Multi-element design of Laves reinforcement phase to create super ferritic heat-resistant steels

2018 Fiscal Year Final Research Report

• Project/Area Number: 16H04533
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Material processing/Microstructural control engineering
• Research Institution: Tohoku University
• Principal Investigator: Yoshimi Kyosuke 東北大学, 工学研究科, 教授 (80230803)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: フェライト鋼 / ラーベス相 / 耐熱鋼 / 組織制御

Outline of Final Research Achievements

In this research project, Laves phases are focused on as a factor to increase high temperature strength of ferritic heat-resistant steels. Since Laves phases in steels are thermodynamically in equilibrium with ferrite parent phase, they are composed of multiple elements. Hence, the topologically close-packed structure that is the characteristic crystal structure of binary Fe2M Laves phases (M : refractory metals) is changed by off-stoichiometry, third, fourth and fifth elements such as Al, Cr, B etc. and further the concentration and addition ratio of Laves formation refractory metals such as Nb and W. Moreover, due to change in thermodynamic stability, the precipitation size and distribution as well as the precipitation rate are also largely changed.

Free Research Field

耐熱材料

Academic Significance and Societal Importance of the Research Achievements

化石燃料の価格や可採年数などの観点から，石炭火力発電は長期にわたって安定的に大規模発電を実現するのに適している。しかしその一方で，発電プラントはより一層大型化するため，高価なニッケル基合金ではなく，鉄基の耐熱合金（耐熱鋼）に対する依存度が高い。近年，石炭火力発電では，先進超々臨界圧（A-USC）発電技術の開発が国家プロジェクトとして推進されているが，主蒸気を発生させるボイラー等ではフェライト系耐熱鋼の需要が高い。しかし，従来のフェライト系耐熱鋼ではA-USC発電を長期間安定操業するのに十分な耐熱性が得られておらず，より耐熱性の優れた超フェライト系耐熱鋼の開発が切望されている。