Fig. 1 Inverse pole figure a and {0001}{0001} and {10\(\overline{1}\)0}{10\(\overline{1}\)0} pole figures b of recrystallized Ti sample

Fig. 2 Optical microscope images of laser-treated surfaces for specimen 1 a, specimen 2 b specimen 3 c

Fig. 3 Electron channeling contrast showing microstructural characteristics of cross-sectional views of specimen 1 a, b, specimen 2 c, d and specimen 3 e, f with three distinctly different zones including zone I (melting zone), zone II (heat-affected zone) and zone III (base metal) a, c, e α martensitic plates in zone I b, d columnar grains in zone I f

Fig. 4 All Euler angle map superposed by a band contrast map showing bowl-like profiles in laser-modified Ti samples for specimen 1 a, specimen 2 b specimen 3 c

Fig. 5 EBSD maps of specimen 1 showing three zone, including melting zone (MZ), heat-affected zone (HAZ) and base metal (BM) which are separated by two broken lines a and grain boundary map showing special boundaries with Burgers misorientation (marked by different colored lines) b

Fig. 6 EBSD maps showing microstructure characteristics for specimen 2: a zones I and II; b zones II and III; c GB map for zone I; d GB map for zone II; e GB map for zone III; f-g rotation axis distributions around Burgers misorientation of 8°-13°, 57°-66° and 87°-90° for zone I, zone II and zone III, respectively

Fig. 7 EBSD maps showing microstructure characteristics for specimen 3: a three different zones; b GB map for zone I; c GB map for zone II; d GB map for zone III

Fig. 8 Micro-hardness variations along depth from surface including MZ, HAZ and BM for specimen 1 a, specimen 2 b specimen 3 c The lowest hardness value is always located in zone II, which is determined to be generally softer than the substrate. This may be ascribed to the very heterogeneous grain structures in zone II, where the coarsening grains are found to exist extensively. These coarsening grains in zone II would contribute less to the hardness than that in the substrate. Although there are some LABs and α boundary inside these un-completed grains, the overall impediment to dislocation motion provided by them remains relatively weak. Thus, the hardness in zone II is even lower than the hardness in BM (Fig. 8).