What are the similarities and differences between weathering steel and ordinary steel?

The similarities and differences between weathering steel plate and ordinary steel plate

Thing in common:
1. The surface is red rust color.
2. Surface oxidation layer treatment is required before rust.
3. The rust layer on the surface of the naturally rusted red steel plate is not uniform.
4. Both can be obtained by manual rust treatment.

Difference:
1. Different materials.
Common steel plate generally uses Q235B, Q345B, these two materials are very common.
Weathering steel plate is 09Cu, SPA-H and other weathering steel.
2. Different colors.
The color of ordinary steel plate is dark and tends to black and red.
Weather resistant steel plate in bright color.
3. Stability of rust layer.
Weather resistant steel plate rust layer stable, hand touch will not have yellow rust off.
When the ordinary steel plate touches the hand, there will be yellow rust, and in the later period of serious corrosion will be layer upon layer of rust skin off.