METHOD FOR PRODUCING A HOT-ROLLED HIGH-TENSILE STEEL STRIP

摘要

The invention features a method for producing a hot-rolled high-tensile steel strip. The carbon, manganese and silicon content of the said strip lies between 0,04 % and 0,2 %, between 0,5 % and 2 % and between 0,01 % and 0,5 % by weight respectively. Further the steel contains a niobium content of between 0,01 % and 0,1 % by weight, the remainder being iron and the usuel impurities. The finish hot-rolling of the steel is done between an initial temperature of less than 950 % C and a final temperature higher than the conversion temperature of the austenite into ferrite (Ar3) with a thickness reduction rate of at least 85 %. Within a period of less than 5s, preferably less than 1s, after the hot-rolling, the steel is cooled continuously and monotonically at a rate of cooling above 20 DEG C/s from the above mentioned final temperature to a temperature below 200 DEG C and the hot-rolled steel strip is coiled at said temperature of below 200 DEG C.