1989 年 38 巻 430 号 p. 771-776
The injection moulding for sintered products has recently attracted a great deal of interest because the moulding method has a relative freedom to shape intricate geometries. The purpose of this investigation was to clarify the effects of Mn/Si ratio and sintering temperature on the mechanical properties of sintered stainless steel. The materials used were two kinds of stainless steel powder having an approximately equal particle size and a similar chemical composition except Mn.
The results obtained are as follows;
(1) The tensile strength of the sintered stainless steels was 540MPa regardless of the Mn/Si ratio and was almost equivalent to that of the conventional SUS304. In addition, it was found that the logarithm of the tensile strength was proportional to the volume fraction of pores.
(2) The fatigue limit of the specimen having a relatively low Mn/Si ratio was 328MPa, while the specimen having a high Mn/Si ratio exhibited a significantly low fatigue limit, that is, 265MPa.
(3) It became clear from these results that the fatigue properties varied considerably with the Mn/Si ratio. The ratio affected the volume fraction, the composition and the shape of the oxides. The high Mn/Si ratio seemed to produce sharp pores from which the fatigue cracks initiated easily.