PROCEDURE FOR MANUFACTURE OF COLD ROLLED STRIPS OF LOW ALLOYED STEEL OF 260 CLASS OF STRENGTH Russian patent published in 2011 - IPC C21D8/04 C21D9/48 C22C38/16 C22C38/46 

FIELD: metallurgy.

SUBSTANCE: there is melted steel containing wt %: carbon 0.06÷0.10, manganese - 0.20÷0.50, silicon - 0.01÷0.30, copper - 0.01÷0.30, aluminium - 0.02÷0.07, phosphorus - 0.07÷0.12, nitrogen - 0.003÷0.009, sulphur - 0.005÷0.025, calcium - 0.0005÷0.001, boron - 0008÷0.005, chromium - 0.01÷0.30, nickel - 0.01÷0.30, niobium + molybdenum + vanadium + titanium ≤ 0.032, iron - the rest. Further, steel is teemed producing crystallised slab; hot slab is rolled in stands of a wide rolling mill and there is manufactured hot rolled strip of thickness by dependence: where: h_hr - thickness of hot rolled strip, mm, h_cr - finish thickness of cold rolled strip, mm. Surface of strip is cooled with water and it is wound in reel. Scale is removed off strip surface by etching. Successively, strip is cold rolled on a continuous mill, heat treated and dressed, also, temperature of rolling finish and strip winding into coil is chosen depending on thickness of hot rolled strip correspondingly: for strips of thickness over 4.01 mm - 800-820°C, 535-565°C, of thickness from 3.01 to 4.00 mm - 820-840°C, 565-595°C, of thickness from 2.00 to 3.00 mm - 840-860°C, 595-625°C.

EFFECT: manufacture of strip with thickness 0,6-3,0 mm with complex of mechanical properties of 260 class of strength; increased output of accepted product due to elimination of micro-cracks and ruptures.

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