Proceedings of International Conference on Advanced Structural Steels 2006 (ICASS 2006)
巻, 号, ページ
pp. 150-155
出版年月
2006年8月
出版者
和文:
英文:
会議名称
和文:
英文:
International Conference on Advanced Structural Steels 2006 (ICASS 2006)
開催地
和文:
英文:
Gyeongju, Korea
アブストラクト
In the present study, we tried to fabricate dual-phased steels with ultrafine grained (UFG) duplex
microstructure composed of ferrite and martensite, in order to manage both high strength and adequate ductility.
Plain low-carbon steel (SM490: 490 MPa class) sheet was heavily deformed up to equivalent strain of 4.8 at
room temperature by the ARB (Accumulative Roll Bonding), which is a severe plastic deformation process
using rolling deformation. The ARB processed materials exhibited the ultrafine lamellar boundary structure
with mean lamella spacing of 60 nm. The ARB processed sheets performed tensile strength of 1380 MPa but
uniform elongation was only 1.5 %. The ARB Processed sheets were quickly annealed at intercritical ferrite +
austenite temperatures ranging from 740℃ to 800℃ by induction heating system and then quenched into water.
The annealed specimens showed the UFG duplex structure where the mean grain size of ferrite and martensite
were 1.3 μm and 0.84 μm, respectively. The UFG duplex steels performed not only high tensile strength of 700-
900 MPa but also satisfactory uniform elongation of 13% in maximum, which was different from the ARB
processed sheets having UFG ferrite single phase previously reported. The UFG duplex steels performed much
larger strain hardening than the UFG single phased steels, which leaded to the improvement of uniform and total
elongation.
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