What is the maximum salt spray corrosion resistance achievable for stainless ste

Release time：2020-01-16 18:44 Browse：

1. Material Selection

• 304 Stainless Steel: Without surface treatment, salt spray resistance typically ranges from 48 hours (screws) to 96 hours (nuts).

• 316 Stainless Steel: Offers better corrosion resistance than 304, suitable for marine environments, but untreated performance remains limited (usually under 100 hours).

• Special Alloys: Duplex stainless steels (e.g., 2205) provide superior salt spray resistance but at higher costs.

2. Surface Treatment Methods

• Passivation: 304/316 stainless steel after passivation can achieve 72–120 hours (e.g., passivated 303 nuts reach 120 hours).

• Electropolishing + Passivation: Extends resistance to 200–500 hours.

• Special Coatings (e.g., Dacromet, Zinc-Nickel Plating): Non-stainless steels (e.g., carbon steel) with these treatments may reach 500–1,000 hours, but stainless steel rarely uses such methods.

3. Process Optimization

• Multi-Layer Protection: Passivation + sealants (e.g., silane treatment) can push stainless steel beyond 1,000 hours (e.g., high-end fasteners).

• Precision Polishing: Reducing surface roughness delays corrosion initiation.

4. Industry Examples

• Standard Stainless Fasteners: With optimized treatments, some manufacturers report 720–1,000 hours (e.g., per GB/T 5267.2 coating standards).

• Extreme Environments: Nuclear or marine-grade screws with composite protection (passivation + Teflon coating) may exceed 2,000 hours.