The main benefits of bead blast surface treatment for stainless steel pipes are seen in two areas: improved material performance and cost-effectiveness.
Here’s a closer look:
- Strengthen Mechanical Performance
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Enhance Fatigue Strength: High-speed steel shot strikes the surface, creating a residual compressive stress layer (0.1-0.5mm deep). This layer helps prevent crack growth and extends the pipeline’s service life under varying loads.
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Improve Wear Resistance: Shot blasting refines the surface grain and creates a cold work hardening effect. This is ideal for industrial pipelines that carry abrasive materials.
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2.Optimize Corrosion Resistance
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Passivated Film Stability: The mechanical impact removes surface impurities. It also helps to rebuild a dense Cr2O3 passivated film. This lowers the risk of local corrosion.
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Stress Corrosion Resistance: The residual compressive stress counteracts external tensile stress. This boosts the pipes’ resistance to stress corrosion cracking in corrosive environments, like those with chlorine, by 30% to 50%.
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3. Balance Between Surface Quality and Cost
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Controllable Roughness: After shot blasting, surface roughness (Ra) is 0.8–6.3 μm. This is more consistent and denser than sandblasting (Ra 1.6–12.5 μm), minimizing the risk of medium residue.
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Cost-Effective Medium Reuse: Stainless steel pellets are dense (7.9g/cm³) and highly impact-resistant. Their lifespan is 3-5 times longer than ordinary steel pellets, significantly lowering consumable costs.
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4. Process Compatibility
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Pre-Treatment Adaptability: The surface, post-shot peening, is very clean and free of oxide skin. This makes it an excellent base for coatings, like anti-corrosion paint.
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Post-Weld Treatment: It removes residual tensile stress in weld areas and can replace costly heat treatment processes.
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Typical Application Scenarios
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Energy Transportation: In the Arctic LNG project, low-temperature stainless steel pipelines use shot peening. This helps improve cold and fatigue resistance.
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Chemical Equipment: The corrosion rate of 316L stainless steel pipes drops by 80% in acidic environments after treatment.
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Architectural Decoration: The matte metallic finish meets modern aesthetic demands for building facades and interiors.
Process Comparison
Shot peening offers a balance of functionality, such as fatigue and corrosion resistance, while keeping costs reasonable compared to polishing. Unlike acid washing, it avoids the risk of chemical contamination.