Characterization of Microstructure of Crept Samples of Dissimilar Weld\nJoint Using Standard and Advanced Electron Microscopy Techniques

0535536 - ÚPT 2021 RIV CH eng J - Journal Article
Kasl, J. - Jandová, D. - Mikmeková, Šárka - Ambrož, Ondřej
Characterization of Microstructure of Crept Samples of Dissimilar Weld
Joint Using Standard and Advanced Electron Microscopy Techniques.
Defect and Diffusion Forum. Roč. 405, NOV (2020), s. 294-299. ISSN 1662-9507
R&D Projects: GA TA ČR(CZ) TE01020118
Institutional support: RVO:68081731
Keywords : electron microscopy * microstructure * creep test * martensitic steels
OECD category: Materials engineering
Method of publishing: Limited access
https://www.scientific.net/DDF.405.294

Conventional long-term creep test (CCT) to the rupture and so called accelerated creep
test (ACT) of the dissimilar weld joint made of FB2 and F martensitic steels and of the base
materials were carried out at temperatures ranging from 550 °C to 650 °C in the stress range from 70 to 220 MPa. Assessment of microstructure development and changes of hardness was correlated with the creep strength. During creep at temperatures above 575 °C Laves phase precipitated in all parts of the weld joint and especially in the heat affected zones. Coarse Laves phase particles and their clusters with chromium carbides served as nucleation centers for cavities. As the fine grained heat affected zone of F steel was the softest part of the weld joint, many cavities originated and cause failure of samples. The aim of this paper is to compare results and possibilities of the “standard” methods and advanced scanning electron microscopy performed by instrument equipped with a concentric backscatter electron detector (CBS). Filtering of the signal enables improving
and/or diminishing of selected type of contrast caused by various types of particles of secondary phases. The images were used as an input data for image analysis and developments of microstructures during CCT and ACT were compared. Results have shown that specimens afterACT contains significantly lower content of the Laves phase.
Permanent Link: http://hdl.handle.net/11104/0313541