Transformations of Carbides During Tempering of D3 Tool Steel

The studies were performed on D3 tool steel hardened after austenitizing at 1050 °C during 30 min and tempering at 200-700 °C. Based on the diffraction studies performed from the extraction replicas, using electron microscopy, it was found that after 120-min tempering in the consecutive temperatures, the following types of carbides occur: $$ 200\;^\circ {\text{C}} \to \upvarepsilon + \upchi + {\text{ Fe}} ₃ {\text{C}},\quad 3 50\;^\circ {\text{C}} \to \upvarepsilon + \upchi + {\text{ Fe}} ₃ {\text{C,}} $$ $$ 500\;^\circ {\text{C}} \to \upchi + {\text{ M}} ₃ {\text{C }} + {\text{ M}} ₇ {\text{C}} ₃ ,\quad 600\;^\circ {\text{C}} \to \upchi + {\text{ M}} ₃ {\text{C }} + {\text{ M}} ₇ {\text{C}} ₃ , $$ $$ 700\;^\circ {\text{C}} \to {\text{M}} ₃ {\text{C }} + {\text{ M}} ₇ {\text{C}} ₃ . $$ Apart from higher mentioned carbides, there are also big primary carbides and fine secondary M7C3 carbides occurring, which did not dissolve during austenitizing.