Abstract
It has been known B is the most effective sintering enhancer for stainless steel powders. But at the same time, a considerable grain growth was often seen in the sintered compacts containing B. In order to obtain the sintered compacts with high densities and fine-grain structures, 0.2-1.4 mass%Al2O3 fine powders were mixed with SUS316L water atomized steel powder, in addition to 0.4 mass% B powders. These mixed powders were compacted and sintered in H2 atmosphere at 1232-1252°C for 1 hr.
It was shown that the SUS316L steel powder compacts were much more densified during sintering when Al2O3 fine powders were added together with B powders, compared with when B powders alone were added. It was considered Al2O3 fine powders prevented the formation of isolated large pores which tended to emerge during sintering of SUS316L steel powders containing only B powders, and resulted in the high densification. It was also shown that the tensile strengths of the sintered compacts were fairly improved by the addition of Al2O3 fine powders because of its function making the grains finer. The reduction of the elongation causing by the addition of Al2O3 fine powders was in allowable ranges.
