METHOD OF HOT ROLLED SHEETS MANUFACTURING FROM K60 DURABILITY CLASS LOW-ALLOYED STEEL WITH THE THICKNESS OF UP TO 40 mm

摘要

FIELD: metallurgy.;SUBSTANCE: invention relates to the metallurgy, in particular to the up to 40 mm thick hot-rolled steel production for the mainline pipes on the reversible plate mill. Method comprises the continuously cast billets heating, rough rolling into the intermediate thickness roll, its cooling-down, finishing rolling, accelerated cooling with water in the sprayer unit and further cooling in air. Continuous castings are obtained from the steel with the following content of elements, wt. %: carbon 0.03–0.07; silicon is 0.10–0.25; manganese 1.30–1.65; nickel is not more than 0.30; copper is not more than 0.30; titanium 0.010–0.030; vanadium is not more than 0.05; niobium 0.030–0.080; molybdenum is not more than 0.30; nitrogen not more than 0.007; aluminum 0.020–0.060; sulfur is not more than 0.002; phosphorus is not more than 0.012; iron and inevitable impurities are the rest being, with carbon equivalent (CE_IIW) and the embrittlement due to structural transformation (P_CM) coefficient should be not more than 0.40 and 0.18 %, respectively. Before rolling, the billets are heated to the temperature, which is regulated by the mathematical dependence, performing their rough-rolling with the total degree of deformation of at least 40 %, finishing rolling is started and completed at the regulated temperature, performing the accelerated cooling with water, followed by cooling in air.;EFFECT: increase in the rolled products and large diameter pipes deformation capacity.;4 cl, 3 tbl