Abstract
The decomposition rate of the carbides in Fe-C-Si alloy treated with calcium-silicon was measured at 600°, 700° and 800°C to learn the effects of calcium on the stability of the carbides.
It was observed that the decomposition rate of carbides in the alloys treated with calcium-silicon was considerably faster than that of the carbides in the alloys treated with silicon, in an equivalent amount of silicon. Namely, calcium lowered the stability of the carbide. However, in comparison with the stabilities of various carbides in the case of treated alloy, the decomposition rate of the primary cementite (crystalized along the Acm line) was the largest, that of pearlite cementite next to it, and that of ledebulite cementite the smallest. The decomposition rate of the carbides varied with the composition of the alloys, and was the largest at a little higher carbon content than the carbon saturated solubility of austenite. Treating with calcium-silicon, the decomposition rate of the carbides in steel was, moreover, in the same order as that of the carbides of low carbon cast iron, at a temperature between 700°C and A1.
