燒結鐵의 硬度 및 組織에 미치는 密度의 영향에 관한 硏究 = Effect of Density on Hardness and Microstructres of Ferrous Sintered Alloys

다국어 초록 (Multilingual Abstract)

This study has been investigated into the change of hardness and microstrure as a function of density for ferrous sintered alloys.
The specimens were prepared from Sweden Ho¨gana¨s atomized iron powder(ASC 100.29) and partially prealloyed powder (Distaloy AB) with 1.75% Ni, 1.5% Cu, and 0.3% Mo based on the same iron powder which is typically used in P/M parts production was blended with 0.2% grephite powder, and then compacted, sintered and carburized.
The results obtained from the experiment are summarized as follows;
1. The green density increased with the increase of compacting pressure, and the compressibility decreased with adding alloy composition.
2. The true hardness was higher than the apparent hardness in the ferrous sintered metals. And the difference between apparent and true hardness values decreased with decreasing porosity or adding
3. The difference between the apparent hardness values of different sections was reduced with decreasing porosity, adding alloy composition or being longer carburization times.
4. The apparent hardness values after gas carburizing treatment were highly dependent upon the density and carburization depth.
5. After gas carburizing treatment the hardness values both on the surface and in the core were increased as the porosity decrease. In a certain intermediation zone, however the hardness values of the low density was higher than those of the high density.
6. The average grain size was larger with decreasing porosity, and the homogeneous microstructure could be obtained with decreasing porosity.