抄録
The authors have previously investigated the sintering process and spheroidization of the pores of iron and ferrophosphorus mixed powder compacts. In this paper, the tensile and impact properties of Fe-P and Fe-P-C are investigated, and the correlation between the spherical pore and the properties is discussed.
Addition of finer ferrophosphorus powder improves the tensile properties; particularly ductility increases with sintering above eutectic temperature (1050°C) as a result of appearance of small and spherical pores. On the other hand, the ductile-brittle transition curve appears more evidently with the ferrophosphorus additions, and the transition temperature increases with increase of phosphorus content. Though favourable combinations of strength and ductility can be attained with Fe-0.4 wt%P, the limiting concentration of phosphorus is 0.3 wt% in view of practical toughness. Addition of graphite to iron compacts containing low phosphorus content increases the strength, while it causes a drop of both ductility and toughness. However, the addition of graphite to that of high phosphorus content above 0.4 wt% improves somewhat the toughness as a result of grain refinement.
