Advantages: the blooms are rolled by the bloomer with large ingots, so its structure is relatively dense, there is no as cast structure stress, and it can be heated at a higher heating speed than the ingots; Because the blooms have been compressed

(1) The content of harmful elements phosphorus and sulfur shall be as low as possible; (2) The range of upper and lower limits of element content should be as small as possible, especially the content of carbon element;