Fatigue characterization of 3D-printed maraging steel by infrared thermography

Abstract

Fatigue performances of additively manufactured metals are affected by the high temperature gradients and high cooling rates occurring during laser beam melting. More generally, mechanical properties strongly depend on the process parameters (scan speed, laser power, laser spot size, etc.). The present study proposes a calorific analysis of the fatigue response of 3D-printed maraging steel from thermal measurements obtained by infrared (IR) thermography. Fatigue damage is indeed associated with heat production leading to material self-heating. Analysis of the thermomechanical response was performed in two steps: first, measurement of temperature maps on the specimen surface by IR camera; second, calculation of the calorific origin of the temperature changes by image processing based on the heat diffusion equation. Using specific thermal data acquisition conditions, the processing enabled us to extract the heat power density corresponding to the mechanical dissipation caused by fatigue. The study was performed on specimens featuring a specific geometry and printed with different process parameters. Distinguishing differences in the production of mechanical dissipation at the beginning of fatigue tests can be useful to determine relevant configurations for long-term fatigue durability.