Scrap steel refers to iron and steel waste (such as trimming, cutting head, etc. ) Steel in equipment and parts that do not become products in the production process of iron and steel plants and are scrapped after use. The composition of steel is called scrap steel; The composition of pig iron is called scrap iron, collectively referred to as scrap steel.

At present, the total amount of scrap steel produced in the world every year is 300-400 million tons, accounting for 45-50% of the total steel output, of which 85-90% is used as raw materials for steelmaking, and 10- 15% is used for casting, ironmaking and recycled steel.

Scrap steel produced in the production process of iron and steel works is called "returned scrap steel", "self-produced scrap steel" or "recovered scrap steel". Its carbon content is generally less than 2.0%, and its sulfur and phosphorus content does not exceed 0.05%. Scrap steel exists in various forms due to different conditions, and its performance is basically the same as that of finished products, but it is also affected by factors such as aging effectiveness and fatigue, and its performance is reduced. Scrap steel produced by ordinary steel mills accounts for about15 ~ 25% of steel output; 30-50% of special steel mills.