Thesis
Application of grain boundary engineering to improve resistance of alloy 625 plus to hydrogen embrittlement
Master of Science (M.S.), Drexel University
Jun 2017
DOI:
https://doi.org/10.17918/etd-7438
Abstract
The field of grain boundary engineering seeks to improve various materials properties by promoting the formation of low-energy grain boundaries such as the coherent [sigma]3, or twin, boundary. This field has historically relied on empirically discovered methods with little understanding of the underlying mechanisms. More recently it has come to light that the primary mechanism for the development of grain boundary engineered microstructures is the growth of large twin related grain clusters known as TRDs. One property that grain boundary engineering may be applied to is improving resistance to hydrogen embrittlement. Hydrogen embrittlement is a deterioration of mechanical properties in a metal exposed to hydrogen, characterized by brittle, intergranular fracture at low applied stresses. While grain boundary engineering has been applied to mitigate this issue, ambiguity in the mechanisms behind hydrogen embrittlement leads to ambiguity in the mechanism by which grain boundary engineering helps to mitigate this problem. In this study, grain boundary engineering was applied to improve resistance to hydrogen embrittlement in alloy 625 plus, an alloy frequently used in corrosive environments where hydrogen embrittlement is of particular concern. A grain boundary engineered microstructure was successfully produced by applying understanding of the underlying mechanisms of grain boundary engineering. RSL testing demonstrated that grain boundary engineering increased the stress intensity at which failure from hydrogen embrittlement occurred, and caused a shift from intergranular to transgranular crack propagation. These results are discussed in the context of underlying hydrogen embrittlement mechanisms.
Metrics
78 File views/ downloads
51 Record Views
Details
- Title
- Application of grain boundary engineering to improve resistance of alloy 625 plus to hydrogen embrittlement
- Creators
- Ryan Warren DeMott - DU
- Contributors
- Mitra Taheri (Advisor) - Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Master of Science (M.S.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- xi, 70 pages
- Resource Type
- Thesis
- Language
- English
- Academic Unit
- Materials (Science and) Engineering (Metallurgical Engineering) (1970-2026); College of Engineering (1970-2026); Drexel University
- Other Identifier
- 7438; 991014632191704721