| 摘要 |
<p>1311156 Adding lead to molten steel J J A ORMAECHEA 28 May 1970 [3 Feb 1970 25745/70 Heading C7D A machinable Pb-bearing steel is made by adding solid or liquid Pb to a stream of molten steel directly after it leaves a melting furnace during discharge to a ladle, preferably at a temperature more than 1600‹C. The Pb reacts with O 2 in the steel to form PbO 2 which precipitates as a fine homogeneous dispersion as the temperature drops below 1600‹C. in the ladle. Preferably the steel is allowed to stand in the ladle for at least 5 minutes, then Al killed, before it is poured or tapped into a mould. The quantity of Pb added is preferably 40% greater than that desired to incorporate, e.g. 0À1-0À8% homogeneously distributed, in the steel.</p> |
