Abstract
The influence of powder types on the properties of sintered bodies was investigated on iron powders. Four types of iron powders, i.e., reduced-, atomized-, electrolytic-, and carbonyl iron powder, were used.
The relationship between mechanical properties and the porosity was obtained. In the high density region, the observed data fit the exponential relation expressed by the form,
S=S 0exp(-bP)
where S is the tensile strength (or hardness), S 0, that of bulk material, P, the porosity, and b, an empirical constant. In the low density region, however, the observed data did not fit the exponential relation, but increased abruptly as it was calculated by Knudsen. The appreciable difference of the strength among the powder types was observed in the whole region. The value of b in the above expression determined in this experiment, regarding as it is independent of temperature, ranged from 3.7 to 4.5. The effect of the grain size on the tensile strength of sintered body was also studied for the carbonyl iron powder. An equation representing the tensile strength of sintered carbonyl iron powder was determined as follows,
S=27.0G-12exp(-3.7P)[kg/mm2]
where S is the tensile strength in kg/mm2, G, the grain size in mm, and P, the porosity.
