Why rust resistant steel plate why rust more obvious more durable?

I do not know whether we have found in recent years, in parks or public places will find some buildings also use solid steel structure materials, but after careful observation found that its surface is covered with black and red rust. However, such appearance seems to give people a special aesthetic feeling. Of course, some people will be curious, can you continue to use it after it has been rusted like this? Aren't there safety concerns? In fact, the weathering rust steel plate is stronger and more durable than ordinary steel, even if exposed to the air environment despite wind and rain can adhere to decades.
First of all, compared with ordinary steel, weathering steel will produce corrosion phenomenon on its surface under specific environment. But the difference is that the degree of alloy is relatively high, especially the addition of a variety of corrosion resistance elements such as phosphorus, chromium, nickel, etc., also has the characteristics of fatigue resistance and easy to extend of ordinary steel, and through the relevant data testing found that the weathering rust steel plate is nearly 2-8 times higher than ordinary carbon steel.

Because ordinary steel is rich in impurities such as copper and carbon, it will accelerate the corrosion of steel after meeting with the moisture in the air. In the process of rust, the physical structure of iron and steel is porous, and the cracks can realize the interconnectivity of the voids. That is to say, the rust of ordinary steel is equal to that of sponge, which is full of porous and can absorb the moisture in the air. So in the long-term action will further aggravate the corrosion phenomenon. But the difference between weatherproof rust steel plate and ordinary steel is that the internal lattice is more complex, although the surface is rich in rust but will produce special dense rust, can effectively inhibit corrosive anion through, in addition to the price is much higher than ordinary steel, so do not look at the surface rust, general buildings really can not afford to use.