Tohoku University. Research Profiles


Suppression of Intergranular Degradation of Polycrystalline Materials by Grain Boundary Engineering



Intergranular degradation often results in decreased lifetime, reliability and economical efficiency of polycrystalline materials. In spite of persistent efforts to prevent such degradation, its complete suppression has not yet been achieved. Grain boundary studies have revealed that coincidence-site-lattice (CSL) boundaries have stronger resistance to intergranular degradations than random boundaries. The concept of ‘grain boundary design and control' has been refined as grain boundary engineering (GBE). GBEed materials which are characterized by high frequencies of CSL boundaries are resistant to intergranular degradations. Our group has achieved very high frequencies of CSL boundaries in commercial stainless steels by GBE. GBEed stainless steels showed significantly stronger resistance to intergranular corrosion (see Figs. 1 and 2), weld-decay, knife-line attack, stress corrosion cracking, liquid-metal embrittlement, radiation damage, etc. and much longer creep life (see Fig. 3) than the unGBEed ones.

Targeted Application(s)/Industry

By using this GBE processing, we expect to conduct effective collaborative research in related fields.


Department of Materials Processing, Graduate School of Engineering

SATO, Yutaka , Professor


Related Information

1)Masayuki Shimada, Hiroyuki Kokawa, Zhan Jie Wang, Yutaka S. Sato and Isao Karibe: Optimization of grain boundary character distribution for intergranular corrosion resistant 304 stainless steel by twin-induced grain boundary engineering, Acta Materialia, 50-9 (2002), 2331-2341. DOI: 10.1016/S1359-6454(02)00064-2

2) H. Kokawa, Potential of grain boundary engineering to suppress welding degradations of austenitic stainless steels, Science and Technology of Welding and Joining, 16-4 (2011), 357-362. (invited paper to Special issue celebrating 1000 articles published in STWJ) DOI: 10.1179/1362171811Y.0000000021