The effect of β grain coarsening on variant selection and texture evolution in a near-β Ti alloy

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:576

Article

Obasi, G.¹  da Fonseca, J. Quinta¹  Rugg, D.²  Preuss, M.¹ 

[1] Univ Manchester, Manchester Mat Sci Ctr, Manchester M13 9PL, Lancs, England

[2] Rolls Royce Plc, Derby DE24 8BJ, England

关键词: Near-beta Ti alloy;    Texture evolution;    Variant selection;   

DOI  :  10.1016/j.msea.2013.04.018

来源: Elsevier

【 摘 要 】

In the present study, the role of beta grain coarsening on alpha variant selection has been investigated in the near-titanium alloy Ti-21S (Ti-15Mo-3Nb-3Al-0.21Si). The material was first thermomechanically processed in a fully beta stabilised condition in order to obtain a fine beta grain size before undertaking controlled beta grain-coarsening heat treatments. Two different cooling regimes ensured that either all beta was retained at room temperature or significant alpha formation was achieved during cooling with predominant nucleation from beta grain boundaries. Detailed electron backscatter diffraction (EBSD) characterisation was carried out on the beta quenched and slowly cooled samples in order to compare the predicted alpha texture based on the beta texture measurements assuming no variant selection with the measured alpha textures. A strong correlation was found between beta coarsening and level of variant selection. It was also found that the grain coarsening is driven by the predominant growth of low energy grain boundaries, which strengthen specific beta texture components that are part of the (1 1 1)parallel to ND gamma fibre. Finally, it was possible to demonstrate that the strengthened beta texture components promote beta grain pairs with a common (110), which is known to enhance variant selection when alpha nucleates from beta grain boundaries. (C) 2013 The Authors. Published by Elsevier B.V. All rights reserved.

【 授权许可】

Free