Chiang Mai Journal of Science

Copper can precipitate as f.c.c. e -Cu within various phases of steels including proeutectoid cementite. It is expected that copper precipitates may affect the properties of the cementite and this could be significant for a wide range of carbon steels, from mild steel to higher-carbon steels, within which cementite is a major microstructural constituent. The degree of any effect should depend on the precipitate distribution, which alters with heat treatment. Therefore, the number density and volume fraction of precipitates is important to the properties of copper-containing steels, and also for clarifying the mechanism of precipitation of copper within proeutectoid cementite. A method for measuring approximately the number density and the volume fraction of copper precipitates within proeutectoid allotriomorphic cementite in high-carbon copper-containing steels using transmission electron microscopy (TEM) is described. The correspondence of the results with the proposed mechanism of copper precipitation within proeutectoid allotriomorphic cementite is discussed, and the inaccuracy of the measurement is addressed.