PSI - Issue 60

A.H.V. Pavan et al. / Procedia Structural Integrity 60 (2024) 277–285 A.H.V.Pavan/ StructuralIntegrity Procedia 00 (2024) 000 – 000

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Subsequent to grinding, polishing operation was performed on a polishing cloth by using 1 μ m polycrystalline diamond suspension. Final polishing using 0.05 μ m alumina suspension was also conducted. Microstructural features were revealed by etching this polished sample using Vilella’s reagent. Microstructural characterization studies were carried out using light optical microscopy on Leica DMI 5000M Inverted Metallurgical Microscope. Wherever fractography was essential for analysis, the same was carried out using Leica Z6 APO stereomicroscope and Carl Zeiss Supra 55 VP Field Emission Scanning Electron Microscope (FESEM). Sample preparation was carried out by subjecting the fractured surface to ultrasonic cleaning in ethanol for a duration of 15 minutes. Post cleaning, the samples were vacuum dried for 48 hours prior to fractographic studies. 3. Results 3.1. Microstructural Characterization Microstructure of the X5CrNiCuNb16-4 steel Blade Material (BM) comprises of tempered martensite consists of large laths relative to the laser processed region (L) which comprises of fine laths (as seen in Fig. 2). The transition region (T in Fig. 2) comprises of large lath colonies decorated with fine lath colonies around them. Precipitates are observed dominantly at the lath boundaries, however, they are also present within the laths in minor fractions.

Fig. 2. Cross-section microstructures of laser hardened blade at (L) Laser Hardened, (T) Transition and (BM) Unaffected blade material

3.2. Hardness Profiling Hardness profiles from suction side of the blade which is laser hardened at various distances from the leading edge is presented in Fig. 3. This indicates the beneficial effect of laser hardening upto ~ 2.75 mm as seen from