METHOD FOR MANUFACTURING TENSILE STRENGTH 590MPa CLASS HOT ROLLED HIGH BURRING STEEL WITH EXCELLENT VARIATION OF MECHANICAL PROPERTY

摘要

PURPOSE: A method for manufacturing high-strength hot-rolled and burred steel with low variation of materials and tensile strength of 590MPa is provided to manufacture high-quality hot-rolled high-burring steel by reducing the variation of materials in the width and length directions of strip. CONSTITUTION: A method for manufacturing high-strength hot-rolled and burred steel with low variation of materials and tensile strength of 590MPa comprises the steps of: continuously casting steel to thin slab(a) with a thickness of 30-150mm, roughly rolling, heating, finally rolling, and winding the thin slab, a step of finish rolling the strip with a rolling speed difference of 15% or less, continuously cooling the finally rolled strip to 630-690C on a runout table(60), and air-cooling the strip for 3-9 seconds and winding at 380-490C. The steel comprises C(Carbon) of 0.03-0.1wt.%, Si(Silicon) of 0.01-0.3wt.%, Mn(Manganese) of 1.0-2.0wt.%, P(Phosphorus) of 0.001-0.025wt.%, S(Sulfur) of 0.001-0.004wt.%, Cr(Chromium) of 0.001-2.0wt.%, Al(Aluminum) of 0.01-1.0wt.%, N(Nitrogen) of 0.001-0.02wt.%, the total tramp element of 0.18wt.% or less, one or more among Ti(Titanium) of 0.001-0.1wt.%, Nb(Niobium) of 0.001-0.1wt.%, V(Vanadium) of 0.001-0.1wt.%, and B(Boron) of 0.0002-0.003wt.%, and Fe(Iron) and inevitable impurities of the remaining amount.