Steel Powder and Die-lubricated
Warm Compaction for Automotive Sintered Parts
with High Density and Excellent Fatigue Property
UNAMI Shigeru OZAKI Yukiko UENOSONO Satoshi
Abstract
JFE Steel has
developed a new powder metallurgical process
named die-lubricated warm compaction method
for producing high-density sintered parts
using premixed steel powder containing only
small amount of internal lubricant. In this
method, a newly developed spraying equipment
precisely controls the amount of lubricant
applied over the die wall. The sintered and
bright-quenched compacts were prepared by
this method using partially alloyed steel
powder, KIP SIGMALOY 415S, containing 4mass%
Ni, 1.5mass% Cu, and 0.5mass% Mo. They gave
a density as high as 7.5Mg/m³ and rotating
bending fatigue strengths of 450MPa and 470MPa
with carbon contents of 0.52mass% and 0.92mass%
respectively. The density and fatigue strength
were superior to those obtained by the conventional
double-pressing and double-sintering method.
Presumably, the fatigue strength was enhanced
by increasing the carbon content because the
amount of retained austenite was increased.
