Microstructural characterisation of metallic shot peened and laser shock peened Ti–6Al–4V

Microstructure characteristics and formation mechanism of TC17 titanium alloy induced by laser shock processing

“…Seen from the TEM images at different depths, twins were prevalent at deeper layers where the strains and strain rates were lower than that of near top surface because the shock wave attenuated gradually when propagating into the TC17 titanium alloy during the process of LSP, and the occurrence of twinning can coordinate the plastic deformation of TC17 titanium alloy [30]. There were few deformation twins closer to the top surface where the strain rates were ultrahigh (10 7 s À1 ), which was the same with experimental results of literatures [17,31], and it can be deduced that there is an upper limit on strain rate for occurrence of deformation twins because the atoms participated twinning need certain time to reposition [17]. According to the TEM observation results, the equiaxed grains at submicron level in the top surface of LSPed TC17 titanium alloy had characteristics of dynamic recrystallization.…”

“…There are limited investigations of microstructural characteristics of titanium alloys treated by LSP. Lain e [17] compared the different dislocation structures in Ti-6Al-4V titanium alloy treated by metallic SP and LSP, and explained the reason for few deformation twins appeared in LSP was the ultrahigh strain rate which limited the deformation time that was too short for the formation of deformation twins; Ren [18] investigated the evolution of microstructure in Ti-6Al-4V titanium alloy treated by LSP and concluded that the multidirectional twin intersections and division of subgrain boundaries led to the grain refinement; Zhou [19] found nanocrystalline grains with size of 30e60 nm in the surface of TC17 titanium alloy after LSP with 3 impacts, and the dislocation activities were the main reason of the grain refinement; Qiao [20] got refined grains which was half of the original in surface of Ti17 titanium alloy after 3 impacts LSP and the grains could be further refined with more impact times. Most of the investigations of microstructural characteristics of titanium alloys treated by LSP were limited to the treated top surface, while there are few studies on the evolution of microstructures at different depths, and the grain refinement mechanisms with no evidence of quantitative analysis of recrystallization kinetics in top surface were inconsistent with each other.…”

Processing of Beta Titanium Alloys for Aerospace and Biomedical Applications

“…Since 1970s, shot peening is being employed in enhancing the mechanical behaviour of Ti alloys in aerospace industries [24]. Schematic representation of shot peening is shown in the Figure 2.…”

Influence of Nanocrystalline Structure on Wear and Corrosion Behavior of Al-SiC<sub>P</sub> Composite

“…The shot media used in this work are cast steel (S-230) according to standard SAE-AMS-2431/1 [23]. The diameter of shots used in this work ranging from 0.45 to 0.6 mm and having hardness 45 -52 HRC [24]. The other SP parameters selected in this work such as air pressure, nozzle distance, and impact angle are similar to the earlier work [25].…”