Grain growth and texture evolution in electroformed copper liners of shaped charges

Electron backscattered Kikuchi patterns (EBSP) and optical microscopy (OM) have been employed to reveal grain growth and texture evolution in electroformed copper liners of shaped charges with ultrafine grains and a strong 〈1 1 0〉 fiber texture, which were annealed at various temperatures. By annealing below 410 °C, the grains grow uniformly and show a normal growth. By annealing at 530 °C, a different growth mode has been observed. The grains grow non-uniformly by the growth of a few grains and numerous annealing twins were observed in the samples. Up to 650 °C annealing, extensive abnormal grain growth appears in the sample. EBSP analysis shows that the 〈1 1 0〉 fiber texture, which exists originally in the as-electroformed copper sample, was weakened and tended to disappear during grain growth with increasing annealing temperature over 410 °C. Meanwhile, the changes of grain boundary misorientations in specimens subjected to higher annealing temperature (530 °C and 650 °C) suggest that a progressive weakening of the 〈1 1 0〉 fiber texture results in decreasing in the fraction of low-angle boundaries. Possible recrystallization mechanism in electroformed copper liners of shaped charges is discussed.