Journal of the Japan Society of Powder and Powder Metallurgy

Alloyed steel powders have been developed specifically for the production of high strength sintered parts. The alloyed steel powder designed for sinter-hardening enables the production of sintered parts with comparable strength and hardness to heat-treated materials, eliminating the need for post-sintering heat treatment. The molybdenum (Mo) hybrid alloyed steel powder results in sintered parts with enhanced fatigue strength, achieved through the formation of a fine pore structure and a reinforcement of the sintering neck through Mo concentration around the pores. On the other hand, the Ni-free alloyed steel powder achieves both high strength and excellent machinability by homogenizing the microstructure of the sintered parts. These developed alloyed steel powders have been successfully implemented as raw material powders for high strength sintered parts, leading to improved productivity and cost reduction in the production of sintered parts.

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Additive manufacturing (AM) technology has advantages in manufacturing free-shape parts and simplification of manufacturing process. In order to manufacture high quality parts, it is significant to investigate the influence of not only fabrication conditions but also powder characteristics on the properties of parts. In this study, the influences of powder characteristics on the density, microstructure and tensile properties of Al-10%Si-0.4%Mg alloy fabricated by laser powder bed fusion (PBF-LB/M) process were investigated using the virgin and recycled spherical powders and the virgin and recycled non-spherical powder. As a result, the density of the as-built specimen of spherical powder was higher than that of non-spherical powder. Moreover, the density of the as-built specimen of recycled spherical powder is almost equal to that of virgin spherical powder. On the other hand, the density of the as-built specimen of recycled non-spherical powder is lower than that of virgin non-spherical powder. The tensile properties of the as-built specimens of spherical powder were superior to those of non-spherical powder. Thus, it was revealed that high quality parts are able to be stably manufactured using spherical powder.

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