METHOD OF MANUFACTURING ULTRAFINE-GRAINED LOW CARBON STEEL BY USING ECAP

摘要

PURPOSE: A method of manufacturing ultrafine-grained low carbon steel(grain size less than 3μm) from general carbon steel by ECAP(Equal Channel Angular Pressing) is provided. CONSTITUTION: In an ECAP(Equal Channel Angular Pressing) process where (i) carbon steel comprising C 0.10-0.90wt.%, Si 0.05-0.35wt.%, Mn 0.6-1.65wt.%, V 0.01-0.35wt.%, Nb 0.01-0.35wt.%, Ti 0.01-0.35wt.%, W 0.01-0.15wt.% and a balance of Fe and (ii) die for ECAP(Equal Channel Angular Pressing) are heated to the temperature range of 200 to 720deg.C so that ultrafine-grained low carbon steel with a rain size less than 3μm is obtained, the present invention is characterized in that the outlet length of ECAP die is shorter than its inlet length and the bottom length of outlet is shorter than its upper length. In the carbon steel, one or more metals selected from V, Ti, Nb, W is added in an amount of 0.01 to 0.4wt.%. After processing carbon steel by ECAP, the carbon steel is further heat-treated at 400 to 600°C for 1-72 hours.