一部分。估计更多的是生产中产生的边角废料，原料利用率的高低看工艺水平。

Recycled steel in the USA comes from three main sources: home scrap (waste from within steel mills), prompt (industrial) scrap (excess material from manufacturing, like cars and appliances), and obsolete scrap (end-of-life products and structures like old cars, buildings, and appliances).