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\;^∘ C → + + Fe₃ C, 3 50\;^∘ C → + + Fe₃ C, $$ 500\;^∘ {C} → + { M}₃ {C } + { M}₇ {C}₃ , 600\;^∘ {C} → + { M}₃ {C } + { M}₇ {C}₃ , $$ $$ 700\;^∘ {C} → {M}₃ {C } + { M}₇ {C}₃ . $$ Apart from higher mentioned carbides, there are also big primary carbides and fine secondary M7C3 carbides occurring, which did not dissolve during austenitizing.