Dynamic compressive behavior of additively manufactured 17-4 PH stainless steel

Abstract

This work focuses on additively manufactured 17-4 PH stainless steel and establishing a correlation between microstructure/printing speed to the dynamic response. Two different methods of additive manufacturing namely Laser Powder Bed Fusion (L-PBF) and Fused Filament Fabrication (FFF) have been employed. The study on L-PBF samples focuses on the role of heat treatment on their dynamic response. Printed samples are subjected to different heat treatment conditions and then to dynamic compression test through the Kolsky compression bar. These samples are examined under electron backscattering diffraction (EBSD) to analyze the texture of specimens before and after impact with and without heat treatment. Additionally, Johnson-Cook (J-C) model is fit to the stress-strain curve to extract their respective plasticity constants. The influence of heat treatment on these material constants during dynamic compression tests is also analyzed. FFF methodology focuses on the influence of printing parameters on the dynamic response. Porosity is an inherent feature during manufacturing. The porosity of the fabricated specimen is examined through X-Ray Computed Tomography (X-Ray CT) and a correlation between porosity and printing speed is established. To observe the effects of printing speed and strain rate on stress-strain response and microstructure, printed specimens are subjected to quasi-static compression and dynamic compression tests through the Kolsky compression bar. The influence of printing parameters, and strain rate on these material constants during dynamic compression test is also analyzed.