Low-alloyed Mo-steel powders for high performance PM applications - Ray Guo, Quebec Metal Powders (Suzhou) Co. Ltd., China

A large number of PM applications require sintered components capable of withstanding high operational static and dynamic stresses.  High sintered density is one of the key parameters to enhance dynamic properties together with appropriate microstructure. Low alloy Mo-steel powders present interesting attributes since the alloying element only slightly affects powder compressibility and but is very efficient in increasing hardenability and hence mechanical properties.  Furthermore, key elements such as Ni and Cu admixed to the Mo-steel powder or diffusion bonded to the steel particles during the annealing treatment also improve mechanical properties through modification of the microstructure. This paper illustrates the tensile and dynamic properties of steel powders containing various levels of pre-alloyed molybdenum.  The effects of either admixing or diffusion bounding Ni and Cu to these Mo-steels are also discussed particularly with respect to axial fatigue properties and strength.  Comparison with results obtained with other types of fatigue specimens and/or testing methods is also presented. These low alloyed Mo-steel powders have been widely used for high performance PM structural parts.