| 摘要 |
<p>1,190,321. Heat-treating cast iron. BRITISH FURNACES Ltd. Jan.29, 1968 [Feb. 6, 1967], No.4516/68. Heading C7A. Ferritic malleable iron is produced from white cast iron containing 2-3% C. and 0À8-1À7% Si by isothermally annealing the cast iron, first at 1700-1750‹ F. for sufficiently long to complete first stage graphitization, then at 1275-1325‹ F. for sufficiently long to partially complete second stage graphitization, and finally at 1225-1275‹ F. for sufficiently long to complete second stage graphitization. Prior processes involve cooling from the first anneal, first rapidly to 1400‹ F., then slowly to 1200‹ F. An example of cast iron castings is specified containing 2À5% C., 1À45% Si, 0À36% Mn, 0À16% S., 0À002% B., 0À02% Cr and 0À005% Bi.</p> |
