Failures of SUS630 laminated steel plates mainly fall into three categories: corrosion, strength reduction, and deformation/cracking. Repairs should follow the principle: diagnose the cause → apply targeted treatment → restore performance.
1. Corrosion Failures (Common)
Symptoms: Surface pitting, rust spots, crevice corrosion; severe cases may develop corrosion pits.
Repair Steps:
Remove corrosion products using stainless steel-specific rust remover or a soft cleaning pad, avoiding hard scraping that could damage the passive layer.
Minor corrosion (no obvious pits): Clean and apply passivation to restore the surface layer.
Moderate corrosion (pit depth <0.5mm): Grind smooth and apply anti-corrosion coating (e.g., fluorocarbon coating or silane passivation).
Severe corrosion (pit depth ≥0.5mm or large area): Evaluate structural strength; if load-bearing is affected, cut and replace the affected area. Weld and perform re-aging treatment on new sections.
Prevention: Optimize the service environment, avoid long-term exposure to high-chloride or acidic/alkaline media, and increase cleaning frequency.

2. Strength Reduction Failures
Causes: Long-term high-temperature use (>600℃) causing decomposition of strengthening phases, or post-weld areas not re-aged.
Repair Steps:
Apply secondary heat treatment (solution + aging): Solution treatment at 1020-1060℃ for 30-60 minutes with air cooling; aging at 480-580℃ for 2-4 hours with air cooling.
Test hardness (HRC28-38) and yield strength (≥1000MPa) after heat treatment to ensure standards are met.
If material aging has caused irreversible strength loss, replace the plate.
Prevention: Strictly control service temperature; post-weld areas must be re-aged according to specifications.

3. Deformation and Cracking Failures
Symptoms: Plate bending, edge warping, or local cracks (typically due to overload, impact, or stress concentration).
Repair Steps:
Minor deformation (<0.5mm/m): Use cold straightening gradually to avoid high-temperature correction that could damage microstructure.
Severe deformation: Cut the deformed area and replace with new plate; weld and re-age.
Small cracks (length <5mm): Repair with argon arc welding, grind smooth, and re-age.
Large cracks (length ≥5mm or through-thickness): Replace the damaged plate to prevent crack propagation.
Prevention: Avoid overloads or sharp impacts during assembly; allow for thermal expansion/contraction gaps to reduce stress concentration.

4. Surface Damage Failures (Affecting Corrosion Resistance)
Symptoms: Protective film damage, deep surface scratches, or passive layer destruction.
Repair Steps:
Shallow scratches (no base metal exposure): Polish with stainless steel polishing compound to restore surface finish.
Deep scratches (base metal exposed): Grind, apply passivation, and if necessary, apply localized anti-corrosion coating.
Residual adhesive marks on protective film: Clean with neutral detergent and soft cloth; avoid organic solvents to prevent corrosion.

5. Post-Repair Verification
Mechanical Properties: Sample testing of hardness and yield strength must meet original standard values.
Corrosion Resistance: Neutral salt spray test ≥48 hours with no new corrosion, or intact surface passivation.
Appearance and Dimensions: Repaired area should be free of visible defects, with deformation within design tolerances.