1. Effects on Processing
Machining & Cutting
Distortion Risk: Residual stresses from rolling or welding can cause warping during cutting or drilling, requiring tighter tolerances or stress-relief annealing.
Thermal Cutting: Plasma/laser cutting may exacerbate stress imbalances, leading to edge cracking in thick sections (>20mm).
Forming (Bending/Rolling)
Springback Variability: Residual stresses interact with applied forces, increasing springback unpredictability during cold forming.
Cracking: High tensile residual stresses in heat-affected zones (HAZs) may promote cracks at sharp bends (minimize with ≥2× thickness bend radii).
Welding
Weld-Induced Stresses: Uneven cooling creates localized stresses, potentially reducing fatigue life. Mitigate via:
Preheating (100–150°C for thick sections).
Post-weld heat treatment (PWHT) for critical applications.
2. Effects on Service Performance
Structural Integrity
Fatigue Life: Tensile residual stresses (e.g., near welds) accelerate fatigue crack initiation, critical for cyclic loads (bridges, towers).
Stress Corrosion Cracking (SCC): While the patina resists uniform corrosion, residual stresses + aggressive environments (e.g., coastal chloride exposure) may trigger SCC.
Dimensional Stability
Long-Term Distortion: Residual stresses can gradually relax, causing misalignment in precision structures (e.g., façades).
Corrosion Resistance
Patina Uniformity: Compressive residual stresses (e.g., from shot peening) may enhance patina adhesion, while tensile stresses could disrupt it.
3. Mitigation Strategies
| Issue | Solution | Application Example |
|---|---|---|
| Machining Distortion | Stress-relief annealing (600–650°C) | Precision structural components |
| Weld Cracking | Low-hydrogen electrodes + controlled cooling | Bridges, offshore platforms |
| Fatigue Resistance | Post-weld shot peening (induce compressive stress) | High-cycle load structures |
Key Takeaways
Processing: Residual stresses complicate fabrication (cutting/forming/welding), often requiring thermal or mechanical stress relief.
Service: They degrade fatigue life and dimensional stability but can be managed via design (e.g., avoid stress concentrators) and post-treatment.
