Oxygen Removal during Sintering of Steels Prepared from Cr-Mo and Mo Prealloyed Powders
The removal of oxygen during sintering by carbothermic reduction and the resulting carbon loss were studied for steel compacts prepared with the compositions Fe-3%Cr-0.5%Mo- 0.5%C and Fe-1.5%Mo-0.5%C, respectively, prepared from prealloyed powders. The compacts were prepared by pressing at 600 and 1000 MPa, and sintering was done at 1100 and 1300°C in vacuum. It showed that for the Cr-Mo steel, deoxidation strongly depends on the sintering temperature, in contrast to the plain Mo steel; at 1300°C very low oxygen levels were measured with the standard density compact while after pressing at 1000 MPa, still significant oxygen is contained, which is in agreement with the lower carbon loss measured. This indicates inhibition of final deoxidation by pore closure; nevertheless, the impact energy was very high and exceeded that of the Mo alloyed steels, indicating that finely dispersed oxides within the matrix are irrelevant if only the surface oxides have been completely removed.
Duk Yong Yoon, Suk-Joong L. Kang, Kwang Yong Eun and Yong-Seog Kim
H. Danninger et al., "Oxygen Removal during Sintering of Steels Prepared from Cr-Mo and Mo Prealloyed Powders", Materials Science Forum, Vols. 534-536, pp. 577-580, 2007