Synchrotron X-ray diffraction for carbide evolution during tempering of laser powder bed fusion tool steel

In pursuit of enhancing the mechanical properties of laser powder bed fusion (L-PBF)-produced hot work tool steels, this study investigates the evolution of carbides from the as-built state to the quenched and tempered conditions of a modified H13 steel. The heat treatment involved austenitization and quenching, followed by tempering at two temperatures: 600 °C and 625 °C. To monitor microstructural changes over time, tempering durations of 10, 20, 40, 80, 120, 130, 140, 160, 200, and 240 min were applied at both temperatures. Subsequently, the samples underwent synchrotron radiation analysis, scanning electron microscopy (SEM), and hardness testing. The results revealed notable variations in carbide fractions, martensite tetragonality, and micro-strain depending on tempering time and temperature. Synchrotron X-ray diffraction (XRD) is shown to effectively track carbide evolution in L-PBF tool steels which provides guidance for optimizing post-process heat treatment.