Recrystallization suppression and electrochemical corrosion behavior enhancement in DD6 superalloy via warm laser shock peening

Under high-temperature operating circumstances, the single-crystal turbine blades of gas turbines and aero engines are at risk of electrochemical corrosion and high-temperature recrystallization, and this paper is aimed at the study of this issue. Warm laser shock peening (WLSP) and laser shock peening (LSP), two surface modifications for DD6 single-crystal superalloy surface strengthening, were compared in the study. The material's near-surface was coated with a compressive residual stress (CRS) layer, which destroyed the high-temperature recrystallization nucleation sites of the alloy, increased the activation energy gap of the recrystallization, and prevented the DD6 superalloy from recrystallizing at high temperatures. The WLSP sample was not nucleated near the surface after holding at 1050°C for 2 h, with only localized grain orientation shifts. Because of the high-density dislocations' pipe diffusion effect, the alloy's surface forms a protective oxide coating faster during electrochemical corrosion behavior, which stops the electrolyte from corroding the substrate. The CRS layer enhances the adhesion between the substrate and the protective oxide film. The CRS thermal release rate on the surface of the WLSP sample being 19.10 % and that of the LSP sample being 32.93 %. Electrochemical corrosion resistance is improved in the DD6 single-crystal superalloy by combining high-density dislocations with the CRS layer.