Managing Both Strength and Ductility in Ultrafine Grained Steels

概要

論文の詳細を見る
Ultrafine grained (UFG) steels provide surprisingly high strength but sometimes show limited tensile ductility. In the present paper, systematic experimental results on mechanical properties of UFG steel with ferrite single phase are shown first. The limited tensile ductility of the UFG ferritic steel was due to very small uniform elongation, which was attributed to the early plastic instability in the UFG microstructures. This basic understanding suggested a way to overcome the low tensile ductility: if the strain-hardening of the matrix is enhanced by any means, both high strength and adequate ductility can be managed even in UFG structures. Actual examples of the UFG steels that could achieve good strength–ductility balance are also presented. Dispersing fine carbides within the UFG ferrite matrix, and making the UFG dual-phase structure composed of ferrite and martensite were both effective to manage high strength and large uniform elongation. It was clearly shown that the future studies on the UFG steels from practical viewpoint should be directed to make the UFG structures multi-phased.
社団法人日本鉄鋼協会の論文
2008-08-15