Effect of silicon on uniform elongation of 1420 MPa grade steel bar for prestressed concrete

Recent antiearthquake design is on the basis of ultimate state design which aims absorption of earthquake's energy by plastic deformation of buildings . From this point of view, it is required that deformability of buildings' pile should be improved much more. Inside pile, steel bar for prestressed c oncrete (PC-bar) is used for reinforcement. One of the main factors which a ffect deformability of the pile is uniform elongation of PC-bar. Therefore it is pointed out that the PC-bar with high uniform elongation is indispens able. It is known that high uniform elongation is attained by dual phase in the case of tower strength steels. But study which treats with high streng th steels such as 1420 MPa grade PC-bar is quite few. In this paper, we foc us on Si and study the effect of Si on ductility of high strength steels. F inally we found that uniform elongation was improved to 5% by 3.5% Si addit ion. Improvement on uniform elongation by Si addition is mainly attributed to appearance of ferrite and refinement of carbide.