Chemical problems talk about the harm of metal corrosion?

Corrosion has spread to all sectors of the national economy and brought huge economic losses to the national economy. Before 1950s, the definition of corrosion was limited to metal corrosion. Since 1950s, many authoritative corrosion scholars or research institutions tend to extend the definition of corrosion to all materials. But it usually refers to metal damage. Because metals and their alloys are still the most important structural materials, metal corrosion is still one of the most noticeable problems. The direct loss caused by corrosion to alloy materials is huge. According to statistics, about 1 100 million tons of metals are corroded and scrapped every year in the world, accounting for 20% ~ 40% of the annual output. Moreover, with the process of industrialization, the corrosion problem is becoming more and more serious. The corrosion consumption in the United States (material consumption and corrosion) 1949 is $5 billion, 1975 is $70 billion, and 1985 is168 billion, which is more than 80 times higher than 1949. It is estimated that the annual steel equipment scrapped due to corrosion in the world is equivalent to 30% of the annual output. Obviously, the damage of metal components is far greater than the value of metal materials; The annual economic losses caused by corrosion in developed countries account for about 2-4% of the gross national product; The United States consumes 3.4% more energy every year because of corrosion; The economic loss caused by corrosion in China is at least 20 billion every year. The great harm of corrosion is not only reflected in economic losses, but also brings great casualties, environmental pollution and waste of resources, which hinders the development of new technologies and promotes the loss of natural resources.