The Effect of Strain Aging on the Microstructure and Mechanical Properties of Steel for Reel-Lay Coiled Steel Pipelines
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View abstract on PubMed
Summary
This summary is machine-generated.Deep-sea pipeline steel experiences reduced plasticity due to plastic strain and aging. Microstructural analysis reveals increased dislocation density and Cottrell atmosphere pinning, impairing work hardening capacity.
Area Of Science
- Materials Science
- Mechanical Engineering
- Metallurgy
Background
- Deep-sea oil and gas pipelines face significant plastic strain during installation.
- Static strain aging during service further degrades pipeline mechanical properties.
Purpose Of The Study
- Investigate the plastic deformation mechanism in reel-lay pipeline steel.
- Correlate mechanical property evolution with microstructural changes after pre-straining and aging.
Main Methods
- Subjecting test steel to 5% pre-strain followed by aging at 250 °C for 1 hour.
- Utilizing electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), and X-ray diffraction (XRD) for microstructural characterization.
Main Results
- Pre-straining increased yield strength and decreased uniform elongation due to dislocation strengthening and residual stress.
- Microstructural analysis showed increased dislocation density, forming cells and walls, reducing work hardening capacity.
- Aging treatment further increased yield strength and reduced uniform elongation, with Cottrell atmosphere pinning exacerbating plasticity deterioration.
Conclusions
- Pre-straining and aging significantly degrade the plasticity of reel-lay pipeline steel.
- Dislocation substructures and Cottrell atmosphere pinning are key mechanisms behind this degradation.
- Understanding these mechanisms is crucial for ensuring the integrity of deep-sea pipelines.
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