METHOD OF PRODUCING TUBE STEEL HOT-ROLLED COILS Russian patent published in 2010 - IPC B21B1/26 

FIELD: process engineering.

SUBSTANCE: proposed method comprises heating slabs for hot rolling, rolling them at roughing and finishing continuous stands, differential cooling of strips by spraying water from above and from below on outgoing roller table and coiling at 570÷610°C. Identical mechanical properties are produced corresponding to strength class X65, in a wide range of strip width, is provided by that tube steel billet with carbon content not exceeding 0.12%, that of silicon not exceeding 0.15÷0.30%, that of manganese not exceeding 1.55÷1.75%, that of niobium not exceeding 0.020÷0.050% and that of vanadium not exceeding 0.08÷0.12%, is rolled at broad-strip hot roll mill at the temperature of rolling end making 790÷850°C into 6÷16 mm-thick strip from strip plate with thickness determined subject to mathematical relationship. Prior to coiling hot-rolled strip, it is subjected to differential cooling by water. Note here that the rate of cooling strip top surface on outgoing roll table, depending upon final thickness is the strip, is subjected to mathematical relationship.

EFFECT: identical mechanical properties are produced corresponding to strength class X65, in a wide range of strip width.

1 tbl, 1 ex