| 摘要 |
An as-continuously cast beam blank comprising a web portion and a plurality of opposed flange precursor portions extending from opposite ends of the web portion, the web portion having an average thickness of no greater than about 3 inches, each of said flange precursor portions having an average thickness of no greater than about 3 inches, wherein the ratio of the average thickness of the flange precursor portions to the average thickness of the web portion preferably is between about 0.5:1 to about 2:1; a beam formed from that beam blank, and a method for casting a continuously-cast beam blank having those characteristics from a single molten metal stream open poured into a beam blank mold at a location in the mold within the mold portion which forms the web of the blank, proximate to one of the ends of the web portion, or, alternatively, from two separate, simultaneously poured molten metal streams, each of said streams being open poured into a beam blank mold at a location in the mold within the mold portion which forms the web of the blank, proximate to each of a respective one of the ends of the web portion; the resulting beam blank having a crystal grain structure of fine ferrite and pearlite, substantially free of acicular ferrite and grain boundary ferrite films. |
