Ultrahigh strengthening sintered low alloy steels by advanced powder processing for heterogeneous microstructural control

2015 Fiscal Year Final Research Report

• Project/Area Number: 24246123
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Material processing/treatments
• Research Institution: Kyushu University
• Principal Investigator: Miura Hideshi 九州大学, 工学(系)研究科(研究院), 教授 (30117254)
• Co-Investigator(Kenkyū-buntansha): TSUMORI FUJIO 九州大学, 大学院工学研究院, 准教授 (10343237) ; OSADA TOSHIKO 九州大学, 大学院工学研究院, 助教 (90452812)
• Project Period (FY): 2012-04-01 – 2016-03-31
• Keywords: MIM / ヘテロ組織 / ネット構造 / 転造 / 超強靭化 / 有限要素法

Outline of Final Research Achievements

Extraordinary static mechanical properties were obtained by MIM (Metal Injection Molding) Fe-6Ni-0.4C steels, which is considered as a result of heterogeneous microstructure with the Ni rich phases (martensite or retained austenite) surrounded by network of tempered martensite. Moreover, 3 kinds of MIM Fe-Ni steels with different content of Ni (4, 6, 8 mass%) are fabricated and the dynamic fatigue properties are investigated by the rotary bending fatigue testing. The Fe-6Ni-0.4C steel with the relative density of 95 % shows the highest fatigue strength of 650 MPa, which is as same strength as the powder forged steel with full density. As the results, the heterogeneous microstructure can be proved to have a great effect on not only the static but also the dynamic mechanical properties. And to obtain the best mechanical properties, the heterogeneity of the microstructure should be controlled appropriately.

Free Research Field

粉体加工学