Abstract
The mixtures of Type 410 stainless steel powder and the binder were injected into dumbbell type tensile test bars, and the green compacts thus obtained were subjected to pre-sintering at 873 K for 7.2 ks in the vacuum with various degrees of 0.1, 4 and 133 Pa followed by sintering at 1623 K for 7.2 ks under Ar gas flowing in the same vacuum of 0.1, 4 and 133 Pa. The Type 410 specimens sintered in vacuum of 0.1, 4, and 133 Pa were designated as Specimen 1, 2 and 3, respectively. In addition, the Type 410 specimen pre-sintered at 873 K for 7.2 ks in H2 gas and sintered at 1623 K for 7.2 ks under Ar gas flowing in the same vacuum of 0.1 Pa was also prepared. It was referred to as Specimen 1 A. By using these four specimens mentioned above, the influence of sintering atmosphere on the corrosion behavior of the Type 410 stainless steel specimen prepared by MIM process was studied. The dissolution rate of Specimen 1 A is almost same as that of Specimen 1, while Specimen 2 and 3 showed 2.15 times and 4.31 times larger dissolution rate than Specimen 1. EIS test showed that the larger the sintering vacuum degree was applied, the more anodic reaction was accelerated and the less corrosion resistance was observed. Alternate wetting and drying test clarified that Specimen 1 A had the best corrosion resistance, while Specimen 3 had the worst, which agrees well with the results of polarization curve measurement and EIS test.
