Effect of initial grain size on the secondary grain growth in molybdenum sheet

Abstract

In order to understand in more detail the secondary recrystallization behaviour of rolled molybdenum sheet doped with CaO and MgO, the effect of initial grain size on the secondary grain growth behaviour was investigated using optical microscopy and X-ray diffraction. For the case where the initial grain size was smaller than 83 μm, a uniform and finegrained recrystallized structure was obtained after an anneal at 1500 or 1800°C, whilst an abnormal grain growth occurred after an anneal at 2000°C and a single crystal was obtained. In contrast, for the case where the initial grain size was larger than 150 μm, a partially recrystallized structure was obtained after an anneal at 1500°C, whilst normal and abnormal grain growth occurred concurrently and a duplex grain structure was obtained after an anneal at 1800 or 2000°C.