Development of Molybdenum Hybrid-Alloyed Steel Powder for High Fatigue Strength Sintered Parts

Abstract

A new molybdenum hybrid-alloyed steel powder has been developed. This powder gives sintered parts with improved fatigue strength by a conventional belt furnace sintering. The powder is based on a molybdenum prealloyed steel powder to which molybdenum powder particles have been diffusion bonded. The sintered compact made of the developed powder has a finer pore structure than that of the conventional molybdenum prealloyed steel powder, because the ferritic iron phase (α-iron phase) with a high diffusion coefficient is formed in the sintering necks where molybdenum is concentrated resulting in enhanced sintering.
This developed powder has already been applied as a raw material of a high strength part for automotive engines with advantages of sintering cost, productivity improvement and enhanced flexibility in manufacturing process. This powder also gives an advantage over the conventional diffusion-alloyed steel powder in terms of raw material cost reduction.