Corrosion can lead to the loss in purity of the metal. Some important properties of the metal might also be lost due to corrosion. For example, the sturdiness of iron is lost when it undergoes rusting and the rusted iron crumbles easily. When a metal structure undergoes corrosion, it loses its strength and the tendency to undergo structural collapse increases.
The appearance of the metal is also compromised as it loses its lustre. If measures for the prevention of corrosion are not taken, the corrosive attacks on the metal can greatly increase the cost of maintenance of the structure. Corrosion can also prove dangerous to humans. A good example would be the cuts that pierce the skin from rusted iron leading to tetanus.