EFFECT: sheet possesses excellent ability to steel thermal strengthening at solidification of paint and non-ageing property at normal temperature.

4 cl, 3 tbl, 2 ex