METHOD OF PRODUCTION OF LOW ALLOYED COLD-RESISTANT WELDED ROLLED PLATES WITH INCREASED CORROSION RESISTANT Russian patent published in 2015 - IPC C21D8/02 C21D9/46 C22C38/54 

FIELD: metallurgy.

SUBSTANCE: production method of low alloyed cold-resistant welded rolled plate with increased corrosion resistance includes steel melting, continuous pouring to slabs, slabs heating and hot rolling. Steel is melted with following composition, in wt %: carbon - 0.06-0.12, manganese - 0.30-0.60, silicon - 0.15-0.60, nitrogen - max. 0.008, aluminium - 0.02-0.05, chromium - max. 1.0, nickel - max. 0.30, molybdenum - 0.08-0.20, vanadium - 0.04-0.10, calcium - 0.001-0.006, copper - max. 0.30, titanium - max. 0.03, niobium - max. 0.04, sulphur - max. 0.003, phosphorus - max. 0.012, boron - max. 0.0005, iron - rest, at that Ce = C+Mn/6+(Cr+V+Nb+Ti)/5+(Ni+Cu)/15 ≤ 0.43%, where Pcm = C+(Mn+Cu+Cr)/20+Si/30+Ni/60+V/10+Mo/15+5B ≤ 0.26%, V+Nb+Ti ≤ 0.15%, where Ce is carbon equivalent, %; C, Mn, Cr, V, Nb, Ti, Ni, Cu, Si, Mo, B are content in steel of carbon, manganese, chromium, vanadium, niobium, titanium, nickel, copper, silicon, molybdenum, boron in %wt, Pcm is crack strength coefficient, %. Steel after melting is subjected to out of furnace treatment and vacuum treatment to ensure mass fraction of hydrogen and oxygen maximum 2 and 25 ppm respectively, score of non-metal inclusions max. 2.5 as per average, and max. 3.0 as per maximum value, and total content of arsenic, lead, zink, tin, stibium, bismuth is max. 0.020%, the rolled plates after rolling and cooling are subjected to additional heating for hardening to temperature Ac3÷(Ac3+50)°C and tempering, its temperature is set depending on roll thickness in range 680÷730°C, at that in roll banded orientation shall be maximum 2 scores.

EFFECT: increased corrosion resistance, assurance of high and stable impact toughness at negative temperatures, this ensures increased service life of pipelines for transportation of corrosive mediums and manufactured from said rolled plates.

2 tbl