Abstract
High performance sintered 4600 steels were obtained by Metal Injection Molding (MIM) process in our previous study. This was due to the fine heterogeneous structure which were consisted of bainite, martensite and retained austenite by the segregation of Ni added as alloying element. This study has been performed to confirm whether the effect of heterogeneous structure upon the steel strengthening in other steels. With respect to the mechanical properties, not only static tensile test but also dynamic impact test were performed by using prealloyed and elemental 4100 powders.
For both specimens of prealloyed and elemental powders, the final carbon content was widely controlled by adjusting the debinding atmosphere, and the similar densities were also obtained by adjusting the sintering conditions. Sintered microstructures of prealloyed powder specimens were dual homogeneous structures consisted of ferrite and fine pearlite. On the other hand, heterogeneous structure of bainite and martensite appeared in the elemental powder specimens. Both sintered specimens showed almost the same ductility and toughness, but the strength of elemental powder specimens were higher than that of prealloyed powder specimens because of the heterogeneous structure with high strength bainite and martensite. However, the difference of strength between the both powder specimens were diminished with an increase in tempering temperature through the homogenization in the structures.
