Precipitation and evolution behaviors of grain boundary α and α side plates for ultra-high strength titanium alloy during continuous cooling

•The λ value is put forward to quantitatively evaluate morphology of αGB.•Crystal orientation of αGB is influenced by the BOR of βBOR and s-BOR of βnBOR.•The s-BOR is defined in this work to represent the effect of βnBOR on αGB.•Orientation of αSP is influenced by both αGB and parent β phase.