一部分。估計更多的是生產中產生的邊角廢料，原料利用率的高低看工藝水平。

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).