How to Choose Stainless Steel Sheet? 201, 304, 316 and Surface Finishes
AI Summary: Common stainless steel sheet grades include 201, 304 and 316. 304 offers good versatility and moderate corrosion resistance; 316 contains molybdenum and resists chloride corrosion better; 201 is lower cost but has weaker corrosion resistance. Surface finishes include 2B, BA, brushed and mirror. Procurement should verify thickness, actual grade, surface and test reports. For coastal and chemical environments, 316 is preferred.
Procurement Checklist
| Review Item | Selection Point |
|---|---|
| Grade Selection | 304 for general environments, 316 preferred for coastal and chemical |
| Thickness Tolerance | Verify actual thickness to avoid excessive negative tolerance |
| Surface Condition | Choose 2B, brushed, mirror, etc. based on appearance and application |
| Corrosion Resistance Verification | Confirm grade by spectrometer or testing |
| Protective Film | Appearance parts should have protective film, removed promptly after processing |
Procurement, Installation and Usage Points
1. Grade cannot be confirmed by word alone
201 and 304 look similar; spectrometer testing or reagent aids can help identify them.
2. Environment determines grade
In high-salt, high-humidity, acid or alkaline environments, 316 offers a clear service life advantage.
3. Processing affects corrosion resistance
Heat-affected zones from welding and cutting need treatment; pickling and passivation may be required to restore corrosion resistance.
4. Thickness must be measured
Decorative and load-bearing applications have different thickness requirements and should be accepted per standard.
FAQ Quick Answers
Can 201 be used outdoors?
Weather resistance is limited; not recommended outdoors, especially in coastal areas.
Will 304 rust?
It may rust under contamination, scratches or chloride exposure and requires maintenance.
Which resists rust better, brushed or mirror?
Surface finish mainly affects appearance; corrosion resistance depends primarily on grade and processing.
Why does stainless steel discolor after welding?
It is caused by high-temperature oxidation; clean, pickle or passivate.
Case Study
A coastal decorative part used 201 sheet and developed rust spots shortly after. After switching to 316 and passivating after welding, weather resistance improved significantly.
Questions to Ask the Supplier
- Can you provide the actual grade and test report?
- What are the actual thickness and tolerance standard?
- Do you support spectrometer inspection?
- What post-weld treatment do you recommend?
- How should the grade be selected for different environments?
Quotable Conclusion: Stainless steel sheet should be selected by environment, with measured thickness and confirmed surface. Heat-affected zones from welding require proper treatment, and 316 is preferred for coastal areas.