The effect of vacancy diffusion and concentration on creep crack initiation in weldment of a C(T) specimen for high Cr steel

Issue title: Special Issue: Proceedings of a Special Symposium in the Honor of David M.R. Taplin

Guest editors: Ashok Saxena and Toshimitsu Yokobori Jr.

Article type: Research Article

Authors: Toshimitsu Yokobori, Jr, A.^a; | Sugiura, Ryuji^b | Sato, Kazuto^{c; †} | Shigeyama, Haruhisa^{c; †} | Tabuchi, Masaaki^d

Affiliations: [a] Teikyo University, Strategic Innovation Research Center, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605, Japan | [b] College of Engineering, Nihon University, Nakagawara 1, Tokusada, Tamura, Koriyama 963-8642, Japan | [c] Graduate School of Engineering, Tohoku University, Aoba 6-6-01, Aramaki-aza, Aoba-ku, Sendai 980-8579, Japan | [d] National Institute for Materials Science, Tsukuba, Ibaraki, Japan

Correspondence: [*] Corresponding author. E-mail: toshi.yokobori@med.teikyo-u.ac.jp

Note: [†] Present addresses: Nippon Steel & Sumitomo Metal, Japan (K. Sato); Central Research Institute of Electric Power Industry, Japan (H. Shigeyama).

Abstract: In the present paper, to investigate the effect of vacancy diffusion and concentration on creep crack initiation and growth process for weldments, the numerical analyses of diffusion and concentration of vacancy around a notch tip of C(T) specimen in the heat affected zone (HAZ) were conducted based on the proposed 𝛼 multiplication and FEM-FDM methods. As an analytical result, the vacancy diffusion and concentration behavior around a notch tip of C(T) specimen in the heat affected zone for P92 steel was found to be dominated by the distribution of multi-axiality of the stress caused by inhomogeneous property of regions of fine and coarse grains in HAZ. It is also found to be closely related to the creep damage formation and the initial direction of creep crack growth.

Keywords: Weldment, HAZ, fine grain, coarse grain, local stress induced vacancy diffusion, creep crack initiation

DOI: 10.3233/SFC-180217

Journal: Strength, Fracture and Complexity, vol. 11, no. 2-3, pp. 107-120, 2018