| 摘要 |
Improved sintered alloy steel is produced by (1) mixing powdery stainless steel with a binder, moulding it and removing the binder by heating, (2) sintering the moulding under a reduced pressure of 30 Torr or less at 1000-1350 deg.C, and (3) resintering it in a non-oxidative atmos. eg. mixt. of inert gases contg. nitrogen, under normal pressure at a temp. higher than those of (1) and (2), 1250-1400 deg.C. The mean particulate size of the powdery stainless steel is 15 micro of less. When the binder is removed from the moulding by heating at (1), the C/O mole ratio of the moulding is adjusted to be 0.3-3.0. At (2) the C/O mole ratio is adjusted to 0.3-3.0. Pref. powdery stainless steel contains Cr (16-25 wt.%) and Ni (8-24 wt.%). Obtd. stainless alloy steel has the following properties: a stainless steel compsn., a density ratio of 92% or higher, max. radius of the pores in the organisation of 20 micro or less. The amt. of Cr in the surface of the sintered alloy steel is 80% or more of the amt. of Cr in the interior. |
