Effect of Flux Addition on Enhancement of Sintering in Stainles Steel Powder Compacts.

The sintering of stainless steel powder (-100 mesh water-atomized SUS316L powder ) compacts by use of fluxing has been tried. As a result, it was found that the sintering was activated noticeably by the addition of a small amount of flux. A sintered density of 94.5% was achieved with a 2mass% of Na2B4O7 as the flux for a compact having a green density of 77.2% by sintering it at 1620K for 60min in vacuum. Without the flux, a compact sintered in the same conditions had a density of 85.4%. We think the enhancement of the sintering is associated with the removal of oxide from the surface of the steel particle and the liquid phase sintering following the formation of a Fe-Cr-B eutectic liquid. The flux became a slag including SiO2, MnO and Na2O in the spherical pores during sintering.