| 摘要 |
1,259,550. Sintered chromium steel. SUMITOMO ELECTRIC INDUSTRIES Ltd. Dec. 15, 1969 [Dec. 13, 1968; March 12, 1969 and Nov. 4, 1969], No.61086/69. Headings C7A and C7D. A sintered Cr steel having a sintered density >6À8 g/cc. is made by sintering a powder mixture of sigma Fe-Cr having an average particle size < 20 microns with C and Fe. The sigma Fe-Cr is formed by annealing an Fe-Cr alloy containing 40-60% Cr at 600-800‹ C. The sigma Fe Cr may be ground to the required size during simultaneous mixing with the Fe and C powders. Alloying additions of Ni, Mo, Nb, Si, W, Al, Ti, Cu, Mn and V may also be made. Sufficient Fe-Cr is added to give a Cr content of 0À5-30%, preferably 0À5-20% in the sintered steel. The C content is 0À1-2À5%. The pressed compacts are preferably sintered at 1250-1300‹C. in H2 and the sintered steel may be cold or hot forged. The following steels are specified: Fe-5Cr-0À5C; Fe-5Cr-1C; Fe-2Cr-1À5C; Fe-8Cr-0À5C; Fe-4Cr-0À8C-18W-1V; Fe-4Cr-1C-6W-5M 0 -2V. |
