Executive Summary : | The proposed research is oriented towards adaptation of laser ultrasonic technique (LUT) for non- destructive evaluation of the structural integrity of laser powder bed fusion (LPBF) manufactured components made out of gas atomized powder titanium alloy powder. As LUT offers higher energy content and wider range of frequencies than conventional ultrasonic technology, outcomes of the proposed project are envisioned to have wider applicability in qualification of additive manufactured (AM) components. Metal AM technologies such as laser powder bed fusion and directed energy deposition intrinsically involve several challenges related to high thermal gradients, porosity, anisotropy and thermally induced residual stresses with consequential deleterious impact on density, strength and fatigue characteristics of the realised AM components. Typically, extensive microscopy is necessitated for qualification of AM parts. These qualification tasks are destructive and can only be scheduled in the downstream phase. Proposed laser ultrasonic technology is non-destructive, and it has the potential for both online / offline applications that accelerate the qualification process. The research content of the project comprises of – • Development of a process window for laser powder bed fusion (LPBF) of gas atomized powder of Ti-6Al-4V for maximization of the relative density • Development of calibration standard test blocks with reference markers for calibration of LUT results. • Qualitative and quantitative assessment of the defects using Rayleigh waves and longitudinal waves • To develop the synthetic aperture focusing technique (SAFT) for ensuring high lateral resolution of the ultrasound image and enhancing the sensitivity of B-scan or C-scan data. • To assess the applicability of the proposed method for non-destructive and non-contact inspection of hot isostatic processed LPBF parts. In the initial phase of the project, the NDT protocol for Ti-6Al-4V will be developed and in the ensuing phases the same will be extended for wide range of materials including super alloy IN718, steels such as SS316 etc. Hence the significance of the project is substantial for applications in multifarious contexts connected with aerospace, biomedical and energy applications. |