Ni-Mo-Cu alloyed steel powder suitable for sinter-hardening process

摘要

A new hybrid type alloyed steel powder has been developed to produce sintered compacts with high strength and hardness without secondary heat-treatment process after sintering. The new alloyed steel powder is 2mass% Ni-1mass% Mo prealloyed steel powder admixed with nickel, copper and graphite powders. The sintered compact made of the new powder gave a tensile strength of over 950 MPa and a hardness of over 35HRC at a sintering temperature of 1130°C and a cooling rate of 30°C/min. As the cooling rate increases, the fraction of martensite in the microstructure of the sintered compact also increases, resulting in improved tensile strength and hardness. The martensite content of 50 to 70 % is suitable for attaining high performance in sintered compacts.