Effects of rolling reduction on Burgers orientation relationship and slip behavior of a Ti–5.5Mo–7.2Al–4.5Zr–2.6Sn–2.1Cr alloy

Abstract

The important but highly complex α/β Burgers orientation relationship and slip behavior of a Ti–5.5Mo–7.2Al–4.5Zr–2.6Sn–2.1Cr titanium alloy plate were obtained and elaborated, which was subjected to hot rolling with 20%, 40%, and 60% reductions in thickness. The electron backscatter diffraction statistical results showed that the Burgers orientation relationship was strictly maintained in the initial microstructure and exhibited a slight deviation of ∼10° at 20% reduction. With the thickness reduction increasing to 40% and 60%, this classical relation between α- and β-Ti will be gradually broken. Furthermore, the low-angle grain boundaries fractions of the β phase were 94.95% and 92.77% at 20% and 40% reductions, respectively, indicating that the β phase had a significant contribution to the overall plastic deformation. For the α phase, the relative frequencies of the {0001}α and {101¯0}α slip systems were 32.81% and 44.43% at 20% reduction, respectively. Noticeably, under the applied loading of normal direction, the {0001}α slip system became more pronounced at 60% reduction (i.e., 59.01%) and, hence promoted a considerable strain partitioning in the α phase. In terms of typical α grains, an obvious intragranular misorientation diversity at 60% reduction was further traced, thereby reasonably leading to the Schmid factor gradient within grain interior and the breakdown of Burgers orientation relationship.

Keywords

• Titanium alloy
• Hot rolling
• Burgers orientation relationship
• Schmid factor