| Surface Treatment Type | Code | Features |
| Chromic Acid Treatment | C | Good corrosion resistance, suitable for bare state |
| Chromic Acid Treatment+Oiling | S | Good corrosion resistance |
| Phosphoric Acid Treatment (Including Sealing Treatment) | P | Have a certain corrosion resistance, good paint performance |
| Phosphoric Acid Treatment (Including Sealing Treatment)+Oiling | Q | Has a certain corrosion resistance, good paint performance, prevent rust during transportation and storage |
| Phosphoric Acid Treatment (Excluding Sealing Treatment) | T | Have a certain corrosion resistance, good paint performance |
| Phosphoric Acid Treatment (Excluding Sealing Treatment)+Oiling | V | Has a certain corrosion resistance, good paint performance, and prevent rust |
| Oiling | O | Prevent rust during transportation and storage |
| No Treatment | M | Suitable for immediate painting |