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ISSN : 1225-0562(Print)
ISSN : 2287-7258(Online)
Korean Journal of Materials Research Vol.29 No.6 pp.349-355
DOI : https://doi.org/10.3740/MRSK.2019.29.6.349

Microstructure and Mechanical Properties of 600 MPa-Grade Seismic Resistant Reinforced Steel Bars Fabricated by a Pilot Plant

Tae-Woon Hong,Byoungchul Hwang
Department of Materials Science and Engineering, Seoul National University of Science and Technology, Seoul 01811, Republic of Korea
Corresponding author
E-Mail : bhwang@seoultech.ac.kr (B. Hwang, SEOULTECH)

Abstract

This study deals with the microstructure and tensile properties of 600 MPa-grade seismic reinforced steel bars fabricated by a pilot plant. The steel bar specimens are composed of a fully ferrite-pearlite structure because they were air-cooled after hot-rolling. The volume fraction and interlamellar spacing of the pearlite and the ferrite grain size decrease from the center region to the surface region because the surface region is more rapidly cooled than the center region. The A steel bar specimenwith a relatively high carbon content generally has a higher pearlite volume fraction and interlamellar spacing of pearlite and a finer ferrite grain size because increasing the carbon content promotes the formation of pearlite. As a result, the A steel bar specimen has a higher hardness than the B steel bar in all the regions. The hardness shows a tendency to decrease from the center region to the surface region due to the decreased pearlite volume fraction. On the other hand, the tensile-to-yield strength ratio and the tensile strength of the A steel bar specimen are higher than those of the B steel bar with a relatively low carbon content because a higher pearlite volume fraction enhances work hardening. In addition, the B steel bar specimen has higher uniform and total elongations because a lower pearlite volume fraction facilitates plastic deformation caused by dislocation slip.

Pilot Plant를 이용한 600 MPa급 내진용 철근들의 제조, 미세조직과 기계적 특성 비교

홍태운,황병철
서울과학기술대학교 신소재공학과

초록

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