The general chemical composition and mechanical performance requirements of SPV490 steel plate are as follows:

Chemical composition of SPV490 steel plate
- Carbon content (C): ≤0.18%
- Silicon content (Si): ≤0.75%
- Manganese content (Mn): 1.60-1.90%
- Phosphorus content (P): ≤0.030%
- Sulfur content (S): ≤0.030%

Mechanical performance requirements of SPV490 steel plate
- Tensile strength: 610-740 MPa
- Yield strength: ≥490 MPa
- Elongation: 16%
- Impact toughness: At room temperature, the specimen perpendicular to the rolling direction should have a minimum impact energy absorption capacity, usually measured in J units.

These values are basic general requirements and actual chemical composition and mechanical properties may vary slightly based on specific standards, specifications or customer needs. When using SPV490 steel plates, be sure to refer to the relevant JIS G3115 standard or specific product specification sheet for accurate data and requirements.