Microstructure evolution of hot-rolled pure and doped tungsten under various rolling reductions

Abstract A batch of hot-rolled pure W and doped W sheets (mainly containing impurity atoms O, C, Mo) under 27%–90% rolling reduction were prepared, aiming to elucidate how rolling reduction and impurity elements influence the microstructure evolution. EBSD results revealed the three-stage evolution during hot rolling, including original grain smashing, recrystallization, and fibrous process. The intermediate recrystallization leads to a typical bimodal morphology in pure W (the necklace shaped grains sandwiched between abnormally recrystallized grains), which facilitates the formation of fiber structure at a larger strain. It is the necklace shaped grains that cause non-uniform stress and control the slip systems of //ND and //ND. The doped W sample exhibits a milder dynamic recrystallization behavior and a relative homogeneous recrystallized morphology, due to the drag effect of impurities on grain boundaries that inhibit abnormal grain growth during dynamic recrystallization. It is believed that this homogeneous recrystallized morphology of doped W causes the discontinuity of fiber structure and aggravates the generation of the transversal cracks.