1977 年 48 巻 2 号 p. 132-136
As to water-atomized ferritic stainless steel powders containing 12/23% Cr and Mo less than 2%, the influence of Cr and Mo compositions on the corrosion resistance of the sintered steels was studied.
Results were summarized as follows.
(1) In 5% NaCl solution spray, sintered steels containing Cr more than 18% were almost free of rusting after 8hrs. The effect of Mo alloying on this test was not observed.
(2) The corrosion resistance of sintered steels in 5% H2SO4 solution was remarkably improved by Mo alloying. The corrosion rate of 18% Cr sintered steels containing 1% and 2% Mo was 1/5 and 1/10 respectively to the sintered steels without Mo.
(3) If the sulfuric corrosion rate of 18% Cr and 18% Cr-2% Mo sintered steels was compared with the annealed cast steel, logarithm of the corrosion rate of 18% Cr-2% Mo could be expressed as a linear equation of the sintered density, while in the case of 18% Cr the rate of fully dense sintered steel is bigger than that of annealed cast steel.
(4) In this solution, the dropping of powder particle from the surface of 18% Cr sintered steel was observed, while this phenomenon was not observed in 18% Cr-2% Mo sintered steel.
Therefore, Mo alloying remarkably improves the corrosion resistance of sintered ferritic stainless steels.