抄録
A study has been made on the effects of molybdenum content and carbon content on the transformation features of sintered Cr-Mo steels made from premixed powders. Metallic molybdenum, molybdenum carbide, or ferro-molybdenum powder was added to an atomized iron powder together with chromium carbide and graphite powders. The specimens having the chemical compositions of Fe-1%Cr-l%Mo-0.35%C and Fe-l%Cr-0.2%Mo-0.86%C were prepared, and the CCT diagrams, microstructures, and distribution of molybdenum of these specimens were compared with those of Fe-1%Cr-0.2%Mo-0.35%C specimens.
The results obtained are as follows:
(1) The microstructures of molybdenum segregated area in the specimens containing 1%Mo were similar to those of the specimens containing 0.2%Mo for each premixing method. On the other hand, the number of molybdenum segregated area per unit area was increased with increasing molybdenum content. The regions of bainite formation in CCT diagrams were, consequently extended to longer cooling time.
(2) The molybdenum content of the segregated area in the specimens containing 0.86%C was markedly decreased by liquid phase formation. The diffused area of molybdenum was extended by increasing carbon content, regardless of the premixing method.
