"Scrap iron" is a noun that refers to pieces of iron that are no longer useful in their current form and are often collected to be melted down and made into new products. It is essentially old or discarded iron.
You can use "scrap iron" when talking about recycling, metalworking, or when discussing materials that can be reused. It is often used in contexts related to construction, manufacturing, or environmental discussions.
In more advanced contexts, you might discuss the economic implications of scrap iron, such as its value in the recycling industry or its impact on the environment.
While "scrap iron" specifically refers to iron, "scrap" on its own can refer to any waste material.
There are no specific idioms or phrasal verbs that directly involve "scrap iron," but you could encounter phrases like "scrap it" which means to discard or abandon an idea or project.
In summary, "scrap iron" refers to discarded iron that can be melted down and reused.