Research involving stress-corrosion cracking (SCC) and corrosion fatigue (CF) is the most recent addition to ORNL's internationally recognized materials and corrosion research and development programs. SCC/CF crack propagation results from the combined and synergistic interaction of mechanical stress and corrosion reactions. Static loading is considered to be responsible for SCC, while CF is defined as environmentally induced crack propagation due to cyclic loading. The stresses required to cause SCC or CF usually are well below the macroscopic yield strength. Materials classes that exhibit SCC/CF include metallic alloys, composites, polymers, and ceramics. During the past two decades, environmentally assisted cracking (specifically SCC and CF) has been a progressive mechanism of material failure responsible for many, if not most, service failures in numerous applications where components and structures come into contact with natural or technological environments.
A highly sensitive crack-growth monitoring technique, usable in a variety of corrosive environments, was successfully applied for both industrially oriented and fundamental mechanistic studies of SCC/CF in a range of material systems. It can detect as little as 0.001-mm (approx. 1/100th the width of a human hair) crack extension and provides measurements of electrochemical parameters during crack growth. Environments of interest include aqueous solutions and associated environments (such as aqueous variations in nuclear and petroleum facilities), H2S environments, high-pressure hydrogen, and high-temperature gases. The setup makes it possible to measure in situ crack growth rates above 20 nm/min (0.001 mm/h) at temperatures ranging from 4C (seawater) to ~300C in light-water nuclear reactor environments. It also is possible to monitor crack growth rates in post-irradiated materials.
The experimental setup is one of only a few sensitive capabilities of this type in existence.
Facilities are available for collaboration. Collaborative work is performed by ORNL staff.
Sergei A. Shipilov, Senior R&D Staff, firstname.lastname@example.org, 865-574-4450
- Shipilov, S.A., Location of the Fracture Process Zone for Hydrogen-Induced Corrosion Fatigue Crack Propagation, Scripta Materialia, 47(5) 2002, 301-305.
- Shipilov, S.A., Mechanisms for Corrosion Fatigue Crack Propagation, Fatigue & Fracture of Engineering Materials & Structures, 25(3) 2002, 243-259.