Manufacturing of high-strength ultrafine grained steels using Strain Induced Dynamic Transformations

摘要

dynamic transformation of organic transformation using ultra high-strength fine-grained steel fabrication method is provided. ; The present invention is, by weight%,, C: more than 0.3%, Si: less than 2.0%, Mn: less than 3.0%, Nb: 0.01 ~ 0.08%, the balance of the composition being iron and unavoidable impurities including comprising the steps of: providing a steel material; And controlling such that the average grain size of less than 50 austenite structure before the finish-rolled steel; The organization of the steel Ar ₃ ~ Ar ₃ + a reduction ratio per one pass in the temperature range of 100 kept at 30% or less that the total rolling reduction of 60% multi-step process to ensure that more than hot; High-strength fine-grained steel manufacturing method using the second transformation comprises a transformation organic dynamic; and the step of transformation the remaining austenite to martensite the hot-rolled steel to the cooling end temperature was cooled to below 300 5 / sec or more cooling rate relate to.