Impact Factor:11.2
DOI number:10.1016/j.jmst.2018.10.017
Affiliation of Author(s):中国金属协会
Teaching and Research Group:0
Journal:Journal of Materials Science & Technology
Place of Publication:中国
Funded by:核材料研究与开发与服役安全保障技术，国家自然科学基金
Key Words:25Cr-20Ni steel; weld metal; Nb; aging treatment; α-Cr phase; mechanical property.
Abstract:The microstructure evolutions and the mechanical properties of the 25Cr-20Ni austenitic stainless steel weld metals with different Nb contents were investigated during the long term aging treatment at 700 °C. M23C6, Nb(C, N), α-Cr phase and Nb-nitride phase (Z phase) were observed in the microstructures of the aged weld metals. The results showed that the α-Cr phase precipitated in the interdendritic regions of the weld metals after being exposed to 700 °C for 500 h and the element Nb accelerated the precipitation of the α-Cr phase significantly. The density of the α-Cr phase decreased with the increase of the distance away from the primary Nb(C, N). Additionally, the α-Cr phase showed a crystallographic relationship with the austenitic matrix, α-Cr // γ and α-Cr // γ. It was observed that the Z phase precipitated in the periphery of the Nb(C, N) and may replace the Nb(C, N) after long term exposure to high temperature. The transformation of the Nb(C, N) into Z phase suggested that the Z phase had a higher stability than the Nb(C, N) particles at 700 °C for long term aging. The tensile strength of the Nb-bearing weld metal showed a continuous decrease at the initial stage of the aging treatment and then went up slightly with the prolonged aging time. However, the elongations and the impact energies of the weld metals decreased monotonously with the increase of the aging time.
Note:0
Indexed by:研究论文
Discipline:Engineering
Volume:35
Issue:4
Page Number:520-529
ISSN No.:1941-1162
Translation or Not:no
CN No.:0
Date of Publication:2019-01-01