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Probing intergranular mixed transgranular stress corrosion cracking under the high constant load
1Beijing Institute of Structure and Environment Engineering, China Academy of Launch Vehicle Technology, China Aerospace Science and Technology Corporation, Beijing, 100076, China. l.k.zhu@163.com.
Scientific Reports
|July 20, 2022
Summary
Stress corrosion cracking in stainless steel exposed to magnesium chloride solutions primarily follows a transgranular path, shifting to intergranular stress corrosion cracking (IGSCC) under high loads. This failure involves cleavage, slip bands, and pits, not ductile dimples.
Area of Science:
- Materials Science
- Corrosion Engineering
- Metallurgy
Background:
- Austenitic stainless steels are susceptible to stress corrosion cracking (SCC) in chloride environments.
- Understanding crack propagation mechanisms is crucial for material integrity and component design.
Purpose of the Study:
- To investigate the stress corrosion cracking (SCC) behavior of non-sensitized austenitic stainless steel in MgCl2 solutions.
- To elucidate the crack propagation modes and fracture surface characteristics under high constant load.
Main Methods:
- X-ray computed tomography was used to visualize crack propagation.
- Scanning electron microscopy (SEM) was employed for fractographic analysis.
Main Results:
- SCC cracks initially propagated transgranularly, then transitioned to intergranular stress corrosion cracking (IGSCC) under high load.
- Fractography revealed cleavage facets, slip bands, and pits, with no ductile dimples.
- A cohesive zone was observed ahead of the crack tip.
Conclusions:
- High-load SCC in this system involves a cleavage dissolution mechanism.
- Particle-assisted cleavage and obstacle-induced dislocation pinning are key contributors to the observed failure modes.
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