New challenge of grain boundary engineering for development of ferritic/martensitic heat-resistant steels with superior environmental durability

2015 Fiscal Year Final Research Report

• Project/Area Number: 24246125
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Metal making engineering
• Research Institution: Kumamoto University
• Principal Investigator: Tsurekawa Sadahiro 熊本大学, 自然科学研究科, 教授 (40227484)
• Co-Investigator(Kenkyū-buntansha): WATANABE Seiichi 北海道大学, 大学院工学研究院, 教授 (60241353) ; SIBAYAMA Tamaki 北海道大学, 大学院工学研究院, 教授 (10241564) ; MORIZONO Yasuhiro 熊本大学, 大学院自然科学研究科, 准教授 (70274694)
• Research Collaborator: YAMAMURO Takateru 熊本大学, 工学部, 技術専門職員 (30747407)
• Project Period (FY): 2012-04-01 – 2016-03-31
• Keywords: 粒界工学 / 粒界性格分布 / フェライト系耐熱鋼 / ラスマルテンサイト / 高温クリープ / 高温水蒸気酸化 / 液体金属脆化

Outline of Final Research Achievements

Grain boundary engineering (GBE) was applied to 9-12Cr heat-resistant ferritic steels with lath-martensite for achieving enhanced environmental durability. We could observably increase the fraction of coincidence site lattice (CSL) boundaries along the prior austenitic boundaries in martensite through a new processing route with a combination of thermomechanical treatment and martensitic transformation. In addition, the GBE could introduce a high density of subblock structure in martensite, which resulted in a homogeneous distribution of fine M23C6 precipitates in tempered martensite. These GBEed ferricitc steels showed superior resistances against high temperature creep, steam oxidation and liquid metal corrosion.

Free Research Field

材料界面物性学