Development of Mechanical Properties in Dual Phase Steels by Percolation Control

2017 Fiscal Year Final Research Report

• Project/Area Number: 15K06488
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Structural/Functional materials
• Research Institution: Tokyo Institute of Technology
• Principal Investigator: Nakada Nobuo 東京工業大学, 物質理工学院, 准教授 (50380580)
• Project Period (FY): 2015-04-01 – 2018-03-31
• Keywords: 構造材料 / 組織連結性 / パーコレーション / マルテンサイト変態

Outline of Final Research Achievements

For an essential understanding the microstructural factors dominating mechanical properties of metals with duplex microstructure in a meso scale, a change in 0.2% proof stress depending upon hard austenite fraction was investigated in terms of a microstructural connectivity using Fe-Ni austenitic alloy having a duplex microstructure composed of soft and hard austenite. 0.2% proof stress is continuously increased with increasing the fraction of the hard austenite. Especially, it is efficiently increased according to iso-strain condition when the hard austenite fraction exceeds a critical value. The non-linear strengthening tends to have good correlation with a connectivity of the hard austenite, that is, percolation phenomenon. This suggests that when the hard austenite grains are firmly connected to each other, plastic strain is uniformly distributed between soft and hard austenite during deformation, which leads to a significant strengthening in metals with duplex microstructure.

Free Research Field

鉄鋼材料