Microstructural characterization and mechanical property of GH4169 superalloy joints obtained by linear friction welding

Thermomechanical modelling for the linear friction welding process of Ni-based superalloy and verification

“…The black curve and scattered triangular symbols represent the profile of the grain size, and the green curve and scattered circular symbols represent the profile of the hardness of the weld according to Geng et al's experimental results. 32 The maximum temperature is observed at the interface as 1165:4 C and decreases to 550 C at a distance of 3.2 mm from the weld line. Similarly, the maximum value of microhardness (312 HV) is observed at the interface, which decreases to a minimum value of 283 HV at approximately 1.0 mm from the weld line.…”

“…Comparative axial shortening of the FE model against experimentally measured data for a total welding time of 5 s for setup J6. 44 results-such as temperature and stress-were correlated to the microstructure and mechanical properties of the weld joint that were characterised by Geng et al 32,33 based on using the LFW setup J6. IN-718 is a solid-solution strengthened superalloy.…”

“…44 By FEA calculated axial shortening in the current study, the total shortening length was approximately 5.9 mm. Geng et al 32 recommended that axial shortening must be greater than 4.8 mm to achieve a sound IN718 weld joint manufactured free of oxides at the interface. The FEA results of flash formation and axial shortening are pertinent because of their role in understanding the plastic deformation mechanism and the determination of optimal LFW process parameters.…”

“…Between 1.0 s and 5.0 s of welding time, for the computational modelling results, the temperature field on the flash shape has increased from 558.58 C to 1003.22 C. This is concurrently accompanied by increasing flash size and burn-off length up to 4.5 mm for the oscillating workpiece and 4.65 mm for the stationary workpiece. Because there is no temperature measurement scale presented in the referenced experimental LFW publication by Geng et al, 32,44 only the cooled macrostructure shape of flash is compared at 5.0 s of welding completion.…”

“…19,32,33,86 The major strengthening phase has been reported to be a metastable gamma double-prime ð 00 Þ phase, which usually precipitates at 550-900 C. 32,33,85 It can transform to the deleterious stable delta ðÞ phase that deteriorates mechanical properties. Figure 18 shows the qualitative comparison between the FE modelling result of temperature profile of the weld of this paper and Geng et al's 32 experimental results of the microhardness ðHVÞ and averaged-size of grains m ð Þ of the weld in the weldline friction interface zone (FIZ) and thermomechanically-affected zone (TMAZ). These results are based on setup J6 that utilises friction pressure ð p f Þ, oscillation amplitude ðA 0 Þ and oscillation frequency ð f 0 Þ of 400 MPa, 2.9 mm and 25 Hz, respectively.…”