Mechanical properties of the pre-mixed adamite P/M steel have been investigated in comparison with the conventional adamite steel (1.7%C-1.2%Cr). High chromium iron powder was mixed with adamite steel powder containing 1.7%C-1.2%Cr and then hot-isostatically pressed to a full density. During hot isostatic pressing, high chromium iron powder containing 3.5%C-14%Cr changed into massive carbides whose size were almost the same as that of powder particles.
Mechanical properties of the pre-mixed adamite P/M steel are as follows: The bend strength, tensile properties, fire cracking properties and fracture toughness of the pre-mixed adamite P/M steel with an optimum mixing ratio of 6% were found to be superior to those of conventional adamite steel. It should be noted that fracture toughness and fire cracking properties are improved by the addition of high chromium iron powder. These phenomena were interpreted by the branching of the cracks with the added powder.